Wikia

Wikihack

Source:Vision.c

2,032pages on
this wiki
Talk0

Below is the full text to src/vision.c from NetHack 3.4.3. To link to a particular line, write [[vision.c#line123]], for example.

Top of file Edit

1.    /*	SCCS Id: @(#)vision.c	3.4	1999/02/18	*/
2.    /* Copyright (c) Dean Luick, with acknowledgements to Dave Cohrs, 1990.	*/
3.    /* NetHack may be freely redistributed.  See license for details.	*/
4.    
The NetHack General Public License applies to screenshots, source code and other content from NetHack.
5.    #include "hack.h"
6.    

Circles Edit

7.    /* Circles ==================================================================*/
8.    
9.    /*
10.    * These numbers are limit offsets for one quadrant of a circle of a given
11.    * radius (the first number of each line) from the source.  The number in
12.    * the comment is the element number (so pointers can be set up).  Each
13.    * "circle" has as many elements as its radius+1.  The radius is the number
14.    * of points away from the source that the limit exists.  The radius of the
15.    * offset on the same row as the source *is* included so we don't have to
16.    * make an extra check.  For example, a circle of radius 4 has offsets:
17.    *
18.    *				XXX	+2
19.    *				...X	+3
20.    *				....X	+4
21.    *				....X	+4
22.    *				@...X   +4
23.    *
24.    */
25.   char circle_data[] = {
26.   /*  0*/	 1, 1,
27.   /*  2*/	 2, 2, 1,
28.   /*  5*/	 3, 3, 2, 1,
29.   /*  9*/	 4, 4, 4, 3, 2,
30.   /* 14*/	 5, 5, 5, 4, 3, 2,
31.   /* 20*/	 6, 6, 6, 5, 5, 4, 2,
32.   /* 27*/	 7, 7, 7, 6, 6, 5, 4, 2,
33.   /* 35*/	 8, 8, 8, 7, 7, 6, 6, 4, 2,
34.   /* 44*/	 9, 9, 9, 9, 8, 8, 7, 6, 5, 3,
35.   /* 54*/	10,10,10,10, 9, 9, 8, 7, 6, 5, 3,
36.   /* 65*/	11,11,11,11,10,10, 9, 9, 8, 7, 5, 3,
37.   /* 77*/	12,12,12,12,11,11,10,10, 9, 8, 7, 5, 3,
38.   /* 90*/	13,13,13,13,12,12,12,11,10,10, 9, 7, 6, 3,
39.   /*104*/	14,14,14,14,13,13,13,12,12,11,10, 9, 8, 6, 3,
40.   /*119*/	15,15,15,15,14,14,14,13,13,12,11,10, 9, 8, 6, 3,
41.   /*135*/ 16 /* should be MAX_RADIUS+1; used to terminate range loops -dlc */
42.   };
43.   
44.   /*
45.    * These are the starting indexes into the circle_data[] array for a
46.    * circle of a given radius.
47.    */
48.   char circle_start[] = {
49.   /*  */	  0,	/* circles of radius zero are not used */
50.   /* 1*/    0,
51.   /* 2*/	  2,
52.   /* 3*/	  5,
53.   /* 4*/	  9,
54.   /* 5*/	 14,
55.   /* 6*/	 20,
56.   /* 7*/	 27,
57.   /* 8*/	 35,
58.   /* 9*/	 44,
59.   /*10*/	 54,
60.   /*11*/	 65,
61.   /*12*/	 77,
62.   /*13*/	 90,
63.   /*14*/	104,
64.   /*15*/	119,
65.   };
66.   
67.   

Vision (arbitrary line of sight) Edit

68.   /*===========================================================================*/
69.   /* Vision (arbitrary line of sight) =========================================*/
70.   
71.   /*------ global variables ------*/
72.   
73.   #if 0	/* (moved to decl.c) */
74.   /* True if we need to run a full vision recalculation. */
75.   boolean	vision_full_recalc = 0;
76.   
77.   /* Pointers to the current vision array. */
78.   char	**viz_array;
79.   #endif
80.   char	*viz_rmin, *viz_rmax;		/* current vision cs bounds */
81.   
82.   
83.   /*------ local variables ------*/
84.   
85.   
86.   static char could_see[2][ROWNO][COLNO];		/* vision work space */
87.   static char *cs_rows0[ROWNO], *cs_rows1[ROWNO];
88.   static char  cs_rmin0[ROWNO],  cs_rmax0[ROWNO];
89.   static char  cs_rmin1[ROWNO],  cs_rmax1[ROWNO];
90.   
91.   static char  viz_clear[ROWNO][COLNO];		/* vision clear/blocked map */
92.   static char *viz_clear_rows[ROWNO];
93.   
94.   static char  left_ptrs[ROWNO][COLNO];		/* LOS algorithm helpers */
95.   static char right_ptrs[ROWNO][COLNO];
96.   
97.   /* Forward declarations. */
98.   STATIC_DCL void FDECL(fill_point, (int,int));
99.   STATIC_DCL void FDECL(dig_point, (int,int));
100.  STATIC_DCL void NDECL(view_init);
101.  STATIC_DCL void FDECL(view_from,(int,int,char **,char *,char *,int,
102.  			     void (*)(int,int,genericptr_t),genericptr_t));
103.  STATIC_DCL void FDECL(get_unused_cs, (char ***,char **,char **));
104.  #ifdef REINCARNATION
105.  STATIC_DCL void FDECL(rogue_vision, (char **,char *,char *));
106.  #endif
107.  
108.  /* Macro definitions that I can't find anywhere. */
109.  #define sign(z) ((z) < 0 ? -1 : ((z) ? 1 : 0 ))
110.  #define v_abs(z)  ((z) < 0 ? -(z) : (z))	/* don't use abs -- it may exist */
111.  

vision_init Edit

112.  /*
113.   * vision_init()
114.   *
115.   * The one-time vision initialization routine.
116.   *
117.   * This must be called before mklev() is called in newgame() [allmain.c],
118.   * or before a game restore.   Else we die a horrible death.
119.   */
120.  void
121.  vision_init()
122.  {
123.      int i;
124.  
125.      /* Set up the pointers. */
126.      for (i = 0; i < ROWNO; i++) {
127.  	cs_rows0[i] = could_see[0][i];
128.  	cs_rows1[i] = could_see[1][i];
129.  	viz_clear_rows[i] = viz_clear[i];
130.      }
131.  
132.      /* Start out with cs0 as our current array */
133.      viz_array = cs_rows0;
134.      viz_rmin  = cs_rmin0;
135.      viz_rmax  = cs_rmax0;
136.  
137.      vision_full_recalc = 0;
138.      (void) memset((genericptr_t) could_see, 0, sizeof(could_see));
139.  
140.      /* Initialize the vision algorithm (currently C or D). */
141.      view_init();
142.  
143.  #ifdef VISION_TABLES
144.      /* Note:  this initializer doesn't do anything except guarantee that
145.  	      we're linked properly.
146.      */
147.      vis_tab_init();
148.  #endif
149.  }
150.  

does_block Edit

151.  /*
152.   * does_block()
153.   *
154.   * Returns true if the level feature, object, or monster at (x,y) blocks
155.   * sight.
156.   */
157.  int
158.  does_block(x,y,lev)
159.      int x, y;
160.      register struct rm    *lev;
161.  {
162.      struct obj   *obj;
163.      struct monst *mon;
164.  
165.      /* Features that block . . */
166.      if (IS_ROCK(lev->typ) || lev->typ == TREE || (IS_DOOR(lev->typ) &&
167.  			    (lev->doormask & (D_CLOSED|D_LOCKED|D_TRAPPED) )))
168.  	return 1;
169.  
170.      if (lev->typ == CLOUD || lev->typ == WATER ||
171.  			(lev->typ == MOAT && Underwater))
172.  	return 1;
173.  
174.      /* Boulders block light. */
175.      for (obj = level.objects[x][y]; obj; obj = obj->nexthere)
176.  	if (obj->otyp == BOULDER) return 1;
177.  
178.      /* Mimics mimicing a door or boulder block light. */
179.      if ((mon = m_at(x,y)) && (!mon->minvis || See_invisible) &&
180.  	  ((mon->m_ap_type == M_AP_FURNITURE &&
181.  	  (mon->mappearance == S_hcdoor || mon->mappearance == S_vcdoor)) ||
182.  	  (mon->m_ap_type == M_AP_OBJECT && mon->mappearance == BOULDER)))
183.  	return 1;
184.  
185.      return 0;
186.  }
187.  

vision_reset Edit

188.  /*
189.   * vision_reset()
190.   *
191.   * This must be called *after* the levl[][] structure is set with the new
192.   * level and the level monsters and objects are in place.
193.   */
194.  void
195.  vision_reset()
196.  {
197.      int y;
198.      register int x, i, dig_left, block;
199.      register struct rm    *lev;
200.  
201.      /* Start out with cs0 as our current array */
202.      viz_array = cs_rows0;
203.      viz_rmin  = cs_rmin0;
204.      viz_rmax  = cs_rmax0;
205.  
206.      (void) memset((genericptr_t) could_see, 0, sizeof(could_see));
207.  
208.      /* Reset the pointers and clear so that we have a "full" dungeon. */
209.      (void) memset((genericptr_t) viz_clear,        0, sizeof(viz_clear));
210.  
211.      /* Dig the level */
212.      for (y = 0; y < ROWNO; y++) {
213.  	dig_left = 0;
214.  	block = TRUE;	/* location (0,y) is always stone; it's !isok() */
215.  	lev = &levl[1][y];
216.  	for (x = 1; x < COLNO; x++, lev += ROWNO)
217.  	    if (block != (IS_ROCK(lev->typ) || does_block(x,y,lev))) {
218.  		if(block) {
219.  		    for(i=dig_left; i<x; i++) {
220.  			left_ptrs [y][i] = dig_left;
221.  			right_ptrs[y][i] = x-1;
222.  		    }
223.  		} else {
224.  		    i = dig_left;
225.  		    if(dig_left) dig_left--; /* point at first blocked point */
226.  		    for(; i<x; i++) {
227.  			left_ptrs [y][i] = dig_left;
228.  			right_ptrs[y][i] = x;
229.  			viz_clear[y][i] = 1;
230.  		    }
231.  		}
232.  		dig_left = x;
233.  		block = !block;
234.  	    }
235.  	/* handle right boundary; almost identical for blocked/unblocked */
236.  	i = dig_left;
237.  	if(!block && dig_left) dig_left--; /* point at first blocked point */
238.  	for(; i<COLNO; i++) {
239.  	    left_ptrs [y][i] = dig_left;
240.  	    right_ptrs[y][i] = (COLNO-1);
241.  	    viz_clear[y][i] = !block;
242.  	}
243.      }
244.  
245.      iflags.vision_inited = 1;	/* vision is ready */
246.      vision_full_recalc = 1;	/* we want to run vision_recalc() */
247.  }
248.  
249.  

get_unused_cs Edit

250.  /*
251.   * get_unused_cs()
252.   *
253.   * Called from vision_recalc() and at least one light routine.  Get pointers
254.   * to the unused vision work area.
255.   */
256.  STATIC_OVL void
257.  get_unused_cs(rows, rmin, rmax)
258.      char ***rows;
259.      char **rmin, **rmax;
260.  {
261.      register int  row;
262.      register char *nrmin, *nrmax;
263.  
264.      if (viz_array == cs_rows0) {
265.  	*rows = cs_rows1;
266.  	*rmin = cs_rmin1;
267.  	*rmax = cs_rmax1;
268.      } else {
269.  	*rows = cs_rows0;
270.  	*rmin = cs_rmin0;
271.  	*rmax = cs_rmax0;
272.      }
273.  
274.      /* return an initialized, unused work area */
275.      nrmin = *rmin;
276.      nrmax = *rmax;
277.  
278.      (void) memset((genericptr_t)**rows, 0, ROWNO*COLNO);  /* we see nothing */
279.      for (row = 0; row < ROWNO; row++) {		/* set row min & max */
280.  	*nrmin++ = COLNO-1;
281.  	*nrmax++ = 0;
282.      }
283.  }
284.  
285.  

rogue_vision Edit

286.  #ifdef REINCARNATION
287.  /*
288.   * rogue_vision()
289.   *
290.   * Set the "could see" and in sight bits so vision acts just like the old
291.   * rogue game:
292.   *
293.   *	+ If in a room, the hero can see to the room boundaries.
294.   *	+ The hero can always see adjacent squares.
295.   *
296.   * We set the in_sight bit here as well to escape a bug that shows up
297.   * due to the one-sided lit wall hack.
298.   */
299.  STATIC_OVL void
300.  rogue_vision(next, rmin, rmax)
301.      char **next;	/* could_see array pointers */
302.      char *rmin, *rmax;
303.  {
304.      int rnum = levl[u.ux][u.uy].roomno - ROOMOFFSET; /* no SHARED... */
305.      int start, stop, in_door, xhi, xlo, yhi, ylo;
306.      register int zx, zy;
307.  
308.      /* If in a lit room, we are able to see to its boundaries. */
309.      /* If dark, set COULD_SEE so various spells work -dlc */
310.      if (rnum >= 0) {
311.  	for (zy = rooms[rnum].ly-1; zy <= rooms[rnum].hy+1; zy++) {
312.  	    rmin[zy] = start = rooms[rnum].lx-1;
313.  	    rmax[zy] = stop  = rooms[rnum].hx+1;
314.  
315.  	    for (zx = start; zx <= stop; zx++) {
316.  		if (rooms[rnum].rlit) {
317.  		    next[zy][zx] = COULD_SEE | IN_SIGHT;
318.  		    levl[zx][zy].seenv = SVALL;	/* see the walls */
319.  		} else
320.  		    next[zy][zx] = COULD_SEE;
321.  	    }
322.  	}
323.      }
324.  
325.      in_door = levl[u.ux][u.uy].typ == DOOR;
326.  
327.      /* Can always see adjacent. */
328.      ylo = max(u.uy - 1, 0);
329.      yhi = min(u.uy + 1, ROWNO - 1);
330.      xlo = max(u.ux - 1, 1);
331.      xhi = min(u.ux + 1, COLNO - 1);
332.      for (zy = ylo; zy <= yhi; zy++) {
333.  	if (xlo < rmin[zy]) rmin[zy] = xlo;
334.  	if (xhi > rmax[zy]) rmax[zy] = xhi;
335.  
336.  	for (zx = xlo; zx <= xhi; zx++) {
337.  	    next[zy][zx] = COULD_SEE | IN_SIGHT;
338.  	    /*
339.  	     * Yuck, update adjacent non-diagonal positions when in a doorway.
340.  	     * We need to do this to catch the case when we first step into
341.  	     * a room.  The room's walls were not seen from the outside, but
342.  	     * now are seen (the seen bits are set just above).  However, the
343.  	     * positions are not updated because they were already in sight.
344.  	     * So, we have to do it here.
345.  	     */
346.  	    if (in_door && (zx == u.ux || zy == u.uy)) newsym(zx,zy);
347.  	}
348.      }
349.  }
350.  #endif /* REINCARNATION */
351.  

new_angle Edit

352.  /*#define EXTEND_SPINE*/	/* possibly better looking wall-angle */
353.  
354.  #ifdef EXTEND_SPINE
355.  
356.  STATIC_DCL int FDECL(new_angle, (struct rm *, unsigned char *, int, int));
357.  /*
358.   * new_angle()
359.   *
360.   * Return the new angle seen by the hero for this location.  The angle
361.   * bit is given in the value pointed at by sv.
362.   *
363.   * For T walls and crosswall, just setting the angle bit, even though
364.   * it is technically correct, doesn't look good.  If we can see the
365.   * next position beyond the current one and it is a wall that we can
366.   * see, then we want to extend a spine of the T to connect with the wall
367.   * that is beyond.  Example:
368.   *
369.   *	 Correct, but ugly			   Extend T spine
370.   *
371.   *		| ...					| ...
372.   *		| ...	<-- wall beyond & floor -->	| ...
373.   *		| ...					| ...
374.   * Unseen   -->   ...					| ...
375.   * spine	+-...	<-- trwall & doorway	-->	+-...
376.   *		| ...					| ...
377.   *
378.   *
379.   *		   @	<-- hero		-->	   @
380.   *
381.   *
382.   * We fake the above check by only checking if the horizontal &
383.   * vertical positions adjacent to the crosswall and T wall are
384.   * unblocked.  Then, _in general_ we can see beyond.  Generally,
385.   * this is good enough.
386.   *
387.   *	+ When this function is called we don't have all of the seen
388.   *	  information (we're doing a top down scan in vision_recalc).
389.   *	  We would need to scan once to set all IN_SIGHT and COULD_SEE
390.   *	  bits, then again to correctly set the seenv bits.
391.   *	+ I'm trying to make this as cheap as possible.  The display &
392.   *	  vision eat up too much CPU time.
393.   *	
394.   *
395.   * Note:  Even as I write this, I'm still not convinced.  There are too
396.   *	  many exceptions.  I may have to bite the bullet and do more
397.   *	  checks.	- Dean 2/11/93
398.   */
399.  STATIC_OVL int
400.  new_angle(lev, sv, row, col)
401.      struct rm *lev;
402.      unsigned char *sv;
403.      int row, col;
404.  {
405.      register int res = *sv;
406.  
407.      /*
408.       * Do extra checks for crosswalls and T walls if we see them from
409.       * an angle.
410.       */
411.      if (lev->typ >= CROSSWALL && lev->typ <= TRWALL) {
412.  	switch (res) {
413.  	    case SV0:
414.  		if (col > 0	  && viz_clear[row][col-1]) res |= SV7;
415.  		if (row > 0	  && viz_clear[row-1][col]) res |= SV1;
416.  		break;
417.  	    case SV2:
418.  		if (row > 0	  && viz_clear[row-1][col]) res |= SV1;
419.  		if (col < COLNO-1 && viz_clear[row][col+1]) res |= SV3;
420.  		break;
421.  	    case SV4:
422.  		if (col < COLNO-1 && viz_clear[row][col+1]) res |= SV3;
423.  		if (row < ROWNO-1 && viz_clear[row+1][col]) res |= SV5;
424.  		break;
425.  	    case SV6:
426.  		if (row < ROWNO-1 && viz_clear[row+1][col]) res |= SV5;
427.  		if (col > 0	  && viz_clear[row][col-1]) res |= SV7;
428.  		break;
429.  	}
430.      }
431.      return res;
432.  }
433.  #else
434.  /*
435.   * new_angle()
436.   *
437.   * Return the new angle seen by the hero for this location.  The angle
438.   * bit is given in the value pointed at by sv.
439.   *
440.   * The other parameters are not used.
441.   */
442.  #define new_angle(lev, sv, row, col) (*sv)
443.  
444.  #endif
445.  
446.  

vision_recalc Edit

447.  /*
448.   * vision_recalc()
449.   *
450.   * Do all of the heavy vision work.  Recalculate all locations that could
451.   * possibly be seen by the hero --- if the location were lit, etc.  Note
452.   * which locations are actually seen because of lighting.  Then add to
453.   * this all locations that be seen by hero due to night vision and x-ray
454.   * vision.  Finally, compare with what the hero was able to see previously.
455.   * Update the difference.
456.   *
457.   * This function is usually called only when the variable 'vision_full_recalc'
458.   * is set.  The following is a list of places where this function is called,
459.   * with three valid values for the control flag parameter:
460.   *
461.   * Control flag = 0.  A complete vision recalculation.  Generate the vision
462.   * tables from scratch.  This is necessary to correctly set what the hero
463.   * can see.  (1) and (2) call this routine for synchronization purposes, (3)
464.   * calls this routine so it can operate correctly.
465.   *
466.   *	+ After the monster move, before input from the player. [moveloop()]
467.   *	+ At end of moveloop. [moveloop() ??? not sure why this is here]
468.   *	+ Right before something is printed. [pline()]
469.   *	+ Right before we do a vision based operation. [do_clear_area()]
470.   *	+ screen redraw, so we can renew all positions in sight. [docrt()]
471.   *
472.   * Control flag = 1.  An adjacent vision recalculation.  The hero has moved
473.   * one square.  Knowing this, it might be possible to optimize the vision
474.   * recalculation using the current knowledge.  This is presently unimplemented
475.   * and is treated as a control = 0 call.
476.   *
477.   *	+ Right after the hero moves. [domove()]
478.   *
479.   * Control flag = 2.  Turn off the vision system.  Nothing new will be
480.   * displayed, since nothing is seen.  This is usually done when you need
481.   * a newsym() run on all locations in sight, or on some locations but you
482.   * don't know which ones.
483.   *
484.   *	+ Before a screen redraw, so all positions are renewed. [docrt()]
485.   *	+ Right before the hero arrives on a new level. [goto_level()]
486.   *	+ Right after a scroll of light is read. [litroom()]
487.   *	+ After an option has changed that affects vision [parseoptions()]
488.   *	+ Right after the hero is swallowed. [gulpmu()]
489.   *	+ Just before bubbles are moved. [movebubbles()]
490.   */
491.  void
492.  vision_recalc(control)
493.      int control;
494.  {
495.      char **temp_array;	/* points to the old vision array */
496.      char **next_array;	/* points to the new vision array */
497.      char *next_row;	/* row pointer for the new array */
498.      char *old_row;	/* row pointer for the old array */
499.      char *next_rmin;	/* min pointer for the new array */
500.      char *next_rmax;	/* max pointer for the new array */
501.      char *ranges;	/* circle ranges -- used for xray & night vision */
502.      int row;		/* row counter (outer loop)  */
503.      int start, stop;	/* inner loop starting/stopping index */
504.      int dx, dy;		/* one step from a lit door or lit wall (see below) */
505.      register int col;	/* inner loop counter */
506.      register struct rm *lev;	/* pointer to current pos */
507.      struct rm *flev;	/* pointer to position in "front" of current pos */
508.      extern unsigned char seenv_matrix[3][3];	/* from display.c */
509.      static unsigned char colbump[COLNO+1];	/* cols to bump sv */
510.      unsigned char *sv;				/* ptr to seen angle bits */
511.      int oldseenv;				/* previous seenv value */
512.  
513.      vision_full_recalc = 0;			/* reset flag */
514.      if (in_mklev || !iflags.vision_inited) return;
515.  
516.  #ifdef GCC_WARN
517.      row = 0;
518.  #endif
519.  
520.      /*
521.       * Either the light sources have been taken care of, or we must
522.       * recalculate them here.
523.       */
524.  
525.      /* Get the unused could see, row min, and row max arrays. */
526.      get_unused_cs(&next_array, &next_rmin, &next_rmax);
527.  
528.      /* You see nothing, nothing can see you --- if swallowed or refreshing. */
529.      if (u.uswallow || control == 2) {
530.  	/* do nothing -- get_unused_cs() nulls out the new work area */
531.  
532.      } else if (Blind) {
533.  	/*
534.  	 * Calculate the could_see array even when blind so that monsters
535.  	 * can see you, even if you can't see them.  Note that the current
536.  	 * setup allows:
537.  	 *
538.  	 *	+ Monsters to see with the "new" vision, even on the rogue
539.  	 *	  level.
540.  	 *
541.  	 *	+ Monsters can see you even when you're in a pit.
542.  	 */
543.  	view_from(u.uy, u.ux, next_array, next_rmin, next_rmax,
544.  		0, (void FDECL((*),(int,int,genericptr_t)))0, (genericptr_t)0);
545.  
546.  	/*
547.  	 * Our own version of the update loop below.  We know we can't see
548.  	 * anything, so we only need update positions we used to be able
549.  	 * to see.
550.  	 */
551.  	temp_array = viz_array;	/* set viz_array so newsym() will work */
552.  	viz_array = next_array;
553.  
554.  	for (row = 0; row < ROWNO; row++) {
555.  	    old_row = temp_array[row];
556.  
557.  	    /* Find the min and max positions on the row. */
558.  	    start = min(viz_rmin[row], next_rmin[row]);
559.  	    stop  = max(viz_rmax[row], next_rmax[row]);
560.  
561.  	    for (col = start; col <= stop; col++)
562.  		if (old_row[col] & IN_SIGHT) newsym(col,row);
563.  	}
564.  
565.  	/* skip the normal update loop */
566.  	goto skip;
567.      }
568.  #ifdef REINCARNATION
569.      else if (Is_rogue_level(&u.uz)) {
570.  	rogue_vision(next_array,next_rmin,next_rmax);
571.      }
572.  #endif
573.      else {
574.  	int has_night_vision = 1;	/* hero has night vision */
575.  
576.  	if (Underwater && !Is_waterlevel(&u.uz)) {
577.  	    /*
578.  	     * The hero is under water.  Only see surrounding locations if
579.  	     * they are also underwater.  This overrides night vision but
580.  	     * does not override x-ray vision.
581.  	     */
582.  	    has_night_vision = 0;
583.  
584.  	    for (row = u.uy-1; row <= u.uy+1; row++)
585.  		for (col = u.ux-1; col <= u.ux+1; col++) {
586.  		    if (!isok(col,row) || !is_pool(col,row)) continue;
587.  
588.  		    next_rmin[row] = min(next_rmin[row], col);
589.  		    next_rmax[row] = max(next_rmax[row], col);
590.  		    next_array[row][col] = IN_SIGHT | COULD_SEE;
591.  		}
592.  	}
593.  
594.  	/* if in a pit, just update for immediate locations */
595.  	else if (u.utrap && u.utraptype == TT_PIT) {
596.  	    for (row = u.uy-1; row <= u.uy+1; row++) {
597.  		if (row < 0) continue;	if (row >= ROWNO) break;
598.  
599.  		next_rmin[row] = max(      0, u.ux - 1);
600.  		next_rmax[row] = min(COLNO-1, u.ux + 1);
601.  		next_row = next_array[row];
602.  
603.  		for(col=next_rmin[row]; col <= next_rmax[row]; col++)
604.  		    next_row[col] = IN_SIGHT | COULD_SEE;
605.  	    }
606.  	} else
607.  	    view_from(u.uy, u.ux, next_array, next_rmin, next_rmax,
608.  		0, (void FDECL((*),(int,int,genericptr_t)))0, (genericptr_t)0);
609.  
610.  	/*
611.  	 * Set the IN_SIGHT bit for xray and night vision.
612.  	 */
613.  	if (u.xray_range >= 0) {
614.  	    if (u.xray_range) {
615.  		ranges = circle_ptr(u.xray_range);
616.  
617.  		for (row = u.uy-u.xray_range; row <= u.uy+u.xray_range; row++) {
618.  		    if (row < 0) continue;	if (row >= ROWNO) break;
619.  		    dy = v_abs(u.uy-row);	next_row = next_array[row];
620.  
621.  		    start = max(      0, u.ux - ranges[dy]);
622.  		    stop  = min(COLNO-1, u.ux + ranges[dy]);
623.  
624.  		    for (col = start; col <= stop; col++) {
625.  			char old_row_val = next_row[col];
626.  			next_row[col] |= IN_SIGHT;
627.  			oldseenv = levl[col][row].seenv;
628.  			levl[col][row].seenv = SVALL;	/* see all! */
629.  			/* Update if previously not in sight or new angle. */
630.  			if (!(old_row_val & IN_SIGHT) || oldseenv != SVALL)
631.  			    newsym(col,row);
632.  		    }
633.  
634.  		    next_rmin[row] = min(start, next_rmin[row]);
635.  		    next_rmax[row] = max(stop, next_rmax[row]);
636.  		}
637.  
638.  	    } else {	/* range is 0 */
639.  		next_array[u.uy][u.ux] |= IN_SIGHT;
640.  		levl[u.ux][u.uy].seenv = SVALL;
641.  		next_rmin[u.uy] = min(u.ux, next_rmin[u.uy]);
642.  		next_rmax[u.uy] = max(u.ux, next_rmax[u.uy]);
643.  	    }
644.  	}
645.  
646.  	if (has_night_vision && u.xray_range < u.nv_range) {
647.  	    if (!u.nv_range) {	/* range is 0 */
648.  		next_array[u.uy][u.ux] |= IN_SIGHT;
649.  		levl[u.ux][u.uy].seenv = SVALL;
650.  		next_rmin[u.uy] = min(u.ux, next_rmin[u.uy]);
651.  		next_rmax[u.uy] = max(u.ux, next_rmax[u.uy]);
652.  	    } else if (u.nv_range > 0) {
653.  		ranges = circle_ptr(u.nv_range);
654.  
655.  		for (row = u.uy-u.nv_range; row <= u.uy+u.nv_range; row++) {
656.  		    if (row < 0) continue;	if (row >= ROWNO) break;
657.  		    dy = v_abs(u.uy-row);	next_row = next_array[row];
658.  
659.  		    start = max(      0, u.ux - ranges[dy]);
660.  		    stop  = min(COLNO-1, u.ux + ranges[dy]);
661.  
662.  		    for (col = start; col <= stop; col++)
663.  			if (next_row[col]) next_row[col] |= IN_SIGHT;
664.  
665.  		    next_rmin[row] = min(start, next_rmin[row]);
666.  		    next_rmax[row] = max(stop, next_rmax[row]);
667.  		}
668.  	    }
669.  	}
670.      }
671.  
672.      /* Set the correct bits for all light sources. */
673.      do_light_sources(next_array);
674.  
675.  
676.      /*
677.       * Make the viz_array the new array so that cansee() will work correctly.
678.       */
679.      temp_array = viz_array;
680.      viz_array = next_array;
681.  
682.      /*
683.       * The main update loop.  Here we do two things:
684.       *
685.       *	    + Set the IN_SIGHT bit for places that we could see and are lit.
686.       *	    + Reset changed places.
687.       *
688.       * There is one thing that make deciding what the hero can see
689.       * difficult:
690.       *
691.       *  1.  Directional lighting.  Items that block light create problems.
692.       *      The worst offenders are doors.  Suppose a door to a lit room
693.       *      is closed.  It is lit on one side, but not on the other.  How
694.       *      do you know?  You have to check the closest adjacent position.
695.       *	    Even so, that is not entirely correct.  But it seems close
696.       *	    enough for now.
697.       */
698.      colbump[u.ux] = colbump[u.ux+1] = 1;
699.      for (row = 0; row < ROWNO; row++) {
700.  	dy = u.uy - row;                dy = sign(dy);
701.  	next_row = next_array[row];     old_row = temp_array[row];
702.  
703.  	/* Find the min and max positions on the row. */
704.  	start = min(viz_rmin[row], next_rmin[row]);
705.  	stop  = max(viz_rmax[row], next_rmax[row]);
706.  	lev = &levl[start][row];
707.  
708.  	sv = &seenv_matrix[dy+1][start < u.ux ? 0 : (start > u.ux ? 2:1)];
709.  
710.  	for (col = start; col <= stop;
711.  				lev += ROWNO, sv += (int) colbump[++col]) {
712.  	    if (next_row[col] & IN_SIGHT) {
713.  		/*
714.  		 * We see this position because of night- or xray-vision.
715.  		 */
716.  		oldseenv = lev->seenv;
717.  		lev->seenv |= new_angle(lev,sv,row,col); /* update seen angle */
718.  
719.  		/* Update pos if previously not in sight or new angle. */
720.  		if ( !(old_row[col] & IN_SIGHT) || oldseenv != lev->seenv)
721.  		    newsym(col,row);
722.  	    }
723.  
724.  	    else if ((next_row[col] & COULD_SEE)
725.  				&& (lev->lit || (next_row[col] & TEMP_LIT))) {
726.  		/*
727.  		 * We see this position because it is lit.
728.  		 */
729.  		if ((IS_DOOR(lev->typ) || lev->typ == SDOOR ||
730.  		     IS_WALL(lev->typ)) && !viz_clear[row][col]) {
731.  		    /*
732.  		     * Make sure doors, walls, boulders or mimics don't show up
733.  		     * at the end of dark hallways.  We do this by checking
734.  		     * the adjacent position.  If it is lit, then we can see
735.  		     * the door or wall, otherwise we can't.
736.  		     */
737.  		    dx = u.ux - col;	dx = sign(dx);
738.  		    flev = &(levl[col+dx][row+dy]);
739.  		    if (flev->lit || next_array[row+dy][col+dx] & TEMP_LIT) {
740.  			next_row[col] |= IN_SIGHT;	/* we see it */
741.  
742.  			oldseenv = lev->seenv;
743.  			lev->seenv |= new_angle(lev,sv,row,col);
744.  
745.  			/* Update pos if previously not in sight or new angle.*/
746.  			if (!(old_row[col] & IN_SIGHT) || oldseenv!=lev->seenv)
747.  			    newsym(col,row);
748.  		    } else
749.  			goto not_in_sight;	/* we don't see it */
750.  
751.  		} else {
752.  		    next_row[col] |= IN_SIGHT;	/* we see it */
753.  
754.  		    oldseenv = lev->seenv;
755.  		    lev->seenv |= new_angle(lev,sv,row,col);
756.  
757.  		    /* Update pos if previously not in sight or new angle. */
758.  		    if ( !(old_row[col] & IN_SIGHT) || oldseenv != lev->seenv)
759.  			newsym(col,row);
760.  		}
761.  	    } else if ((next_row[col] & COULD_SEE) && lev->waslit) {
762.  		/*
763.  		 * If we make it here, the hero _could see_ the location,
764.  		 * but doesn't see it (location is not lit).
765.  		 * However, the hero _remembers_ it as lit (waslit is true).
766.  		 * The hero can now see that it is not lit, so change waslit
767.  		 * and update the location.
768.  		 */
769.  		lev->waslit = 0; /* remember lit condition */
770.  		newsym(col,row);
771.  	    }
772.  	    /*
773.  	     * At this point we know that the row position is *not* in normal
774.  	     * sight.  That is, the position is could be seen, but is dark
775.  	     * or LOS is just plain blocked.
776.  	     *
777.  	     * Update the position if:
778.  	     * o If the old one *was* in sight.  We may need to clean up
779.  	     *   the glyph -- E.g. darken room spot, etc.
780.  	     * o If we now could see the location (yet the location is not
781.  	     *   lit), but previously we couldn't see the location, or vice
782.  	     *   versa.  Update the spot because there there may be an infared
783.  	     *   monster there.
784.  	     */
785.  	    else {
786.  not_in_sight:
787.  		if ((old_row[col] & IN_SIGHT)
788.  			|| ((next_row[col] & COULD_SEE)
789.  				^ (old_row[col] & COULD_SEE)))
790.  		    newsym(col,row);
791.  	    }
792.  
793.  	} /* end for col . . */
794.      }	/* end for row . .  */
795.      colbump[u.ux] = colbump[u.ux+1] = 0;
796.  
797.  skip:
798.      /* This newsym() caused a crash delivering msg about failure to open
799.       * dungeon file init_dungeons() -> panic() -> done(11) ->
800.       * vision_recalc(2) -> newsym() -> crash!  u.ux and u.uy are 0 and
801.       * program_state.panicking == 1 under those circumstances
802.       */
803.      if (!program_state.panicking)
804.  	newsym(u.ux, u.uy);		/* Make sure the hero shows up! */
805.  
806.      /* Set the new min and max pointers. */
807.      viz_rmin  = next_rmin;
808.      viz_rmax = next_rmax;
809.  }
810.  
811.  

block_point Edit

812.  /*
813.   * block_point()
814.   *
815.   * Make the location opaque to light.
816.   */
817.  void
818.  block_point(x,y)
819.      int x, y;
820.  {
821.      fill_point(y,x);
822.  
823.      /* recalc light sources here? */
824.  
825.      /*
826.       * We have to do a full vision recalculation if we "could see" the
827.       * location.  Why? Suppose some monster opened a way so that the
828.       * hero could see a lit room.  However, the position of the opening
829.       * was out of night-vision range of the hero.  Suddenly the hero should
830.       * see the lit room.
831.       */
832.      if (viz_array[y][x]) vision_full_recalc = 1;
833.  }
834.  

unblock_point Edit

835.  /*
836.   * unblock_point()
837.   *
838.   * Make the location transparent to light.
839.   */
840.  void
841.  unblock_point(x,y)
842.      int x, y;
843.  {
844.      dig_point(y,x);
845.  
846.      /* recalc light sources here? */
847.  
848.      if (viz_array[y][x]) vision_full_recalc = 1;
849.  }
850.  
851.  
852.  /*===========================================================================*\
853.   |									     |
854.   |	Everything below this line uses (y,x) instead of (x,y) --- the	     |
855.   |	algorithms are faster if they are less recursive and can scan	     |
856.   |	on a row longer.						     |
857.   |									     |
858.  \*===========================================================================*/
859.  
860.  
861.  /* ========================================================================= *\
862.  			Left and Right Pointer Updates
863.  \* ========================================================================= */
864.  
865.  /*
866.   *			LEFT and RIGHT pointer rules
867.   *
868.   *
869.   * **NOTE**  The rules changed on 4/4/90.  This comment reflects the
870.   * new rules.  The change was so that the stone-wall optimization
871.   * would work.
872.   *
873.   * OK, now the tough stuff.  We must maintain our left and right
874.   * row pointers.  The rules are as follows:
875.   *
876.   * Left Pointers:
877.   * ______________
878.   *
879.   * + If you are a clear spot, your left will point to the first
880.   *   stone to your left.  If there is none, then point the first
881.   *   legal position in the row (0).
882.   *
883.   * + If you are a blocked spot, then your left will point to the
884.   *   left-most blocked spot to your left that is connected to you.
885.   *   This means that a left-edge (a blocked spot that has an open
886.   *   spot on its left) will point to itself.
887.   *
888.   *
889.   * Right Pointers:
890.   * ---------------
891.   * + If you are a clear spot, your right will point to the first
892.   *   stone to your right.  If there is none, then point the last
893.   *   legal position in the row (COLNO-1).
894.   *
895.   * + If you are a blocked spot, then your right will point to the
896.   *   right-most blocked spot to your right that is connected to you.
897.   *   This means that a right-edge (a blocked spot that has an open
898.   *    spot on its right) will point to itself.
899.   */

dig_point Edit

900.  STATIC_OVL void
901.  dig_point(row,col)
902.      int row,col;
903.  {
904.      int i;
905.  
906.      if (viz_clear[row][col]) return;		/* already done */
907.  
908.      viz_clear[row][col] = 1;
909.  
910.      /*
911.       * Boundary cases first.
912.       */
913.      if (col == 0) {				/* left edge */
914.  	if (viz_clear[row][1]) {
915.  	    right_ptrs[row][0] = right_ptrs[row][1];
916.  	} else {
917.  	    right_ptrs[row][0] = 1;
918.  	    for (i = 1; i <= right_ptrs[row][1]; i++)
919.  		left_ptrs[row][i] = 1;
920.  	}
921.      } else if (col == (COLNO-1)) {		/* right edge */
922.  
923.  	if (viz_clear[row][COLNO-2]) {
924.  	    left_ptrs[row][COLNO-1] = left_ptrs[row][COLNO-2];
925.  	} else {
926.  	    left_ptrs[row][COLNO-1] = COLNO-2;
927.  	    for (i = left_ptrs[row][COLNO-2]; i < COLNO-1; i++)
928.  		right_ptrs[row][i] = COLNO-2;
929.  	}
930.      }
931.  
932.      /*
933.       * At this point, we know we aren't on the boundaries.
934.       */
935.      else if (viz_clear[row][col-1] && viz_clear[row][col+1]) {
936.  	/* Both sides clear */
937.  	for (i = left_ptrs[row][col-1]; i <= col; i++) {
938.  	    if (!viz_clear[row][i]) continue;	/* catch non-end case */
939.  	    right_ptrs[row][i] = right_ptrs[row][col+1];
940.  	}
941.  	for (i = col; i <= right_ptrs[row][col+1]; i++) {
942.  	    if (!viz_clear[row][i]) continue;	/* catch non-end case */
943.  	    left_ptrs[row][i] = left_ptrs[row][col-1];
944.  	}
945.  
946.      } else if (viz_clear[row][col-1]) {
947.  	/* Left side clear, right side blocked. */
948.  	for (i = col+1; i <= right_ptrs[row][col+1]; i++)
949.  	    left_ptrs[row][i] = col+1;
950.  
951.  	for (i = left_ptrs[row][col-1]; i <= col; i++) {
952.  	    if (!viz_clear[row][i]) continue;	/* catch non-end case */
953.  	    right_ptrs[row][i] = col+1;
954.  	}
955.  	left_ptrs[row][col] = left_ptrs[row][col-1];
956.  
957.      } else if (viz_clear[row][col+1]) {
958.  	/* Right side clear, left side blocked. */
959.  	for (i = left_ptrs[row][col-1]; i < col; i++)
960.  	    right_ptrs[row][i] = col-1;
961.  
962.  	for (i = col; i <= right_ptrs[row][col+1]; i++) {
963.  	    if (!viz_clear[row][i]) continue;	/* catch non-end case */
964.  	    left_ptrs[row][i] = col-1;
965.  	}
966.  	right_ptrs[row][col] = right_ptrs[row][col+1];
967.  
968.      } else {
969.  	/* Both sides blocked */
970.  	for (i = left_ptrs[row][col-1]; i < col; i++)
971.  	    right_ptrs[row][i] = col-1;
972.  
973.  	for (i = col+1; i <= right_ptrs[row][col+1]; i++)
974.  	    left_ptrs[row][i] = col+1;
975.  
976.  	left_ptrs[row][col]  = col-1;
977.  	right_ptrs[row][col] = col+1;
978.      }
979.  }
980.  

fill_point Edit

981.  STATIC_OVL void
982.  fill_point(row,col)
983.      int row, col;
984.  {
985.      int i;
986.  
987.      if (!viz_clear[row][col]) return;
988.  
989.      viz_clear[row][col] = 0;
990.  
991.      if (col == 0) {
992.  	if (viz_clear[row][1]) {			/* adjacent is clear */
993.  	    right_ptrs[row][0] = 0;
994.  	} else {
995.  	    right_ptrs[row][0] = right_ptrs[row][1];
996.  	    for (i = 1; i <= right_ptrs[row][1]; i++)
997.  		left_ptrs[row][i] = 0;
998.  	}
999.      } else if (col == COLNO-1) {
1000. 	if (viz_clear[row][COLNO-2]) {		/* adjacent is clear */
1001. 	    left_ptrs[row][COLNO-1] = COLNO-1;
1002. 	} else {
1003. 	    left_ptrs[row][COLNO-1] = left_ptrs[row][COLNO-2];
1004. 	    for (i = left_ptrs[row][COLNO-2]; i < COLNO-1; i++)
1005. 		right_ptrs[row][i] = COLNO-1;
1006. 	}
1007.     }
1008. 
1009.     /*
1010.      * Else we know that we are not on an edge.
1011.      */
1012.     else if (viz_clear[row][col-1] && viz_clear[row][col+1]) {
1013. 	/* Both sides clear */
1014. 	for (i = left_ptrs[row][col-1]+1; i <= col; i++)
1015. 	    right_ptrs[row][i] = col;
1016. 
1017. 	if (!left_ptrs[row][col-1])		/* catch the end case */
1018. 	    right_ptrs[row][0] = col;
1019. 
1020. 	for (i = col; i < right_ptrs[row][col+1]; i++)
1021. 	    left_ptrs[row][i] = col;
1022. 
1023. 	if (right_ptrs[row][col+1] == COLNO-1)	/* catch the end case */
1024. 	    left_ptrs[row][COLNO-1] = col;
1025. 
1026.     } else if (viz_clear[row][col-1]) {
1027. 	/* Left side clear, right side blocked. */
1028. 	for (i = col; i <= right_ptrs[row][col+1]; i++)
1029. 	    left_ptrs[row][i] = col;
1030. 
1031. 	for (i = left_ptrs[row][col-1]+1; i < col; i++)
1032. 	    right_ptrs[row][i] = col;
1033. 
1034. 	if (!left_ptrs[row][col-1])		/* catch the end case */
1035. 	    right_ptrs[row][i] = col;
1036. 
1037. 	right_ptrs[row][col] = right_ptrs[row][col+1];
1038. 
1039.     } else if (viz_clear[row][col+1]) {
1040. 	/* Right side clear, left side blocked. */
1041. 	for (i = left_ptrs[row][col-1]; i <= col; i++)
1042. 	    right_ptrs[row][i] = col;
1043. 
1044. 	for (i = col+1; i < right_ptrs[row][col+1]; i++)
1045. 	    left_ptrs[row][i] = col;
1046. 
1047. 	if (right_ptrs[row][col+1] == COLNO-1)	/* catch the end case */
1048. 	    left_ptrs[row][i] = col;
1049. 
1050. 	left_ptrs[row][col] = left_ptrs[row][col-1];
1051. 
1052.     } else {
1053. 	/* Both sides blocked */
1054. 	for (i = left_ptrs[row][col-1]; i <= col; i++)
1055. 	    right_ptrs[row][i] = right_ptrs[row][col+1];
1056. 
1057. 	for (i = col; i <= right_ptrs[row][col+1]; i++)
1058. 	    left_ptrs[row][i] = left_ptrs[row][col-1];
1059.     }
1060. }
1061. 
1062. 

Algorithm C or D Edit

1063. /*===========================================================================*/
1064. /*===========================================================================*/
1065. /* Use either algorithm C or D.  See the config.h for more details. =========*/
1066. 
1067. /*
1068.  * Variables local to both Algorithms C and D.
1069.  */
1070. static int  start_row;
1071. static int  start_col;
1072. static int  step;
1073. static char **cs_rows;
1074. static char *cs_left;
1075. static char *cs_right;
1076. 
1077. static void FDECL((*vis_func), (int,int,genericptr_t));
1078. static genericptr_t varg;
1079. 
1080. /*
1081.  * Both Algorithms C and D use the following macros.
1082.  *
1083.  *      good_row(z)	  - Return TRUE if the argument is a legal row.
1084.  *      set_cs(rowp,col)  - Set the local could see array.
1085.  *      set_min(z)	  - Save the min value of the argument and the current
1086.  *			      row minimum.
1087.  *      set_max(z)	  - Save the max value of the argument and the current
1088.  *			      row maximum.
1089.  *
1090.  * The last three macros depend on having local pointers row_min, row_max,
1091.  * and rowp being set correctly.
1092.  */
1093. #define set_cs(rowp,col) (rowp[col] = COULD_SEE)
1094. #define good_row(z) ((z) >= 0 && (z) < ROWNO)
1095. #define set_min(z) if (*row_min > (z)) *row_min = (z)
1096. #define set_max(z) if (*row_max < (z)) *row_max = (z)
1097. #define is_clear(row,col) viz_clear_rows[row][col]
1098. 

clear_path Edit

1099. /*
1100.  * clear_path()		expanded into 4 macros/functions:
1101.  *
1102.  *	q1_path()
1103.  *	q2_path()
1104.  *	q3_path()
1105.  *	q4_path()
1106.  *
1107.  * "Draw" a line from the start to the given location.  Stop if we hit
1108.  * something that blocks light.  The start and finish points themselves are
1109.  * not checked, just the points between them.  These routines do _not_
1110.  * expect to be called with the same starting and stopping point.
1111.  *
1112.  * These routines use the generalized integer Bresenham's algorithm (fast
1113.  * line drawing) for all quadrants.  The algorithm was taken from _Procedural
1114.  * Elements for Computer Graphics_, by David F. Rogers.  McGraw-Hill, 1985.
1115.  */
1116. #ifdef MACRO_CPATH	/* quadrant calls are macros */
1117. 
1118. /*
1119.  * When called, the result is in "result".
1120.  * The first two arguments (srow,scol) are one end of the path.  The next
1121.  * two arguments (row,col) are the destination.  The last argument is
1122.  * used as a C language label.  This means that it must be different
1123.  * in each pair of calls.
1124.  */
1125. 

q1_path macro Edit

1126. /*
1127.  *  Quadrant I (step < 0).
1128.  */
1129. #define q1_path(srow,scol,y2,x2,label)			\
1130. {							\
1131.     int dx, dy;						\
1132.     register int k, err, x, y, dxs, dys;		\
1133. 							\
1134.     x  = (scol);	y  = (srow);			\
1135.     dx = (x2) - x;	dy = y - (y2);			\
1136. 							\
1137.     result = 0;		 /* default to a blocked path */\
1138. 							\
1139.     dxs = dx << 1;	   /* save the shifted values */\
1140.     dys = dy << 1;					\
1141.     if (dy > dx) {					\
1142. 	err = dxs - dy;					\
1143. 							\
1144. 	for (k = dy-1; k; k--) {			\
1145. 	    if (err >= 0) {				\
1146. 		x++;					\
1147. 		err -= dys;				\
1148. 	    }						\
1149. 	    y--;					\
1150. 	    err += dxs;					\
1151. 	    if (!is_clear(y,x)) goto label;/* blocked */\
1152. 	}						\
1153.     } else {						\
1154. 	err = dys - dx;					\
1155. 							\
1156. 	for (k = dx-1; k; k--) {			\
1157. 	    if (err >= 0) {				\
1158. 		y--;					\
1159. 		err -= dxs;				\
1160. 	    }						\
1161. 	    x++;					\
1162. 	    err += dys;					\
1163. 	    if (!is_clear(y,x)) goto label;/* blocked */\
1164. 	}						\
1165.     }							\
1166. 							\
1167.     result = 1;						\
1168. }
1169. 

q4_path macro Edit

1170. /*
1171.  * Quadrant IV (step > 0).
1172.  */
1173. #define q4_path(srow,scol,y2,x2,label)			\
1174. {							\
1175.     int dx, dy;						\
1176.     register int k, err, x, y, dxs, dys;		\
1177. 							\
1178.     x  = (scol);	y  = (srow);			\
1179.     dx = (x2) - x;	dy = (y2) - y;			\
1180. 							\
1181.     result = 0;		 /* default to a blocked path */\
1182. 							\
1183.     dxs = dx << 1;	   /* save the shifted values */\
1184.     dys = dy << 1;					\
1185.     if (dy > dx) {					\
1186. 	err = dxs - dy;					\
1187. 							\
1188. 	for (k = dy-1; k; k--) {			\
1189. 	    if (err >= 0) {				\
1190. 		x++;					\
1191. 		err -= dys;				\
1192. 	    }						\
1193. 	    y++;					\
1194. 	    err += dxs;					\
1195. 	    if (!is_clear(y,x)) goto label;/* blocked */\
1196. 	}						\
1197. 							\
1198.     } else {						\
1199. 	err = dys - dx;					\
1200. 							\
1201. 	for (k = dx-1; k; k--) {			\
1202. 	    if (err >= 0) {				\
1203. 		y++;					\
1204. 		err -= dxs;				\
1205. 	    }						\
1206. 	    x++;					\
1207. 	    err += dys;					\
1208. 	    if (!is_clear(y,x)) goto label;/* blocked */\
1209. 	}						\
1210.     }							\
1211. 							\
1212.     result = 1;						\
1213. }
1214. 

q2_path macro Edit

1215. /*
1216.  * Quadrant II (step < 0).
1217.  */
1218. #define q2_path(srow,scol,y2,x2,label)			\
1219. {							\
1220.     int dx, dy;						\
1221.     register int k, err, x, y, dxs, dys;		\
1222. 							\
1223.     x  = (scol);	y  = (srow);			\
1224.     dx = x - (x2);	dy = y - (y2);			\
1225. 							\
1226.     result = 0;		 /* default to a blocked path */\
1227. 							\
1228.     dxs = dx << 1;	   /* save the shifted values */\
1229.     dys = dy << 1;					\
1230.     if (dy > dx) {					\
1231. 	err = dxs - dy;					\
1232. 							\
1233. 	for (k = dy-1; k; k--) {			\
1234. 	    if (err >= 0) {				\
1235. 		x--;					\
1236. 		err -= dys;				\
1237. 	    }						\
1238. 	    y--;					\
1239. 	    err += dxs;					\
1240. 	    if (!is_clear(y,x)) goto label;/* blocked */\
1241. 	}						\
1242.     } else {						\
1243. 	err = dys - dx;					\
1244. 							\
1245. 	for (k = dx-1; k; k--) {			\
1246. 	    if (err >= 0) {				\
1247. 		y--;					\
1248. 		err -= dxs;				\
1249. 	    }						\
1250. 	    x--;					\
1251. 	    err += dys;					\
1252. 	    if (!is_clear(y,x)) goto label;/* blocked */\
1253. 	}						\
1254.     }							\
1255. 							\
1256.     result = 1;						\
1257. }
1258. 

q3_path macro Edit

1259. /*
1260.  * Quadrant III (step > 0).
1261.  */
1262. #define q3_path(srow,scol,y2,x2,label)			\
1263. {							\
1264.     int dx, dy;						\
1265.     register int k, err, x, y, dxs, dys;		\
1266. 							\
1267.     x  = (scol);	y  = (srow);			\
1268.     dx = x - (x2);	dy = (y2) - y;			\
1269. 							\
1270.     result = 0;		 /* default to a blocked path */\
1271. 							\
1272.     dxs = dx << 1;	   /* save the shifted values */\
1273.     dys = dy << 1;					\
1274.     if (dy > dx) {					\
1275. 	err = dxs - dy;					\
1276. 							\
1277. 	for (k = dy-1; k; k--) {			\
1278. 	    if (err >= 0) {				\
1279. 		x--;					\
1280. 		err -= dys;				\
1281. 	    }						\
1282. 	    y++;					\
1283. 	    err += dxs;					\
1284. 	    if (!is_clear(y,x)) goto label;/* blocked */\
1285. 	}						\
1286. 							\
1287.     } else {						\
1288. 	err = dys - dx;					\
1289. 							\
1290. 	for (k = dx-1; k; k--) {			\
1291. 	    if (err >= 0) {				\
1292. 		y++;					\
1293. 		err -= dxs;				\
1294. 	    }						\
1295. 	    x--;					\
1296. 	    err += dys;					\
1297. 	    if (!is_clear(y,x)) goto label;/* blocked */\
1298. 	}						\
1299.     }							\
1300. 							\
1301.     result = 1;						\
1302. }
1303. 
1304. #else   /* quadrants are really functions */
1305. 
1306. STATIC_DCL int FDECL(_q1_path, (int,int,int,int));
1307. STATIC_DCL int FDECL(_q2_path, (int,int,int,int));
1308. STATIC_DCL int FDECL(_q3_path, (int,int,int,int));
1309. STATIC_DCL int FDECL(_q4_path, (int,int,int,int));
1310. 
1311. #define q1_path(sy,sx,y,x,dummy) result = _q1_path(sy,sx,y,x)
1312. #define q2_path(sy,sx,y,x,dummy) result = _q2_path(sy,sx,y,x)
1313. #define q3_path(sy,sx,y,x,dummy) result = _q3_path(sy,sx,y,x)
1314. #define q4_path(sy,sx,y,x,dummy) result = _q4_path(sy,sx,y,x)
1315. 

_q1_path function Edit

1316. /*
1317.  * Quadrant I (step < 0).
1318.  */
1319. STATIC_OVL int
1320. _q1_path(srow,scol,y2,x2)
1321.     int scol, srow, y2, x2;
1322. {
1323.     int dx, dy;
1324.     register int k, err, x, y, dxs, dys;
1325. 
1326.     x  = scol;		y  = srow;
1327.     dx = x2 - x;	dy = y - y2;
1328. 
1329.     dxs = dx << 1;	   /* save the shifted values */
1330.     dys = dy << 1;
1331.     if (dy > dx) {
1332. 	err = dxs - dy;
1333. 
1334. 	for (k = dy-1; k; k--) {
1335. 	    if (err >= 0) {
1336. 		x++;
1337. 		err -= dys;
1338. 	    }
1339. 	    y--;
1340. 	    err += dxs;
1341. 	    if (!is_clear(y,x)) return 0; /* blocked */
1342. 	}
1343.     } else {
1344. 	err = dys - dx;
1345. 
1346. 	for (k = dx-1; k; k--) {
1347. 	    if (err >= 0) {
1348. 		y--;
1349. 		err -= dxs;
1350. 	    }
1351. 	    x++;
1352. 	    err += dys;
1353. 	    if (!is_clear(y,x)) return 0;/* blocked */
1354. 	}
1355.     }
1356. 
1357.     return 1;
1358. }
1359. 

_q4_path function Edit

1360. /*
1361.  * Quadrant IV (step > 0).
1362.  */
1363. STATIC_OVL int
1364. _q4_path(srow,scol,y2,x2)
1365.     int scol, srow, y2, x2;
1366. {
1367.     int dx, dy;
1368.     register int k, err, x, y, dxs, dys;
1369. 
1370.     x  = scol;		y  = srow;
1371.     dx = x2 - x;	dy = y2 - y;
1372. 
1373.     dxs = dx << 1;	   /* save the shifted values */
1374.     dys = dy << 1;
1375.     if (dy > dx) {
1376. 	err = dxs - dy;
1377. 
1378. 	for (k = dy-1; k; k--) {
1379. 	    if (err >= 0) {
1380. 		x++;
1381. 		err -= dys;
1382. 	    }
1383. 	    y++;
1384. 	    err += dxs;
1385. 	    if (!is_clear(y,x)) return 0; /* blocked */
1386. 	}
1387.     } else {
1388. 	err = dys - dx;
1389. 
1390. 	for (k = dx-1; k; k--) {
1391. 	    if (err >= 0) {
1392. 		y++;
1393. 		err -= dxs;
1394. 	    }
1395. 	    x++;
1396. 	    err += dys;
1397. 	    if (!is_clear(y,x)) return 0;/* blocked */
1398. 	}
1399.     }
1400. 
1401.     return 1;
1402. }
1403. 

_q2_path function Edit

1404. /*
1405.  * Quadrant II (step < 0).
1406.  */
1407. STATIC_OVL int
1408. _q2_path(srow,scol,y2,x2)
1409.     int scol, srow, y2, x2;
1410. {
1411.     int dx, dy;
1412.     register int k, err, x, y, dxs, dys;
1413. 
1414.     x  = scol;		y  = srow;
1415.     dx = x - x2;	dy = y - y2;
1416. 
1417.     dxs = dx << 1;	   /* save the shifted values */
1418.     dys = dy << 1;
1419.     if (dy > dx) {
1420. 	err = dxs - dy;
1421. 
1422. 	for (k = dy-1; k; k--) {
1423. 	    if (err >= 0) {
1424. 		x--;
1425. 		err -= dys;
1426. 	    }
1427. 	    y--;
1428. 	    err += dxs;
1429. 	    if (!is_clear(y,x)) return 0; /* blocked */
1430. 	}
1431.     } else {
1432. 	err = dys - dx;
1433. 
1434. 	for (k = dx-1; k; k--) {
1435. 	    if (err >= 0) {
1436. 		y--;
1437. 		err -= dxs;
1438. 	    }
1439. 	    x--;
1440. 	    err += dys;
1441. 	    if (!is_clear(y,x)) return 0;/* blocked */
1442. 	}
1443.     }
1444. 
1445.     return 1;
1446. }
1447. 

_q3_path function Edit

1448. /*
1449.  * Quadrant III (step > 0).
1450.  */
1451. STATIC_OVL int
1452. _q3_path(srow,scol,y2,x2)
1453.     int scol, srow, y2, x2;
1454. {
1455.     int dx, dy;
1456.     register int k, err, x, y, dxs, dys;
1457. 
1458.     x  = scol;		y  = srow;
1459.     dx = x - x2;	dy = y2 - y;
1460. 
1461.     dxs = dx << 1;	   /* save the shifted values */
1462.     dys = dy << 1;
1463.     if (dy > dx) {
1464. 	err = dxs - dy;
1465. 
1466. 	for (k = dy-1; k; k--) {
1467. 	    if (err >= 0) {
1468. 		x--;
1469. 		err -= dys;
1470. 	    }
1471. 	    y++;
1472. 	    err += dxs;
1473. 	    if (!is_clear(y,x)) return 0; /* blocked */
1474. 	}
1475.     } else {
1476. 	err = dys - dx;
1477. 
1478. 	for (k = dx-1; k; k--) {
1479. 	    if (err >= 0) {
1480. 		y++;
1481. 		err -= dxs;
1482. 	    }
1483. 	    x--;
1484. 	    err += dys;
1485. 	    if (!is_clear(y,x)) return 0;/* blocked */
1486. 	}
1487.     }
1488. 
1489.     return 1;
1490. }
1491. 
1492. #endif	/* quadrants are functions */
1493. 

clear_path Edit

1494. /*
1495.  * Use vision tables to determine if there is a clear path from
1496.  * (col1,row1) to (col2,row2).  This is used by:
1497.  *		m_cansee()
1498.  *		m_canseeu()
1499.  *		do_light_sources()
1500.  */
1501. boolean
1502. clear_path(col1,row1,col2,row2)
1503.     int col1, row1, col2, row2;
1504. {
1505.     int result;
1506. 
1507.     if(col1 < col2) {
1508. 	if(row1 > row2) {
1509. 	    q1_path(row1,col1,row2,col2,cleardone);
1510. 	} else {
1511. 	    q4_path(row1,col1,row2,col2,cleardone);
1512. 	}
1513.     } else {
1514. 	if(row1 > row2) {
1515. 	    q2_path(row1,col1,row2,col2,cleardone);
1516. 	} else if(row1 == row2 && col1 == col2) {
1517. 	    result = 1;
1518. 	} else {
1519. 	    q3_path(row1,col1,row2,col2,cleardone);
1520. 	}
1521.     }
1522. #ifdef MACRO_CPATH
1523. cleardone:
1524. #endif
1525.     return((boolean)result);
1526. }
1527. 

Algorithm D Edit

1528. #ifdef VISION_TABLES
1529. /*===========================================================================*\
1530. 			    GENERAL LINE OF SIGHT
1531. 				Algorithm D
1532. \*===========================================================================*/
1533. 
1534. 
1535. /*
1536.  * Indicate caller for the shadow routines.
1537.  */
1538. #define FROM_RIGHT 0
1539. #define FROM_LEFT  1
1540. 
1541. 
1542. /*
1543.  * Include the table definitions.
1544.  */
1545. #include "vis_tab.h"
1546. 
1547. 
1548. /* 3D table pointers. */
1549. static close2d *close_dy[CLOSE_MAX_BC_DY];
1550. static far2d   *far_dy[FAR_MAX_BC_DY];
1551. 
1552. STATIC_DCL void FDECL(right_side, (int,int,int,int,int,int,int,char*));
1553. STATIC_DCL void FDECL(left_side, (int,int,int,int,int,int,int,char*));
1554. STATIC_DCL int FDECL(close_shadow, (int,int,int,int));
1555. STATIC_DCL int FDECL(far_shadow, (int,int,int,int));
1556. 

view_init D Edit

1557. /*
1558.  * Initialize algorithm D's table pointers.  If we don't have these,
1559.  * then we do 3D table lookups.  Verrrry slow.
1560.  */
1561. STATIC_OVL void
1562. view_init()
1563. {
1564.     int i;
1565. 
1566.     for (i = 0; i < CLOSE_MAX_BC_DY; i++)
1567. 	close_dy[i] = &close_table[i];
1568. 
1569.     for (i = 0; i < FAR_MAX_BC_DY; i++)
1570. 	far_dy[i] = &far_table[i];
1571. }
1572. 
1573. 

close_shadow D Edit

1574. /*
1575.  * If the far table has an entry of OFF_TABLE, then the far block prevents
1576.  * us from seeing the location just above/below it.  I.e. the first visible
1577.  * location is one *before* the block.
1578.  */
1579. #define OFF_TABLE 0xff
1580. 
1581. STATIC_OVL int
1582. close_shadow(side,this_row,block_row,block_col)
1583.     int side,this_row,block_row,block_col;
1584. {
1585.     register int sdy, sdx, pdy, offset;
1586. 
1587.     /*
1588.      * If on the same column (block_row = -1), then we can see it.
1589.      */
1590.     if (block_row < 0) return block_col;
1591. 
1592.     /* Take explicit absolute values.  Adjust. */
1593.     if ((sdy = (start_row-block_row)) < 0) sdy = -sdy; --sdy;	/* src   dy */
1594.     if ((sdx = (start_col-block_col)) < 0) sdx = -sdx;		/* src   dx */
1595.     if ((pdy = (block_row-this_row))  < 0) pdy = -pdy;		/* point dy */
1596. 
1597.     if (sdy < 0 || sdy >= CLOSE_MAX_SB_DY || sdx >= CLOSE_MAX_SB_DX ||
1598. 						    pdy >= CLOSE_MAX_BC_DY) {
1599. 	impossible("close_shadow:  bad value");
1600. 	return block_col;
1601.     }
1602.     offset = close_dy[sdy]->close[sdx][pdy];
1603.     if (side == FROM_RIGHT)
1604. 	return block_col + offset;
1605. 
1606.     return block_col - offset;
1607. }
1608. 
1609. 

far_shadow D Edit

1610. STATIC_OVL int
1611. far_shadow(side,this_row,block_row,block_col)
1612.     int side,this_row,block_row,block_col;
1613. {
1614.     register int sdy, sdx, pdy, offset;
1615. 
1616.     /*
1617.      * Take care of a bug that shows up only on the borders.
1618.      *
1619.      * If the block is beyond the border, then the row is negative.  Return
1620.      * the block's column number (should be 0 or COLNO-1).
1621.      *
1622.      * Could easily have the column be -1, but then wouldn't know if it was
1623.      * the left or right border.
1624.      */
1625.     if (block_row < 0) return block_col;
1626. 
1627.     /* Take explicit absolute values.  Adjust. */
1628.     if ((sdy = (start_row-block_row)) < 0) sdy = -sdy;		/* src   dy */
1629.     if ((sdx = (start_col-block_col)) < 0) sdx = -sdx; --sdx;	/* src   dx */
1630.     if ((pdy = (block_row-this_row))  < 0) pdy = -pdy; --pdy;	/* point dy */
1631. 
1632.     if (sdy >= FAR_MAX_SB_DY || sdx < 0 || sdx >= FAR_MAX_SB_DX ||
1633. 					    pdy < 0 || pdy >= FAR_MAX_BC_DY) {
1634. 	impossible("far_shadow:  bad value");
1635. 	return block_col;
1636.     }
1637.     if ((offset = far_dy[sdy]->far_q[sdx][pdy]) == OFF_TABLE) offset = -1;
1638.     if (side == FROM_RIGHT)
1639. 	return block_col + offset;
1640. 
1641.     return block_col - offset;
1642. }
1643. 
1644. 

right_side D Edit

1645. /*
1646.  * right_side()
1647.  *
1648.  * Figure out what could be seen on the right side of the source.
1649.  */
1650. STATIC_OVL void
1651. right_side(row, cb_row, cb_col, fb_row, fb_col, left, right_mark, limits)
1652.     int row;		/* current row */
1653.     int	cb_row, cb_col;	/* close block row and col */
1654.     int	fb_row, fb_col;	/* far block row and col */
1655.     int left;		/* left mark of the previous row */
1656.     int	right_mark;	/* right mark of previous row */
1657.     char *limits;	/* points at range limit for current row, or NULL */
1658. {
1659.     register int  i;
1660.     register char *rowp;
1661.     int  hit_stone = 0;
1662.     int  left_shadow, right_shadow, loc_right;
1663.     int  lblock_col;		/* local block column (current row) */
1664.     int  nrow, deeper;
1665.     char *row_min;		/* left most */
1666.     char *row_max;		/* right most */
1667.     int		  lim_max;	/* right most limit of circle */
1668. 
1669. #ifdef GCC_WARN
1670.     rowp = 0;
1671. #endif
1672.     nrow    = row + step;
1673.     deeper  = good_row(nrow) && (!limits || (*limits >= *(limits+1)));
1674.     if(!vis_func) {
1675. 	rowp    = cs_rows[row];
1676. 	row_min = &cs_left[row];
1677. 	row_max = &cs_right[row];
1678.     }
1679.     if(limits) {
1680. 	lim_max = start_col + *limits;
1681. 	if(lim_max > COLNO-1) lim_max = COLNO-1;
1682. 	if(right_mark > lim_max) right_mark = lim_max;
1683. 	limits++; /* prepare for next row */
1684.     } else
1685. 	lim_max = COLNO-1;
1686. 
1687.     /*
1688.      * Get the left shadow from the close block.  This value could be
1689.      * illegal.
1690.      */
1691.     left_shadow = close_shadow(FROM_RIGHT,row,cb_row,cb_col);
1692. 
1693.     /*
1694.      * Mark all stone walls as seen before the left shadow.  All this work
1695.      * for a special case.
1696.      *
1697.      * NOTE.  With the addition of this code in here, it is now *required*
1698.      * for the algorithm to work correctly.  If this is commented out,
1699.      * change the above assignment so that left and not left_shadow is the
1700.      * variable that gets the shadow.
1701.      */
1702.     while (left <= right_mark) {
1703. 	loc_right = right_ptrs[row][left];
1704. 	if(loc_right > lim_max) loc_right = lim_max;
1705. 	if (viz_clear_rows[row][left]) {
1706. 	    if (loc_right >= left_shadow) {
1707. 		left = left_shadow;	/* opening ends beyond shadow */
1708. 		break;
1709. 	    }
1710. 	    left = loc_right;
1711. 	    loc_right = right_ptrs[row][left];
1712. 	    if(loc_right > lim_max) loc_right = lim_max;
1713. 	    if (left == loc_right) return;	/* boundary */
1714. 
1715. 	    /* Shadow covers opening, beyond right mark */
1716. 	    if (left == right_mark && left_shadow > right_mark) return;
1717. 	}
1718. 
1719. 	if (loc_right > right_mark)	/* can't see stone beyond the mark */
1720. 	    loc_right = right_mark;
1721. 
1722. 	if(vis_func) {
1723. 	    for (i = left; i <= loc_right; i++) (*vis_func)(i, row, varg);
1724. 	} else {
1725. 	    for (i = left; i <= loc_right; i++) set_cs(rowp,i);
1726. 	    set_min(left);	set_max(loc_right);
1727. 	}
1728. 
1729. 	if (loc_right == right_mark) return;	/* all stone */
1730. 	if (loc_right >= left_shadow) hit_stone = 1;
1731. 	left = loc_right + 1;
1732.     }
1733. 
1734.     /*
1735.      * At this point we are at the first visible clear spot on or beyond
1736.      * the left shadow, unless the left shadow is an illegal value.  If we
1737.      * have "hit stone" then we have a stone wall just to our left.
1738.      */
1739. 
1740.     /*
1741.      * Get the right shadow.  Make sure that it is a legal value.
1742.      */
1743.     if ((right_shadow = far_shadow(FROM_RIGHT,row,fb_row,fb_col)) >= COLNO)
1744. 	right_shadow = COLNO-1;
1745.     /*
1746.      * Make vertical walls work the way we want them.  In this case, we
1747.      * note when the close block blocks the column just above/beneath
1748.      * it (right_shadow < fb_col [actually right_shadow == fb_col-1]).  If
1749.      * the location is filled, then we want to see it, so we put the
1750.      * right shadow back (same as fb_col).
1751.      */
1752.     if (right_shadow < fb_col && !viz_clear_rows[row][fb_col])
1753. 	right_shadow = fb_col;
1754.     if(right_shadow > lim_max) right_shadow = lim_max;
1755. 
1756.     /*
1757.      * Main loop.  Within the range of sight of the previous row, mark all
1758.      * stone walls as seen.  Follow open areas recursively.
1759.      */
1760.     while (left <= right_mark) {
1761. 	/* Get the far right of the opening or wall */
1762. 	loc_right = right_ptrs[row][left];
1763. 	if(loc_right > lim_max) loc_right = lim_max;
1764. 
1765. 	if (!viz_clear_rows[row][left]) {
1766. 	    hit_stone = 1;	/* use stone on this row as close block */
1767. 	    /*
1768. 	     * We can see all of the wall until the next open spot or the
1769. 	     * start of the shadow caused by the far block (right).
1770. 	     *
1771. 	     * Can't see stone beyond the right mark.
1772. 	     */
1773. 	    if (loc_right > right_mark) loc_right = right_mark;
1774. 
1775. 	    if(vis_func) {
1776. 		for (i = left; i <= loc_right; i++) (*vis_func)(i, row, varg);
1777. 	    } else {
1778. 		for (i = left; i <= loc_right; i++) set_cs(rowp,i);
1779. 		set_min(left);	set_max(loc_right);
1780. 	    }
1781. 
1782. 	    if (loc_right == right_mark) return;	/* hit the end */
1783. 	    left = loc_right + 1;
1784. 	    loc_right = right_ptrs[row][left];
1785. 	    if(loc_right > lim_max) loc_right = lim_max;
1786. 	    /* fall through... we know at least one position is visible */
1787. 	}
1788. 
1789. 	/*
1790. 	 * We are in an opening.
1791. 	 *
1792. 	 * If this is the first open spot since the could see area  (this is
1793. 	 * true if we have hit stone), get the shadow generated by the wall
1794. 	 * just to our left.
1795. 	 */
1796. 	if (hit_stone) {
1797. 	    lblock_col = left-1;	/* local block column */
1798. 	    left = close_shadow(FROM_RIGHT,row,row,lblock_col);
1799. 	    if (left > lim_max) break;		/* off the end */
1800. 	}
1801. 
1802. 	/*
1803. 	 * Check if the shadow covers the opening.  If it does, then
1804. 	 * move to end of the opening.  A shadow generated on from a
1805. 	 * wall on this row does *not* cover the wall on the right
1806. 	 * of the opening.
1807. 	 */
1808. 	if (left >= loc_right) {
1809. 	    if (loc_right == lim_max) {		/* boundary */
1810. 		if (left == lim_max) {
1811. 		    if(vis_func) (*vis_func)(lim_max, row, varg);
1812. 		    else {
1813. 			set_cs(rowp,lim_max);	/* last pos */
1814. 			set_max(lim_max);
1815. 		    }
1816. 		}
1817. 		return;					/* done */
1818. 	    }
1819. 	    left = loc_right;
1820. 	    continue;
1821. 	}
1822. 
1823. 	/*
1824. 	 * If the far wall of the opening (loc_right) is closer than the
1825. 	 * shadow limit imposed by the far block (right) then use the far
1826. 	 * wall as our new far block when we recurse.
1827. 	 *
1828. 	 * If the limits are the the same, and the far block really exists
1829. 	 * (fb_row >= 0) then do the same as above.
1830. 	 *
1831. 	 * Normally, the check would be for the far wall being closer OR EQUAL
1832. 	 * to the shadow limit.  However, there is a bug that arises from the
1833. 	 * fact that the clear area pointers end in an open space (if it
1834. 	 * exists) on a boundary.  This then makes a far block exist where it
1835. 	 * shouldn't --- on a boundary.  To get around that, I had to
1836. 	 * introduce the concept of a non-existent far block (when the
1837. 	 * row < 0).  Next I have to check for it.  Here is where that check
1838. 	 * exists.
1839. 	 */
1840. 	if ((loc_right < right_shadow) ||
1841. 				(fb_row >= 0 && loc_right == right_shadow)) {
1842. 	    if(vis_func) {
1843. 		for (i = left; i <= loc_right; i++) (*vis_func)(i, row, varg);
1844. 	    } else {
1845. 		for (i = left; i <= loc_right; i++) set_cs(rowp,i);
1846. 		set_min(left);	set_max(loc_right);
1847. 	    }
1848. 
1849. 	    if (deeper) {
1850. 		if (hit_stone)
1851. 		    right_side(nrow,row,lblock_col,row,loc_right,
1852. 							left,loc_right,limits);
1853. 		else
1854. 		    right_side(nrow,cb_row,cb_col,row,loc_right,
1855. 							left,loc_right,limits);
1856. 	    }
1857. 
1858. 	    /*
1859. 	     * The following line, setting hit_stone, is needed for those
1860. 	     * walls that are only 1 wide.  If hit stone is *not* set and
1861. 	     * the stone is only one wide, then the close block is the old
1862. 	     * one instead one on the current row.  A way around having to
1863. 	     * set it here is to make left = loc_right (not loc_right+1) and
1864. 	     * let the outer loop take care of it.  However, if we do that
1865. 	     * then we then have to check for boundary conditions here as
1866. 	     * well.
1867. 	     */
1868. 	    hit_stone = 1;
1869. 
1870. 	    left = loc_right+1;
1871. 	}
1872. 	/*
1873. 	 * The opening extends beyond the right mark.  This means that
1874. 	 * the next far block is the current far block.
1875. 	 */
1876. 	else {
1877. 	    if(vis_func) {
1878. 		for (i=left; i <= right_shadow; i++) (*vis_func)(i, row, varg);
1879. 	    } else {
1880. 		for (i = left; i <= right_shadow; i++) set_cs(rowp,i);
1881. 		set_min(left);	set_max(right_shadow);
1882. 	    }
1883. 
1884. 	    if (deeper) {
1885. 		if (hit_stone)
1886. 		    right_side(nrow,   row,lblock_col,fb_row,fb_col,
1887. 						     left,right_shadow,limits);
1888. 		else
1889. 		    right_side(nrow,cb_row,    cb_col,fb_row,fb_col,
1890. 						     left,right_shadow,limits);
1891. 	    }
1892. 
1893. 	    return;	/* we're outta here */
1894. 	}
1895.     }
1896. }
1897. 
1898. 

left_side D Edit

1899. /*
1900.  * left_side()
1901.  *
1902.  * This routine is the mirror image of right_side().  Please see right_side()
1903.  * for blow by blow comments.
1904.  */
1905. STATIC_OVL void
1906. left_side(row, cb_row, cb_col, fb_row, fb_col, left_mark, right, limits)
1907.     int row;		/* the current row */
1908.     int	cb_row, cb_col;	/* close block row and col */
1909.     int	fb_row, fb_col;	/* far block row and col */
1910.     int	left_mark;	/* left mark of previous row */
1911.     int right;		/* right mark of the previous row */
1912.     char *limits;
1913. {
1914.     register int  i;
1915.     register char *rowp;
1916.     int  hit_stone = 0;
1917.     int  left_shadow, right_shadow, loc_left;
1918.     int  lblock_col;		/* local block column (current row) */
1919.     int  nrow, deeper;
1920.     char *row_min;		/* left most */
1921.     char *row_max;		/* right most */
1922.     int		  lim_min;
1923. 
1924. #ifdef GCC_WARN
1925.     rowp = 0;
1926. #endif
1927.     nrow    = row + step;
1928.     deeper  = good_row(nrow) && (!limits || (*limits >= *(limits+1)));
1929.     if(!vis_func) {
1930. 	rowp    = cs_rows[row];
1931. 	row_min = &cs_left[row];
1932. 	row_max = &cs_right[row];
1933.     }
1934.     if(limits) {
1935. 	lim_min = start_col - *limits;
1936. 	if(lim_min < 0) lim_min = 0;
1937. 	if(left_mark < lim_min) left_mark = lim_min;
1938. 	limits++; /* prepare for next row */
1939.     } else
1940. 	lim_min = 0;
1941. 
1942.     /* This value could be illegal. */
1943.     right_shadow = close_shadow(FROM_LEFT,row,cb_row,cb_col);
1944. 
1945.     while ( right >= left_mark ) {
1946. 	loc_left = left_ptrs[row][right];
1947. 	if(loc_left < lim_min) loc_left = lim_min;
1948. 	if (viz_clear_rows[row][right]) {
1949. 	    if (loc_left <= right_shadow) {
1950. 		right = right_shadow;	/* opening ends beyond shadow */
1951. 		break;
1952. 	    }
1953. 	    right = loc_left;
1954. 	    loc_left = left_ptrs[row][right];
1955. 	    if(loc_left < lim_min) loc_left = lim_min;
1956. 	    if (right == loc_left) return;	/* boundary */
1957. 	}
1958. 
1959. 	if (loc_left < left_mark)	/* can't see beyond the left mark */
1960. 	    loc_left = left_mark;
1961. 
1962. 	if(vis_func) {
1963. 	    for (i = loc_left; i <= right; i++) (*vis_func)(i, row, varg);
1964. 	} else {
1965. 	    for (i = loc_left; i <= right; i++) set_cs(rowp,i);
1966. 	    set_min(loc_left);	set_max(right);
1967. 	}
1968. 
1969. 	if (loc_left == left_mark) return;	/* all stone */
1970. 	if (loc_left <= right_shadow) hit_stone = 1;
1971. 	right = loc_left - 1;
1972.     }
1973. 
1974.     /* At first visible clear spot on or beyond the right shadow. */
1975. 
1976.     if ((left_shadow = far_shadow(FROM_LEFT,row,fb_row,fb_col)) < 0)
1977. 	left_shadow = 0;
1978. 
1979.     /* Do vertical walls as we want. */
1980.     if (left_shadow > fb_col && !viz_clear_rows[row][fb_col])
1981. 	left_shadow = fb_col;
1982.     if(left_shadow < lim_min) left_shadow = lim_min;
1983. 
1984.     while (right >= left_mark) {
1985. 	loc_left = left_ptrs[row][right];
1986. 
1987. 	if (!viz_clear_rows[row][right]) {
1988. 	    hit_stone = 1;	/* use stone on this row as close block */
1989. 
1990. 	    /* We can only see walls until the left mark */
1991. 	    if (loc_left < left_mark) loc_left = left_mark;
1992. 
1993. 	    if(vis_func) {
1994. 		for (i = loc_left; i <= right; i++) (*vis_func)(i, row, varg);
1995. 	    } else {
1996. 		for (i = loc_left; i <= right; i++) set_cs(rowp,i);
1997. 		set_min(loc_left);	set_max(right);
1998. 	    }
1999. 
2000. 	    if (loc_left == left_mark) return;	/* hit end */
2001. 	    right = loc_left - 1;
2002. 	    loc_left = left_ptrs[row][right];
2003. 	    if (loc_left < lim_min) loc_left = lim_min;
2004. 	    /* fall through...*/
2005. 	}
2006. 
2007. 	/* We are in an opening. */
2008. 	if (hit_stone) {
2009. 	    lblock_col = right+1;	/* stone block (local) */
2010. 	    right = close_shadow(FROM_LEFT,row,row,lblock_col);
2011. 	    if (right < lim_min) return;	/* off the end */
2012. 	}
2013. 
2014. 	/*  Check if the shadow covers the opening. */
2015. 	if (right <= loc_left) {
2016. 	    /*  Make a boundary condition work. */
2017. 	    if (loc_left == lim_min) {	/* at boundary */
2018. 		if (right == lim_min) {
2019. 		    if(vis_func) (*vis_func)(lim_min, row, varg);
2020. 		    else {
2021. 			set_cs(rowp,lim_min);	/* caught the last pos */
2022. 			set_min(lim_min);
2023. 		    }
2024. 		}
2025. 		return;			/* and break out the loop */
2026. 	    }
2027. 
2028. 	    right = loc_left;
2029. 	    continue;
2030. 	}
2031. 
2032. 	/* If the far wall of the opening is closer than the shadow limit. */
2033. 	if ((loc_left > left_shadow) ||
2034. 				    (fb_row >= 0 && loc_left == left_shadow)) {
2035. 	    if(vis_func) {
2036. 		for (i = loc_left; i <= right; i++) (*vis_func)(i, row, varg);
2037. 	    } else {
2038. 		for (i = loc_left; i <= right; i++) set_cs(rowp,i);
2039. 		set_min(loc_left);	set_max(right);
2040. 	    }
2041. 
2042. 	    if (deeper) {
2043. 		if (hit_stone)
2044. 		    left_side(nrow,row,lblock_col,row,loc_left,
2045. 							loc_left,right,limits);
2046. 		else
2047. 		    left_side(nrow,cb_row,cb_col,row,loc_left,
2048. 							loc_left,right,limits);
2049. 	    }
2050. 
2051. 	    hit_stone = 1;	/* needed for walls of width 1 */
2052. 	    right = loc_left-1;
2053. 	}
2054. 	/*  The opening extends beyond the left mark. */
2055. 	else {
2056. 	    if(vis_func) {
2057. 		for (i=left_shadow; i <= right; i++) (*vis_func)(i, row, varg);
2058. 	    } else {
2059. 		for (i = left_shadow; i <= right; i++) set_cs(rowp,i);
2060. 		set_min(left_shadow);	set_max(right);
2061. 	    }
2062. 
2063. 	    if (deeper) {
2064. 		if (hit_stone)
2065. 		    left_side(nrow,row,lblock_col,fb_row,fb_col,
2066. 						     left_shadow,right,limits);
2067. 		else
2068. 		    left_side(nrow,cb_row,cb_col,fb_row,fb_col,
2069. 						     left_shadow,right,limits);
2070. 	    }
2071. 
2072. 	    return;	/* we're outta here */
2073. 	}
2074. 
2075.     }
2076. }
2077. 

view_from D Edit

2078. /*
2079.  * view_from
2080.  *
2081.  * Calculate a view from the given location.  Initialize and fill a
2082.  * ROWNOxCOLNO array (could_see) with all the locations that could be
2083.  * seen from the source location.  Initialize and fill the left most
2084.  * and right most boundaries of what could be seen.
2085.  */
2086. STATIC_OVL void
2087. view_from(srow,scol,loc_cs_rows,left_most,right_most, range, func, arg)
2088.     int  srow, scol;			/* source row and column */
2089.     char **loc_cs_rows;			/* could_see array (row pointers) */
2090.     char *left_most, *right_most;	/* limits of what could be seen */
2091.     int range;		/* 0 if unlimited */
2092.     void FDECL((*func), (int,int,genericptr_t));
2093.     genericptr_t arg;
2094. {
2095.     register int i;
2096.     char	 *rowp;
2097.     int		 nrow, left, right, left_row, right_row;
2098.     char	 *limits;
2099. 
2100.     /* Set globals for near_shadow(), far_shadow(), etc. to use. */
2101.     start_col = scol;
2102.     start_row = srow;
2103.     cs_rows   = loc_cs_rows;
2104.     cs_left   = left_most;
2105.     cs_right  = right_most;
2106.     vis_func = func;
2107.     varg = arg;
2108. 
2109.     /*  Find the left and right limits of sight on the starting row. */
2110.     if (viz_clear_rows[srow][scol]) {
2111. 	left  = left_ptrs[srow][scol];
2112. 	right = right_ptrs[srow][scol];
2113.     } else {
2114. 	left  = (!scol) ? 0 :
2115. 	    (viz_clear_rows[srow][scol-1] ?  left_ptrs[srow][scol-1] : scol-1);
2116. 	right = (scol == COLNO-1) ? COLNO-1 :
2117. 	    (viz_clear_rows[srow][scol+1] ? right_ptrs[srow][scol+1] : scol+1);
2118.     }
2119. 
2120.     if(range) {
2121. 	if(range > MAX_RADIUS || range < 1)
2122. 	    panic("view_from called with range %d", range);
2123. 	limits = circle_ptr(range) + 1; /* start at next row */
2124. 	if(left < scol - range) left = scol - range;
2125. 	if(right > scol + range) right = scol + range;
2126.     } else
2127. 	limits = (char*) 0;
2128. 
2129.     if(func) {
2130. 	for (i = left; i <= right; i++) (*func)(i, srow, arg);
2131.     } else {
2132. 	/* Row optimization */
2133. 	rowp = cs_rows[srow];
2134. 
2135. 	/* We know that we can see our row. */
2136. 	for (i = left; i <= right; i++) set_cs(rowp,i);
2137. 	cs_left[srow]  = left;
2138. 	cs_right[srow] = right;
2139.     }
2140. 
2141.     /* The far block has a row number of -1 if we are on an edge. */
2142.     right_row = (right == COLNO-1) ? -1 : srow;
2143.     left_row  = (!left)		   ? -1 : srow;
2144. 
2145.     /*
2146.      *  Check what could be seen in quadrants.
2147.      */
2148.     if ( (nrow = srow+1) < ROWNO ) {
2149. 	step =  1;	/* move down */
2150. 	if (scol<COLNO-1)
2151. 	    right_side(nrow,-1,scol,right_row,right,scol,right,limits);
2152. 	if (scol)
2153. 	    left_side(nrow,-1,scol,left_row, left, left, scol,limits);
2154.     }
2155. 
2156.     if ( (nrow = srow-1) >= 0 ) {
2157. 	step = -1;	/* move up */
2158. 	if (scol<COLNO-1)
2159. 	    right_side(nrow,-1,scol,right_row,right,scol,right,limits);
2160. 	if (scol)
2161. 	    left_side(nrow,-1,scol,left_row, left, left, scol,limits);
2162.     }
2163. }
2164. 
2165. 
2166. #else	/*===== End of algorithm D =====*/
2167. 
2168. 

Algorithm C Edit

2169. /*===========================================================================*\
2170. 			    GENERAL LINE OF SIGHT
2171. 				Algorithm C
2172. \*===========================================================================*/
2173. 
2174. /*
2175.  * Defines local to Algorithm C.
2176.  */
2177. STATIC_DCL void FDECL(right_side, (int,int,int,char*));
2178. STATIC_DCL void FDECL(left_side, (int,int,int,char*));
2179. 

view_init C Edit

2180. /* Initialize algorithm C (nothing). */
2181. STATIC_OVL void
2182. view_init()
2183. {
2184. }
2185. 

right_side C Edit

2186. /*
2187.  * Mark positions as visible on one quadrant of the right side.  The
2188.  * quadrant is determined by the value of the global variable step.
2189.  */
2190. STATIC_OVL void
2191. right_side(row, left, right_mark, limits)
2192.     int row;		/* current row */
2193.     int left;		/* first (left side) visible spot on prev row */
2194.     int right_mark;	/* last (right side) visible spot on prev row */
2195.     char *limits;	/* points at range limit for current row, or NULL */
2196. {
2197.     int		  right;	/* right limit of "could see" */
2198.     int		  right_edge;	/* right edge of an opening */
2199.     int		  nrow;		/* new row (calculate once) */
2200.     int		  deeper;	/* if TRUE, call self as needed */
2201.     int		  result;	/* set by q?_path() */
2202.     register int  i;		/* loop counter */
2203.     register char *rowp;	/* row optimization */
2204.     char	  *row_min;	/* left most  [used by macro set_min()] */
2205.     char	  *row_max;	/* right most [used by macro set_max()] */
2206.     int		  lim_max;	/* right most limit of circle */
2207. 
2208. #ifdef GCC_WARN
2209.     rowp = row_min = row_max = 0;
2210. #endif
2211.     nrow    = row + step;
2212.     /*
2213.      * Can go deeper if the row is in bounds and the next row is within
2214.      * the circle's limit.  We tell the latter by checking to see if the next
2215.      * limit value is the start of a new circle radius (meaning we depend
2216.      * on the structure of circle_data[]).
2217.      */
2218.     deeper  = good_row(nrow) && (!limits || (*limits >= *(limits+1)));
2219.     if(!vis_func) {
2220. 	rowp    = cs_rows[row];	/* optimization */
2221. 	row_min = &cs_left[row];
2222. 	row_max = &cs_right[row];
2223.     }
2224.     if(limits) {
2225. 	lim_max = start_col + *limits;
2226. 	if(lim_max > COLNO-1) lim_max = COLNO-1;
2227. 	if(right_mark > lim_max) right_mark = lim_max;
2228. 	limits++; /* prepare for next row */
2229.     } else
2230. 	lim_max = COLNO-1;
2231. 
2232.     while (left <= right_mark) {
2233. 	right_edge = right_ptrs[row][left];
2234. 	if(right_edge > lim_max) right_edge = lim_max;
2235. 
2236. 	if (!is_clear(row,left)) {
2237. 	    /*
2238. 	     * Jump to the far side of a stone wall.  We can set all
2239. 	     * the points in between as seen.
2240. 	     *
2241. 	     * If the right edge goes beyond the right mark, check to see
2242. 	     * how much we can see.
2243. 	     */
2244. 	    if (right_edge > right_mark) {
2245. 		/*
2246. 		 * If the mark on the previous row was a clear position,
2247. 		 * the odds are that we can actually see part of the wall
2248. 		 * beyond the mark on this row.  If so, then see one beyond
2249. 		 * the mark.  Otherwise don't.  This is a kludge so corners
2250. 		 * with an adjacent doorway show up in nethack.
2251. 		 */
2252. 		right_edge = is_clear(row-step,right_mark) ?
2253. 						    right_mark+1 : right_mark;
2254. 	    }
2255. 	    if(vis_func) {
2256. 		for (i = left; i <= right_edge; i++) (*vis_func)(i, row, varg);
2257. 	    } else {
2258. 		for (i = left; i <= right_edge; i++) set_cs(rowp,i);
2259. 		set_min(left);      set_max(right_edge);
2260. 	    }
2261. 	    left = right_edge + 1; /* no limit check necessary */
2262. 	    continue;
2263. 	}
2264. 
2265. 	/* No checking needed if our left side is the start column. */
2266. 	if (left != start_col) {
2267. 	    /*
2268. 	     * Find the left side.  Move right until we can see it or we run
2269. 	     * into a wall.
2270. 	     */
2271. 	    for (; left <= right_edge; left++) {
2272. 		if (step < 0) {
2273. 		    q1_path(start_row,start_col,row,left,rside1);
2274. 		} else {
2275. 		    q4_path(start_row,start_col,row,left,rside1);
2276. 		}
2277. rside1:					/* used if q?_path() is a macro */
2278. 		if (result) break;
2279. 	    }
2280. 
2281. 	    /*
2282. 	     * Check for boundary conditions.  We *need* check (2) to break
2283. 	     * an infinite loop where:
2284. 	     *
2285. 	     *		left == right_edge == right_mark == lim_max.
2286. 	     *
2287. 	     */
2288. 	    if (left > lim_max) return;	/* check (1) */
2289. 	    if (left == lim_max) {	/* check (2) */
2290. 		if(vis_func) (*vis_func)(lim_max, row, varg);
2291. 		else {
2292. 		    set_cs(rowp,lim_max);
2293. 		    set_max(lim_max);
2294. 		}
2295. 		return;
2296. 	    }
2297. 	    /*
2298. 	     * Check if we can see any spots in the opening.  We might
2299. 	     * (left == right_edge) or might not (left == right_edge+1) have
2300. 	     * been able to see the far wall.  Make sure we *can* see the
2301. 	     * wall (remember, we can see the spot above/below this one)
2302. 	     * by backing up.
2303. 	     */
2304. 	    if (left >= right_edge) {
2305. 		left = right_edge;	/* for the case left == right_edge+1 */
2306. 		continue;
2307. 	    }
2308. 	}
2309. 
2310. 	/*
2311. 	 * Find the right side.  If the marker from the previous row is
2312. 	 * closer than the edge on this row, then we have to check
2313. 	 * how far we can see around the corner (under the overhang).  Stop
2314. 	 * at the first non-visible spot or we actually hit the far wall.
2315. 	 *
2316. 	 * Otherwise, we know we can see the right edge of the current row.
2317. 	 *
2318. 	 * This must be a strict less than so that we can always see a
2319. 	 * horizontal wall, even if it is adjacent to us.
2320. 	 */
2321. 	if (right_mark < right_edge) {
2322. 	    for (right = right_mark; right <= right_edge; right++) {
2323. 		if (step < 0) {
2324. 		    q1_path(start_row,start_col,row,right,rside2);
2325. 		} else {
2326. 		    q4_path(start_row,start_col,row,right,rside2);
2327. 		}
2328. rside2:					/* used if q?_path() is a macro */
2329. 		if (!result) break;
2330. 	    }
2331. 	    --right;	/* get rid of the last increment */
2332. 	}
2333. 	else
2334. 	    right = right_edge;
2335. 
2336. 	/*
2337. 	 * We have the range that we want.  Set the bits.  Note that
2338. 	 * there is no else --- we no longer handle splinters.
2339. 	 */
2340. 	if (left <= right) {
2341. 	    /*
2342. 	     * An ugly special case.  If you are adjacent to a vertical wall
2343. 	     * and it has a break in it, then the right mark is set to be
2344. 	     * start_col.  We *want* to be able to see adjacent vertical
2345. 	     * walls, so we have to set it back.
2346. 	     */
2347. 	    if (left == right && left == start_col &&
2348. 			start_col < (COLNO-1) && !is_clear(row,start_col+1))
2349. 		right = start_col+1;
2350. 
2351. 	    if(right > lim_max) right = lim_max;
2352. 	    /* set the bits */
2353. 	    if(vis_func)
2354. 		for (i = left; i <= right; i++) (*vis_func)(i, row, varg);
2355. 	    else {
2356. 		for (i = left; i <= right; i++) set_cs(rowp,i);
2357. 		set_min(left);      set_max(right);
2358. 	    }
2359. 
2360. 	    /* recursive call for next finger of light */
2361. 	    if (deeper) right_side(nrow,left,right,limits);
2362. 	    left = right + 1; /* no limit check necessary */
2363. 	}
2364.     }
2365. }
2366. 
2367. 

left_side C Edit

2368. /*
2369.  * This routine is the mirror image of right_side().  See right_side() for
2370.  * extensive comments.
2371.  */
2372. STATIC_OVL void
2373. left_side(row, left_mark, right, limits)
2374.     int row, left_mark, right;
2375.     char *limits;
2376. {
2377.     int		  left, left_edge, nrow, deeper, result;
2378.     register int  i;
2379.     register char *rowp;
2380.     char	  *row_min, *row_max;
2381.     int		  lim_min;
2382. 
2383. #ifdef GCC_WARN
2384.     rowp = row_min = row_max = 0;
2385. #endif
2386.     nrow    = row+step;
2387.     deeper  = good_row(nrow) && (!limits || (*limits >= *(limits+1)));
2388.     if(!vis_func) {
2389. 	rowp    = cs_rows[row];
2390. 	row_min = &cs_left[row];
2391. 	row_max = &cs_right[row];
2392.     }
2393.     if(limits) {
2394. 	lim_min = start_col - *limits;
2395. 	if(lim_min < 0) lim_min = 0;
2396. 	if(left_mark < lim_min) left_mark = lim_min;
2397. 	limits++; /* prepare for next row */
2398.     } else
2399. 	lim_min = 0;
2400. 
2401.     while (right >= left_mark) {
2402. 	left_edge = left_ptrs[row][right];
2403. 	if(left_edge < lim_min) left_edge = lim_min;
2404. 
2405. 	if (!is_clear(row,right)) {
2406. 	    /* Jump to the far side of a stone wall. */
2407. 	    if (left_edge < left_mark) {
2408. 		/* Maybe see more (kludge). */
2409. 		left_edge = is_clear(row-step,left_mark) ?
2410. 						    left_mark-1 : left_mark;
2411. 	    }
2412. 	    if(vis_func) {
2413. 		for (i = left_edge; i <= right; i++) (*vis_func)(i, row, varg);
2414. 	    } else {
2415. 		for (i = left_edge; i <= right; i++) set_cs(rowp,i);
2416. 		set_min(left_edge); set_max(right);
2417. 	    }
2418. 	    right = left_edge - 1; /* no limit check necessary */
2419. 	    continue;
2420. 	}
2421. 
2422. 	if (right != start_col) {
2423. 	    /* Find the right side. */
2424. 	    for (; right >= left_edge; right--) {
2425. 		if (step < 0) {
2426. 		    q2_path(start_row,start_col,row,right,lside1);
2427. 		} else {
2428. 		    q3_path(start_row,start_col,row,right,lside1);
2429. 		}
2430. lside1:					/* used if q?_path() is a macro */
2431. 		if (result) break;
2432. 	    }
2433. 
2434. 	    /* Check for boundary conditions. */
2435. 	    if (right < lim_min) return;
2436. 	    if (right == lim_min) {
2437. 		if(vis_func) (*vis_func)(lim_min, row, varg);
2438. 		else {
2439. 		    set_cs(rowp,lim_min);
2440. 		    set_min(lim_min);
2441. 		}
2442. 		return;
2443. 	    }
2444. 	    /* Check if we can see any spots in the opening. */
2445. 	    if (right <= left_edge) {
2446. 		right = left_edge;
2447. 		continue;
2448. 	    }
2449. 	}
2450. 
2451. 	/* Find the left side. */
2452. 	if (left_mark > left_edge) {
2453. 	    for (left = left_mark; left >= left_edge; --left) {
2454. 		if (step < 0) {
2455. 		    q2_path(start_row,start_col,row,left,lside2);
2456. 		} else {
2457. 		    q3_path(start_row,start_col,row,left,lside2);
2458. 		}
2459. lside2:					/* used if q?_path() is a macro */
2460. 		if (!result) break;
2461. 	    }
2462. 	    left++;	/* get rid of the last decrement */
2463. 	}
2464. 	else
2465. 	    left = left_edge;
2466. 
2467. 	if (left <= right) {
2468. 	    /* An ugly special case. */
2469. 	    if (left == right && right == start_col &&
2470. 			    start_col > 0 && !is_clear(row,start_col-1))
2471. 		left = start_col-1;
2472. 
2473. 	    if(left < lim_min) left = lim_min;
2474. 	    if(vis_func)
2475. 		for (i = left; i <= right; i++) (*vis_func)(i, row, varg);
2476. 	    else {
2477. 		for (i = left; i <= right; i++) set_cs(rowp,i);
2478. 		set_min(left);      set_max(right);
2479. 	    }
2480. 
2481. 	    /* Recurse */
2482. 	    if (deeper) left_side(nrow,left,right,limits);
2483. 	    right = left - 1; /* no limit check necessary */
2484. 	}
2485.     }
2486. }
2487. 
2488. 

view_from C Edit

2489. /*
2490.  * Calculate all possible visible locations from the given location
2491.  * (srow,scol).  NOTE this is (y,x)!  Mark the visible locations in the
2492.  * array provided.
2493.  */
2494. STATIC_OVL void
2495. view_from(srow, scol, loc_cs_rows, left_most, right_most, range, func, arg)
2496.     int  srow, scol;	/* starting row and column */
2497.     char **loc_cs_rows;	/* pointers to the rows of the could_see array */
2498.     char *left_most;	/* min mark on each row */
2499.     char *right_most;	/* max mark on each row */
2500.     int range;		/* 0 if unlimited */
2501.     void FDECL((*func), (int,int,genericptr_t));
2502.     genericptr_t arg;
2503. {
2504.     register int i;		/* loop counter */
2505.     char         *rowp;		/* optimization for setting could_see */
2506.     int		 nrow;		/* the next row */
2507.     int		 left;		/* the left-most visible column */
2508.     int		 right;		/* the right-most visible column */
2509.     char	 *limits;	/* range limit for next row */
2510. 
2511.     /* Set globals for q?_path(), left_side(), and right_side() to use. */
2512.     start_col = scol;
2513.     start_row = srow;
2514.     cs_rows   = loc_cs_rows;	/* 'could see' rows */
2515.     cs_left   = left_most;
2516.     cs_right  = right_most;
2517.     vis_func = func;
2518.     varg = arg;
2519. 
2520.     /*
2521.      * Determine extent of sight on the starting row.
2522.      */
2523.     if (is_clear(srow,scol)) {
2524. 	left =  left_ptrs[srow][scol];
2525. 	right = right_ptrs[srow][scol];
2526.     } else {
2527. 	/*
2528. 	 * When in stone, you can only see your adjacent squares, unless
2529. 	 * you are on an array boundary or a stone/clear boundary.
2530. 	 */
2531. 	left  = (!scol) ? 0 :
2532. 		(is_clear(srow,scol-1) ? left_ptrs[srow][scol-1] : scol-1);
2533. 	right = (scol == COLNO-1) ? COLNO-1 :
2534. 		(is_clear(srow,scol+1) ? right_ptrs[srow][scol+1] : scol+1);
2535.     }
2536. 
2537.     if(range) {
2538. 	if(range > MAX_RADIUS || range < 1)
2539. 	    panic("view_from called with range %d", range);
2540. 	limits = circle_ptr(range) + 1; /* start at next row */
2541. 	if(left < scol - range) left = scol - range;
2542. 	if(right > scol + range) right = scol + range;
2543.     } else
2544. 	limits = (char*) 0;
2545. 
2546.     if(func) {
2547. 	for (i = left; i <= right; i++) (*func)(i, srow, arg);
2548.     } else {
2549. 	/* Row pointer optimization. */
2550. 	rowp = cs_rows[srow];
2551. 
2552. 	/* We know that we can see our row. */
2553. 	for (i = left; i <= right; i++) set_cs(rowp,i);
2554. 	cs_left[srow]  = left;
2555. 	cs_right[srow] = right;
2556.     }
2557. 
2558.     /*
2559.      * Check what could be seen in quadrants.  We need to check for valid
2560.      * rows here, since we don't do it in the routines right_side() and
2561.      * left_side() [ugliness to remove extra routine calls].
2562.      */
2563.     if ( (nrow = srow+1) < ROWNO ) {	/* move down */
2564. 	step =  1;
2565. 	if (scol < COLNO-1) right_side(nrow, scol, right, limits);
2566. 	if (scol)	    left_side (nrow, left,  scol, limits);
2567.     }
2568. 
2569.     if ( (nrow = srow-1) >= 0 ) {	/* move up */
2570. 	step = -1;
2571. 	if (scol < COLNO-1) right_side(nrow, scol, right, limits);
2572. 	if (scol)	    left_side (nrow, left,  scol, limits);
2573.     }
2574. }
2575. 
2576. #endif	/*===== End of algorithm C =====*/
2577. 

do_clear_area Edit

2578. /*
2579.  * AREA OF EFFECT "ENGINE"
2580.  *
2581.  * Calculate all possible visible locations as viewed from the given location
2582.  * (srow,scol) within the range specified. Perform "func" with (x, y) args and
2583.  * additional argument "arg" for each square.
2584.  *
2585.  * If not centered on the hero, just forward arguments to view_from(); it
2586.  * will call "func" when necessary.  If the hero is the center, use the
2587.  * vision matrix and reduce extra work.
2588.  */
2589. void
2590. do_clear_area(scol,srow,range,func,arg)
2591.     int scol, srow, range;
2592.     void FDECL((*func), (int,int,genericptr_t));
2593.     genericptr_t arg;
2594. {
2595. 	/* If not centered on hero, do the hard work of figuring the area */
2596. 	if (scol != u.ux || srow != u.uy)
2597. 	    view_from(srow, scol, (char **)0, (char *)0, (char *)0,
2598. 							range, func, arg);
2599. 	else {
2600. 	    register int x;
2601. 	    int y, min_x, max_x, max_y, offset;
2602. 	    char *limits;
2603. 
2604. 	    if (range > MAX_RADIUS || range < 1)
2605. 		panic("do_clear_area:  illegal range %d", range);
2606. 	    if(vision_full_recalc)
2607. 		vision_recalc(0);	/* recalc vision if dirty */
2608. 	    limits = circle_ptr(range);
2609. 	    if ((max_y = (srow + range)) >= ROWNO) max_y = ROWNO-1;
2610. 	    if ((y = (srow - range)) < 0) y = 0;
2611. 	    for (; y <= max_y; y++) {
2612. 		offset = limits[v_abs(y-srow)];
2613. 		if((min_x = (scol - offset)) < 0) min_x = 0;
2614. 		if((max_x = (scol + offset)) >= COLNO) max_x = COLNO-1;
2615. 		for (x = min_x; x <= max_x; x++)
2616. 		    if (couldsee(x, y))
2617. 			(*func)(x, y, arg);
2618. 	    }
2619. 	}
2620. }
2621. 
2622. /*vision.c*/

Around Wikia's network

Random Wiki