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Below is the full text to light.c from the source code of NetHack 3.2.0. To link to a particular line, write [[NetHack 3.2.0/light.c#line123]], for example.

Warning! This is the source code from an old release. For the latest release, see Source code

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1.    /*	SCCS Id: @(#)light.c	3.2	96/03/07	*/
2.    /* Copyright (c) Dean Luick, 1994					*/
3.    /* NetHack may be freely redistributed.  See license for details.	*/
4.    
5.    #include "hack.h"
6.    #include "lev.h"	/* for checking save modes */
7.    
8.    /*
9.     * Mobile light sources.
10.    *
11.    * This implementation minimizes memory at the expense of extra
12.    * recalculations.
13.    *
14.    * Light sources are "things" that have a physical position and range.
15.    * They have a type, which gives us information about them.  Currently
16.    * they are only attached to objects and monsters.  Note well:  the
17.    * polymorphed-player handling assumes that both youmonst.m_id and
18.    * youmonst.mx will always remain 0.
19.    *
20.    * Light sources, like timers, either follow game play (RANGE_GLOBAL) or
21.    * stay on a level (RANGE_LEVEL).  Light sources are unique by their
22.    * (type, id) pair.  For light sources attached to objects, this id
23.    * is a pointer to the object.
24.    *
25.    * The major working function is do_light_sources(). It is called
26.    * when the vision system is recreating its "could see" array.  Here
27.    * we add a flag (TEMP_LIT) to the array for all locations that are lit
28.    * via a light source.  The bad part of this is that we have to
29.    * re-calculate the LOS of each light source every time the vision
30.    * system runs.  Even if the light sources and any topology (vision blocking
31.    * positions) have not changed.  The good part is that no extra memory
32.    * is used, plus we don't have to figure out how far the sources have moved,
33.    * or if the topology has changed.
34.    *
35.    * The structure of the save/restore mechanism is amazingly similar to
36.    * the timer save/restore.  This is because they both have the same
37.    * principals of having pointers into objects that must be recalculated
38.    * across saves and restores.
39.    */
40.   
41.   #ifdef OVL3
42.   
43.   typedef struct ls_t {
44.       struct ls_t *next;
45.       xchar x, y;		/* source's position */
46.       short range;	/* source's current range */
47.       short flags;
48.       short type;		/* type of light source */
49.       genericptr_t id;	/* source's identifier */
50.   } light_source;
51.   
52.   /* flags */
53.   #define LSF_SHOW	0x1		/* display the light source */
54.   #define LSF_NEEDS_FIXUP	0x2		/* need oid fixup */
55.   
56.   static light_source *light_base = 0;
57.   
58.   static struct monst *FDECL(find_mid, (unsigned));
59.   static void FDECL(write_ls, (int, light_source *));
60.   static int FDECL(maybe_write_ls, (int, int, BOOLEAN_P));
61.   
62.   /* imported from vision.c, for small circles */
63.   extern char circle_data[];
64.   extern char circle_start[];
65.   
66.   
67.   /* Create a new light source.  */
68.   void
69.   new_light_source(x, y, range, type, id)
70.       xchar x, y;
71.       int range, type;
72.       genericptr_t id;
73.   {
74.       light_source *ls;
75.   
76.       if (range > MAX_RADIUS || range < 1) {
77.   	impossible("new_light_source:  illegal range %d", range);
78.   	return;
79.       }
80.   
81.       ls = (light_source *) alloc(sizeof(light_source));
82.   
83.       ls->next = light_base;
84.       ls->x = x;
85.       ls->y = y;
86.       ls->range = range;
87.       ls->type = type;
88.       ls->id = id;
89.       ls->flags = 0;
90.       light_base = ls;
91.   
92.       vision_full_recalc = 1;	/* make the source show up */
93.   }
94.   
95.   /*
96.    * Delete a light source. This assumes only one light source is attached
97.    * to an object at a time.
98.    */
99.   void
100.  del_light_source(type, id)
101.      int type;
102.      genericptr_t id;
103.  {
104.      light_source *curr, *prev;
105.      genericptr_t tmp_id;
106.  
107.      /* need to be prepared for dealing a with light source which
108.         has only been partially restored during a level change
109.         (in particular: chameleon vs prot. from shape changers) */
110.      switch (type) {
111.      case LS_OBJECT:	tmp_id = (genericptr_t)(((struct obj *)id)->o_id);
112.  			break;
113.      case LS_MONSTER:	tmp_id = (genericptr_t)(((struct monst *)id)->m_id);
114.  			break;
115.      default:		tmp_id = 0;
116.  			break;
117.      }
118.  
119.      for (prev = 0, curr = light_base; curr; prev = curr, curr = curr->next) {
120.  	if (curr->type != type) continue;
121.  	if (curr->id == ((curr->flags & LSF_NEEDS_FIXUP) ? tmp_id : id)) {
122.  	    if (prev)
123.  		prev->next = curr->next;
124.  	    else
125.  		light_base = curr->next;
126.  
127.  	    free((genericptr_t)curr);
128.  	    vision_full_recalc = 1;
129.  	    return;
130.  	}
131.      }
132.      impossible("del_light_source: not found type=%d, id=0x%lx", type, (long)id);
133.  }
134.  
135.  /* Mark locations that are temporarily lit via mobile light sources. */
136.  void
137.  do_light_sources(cs_rows)
138.      char **cs_rows;
139.  {
140.      int x, y, min_x, max_x, max_y, offset;
141.      char *limits;
142.      short at_hero_range = 0;
143.      light_source *ls;
144.      char *row;
145.  
146.      for (ls = light_base; ls; ls = ls->next) {
147.  	ls->flags &= ~LSF_SHOW;
148.  
149.  	/*
150.  	 * Check for moved light sources.  It may be possible to
151.  	 * save some effort if an object has not moved, but not in
152.  	 * the current setup -- we need to recalculate for every
153.  	 * vision recalc.
154.  	 */
155.  	if (ls->type == LS_OBJECT) {
156.  	    if (get_obj_location((struct obj *) ls->id, &ls->x, &ls->y, 0))
157.  		ls->flags |= LSF_SHOW;
158.  	} else if (ls->type == LS_MONSTER) {
159.  	    if (get_mon_location((struct monst *) ls->id, &ls->x, &ls->y, 0))
160.  		ls->flags |= LSF_SHOW;
161.  	}
162.  
163.  	/* minor optimization: don't bother with duplicate light sources */
164.  	/* at hero */
165.  	if (ls->x == u.ux && ls->y == u.uy) {
166.  	    if (at_hero_range >= ls->range)
167.  		ls->flags &= ~LSF_SHOW;
168.  	    else
169.  		at_hero_range = ls->range;
170.  	}
171.  
172.  	if (ls->flags & LSF_SHOW) {
173.  	    /*
174.  	     * Walk the points in the circle and see if they are
175.  	     * visible from the center.  If so, mark'em.
176.  	     *
177.  	     * Kevin's tests indicated that doing this brute-force
178.  	     * method is faster for radius <= 3 (or so).
179.  	     */
180.  	    limits = circle_ptr(ls->range);
181.  	    if ((max_y = (ls->y + ls->range)) >= ROWNO) max_y = ROWNO-1;
182.  	    if ((y = (ls->y - ls->range)) < 0) y = 0;
183.  	    for (; y <= max_y; y++) {
184.  		row = cs_rows[y];
185.  		offset = limits[abs(y - ls->y)];
186.  		if ((min_x = (ls->x - offset)) < 0) min_x = 0;
187.  		if ((max_x = (ls->x + offset)) >= COLNO) max_x = COLNO-1;
188.  
189.  		if (ls->x == u.ux && ls->y == u.uy) {
190.  		    /*
191.  		     * If the light source is located at the hero, then
192.  		     * we can use the COULD_SEE bits already calcualted
193.  		     * by the vision system.  More importantly than
194.  		     * this optimization, is that it allows the vision
195.  		     * system to correct problems with clear_path().
196.  		     * The function clear_path() is a simple LOS
197.  		     * path checker that doesn't go out of its way
198.  		     * make things look "correct".  The vision system
199.  		     * does this.
200.  		     */
201.  		    for (x = min_x; x <= max_x; x++)
202.  			if (row[x] & COULD_SEE)
203.  			    row[x] |= TEMP_LIT;
204.  		} else {
205.  		    for (x = min_x; x <= max_x; x++)
206.  			if ((ls->x == x && ls->y == y)
207.  				|| clear_path((int)ls->x, (int) ls->y, x, y))
208.  			    row[x] |= TEMP_LIT;
209.  		}
210.  	    }
211.  	}
212.      }
213.  }
214.  
215.  /* (mon->mx == 0) implies migrating */
216.  #define mon_is_local(mon)	((mon)->mx > 0)
217.  
218.  static struct monst *
219.  find_mid(nid)
220.  unsigned nid;
221.  {
222.  	struct monst *mtmp;
223.  
224.  	if (!nid)
225.  	    return &youmonst;
226.  	for (mtmp = fmon; mtmp; mtmp = mtmp->nmon)
227.  	    if (mtmp->m_id == nid) return mtmp;
228.  	for (mtmp = migrating_mons; mtmp; mtmp = mtmp->nmon)
229.  	    if (mtmp->m_id == nid) return mtmp;
230.  	for (mtmp = mydogs; mtmp; mtmp = mtmp->nmon)
231.  	    if (mtmp->m_id == nid) return mtmp;
232.  	return (struct monst *) 0;
233.  }
234.  
235.  /* Save all light sources of the given range. */
236.  void
237.  save_light_sources(fd, mode, range)
238.      int fd, mode, range;
239.  {
240.      int count, actual, is_global;
241.      light_source **prev, *curr;
242.  
243.      if (perform_bwrite(mode)) {
244.  	count = maybe_write_ls(fd, range, FALSE);
245.  	bwrite(fd, (genericptr_t) &count, sizeof count);
246.  	actual = maybe_write_ls(fd, range, TRUE);
247.  	if (actual != count)
248.  	    panic("counted %d light sources, wrote %d! [range=%d]",
249.  		  count, actual, range);
250.      }
251.  
252.      if (release_data(mode)) {
253.  	for (prev = &light_base; (curr = *prev) != 0; ) {
254.  	    if (!curr->id) {
255.  		impossible("save_light_sources: no id! [range=%d]", range);
256.  		is_global = 0;
257.  	    } else
258.  	    switch (curr->type) {
259.  	    case LS_OBJECT:
260.  		is_global = !obj_is_local((struct obj *)curr->id);
261.  		break;
262.  	    case LS_MONSTER:
263.  		is_global = !mon_is_local((struct monst *)curr->id);
264.  		break;
265.  	    default:
266.  		is_global = 0;
267.  		impossible("save_light_sources: bad type (%d) [range=%d]",
268.  			   curr->type, range);
269.  		break;
270.  	    }
271.  	    /* if global and not doing local, or vice versa, remove it */
272.  	    if (is_global ^ (range == RANGE_LEVEL)) {
273.  		*prev = curr->next;
274.  		free((genericptr_t)curr);
275.  	    } else {
276.  		prev = &(*prev)->next;
277.  	    }
278.  	}
279.      }
280.  }
281.  
282.  /*
283.   * Pull in the structures from disk, but don't recalculate the object
284.   * pointers.
285.   */
286.  void
287.  restore_light_sources(fd)
288.      int fd;
289.  {
290.      int count;
291.      light_source *ls;
292.  
293.      /* restore elements */
294.      mread(fd, (genericptr_t) &count, sizeof count);
295.  
296.      while (count-- > 0) {
297.  	ls = (light_source *) alloc(sizeof(light_source));
298.  	mread(fd, (genericptr_t) ls, sizeof(light_source));
299.  	ls->next = light_base;
300.  	light_base = ls;
301.      }
302.  }
303.  
304.  /* Relink all lights that are so marked. */
305.  void
306.  relink_light_sources(ghostly)
307.      boolean ghostly;
308.  {
309.      char which;
310.      unsigned nid;
311.      light_source *ls;
312.  
313.      for (ls = light_base; ls; ls = ls->next) {
314.  	if (ls->flags & LSF_NEEDS_FIXUP) {
315.  	    if (ls->type == LS_OBJECT || ls->type == LS_MONSTER) {
316.  		if (ghostly) {
317.  		    if (!lookup_id_mapping((unsigned)ls->id, &nid))
318.  			impossible("relink_light_sources: no id mapping");
319.  		} else
320.  		    nid = (unsigned) ls->id;
321.  		if (ls->type == LS_OBJECT) {
322.  		    which = 'o';
323.  		    ls->id = (genericptr_t) find_oid(nid);
324.  		} else {
325.  		    which = 'm';
326.  		    ls->id = (genericptr_t) find_mid(nid);
327.  		}
328.  		if (!ls->id)
329.  		    impossible("relink_light_sources: cant find %c_id %d",
330.  			       which, nid);
331.  	    } else
332.  		impossible("relink_light_sources: bad type (%d)", ls->type);
333.  
334.  	    ls->flags &= ~LSF_NEEDS_FIXUP;
335.  	}
336.      }
337.  }
338.  
339.  /*
340.   * Part of the light source save routine.  Count up the number of light
341.   * sources that would be written.  If write_it is true, actually write
342.   * the light source out.
343.   */
344.  static int
345.  maybe_write_ls(fd, range, write_it)
346.      int fd, range;
347.      boolean write_it;
348.  {
349.      int count = 0, is_global;
350.      light_source *ls;
351.  
352.      for (ls = light_base; ls; ls = ls->next) {
353.  	if (!ls->id) {
354.  	    impossible("maybe_write_ls: no id! [range=%d]", range);
355.  	    continue;
356.  	}
357.  	switch (ls->type) {
358.  	case LS_OBJECT:
359.  	    is_global = !obj_is_local((struct obj *)ls->id);
360.  	    break;
361.  	case LS_MONSTER:
362.  	    is_global = !mon_is_local((struct monst *)ls->id);
363.  	    break;
364.  	default:
365.  	    is_global = 0;
366.  	    impossible("maybe_write_ls: bad type (%d) [range=%d]",
367.  		       ls->type, range);
368.  	    break;
369.  	}
370.  	/* if global and not doing local, or vice versa, count it */
371.  	if (is_global ^ (range == RANGE_LEVEL)) {
372.  	    count++;
373.  	    if (write_it) write_ls(fd, ls);
374.  	}
375.      }
376.  
377.      return count;
378.  }
379.  
380.  /* Write a light source structure to disk. */
381.  static void
382.  write_ls(fd, ls)
383.      int fd;
384.      light_source *ls;
385.  {
386.      genericptr_t arg_save;
387.      struct obj *otmp;
388.      struct monst *mtmp;
389.  
390.      if (ls->type == LS_OBJECT || ls->type == LS_MONSTER) {
391.  	if (ls->flags & LSF_NEEDS_FIXUP)
392.  	    bwrite(fd, (genericptr_t)ls, sizeof(light_source));
393.  	else {
394.  	    /* replace object pointer with id for write, then put back */
395.  	    arg_save = ls->id;
396.  	    if (ls->type == LS_OBJECT) {
397.  		otmp = (struct obj *)ls->id;
398.  		ls->id = (genericptr_t)otmp->o_id;
399.  #ifdef DEBUG
400.  		if (find_oid((unsigned)ls->id) != otmp)
401.  		    panic("write_ls: can't find obj #%u!", (unsigned)ls->id);
402.  #endif
403.  	    } else { /* ls->type == LS_MONSTER */
404.  		mtmp = (struct monst *)ls->id;
405.  		ls->id = (genericptr_t)mtmp->m_id;
406.  #ifdef DEBUG
407.  		if (find_mid((unsigned)ls->id) != mtmp)
408.  		    panic("write_ls: can't find mon #%u!", (unsigned)ls->id);
409.  #endif
410.  	    }
411.  	    ls->flags |= LSF_NEEDS_FIXUP;
412.  	    bwrite(fd, (genericptr_t)ls, sizeof(light_source));
413.  	    ls->id = arg_save;
414.  	    ls->flags &= ~LSF_NEEDS_FIXUP;
415.  	}
416.      } else {
417.  	impossible("write_ls: bad type (%d)", ls->type);
418.      }
419.  }
420.  
421.  /* Change light source's ID from src to dest. */
422.  void
423.  obj_move_light_source(src, dest)
424.      struct obj *src, *dest;
425.  {
426.      light_source *ls;
427.  
428.      for (ls = light_base; ls; ls = ls->next)
429.  	if (ls->type == LS_OBJECT && ls->id == (genericptr_t) src)
430.  	    ls->id = (genericptr_t) dest;
431.      src->lamplit = 0;
432.      dest->lamplit = 1;
433.  }
434.  
435.  /* return true if there exist any light sources */
436.  boolean
437.  any_light_source()
438.  {
439.      return light_base != (light_source *) 0;
440.  }
441.  
442.  /*
443.   * Snuff an object light source if at (x,y).  This currently works
444.   * only for burning light sources.
445.   */
446.  void
447.  snuff_light_source(x, y)
448.      int x, y;
449.  {
450.      light_source *ls;
451.      struct obj *obj;
452.  
453.      for (ls = light_base; ls; ls = ls->next)
454.  	/*
455.  	Is this position check valid??? Can I assume that the positions
456.  	will always be correct because the objects would have been
457.  	updated with the last vision update?  [Is that recent enough???]
458.  	*/
459.  	if (ls->type == LS_OBJECT && ls->x == x && ls->y == y) {
460.  	    obj = (struct obj *) ls->id;
461.  	    if (obj_is_burning(obj)) {
462.  		end_burn(obj, obj->otyp != MAGIC_LAMP);
463.  		/*
464.  		 * The current ls element has just been removed (and
465.  		 * ls->next is now invalid).  Return assuming that there
466.  		 * is only one light source attached to each object.
467.  		 */
468.  		return;
469.  	    }
470.  	}
471.  }
472.  
473.  /* Return TRUE if object sheds any light at all. */
474.  boolean
475.  obj_sheds_light(obj)
476.      struct obj *obj;
477.  {
478.      /* so far, only burning objects shed light */
479.      return obj_is_burning(obj);
480.  }
481.  
482.  /* Return TRUE if sheds light AND will be snuffed by end_burn(). */
483.  boolean
484.  obj_is_burning(obj)
485.      struct obj *obj;
486.  {
487.      return (obj->lamplit &&
488.  		(  obj->otyp == MAGIC_LAMP
489.  		|| obj->otyp == BRASS_LANTERN
490.  		|| obj->otyp == OIL_LAMP
491.  		|| obj->otyp == CANDELABRUM_OF_INVOCATION
492.  		|| obj->otyp == TALLOW_CANDLE
493.  		|| obj->otyp == WAX_CANDLE
494.  		|| obj->otyp == POT_OIL));
495.  }
496.  
497.  /* copy the light source(s) attachted to src, and attach it/them to dest */
498.  void
499.  obj_split_light_source(src, dest)
500.      struct obj *src, *dest;
501.  {
502.      light_source *ls, *new_ls;
503.  
504.      for (ls = light_base; ls; ls = ls->next)
505.  	if (ls->type == LS_OBJECT && ls->id == (genericptr_t) src) {
506.  	    /*
507.  	     * Insert the new source at beginning of list.  This will
508.  	     * never interfere us walking down the list - we are already
509.  	     * past the insertion point.
510.  	     */
511.  	    new_ls = (light_source *) alloc(sizeof(light_source));
512.  	    *new_ls = *ls;
513.  	    new_ls->id = (genericptr_t) dest;
514.  	    new_ls->next = light_base;
515.  	    light_base = new_ls;
516.  	    dest->lamplit = 1;		/* now an active light source */
517.  	}
518.  }
519.  
520.  #ifdef WIZARD
521.  extern char *FDECL(fmt_ptr, (const genericptr, char *));  /* from alloc.c */
522.  
523.  int
524.  wiz_light_sources()
525.  {
526.      winid win;
527.      char buf[BUFSZ], arg_address[20];
528.      light_source *ls;
529.  
530.      win = create_nhwindow(NHW_MENU);	/* corner text window */
531.      if (win == WIN_ERR) return 0;
532.  
533.      Sprintf(buf, "Mobile light sources: hero @ (%2d,%2d)", u.ux, u.uy);
534.      putstr(win, 0, buf);
535.      putstr(win, 0, "");
536.  
537.      if (light_base) {
538.  	putstr(win, 0, "location range flags  type    id");
539.  	putstr(win, 0, "-------- ----- ------ ----  -------");
540.  	for (ls = light_base; ls; ls = ls->next) {
541.  	    Sprintf(buf, "  %2d,%2d   %2d   0x%04x  %s  %s",
542.  		ls->x, ls->y, ls->range, ls->flags,
543.  		(ls->type == LS_OBJECT ? "obj" :
544.  		 ls->type == LS_MONSTER ?
545.  		    (mon_is_local((struct monst *)ls->id) ? "mon" :
546.  		     ((struct monst *)ls->id == &youmonst) ? "you" :
547.  		     "<m>") :		/* migrating monster */
548.  		 "???"),
549.  		fmt_ptr(ls->id, arg_address));
550.  	    putstr(win, 0, buf);
551.  	}
552.      } else
553.  	putstr(win, 0, "<none>");
554.  
555.  
556.      display_nhwindow(win, FALSE);
557.      destroy_nhwindow(win);
558.  
559.      return 0;
560.  }
561.  
562.  #endif /* WIZARD */
563.  
564.  #endif /* OVL3 */
565.  
566.  /*light.c*/

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