Source:NetHack 3.3.0/vision.c

Below is the full text to vision.c from the source code of NetHack 3.3.0. To link to a particular line, write [[NetHack 3.3.0/vision.c#line123 ]], for example.

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

1.   /*	SCCS Id: @(#)vision.c	3.3	99/02/18	*/ 2.   /* Copyright (c) Dean Luick, with acknowledgements to Dave Cohrs, 1990. */ 3.    /* NetHack may be freely redistributed. See license for details. */ 4.     5.    #include "hack.h"  6. 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.    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.  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.   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.   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.      vision_full_recalc = 1;	/* we want to run vision_recalc */ 246. }  247.   248.   249.  /*  250.   * get_unused_cs 251.  *  252.   * Called from vision_recalc and at least one light routine. Get pointers 253.  * to the unused vision work area. 254.  */  255.  STATIC_OVL void 256. get_unused_cs(rows, rmin, rmax) 257.     char ***rows; 258.     char **rmin, **rmax; 259. {  260.      register int  row; 261.     register char *nrmin, *nrmax; 262.  263.      if (viz_array == cs_rows0) { 264. 	*rows = cs_rows1; 265. 	*rmin = cs_rmin1; 266. 	*rmax = cs_rmax1; 267.     } else { 268. 	*rows = cs_rows0; 269. 	*rmin = cs_rmin0; 270. 	*rmax = cs_rmax0; 271.     }  272.   273.      /* return an initialized, unused work area */ 274.     nrmin = *rmin; 275.     nrmax = *rmax; 276.  277.      (void) memset((genericptr_t)**rows, 0, ROWNO*COLNO);  /* we see nothing */ 278.     for (row = 0; row < ROWNO; row++) {		/* set row min & max */ 279. 	*nrmin++ = COLNO-1; 280. 	*nrmax++ = 0; 281.     }  282.  }  283.   284.   285.  #ifdef REINCARNATION 286. /*  287.   * rogue_vision 288.  *  289.   * Set the "could see" and in sight bits so vision acts just like the old 290.  * rogue game: 291.  *  292.   *	+ If in a room, the hero can see to the room boundaries. 293.  *	+ The hero can always see adjacent squares. 294.  *  295.   * We set the in_sight bit here as well to escape a bug that shows up  296. * due to the one-sided lit wall hack. 297.  */  298.  STATIC_OVL void 299. rogue_vision(next, rmin, rmax) 300.     char **next;	/* could_see array pointers */ 301.     char *rmin, *rmax; 302. {  303.      int rnum = levl[u.ux][u.uy].roomno - ROOMOFFSET; /* no SHARED... */ 304.      int start, stop, in_door, xhi, xlo, yhi, ylo; 305.     register int zx, zy; 306.  307.      /* If in a lit room, we are able to see to its boundaries. */ 308.      /* If dark, set COULD_SEE so various spells work -dlc */ 309.     if (rnum >= 0) { 310. 	for (zy = rooms[rnum].ly-1; zy <= rooms[rnum].hy+1; zy++) { 311. 	    rmin[zy] = start = rooms[rnum].lx-1; 312. 	    rmax[zy] = stop  = rooms[rnum].hx+1; 313.  314.  	    for (zx = start; zx <= stop; zx++) { 315. 		if (rooms[rnum].rlit) { 316. 		    next[zy][zx] = COULD_SEE | IN_SIGHT; 317. 		    levl[zx][zy].seenv = SVALL;	/* see the walls */ 318. 		} else 319. 		    next[zy][zx] = COULD_SEE; 320. 	    }  321.  	}  322.      }  323.   324.      in_door = levl[u.ux][u.uy].typ == DOOR; 325.  326.      /* Can always see adjacent. */ 327.      ylo = max(u.uy - 1, 0); 328.     yhi = min(u.uy + 1, ROWNO - 1); 329.     xlo = max(u.ux - 1, 1); 330.     xhi = min(u.ux + 1, COLNO - 1); 331.     for (zy = ylo; zy <= yhi; zy++) { 332. 	if (xlo < rmin[zy]) rmin[zy] = xlo; 333. 	if (xhi > rmax[zy]) rmax[zy] = xhi; 334.  335.  	for (zx = xlo; zx <= xhi; zx++) { 336. 	    next[zy][zx] = COULD_SEE | IN_SIGHT; 337. 	    /*  338.  	     * Yuck, update adjacent non-diagonal positions when in a doorway. 339. 	     * We need to do this to catch the case when we first step into 340. 	     * a room. The room's walls were not seen from the outside, but 341. 	     * now are seen (the seen bits are set just above). However, the 342. 	     * positions are not updated because they were already in sight. 343. 	     * So, we have to do it here. 344. 	     */  345.  	    if (in_door && (zx == u.ux || zy == u.uy)) newsym(zx,zy); 346. 	}  347.      }  348.  }  349.  #endif /* REINCARNATION */ 350.  351.  /*#define EXTEND_SPINE*/	/* possibly better looking wall-angle */ 352.  353.  #ifdef EXTEND_SPINE 354.  355.  STATIC_DCL int FDECL(new_angle, (struct rm *, unsigned char *, int, int)); 356. /*  357.   * new_angle 358.  *  359.   * Return the new angle seen by the hero for this location. The angle 360.  * bit is given in the value pointed at by sv. 361.  *  362.   * For T walls and crosswall, just setting the angle bit, even though 363.  * it is technically correct, doesn't look good. If we can see the 364.  * next position beyond the current one and it is a wall that we can 365.  * see, then we want to extend a spine of the T to connect with the wall 366.  * that is beyond. Example: 367.  *  368.   *	 Correct, but ugly			   Extend T spine 369.  *  370.   *		| ...					| ...  371.   *		| ...	<-- wall beyond & floor -->	| ...  372. *		| ...					| ... 373.   * Unseen   -->   ... | ... 374.   * spine	+-... <-- trwall & doorway	-->	+-... 375. *		| ...					| ... 376.   *  377.   *  378.   *		   @	<-- hero		-->	   @ 379.  *  380.   *  381.   * We fake the above check by only checking if the horizontal & 382.  * vertical positions adjacent to the crosswall and T wall are 383.  * unblocked. Then, _in general_ we can see beyond. Generally, 384.  * this is good enough. 385.  *  386.   *	+ When this function is called we don't have all of the seen 387.  *	  information (we're doing a top down scan in vision_recalc). 388.  *	  We would need to scan once to set all IN_SIGHT and COULD_SEE 389.  *	  bits, then again to correctly set the seenv bits. 390.  *	+ I'm trying to make this as cheap as possible. The display & 391.  *	  vision eat up too much CPU time. 392.  *	  393.   *  394.   * Note:  Even as I write this, I'm still not convinced. There are too 395.  *	  many exceptions. I may have to bite the bullet and do more 396.  *	  checks. - Dean 2/11/93 397.  */  398.  STATIC_OVL int 399. new_angle(lev, sv, row, col) 400.     struct rm *lev; 401.     unsigned char *sv; 402.     int row, col; 403. {  404.      register int res = *sv; 405.  406.      /*  407.       * Do extra checks for crosswalls and T walls if we see them from 408.      * an angle. 409.      */  410.      if (lev->typ >= CROSSWALL && lev->typ <= TRWALL) { 411. 	switch (res) { 412. 	    case SV0: 413. 		if (col > 0	  && viz_clear[row][col-1]) res |= SV7; 414. 		if (row > 0	  && viz_clear[row-1][col]) res |= SV1; 415. 		break; 416. 	    case SV2: 417. 		if (row > 0	  && viz_clear[row-1][col]) res |= SV1; 418. 		if (col < COLNO-1 && viz_clear[row][col+1]) res |= SV3; 419. 		break; 420. 	    case SV4: 421. 		if (col < COLNO-1 && viz_clear[row][col+1]) res |= SV3; 422. 		if (row < ROWNO-1 && viz_clear[row+1][col]) res |= SV5; 423. 		break; 424. 	    case SV6: 425. 		if (row < ROWNO-1 && viz_clear[row+1][col]) res |= SV5; 426. 		if (col > 0	  && viz_clear[row][col-1]) res |= SV7; 427. 		break; 428. 	}  429.      }  430.      return res; 431. }  432.  #else 433. /*  434.   * new_angle 435.  *  436.   * Return the new angle seen by the hero for this location. The angle 437.  * bit is given in the value pointed at by sv. 438.  *  439.   * The other parameters are not used. 440.  */  441.  #define new_angle(lev, sv, row, col) (*sv) 442.  443.  #endif 444.  445.   446.  /*  447.   * vision_recalc 448.  *  449.   * Do all of the heavy vision work. Recalculate all locations that could 450.  * possibly be seen by the hero --- if the location were lit, etc.  Note 451.  * which locations are actually seen because of lighting. Then add to 452. * this all locations that be seen by hero due to night vision and x-ray 453.  * vision. Finally, compare with what the hero was able to see previously. 454.  * Update the difference. 455.  *  456.   * This function is usually called only when the variable 'vision_full_recalc' 457.  * is set. The following is a list of places where this function is called, 458.  * with three valid values for the control flag parameter: 459.  *  460.   * Control flag = 0. A complete vision recalculation. Generate the vision 461.  * tables from scratch. This is necessary to correctly set what the hero 462.  * can see. (1) and (2) call this routine for synchronization purposes, (3) 463.  * calls this routine so it can operate correctly. 464.  *  465.   *	+ After the monster move, before input from the player. [moveloop] 466.  *	+ At end of moveloop. [moveloop ??? not sure why this is here] 467.  *	+ Right before something is printed. [pline] 468.  *	+ Right before we do a vision based operation. [do_clear_area] 469.  *	+ screen redraw, so we can renew all positions in sight. [docrt] 470.  *  471.   * Control flag = 1. An adjacent vision recalculation. The hero has moved 472.  * one square. Knowing this, it might be possible to optimize the vision 473.  * recalculation using the current knowledge. This is presently unimplemented 474.  * and is treated as a control = 0 call. 475.  *  476.   *	+ Right after the hero moves. [domove] 477.  *  478.   * Control flag = 2. Turn off the vision system. Nothing new will be 479. * displayed, since nothing is seen. This is usually done when you need 480.  * a newsym run on all locations in sight, or on some locations but you 481.  * don't know which ones. 482.  *  483.   *	+ Before a screen redraw, so all positions are renewed. [docrt] 484.  *	+ Right before the hero arrives on a new level. [goto_level] 485.  *	+ Right after a scroll of light is read. [litroom] 486.  *	+ After an option has changed that affects vision [parseoptions] 487.  *	+ Right after the hero is swallowed. [gulpmu] 488.  *	+ Just before bubbles are moved. [movebubbles] 489.  */  490.  void 491. vision_recalc(control) 492.     int control; 493. {  494.      char **temp_array;	/* points to the old vision array */ 495.     char **next_array;	/* points to the new vision array */ 496.     char *next_row;	/* row pointer for the new array */ 497.     char *old_row;	/* row pointer for the old array */ 498.     char *next_rmin;	/* min pointer for the new array */ 499.     char *next_rmax;	/* max pointer for the new array */ 500.     char *ranges;	/* circle ranges -- used for xray & night vision */ 501.     int row;		/* row counter (outer loop)  */ 502.     int start, stop;	/* inner loop starting/stopping index */ 503.     int dx, dy;		/* one step from a lit door or lit wall (see below) */ 504.     register int col;	/* inner loop counter */ 505.     register struct rm *lev;	/* pointer to current pos */ 506.     struct rm *flev;	/* pointer to position in "front" of current pos */ 507.     extern unsigned char seenv_matrix[3][3];	/* from display.c */ 508.     static unsigned char colbump[COLNO+1];	/* cols to bump sv */ 509.     unsigned char *sv;				/* ptr to seen angle bits */ 510.     int oldseenv;				/* previous seenv value */ 511.  512.      vision_full_recalc = 0;			/* reset flag */ 513.     if (in_mklev) return; 514.  515.  #ifdef GCC_WARN 516.     row = 0; 517. #endif 518.  519.      /*  520.       * Either the light sources have been taken care of, or we must 521.      * recalculate them here. 522.      */  523.   524.      /* Get the unused could see, row min, and row max arrays. */ 525.      get_unused_cs(&next_array, &next_rmin, &next_rmax); 526.  527.      /* You see nothing, nothing can see you --- if swallowed or refreshing. */ 528.      if (u.uswallow || control == 2) { 529. 	/* do nothing -- get_unused_cs nulls out the new work area */ 530.  531.      } else if (Blind) { 532. 	/*  533.  	 * Calculate the could_see array even when blind so that monsters 534. 	 * can see you, even if you can't see them. Note that the current 535. 	 * setup allows: 536. 	 *  537.  	 *	+ Monsters to see with the "new" vision, even on the rogue 538. 	 *	  level. 539. 	 *  540.  	 *	+ Monsters can see you even when you're in a pit. 541. 	 */  542.  	view_from(u.uy, u.ux, next_array, next_rmin, next_rmax,  543.  		0, (void FDECL((*),(int,int,genericptr_t)))0, (genericptr_t)0); 544.  545.  	/*  546.  	 * Our own version of the update loop below. We know we can't see 547. 	 * anything, so we only need update positions we used to be able 548. 	 * to see. 549. 	 */  550.  	temp_array = viz_array;	/* set viz_array so newsym will work */ 551. 	viz_array = next_array; 552.  553.  	for (row = 0; row < ROWNO; row++) { 554. 	    old_row = temp_array[row]; 555.  556.  	    /* Find the min and max positions on the row. */ 557.  	    start = min(viz_rmin[row], next_rmin[row]); 558. 	    stop  = max(viz_rmax[row], next_rmax[row]); 559.  560.  	    for (col = start; col <= stop; col++) 561. 		if (old_row[col] & IN_SIGHT) newsym(col,row); 562. 	}  563.   564.  	/* skip the normal update loop */ 565. 	goto skip; 566.     }  567.  #ifdef REINCARNATION 568.     else if (Is_rogue_level(&u.uz)) { 569. 	rogue_vision(next_array,next_rmin,next_rmax); 570.     }  571.  #endif 572.     else { 573. 	int has_night_vision = 1;	/* hero has night vision */ 574.  575.  	if (Underwater && !Is_waterlevel(&u.uz)) { 576. 	    /*  577.  	     * The hero is under water. Only see surrounding locations if 578. * they are also underwater. This overrides night vision but 579. 	     * does not override x-ray vision. 580. 	     */  581.  	    has_night_vision = 0; 582.  583.  	    for (row = u.uy-1; row <= u.uy+1; row++) 584. 		for (col = u.ux-1; col <= u.ux+1; col++) { 585. 		    if (!isok(col,row) || !is_pool(col,row)) continue; 586.  587.  		    next_rmin[row] = min(next_rmin[row], col); 588. 		    next_rmax[row] = max(next_rmax[row], col); 589. 		    next_array[row][col] = IN_SIGHT; 590. 		}  591.  	}  592.   593.  	/* if in a pit, just update for immediate locations */ 594. 	else if (u.utrap && u.utraptype == TT_PIT) { 595. 	    for (row = u.uy-1; row <= u.uy+1; row++) { 596. 		if (row < 0) continue;	if (row >= ROWNO) break; 597.  598.  		next_rmin[row] = max(      0, u.ux - 1); 599. 		next_rmax[row] = min(COLNO-1, u.ux + 1); 600. 		next_row = next_array[row]; 601.  602.  		for(col=next_rmin[row]; col <= next_rmax[row]; col++) 603. 		    next_row[col] = IN_SIGHT; 604. 	    }  605.  	} else 606. 	    view_from(u.uy, u.ux, next_array, next_rmin, next_rmax,  607.  		0, (void FDECL((*),(int,int,genericptr_t)))0, (genericptr_t)0); 608.  609.  	/*  610.  	 * Set the IN_SIGHT bit for xray and night vision. 611. 	 */  612.  	if (u.xray_range >= 0) { 613. 	    if (u.xray_range) { 614. 		ranges = circle_ptr(u.xray_range); 615.  616.  		for (row = u.uy-u.xray_range; row <= u.uy+u.xray_range; row++) { 617. 		    if (row < 0) continue;	if (row >= ROWNO) break; 618. 		    dy = v_abs(u.uy-row);	next_row = next_array[row]; 619.  620.  		    start = max(      0, u.ux - ranges[dy]); 621. 		    stop  = min(COLNO-1, u.ux + ranges[dy]); 622.  623.  		    for (col = start; col <= stop; col++) { 624. 			char old_row_val = next_row[col]; 625. 			next_row[col] |= IN_SIGHT; 626. 			oldseenv = levl[col][row].seenv; 627. 			levl[col][row].seenv = SVALL;	/* see all! */ 628.  			/* Update if previously not in sight or new angle. */ 629.  			if (!(old_row_val & IN_SIGHT) || oldseenv != SVALL) 630. 			    newsym(col,row); 631. 		    }  632.   633.  		    next_rmin[row] = min(start, next_rmin[row]); 634. 		    next_rmax[row] = max(stop, next_rmax[row]); 635. 		}  636.   637.  	    } else {	/* range is 0 */ 638. 		next_array[u.uy][u.ux] |= IN_SIGHT; 639. 		levl[u.ux][u.uy].seenv = SVALL; 640. 		next_rmin[u.uy] = min(u.ux, next_rmin[u.uy]); 641. 		next_rmax[u.uy] = max(u.ux, next_rmax[u.uy]); 642. 	    }  643.  	}  644.   645.  	if (has_night_vision && u.xray_range < u.nv_range) { 646. 	    if (!u.nv_range) {	/* range is 0 */ 647. 		next_array[u.uy][u.ux] |= IN_SIGHT; 648. 		levl[u.ux][u.uy].seenv = SVALL; 649. 		next_rmin[u.uy] = min(u.ux, next_rmin[u.uy]); 650. 		next_rmax[u.uy] = max(u.ux, next_rmax[u.uy]); 651. 	    } else if (u.nv_range > 0) { 652. 		ranges = circle_ptr(u.nv_range); 653.  654.  		for (row = u.uy-u.nv_range; row <= u.uy+u.nv_range; row++) { 655. 		    if (row < 0) continue;	if (row >= ROWNO) break; 656. 		    dy = v_abs(u.uy-row);	next_row = next_array[row]; 657.  658.  		    start = max(      0, u.ux - ranges[dy]); 659. 		    stop  = min(COLNO-1, u.ux + ranges[dy]); 660.  661.  		    for (col = start; col <= stop; col++) 662. 			if (next_row[col]) next_row[col] |= IN_SIGHT; 663.  664.  		    next_rmin[row] = min(start, next_rmin[row]); 665. 		    next_rmax[row] = max(stop, next_rmax[row]); 666. 		}  667.  	    }  668.  	}  669.      }  670.   671.      /* Set the correct bits for all light sources. */ 672.      do_light_sources(next_array); 673.  674.   675.      /*  676.       * Make the viz_array the new array so that cansee will work correctly. 677.      */  678.      temp_array = viz_array; 679.     viz_array = next_array; 680.  681.      /*  682.       * The main update loop. Here we do two things: 683.      *  684.       *	    + Set the IN_SIGHT bit for places that we could see and are lit. 685.      *	    + Reset changed places. 686.      *  687.       * There is one thing that make deciding what the hero can see 688.      * difficult: 689.      *  690.       *  1.  Directional lighting. Items that block light create problems. 691.      *      The worst offenders are doors. Suppose a door to a lit room 692.      *      is closed. It is lit on one side, but not on the other. How 693.      *      do you know? You have to check the closest adjacent position. 694.      *	    Even so, that is not entirely correct. But it seems close 695.      *	    enough for now. 696.      */  697.      colbump[u.ux] = colbump[u.ux+1] = 1; 698.     for (row = 0; row < ROWNO; row++) { 699. 	dy = u.uy - row;                dy = sign(dy); 700. 	next_row = next_array[row];     old_row = temp_array[row]; 701.  702.  	/* Find the min and max positions on the row. */ 703.  	start = min(viz_rmin[row], next_rmin[row]); 704. 	stop  = max(viz_rmax[row], next_rmax[row]); 705. 	lev = &levl[start][row]; 706.  707.  	sv = &seenv_matrix[dy+1][start < u.ux ? 0 : (start > u.ux ? 2:1)]; 708.  709.  	for (col = start; col <= stop;  710.  				lev += ROWNO, sv += (int) colbump[++col]) { 711. 	    if (next_row[col] & IN_SIGHT) { 712. 		/*  713.  		 * We see this position because of night- or xray-vision. 714. 		 */  715.  		oldseenv = lev->seenv; 716. 		lev->seenv |= new_angle(lev,sv,row,col); /* update seen angle */ 717.  718.  		/* Update pos if previously not in sight or new angle. */ 719.  		if ( !(old_row[col] & IN_SIGHT) || oldseenv != lev->seenv) 720. 		    newsym(col,row); 721. 	    }  722.   723.  	    else if (next_row[col] & COULD_SEE  724.  				&& (lev->lit || next_row[col] & TEMP_LIT)) { 725. 		/*  726.  		 * We see this position because it is lit. 727. 		 */  728.  		if (IS_DOOR(lev->typ) && !viz_clear[row][col]) { 729. 		    /*  730.  		     * Make sure doors, boulders or mimics don't show up  731. * at the end of dark hallways. We do this by checking 732. 		     * the adjacent position. If it is lit, then we can see 733. 		     * the door, otherwise we can't.  734. */ 735.  		    dx = u.ux - col;	dx = sign(dx); 736. 		    flev = &(levl[col+dx][row+dy]); 737. 		    if (flev->lit || next_array[row+dy][col+dx] & TEMP_LIT) { 738. 			next_row[col] |= IN_SIGHT;	/* we see it */ 739.  740.  			oldseenv = lev->seenv; 741. 			lev->seenv |= new_angle(lev,sv,row,col); 742.  743.  			/* Update pos if previously not in sight or new angle.*/ 744. 			if (!(old_row[col] & IN_SIGHT) || oldseenv!=lev->seenv) 745. 			    newsym(col,row); 746. 		    } else 747. 			goto not_in_sight;	/* we don't see it */ 748.  749.  		} else { 750. 		    next_row[col] |= IN_SIGHT;	/* we see it */ 751.  752.  		    oldseenv = lev->seenv; 753. 		    lev->seenv |= new_angle(lev,sv,row,col); 754.  755.  		    /* Update pos if previously not in sight or new angle. */ 756.  		    if ( !(old_row[col] & IN_SIGHT) || oldseenv != lev->seenv) 757. 			newsym(col,row); 758. 		}  759.  	    } else if (next_row[col] & COULD_SEE && lev->waslit) { 760. 		/*  761.  		 * If we make it here, the hero _could see_ the location, 762. 		 * but doesn't see it (location is not lit). 763. 		 * However, the hero _remembers_ it as lit (waslit is true). 764. 		 * The hero can now see that it is not lit, so change waslit 765. 		 * and update the location. 766. 		 */  767.  		lev->waslit = 0; /* remember lit condition */ 768. 		newsym(col,row); 769. 	    }  770.  	    /*  771.  	     * At this point we know that the row position is *not* in  772. * sight. If the old one *was* in sight, then clean up the 773. 	     * position. 774. 	     */  775.  	    else { 776. not_in_sight: 777. 		if (old_row[col] & IN_SIGHT) newsym(col,row); 778. 	    }  779.   780.  	} /* end for col. . */ 781.      }	/* end for row. . */  782.      colbump[u.ux] = colbump[u.ux+1] = 0; 783.  784.  skip: 785.     newsym(u.ux,u.uy);		/* Make sure the hero shows up! */ 786.   787.      /* Set the new min and max pointers. */ 788.      viz_rmin  = next_rmin; 789.     viz_rmax = next_rmax; 790. }  791.   792.   793.  /*  794.   * block_point 795.  *  796.   * Make the location opaque to light. 797.  */  798.  void 799. block_point(x,y) 800.     int x, y;  801. { 802.      fill_point(y,x); 803.  804.      /* recalc light sources here? */ 805.   806.      /*  807.       * We have to do a full vision recalculation if we "could see" the 808.      * location. Why? Suppose some monster opened a way so that the 809.      * hero could see a lit room. However, the position of the opening 810.      * was out of night-vision range of the hero. Suddenly the hero should 811.      * see the lit room. 812.      */  813.      if (viz_array[y][x]) vision_full_recalc = 1; 814. }  815.   816.  /*  817.   * unblock_point 818.  *  819.   * Make the location transparent to light. 820.  */  821.  void 822. unblock_point(x,y) 823.     int x, y;  824. { 825.      dig_point(y,x); 826.  827.      /* recalc light sources here? */ 828.   829.      if (viz_array[y][x]) vision_full_recalc = 1; 830. }  831.   832.   833.  /*===========================================================================*\  834.   |									     |  835.   |	Everything below this line uses (y,x) instead of (x,y) --- the	     | 836.  |	algorithms are faster if they are less recursive and can scan	     | 837.  |	on a row longer. | 838.   |									     |  839.  \*===========================================================================*/  840.   841.   842.  /* ========================================================================= *\  843.  			Left and Right Pointer Updates 844. \* ========================================================================= */  845.   846.  /*  847.   *			LEFT and RIGHT pointer rules 848.  *  849.   *  850.   * **NOTE**  The rules changed on 4/4/90. This comment reflects the 851.  * new rules. The change was so that the stone-wall optimization 852.  * would work. 853.  *  854.   * OK, now the tough stuff. We must maintain our left and right 855.  * row pointers. The rules are as follows: 856.  *  857.   * Left Pointers: 858.  * ______________  859.   *  860.   * + If you are a clear spot, your left will point to the first 861.  *   stone to your left. If there is none, then point the first 862.  *   legal position in the row (0). 863.  *  864.   * + If you are a blocked spot, then your left will point to the 865.  *   left-most blocked spot to your left that is connected to you. 866.  *   This means that a left-edge (a blocked spot that has an open  867.   *   spot on its left) will point to itself. 868.  *  869.   *  870.   * Right Pointers: 871.  * ---  872.   * + If you are a clear spot, your right will point to the first 873.  *   stone to your right. If there is none, then point the last 874.  *   legal position in the row (COLNO-1). 875.  *  876.   * + If you are a blocked spot, then your right will point to the 877.  *   right-most blocked spot to your right that is connected to you. 878.  *   This means that a right-edge (a blocked spot that has an open  879.   *    spot on its right) will point to itself. 880.  */  881.  STATIC_OVL void 882. dig_point(row,col) 883.     int row,col; 884. {  885.      int i;  886. 887.     if (viz_clear[row][col]) return;		/* already done */ 888.  889.      viz_clear[row][col] = 1; 890.  891.      /*  892.       * Boundary cases first. 893.      */  894.      if (col == 0) {				/* left edge */ 895. 	if (viz_clear[row][1]) { 896. 	    right_ptrs[row][0] = right_ptrs[row][1]; 897. 	} else { 898. 	    right_ptrs[row][0] = 1; 899. 	    for (i = 1; i <= right_ptrs[row][1]; i++) 900. 		left_ptrs[row][i] = 1; 901. 	}  902.      } else if (col == (COLNO-1)) {		/* right edge */ 903.  904.  	if (viz_clear[row][COLNO-2]) { 905. 	    left_ptrs[row][COLNO-1] = left_ptrs[row][COLNO-2]; 906. 	} else { 907. 	    left_ptrs[row][COLNO-1] = COLNO-2; 908. 	    for (i = left_ptrs[row][COLNO-2]; i < COLNO-1; i++) 909. 		right_ptrs[row][i] = COLNO-2; 910. 	}  911.      }  912.   913.      /*  914.       * At this point, we know we aren't on the boundaries. 915.      */  916.      else if (viz_clear[row][col-1] && viz_clear[row][col+1]) { 917. 	/* Both sides clear */ 918. 	for (i = left_ptrs[row][col-1]; i <= col; i++) { 919. 	    if (!viz_clear[row][i]) continue;	/* catch non-end case */ 920. 	    right_ptrs[row][i] = right_ptrs[row][col+1]; 921. 	}  922.  	for (i = col; i <= right_ptrs[row][col+1]; i++) { 923. 	    if (!viz_clear[row][i]) continue;	/* catch non-end case */ 924. 	    left_ptrs[row][i] = left_ptrs[row][col-1]; 925. 	}  926.   927.      } else if (viz_clear[row][col-1]) { 928. 	/* Left side clear, right side blocked. */ 929.  	for (i = col+1; i <= right_ptrs[row][col+1]; i++) 930. 	    left_ptrs[row][i] = col+1; 931.  932.  	for (i = left_ptrs[row][col-1]; i <= col; i++) { 933. 	    if (!viz_clear[row][i]) continue;	/* catch non-end case */ 934. 	    right_ptrs[row][i] = col+1; 935. 	}  936.  	left_ptrs[row][col] = left_ptrs[row][col-1]; 937.  938.      } else if (viz_clear[row][col+1]) { 939. 	/* Right side clear, left side blocked. */ 940.  	for (i = left_ptrs[row][col-1]; i < col; i++) 941. 	    right_ptrs[row][i] = col-1; 942.  943.  	for (i = col; i <= right_ptrs[row][col+1]; i++) { 944. 	    if (!viz_clear[row][i]) continue;	/* catch non-end case */ 945. 	    left_ptrs[row][i] = col-1; 946. 	}  947.  	right_ptrs[row][col] = right_ptrs[row][col+1]; 948.  949.      } else { 950. 	/* Both sides blocked */ 951. 	for (i = left_ptrs[row][col-1]; i < col; i++) 952. 	    right_ptrs[row][i] = col-1; 953.  954.  	for (i = col+1; i <= right_ptrs[row][col+1]; i++) 955. 	    left_ptrs[row][i] = col+1; 956.  957.  	left_ptrs[row][col]  = col-1; 958. 	right_ptrs[row][col] = col+1; 959.     }  960.  }  961.   962.  STATIC_OVL void 963. fill_point(row,col) 964.     int row, col; 965. {  966.      int i;  967. 968.     if (!viz_clear[row][col]) return; 969.  970.      viz_clear[row][col] = 0; 971.  972.      if (col == 0) { 973. 	if (viz_clear[row][1]) {			/* adjacent is clear */ 974. 	    right_ptrs[row][0] = 0; 975. 	} else { 976. 	    right_ptrs[row][0] = right_ptrs[row][1]; 977. 	    for (i = 1; i <= right_ptrs[row][1]; i++) 978. 		left_ptrs[row][i] = 0; 979. 	}  980.      } else if (col == COLNO-1) { 981. 	if (viz_clear[row][COLNO-2]) {		/* adjacent is clear */ 982. 	    left_ptrs[row][COLNO-1] = COLNO-1; 983. 	} else { 984. 	    left_ptrs[row][COLNO-1] = left_ptrs[row][COLNO-2]; 985. 	    for (i = left_ptrs[row][COLNO-2]; i < COLNO-1; i++) 986. 		right_ptrs[row][i] = COLNO-1; 987. 	}  988.      }  989.   990.      /*  991.       * Else we know that we are not on an edge. 992.      */  993.      else if (viz_clear[row][col-1] && viz_clear[row][col+1]) { 994. 	/* Both sides clear */ 995. 	for (i = left_ptrs[row][col-1]+1; i <= col; i++) 996. 	    right_ptrs[row][i] = col; 997.  998.  	if (!left_ptrs[row][col-1])		/* catch the end case */ 999. 	    right_ptrs[row][0] = col; 1000. 1001. 	for (i = col; i < right_ptrs[row][col+1]; i++) 1002. 	   left_ptrs[row][i] = col; 1003. 1004. 	if (right_ptrs[row][col+1] == COLNO-1)	/* catch the end case */ 1005. 	   left_ptrs[row][COLNO-1] = col; 1006. 1007.     } else if (viz_clear[row][col-1]) { 1008. 	/* Left side clear, right side blocked. */ 1009. 	for (i = col; i <= right_ptrs[row][col+1]; i++) 1010. 	   left_ptrs[row][i] = col; 1011. 1012. 	for (i = left_ptrs[row][col-1]+1; i < col; i++) 1013. 	   right_ptrs[row][i] = col; 1014. 1015. 	if (!left_ptrs[row][col-1])		/* catch the end case */ 1016. 	   right_ptrs[row][i] = col; 1017. 1018. 	right_ptrs[row][col] = right_ptrs[row][col+1]; 1019. 1020.     } else if (viz_clear[row][col+1]) { 1021. 	/* Right side clear, left side blocked. */ 1022. 	for (i = left_ptrs[row][col-1]; i <= col; i++) 1023. 	   right_ptrs[row][i] = col; 1024. 1025. 	for (i = col+1; i < right_ptrs[row][col+1]; i++) 1026. 	   left_ptrs[row][i] = col; 1027. 1028. 	if (right_ptrs[row][col+1] == COLNO-1)	/* catch the end case */ 1029. 	   left_ptrs[row][i] = col; 1030. 1031. 	left_ptrs[row][col] = left_ptrs[row][col-1]; 1032. 1033.     } else { 1034. 	/* Both sides blocked */ 1035. 	for (i = left_ptrs[row][col-1]; i <= col; i++) 1036. 	   right_ptrs[row][i] = right_ptrs[row][col+1]; 1037. 1038. 	for (i = col; i <= right_ptrs[row][col+1]; i++) 1039. 	   left_ptrs[row][i] = left_ptrs[row][col-1]; 1040.    }  1041. }  1042.  1043.  1044. /*===========================================================================*/  1045. /*===========================================================================*/  1046. /* Use either algorithm C or D.  See the config.h for more details. =========*/ 1047.  1048. /*  1049.  * Variables local to both Algorithms C and D.  1050. */ 1051. static int  start_row; 1052. static int start_col; 1053. static int step; 1054. static char **cs_rows; 1055. static char *cs_left; 1056. static char *cs_right; 1057. 1058. static void FDECL((*vis_func), (int,int,genericptr_t)); 1059. static genericptr_t varg; 1060. 1061. /*  1062.  * Both Algorithms C and D use the following macros. 1063. *  1064.  *      good_row(z)	  - Return TRUE if the argument is a legal row. 1065. *      set_cs(rowp,col)  - Set the local could see array. 1066. *      set_min(z)	  - Save the min value of the argument and the current 1067. *			      row minimum. 1068. *      set_max(z)	  - Save the max value of the argument and the current 1069. *			      row maximum. 1070. *  1071.  * The last three macros depend on having local pointers row_min, row_max, 1072. * and rowp being set correctly. 1073. */  1074. #define set_cs(rowp,col) (rowp[col] = COULD_SEE) 1075. #define good_row(z) ((z) >= 0 && (z) < ROWNO) 1076. #define set_min(z) if (*row_min > (z)) *row_min = (z) 1077. #define set_max(z) if (*row_max < (z)) *row_max = (z) 1078. #define is_clear(row,col) viz_clear_rows[row][col] 1079. 1080. /*  1081.  * clear_path		expanded into 4 macros/functions: 1082. *  1083.  *	q1_path 1084. *	q2_path 1085. *	q3_path 1086. *	q4_path 1087. *  1088.  * "Draw" a line from the start to the given location. Stop if we hit 1089. * something that blocks light. The start and finish points themselves are 1090. * not checked, just the points between them. These routines do _not_ 1091. * expect to be called with the same starting and stopping point. 1092. *  1093.  * These routines use the generalized integer Bresenham's algorithm (fast  1094.  * line drawing) for all quadrants. The algorithm was taken from _Procedural 1095. * Elements for Computer Graphics_, by David F. Rogers. McGraw-Hill, 1985. 1096. */  1097. #ifdef MACRO_CPATH	/* quadrant calls are macros */ 1098. 1099. /*  1100.  * When called, the result is in "result". 1101. * The first two arguments (srow,scol) are one end of the path. The next 1102. * two arguments (row,col) are the destination. The last argument is 1103. * used as a C language label. This means that it must be different 1104. * in each pair of calls. 1105. */  1106.  1107. /*  1108.  *  Quadrant I (step < 0). 1109. */  1110. #define q1_path(srow,scol,y2,x2,label)			\ 1111. {							\ 1112.     int dx, dy;						\ 1113.    register int k, err, x, y, dxs, dys;		\ 1114. 							\ 1115.     x  = (scol);	y  = (srow);			\ 1116.    dx = (x2) - x;	dy = y - (y2);			\ 1117. 							\ 1118.     result = 0;		 /* default to a blocked path */\ 1119. 							\ 1120.     dxs = dx << 1;	   /* save the shifted values */\ 1121.    dys = dy << 1;					\ 1122.    if (dy > dx) {					\ 1123. 	err = dxs - dy;					\ 1124. 							\ 1125. 	for (k = dy-1; k; k--) {			\ 1126. 	   if (err >= 0) {				\ 1127. 		x++;					\ 1128. 		err -= dys;				\ 1129. 	   }						\  1130. 	    y--;					\ 1131. 	   err += dxs;					\ 1132. 	   if (!is_clear(y,x)) goto label;/* blocked */\ 1133. 	}						\ 1134.     } else {						\ 1135. 	err = dys - dx;					\ 1136. 							\ 1137. 	for (k = dx-1; k; k--) {			\ 1138. 	   if (err >= 0) {				\ 1139. 		y--;					\ 1140. 		err -= dxs;				\ 1141. 	   }						\  1142. 	    x++;					\ 1143. 	   err += dys;					\ 1144. 	   if (!is_clear(y,x)) goto label;/* blocked */\ 1145. 	}						\ 1146.     }							\  1147. 							\  1148.     result = 1;						\ 1149. } 1150.  1151. /*  1152.  * Quadrant IV (step > 0). 1153. */  1154. #define q4_path(srow,scol,y2,x2,label)			\ 1155. {							\ 1156.     int dx, dy;						\ 1157.    register int k, err, x, y, dxs, dys;		\ 1158. 							\ 1159.     x  = (scol);	y  = (srow);			\ 1160.    dx = (x2) - x;	dy = (y2) - y;			\ 1161. 							\ 1162.     result = 0;		 /* default to a blocked path */\ 1163. 							\ 1164.     dxs = dx << 1;	   /* save the shifted values */\ 1165.    dys = dy << 1;					\ 1166.    if (dy > dx) {					\ 1167. 	err = dxs - dy;					\ 1168. 							\ 1169. 	for (k = dy-1; k; k--) {			\ 1170. 	   if (err >= 0) {				\ 1171. 		x++;					\ 1172. 		err -= dys;				\ 1173. 	   }						\  1174. 	    y++;					\ 1175. 	   err += dxs;					\ 1176. 	   if (!is_clear(y,x)) goto label;/* blocked */\ 1177. 	}						\ 1178. 							\  1179.     } else {						\ 1180. 	err = dys - dx;					\ 1181. 							\ 1182. 	for (k = dx-1; k; k--) {			\ 1183. 	   if (err >= 0) {				\ 1184. 		y++;					\ 1185. 		err -= dxs;				\ 1186. 	   }						\  1187. 	    x++;					\ 1188. 	   err += dys;					\ 1189. 	   if (!is_clear(y,x)) goto label;/* blocked */\ 1190. 	}						\ 1191.     }							\  1192. 							\  1193.     result = 1;						\ 1194. } 1195.  1196. /*  1197.  * Quadrant II (step < 0). 1198. */  1199. #define q2_path(srow,scol,y2,x2,label)			\ 1200. {							\ 1201.     int dx, dy;						\ 1202.    register int k, err, x, y, dxs, dys;		\ 1203. 							\ 1204.     x  = (scol);	y  = (srow);			\ 1205.    dx = x - (x2);	dy = y - (y2);			\ 1206. 							\ 1207.     result = 0;		 /* default to a blocked path */\ 1208. 							\ 1209.     dxs = dx << 1;	   /* save the shifted values */\ 1210.    dys = dy << 1;					\ 1211.    if (dy > dx) {					\ 1212. 	err = dxs - dy;					\ 1213. 							\ 1214. 	for (k = dy-1; k; k--) {			\ 1215. 	   if (err >= 0) {				\ 1216. 		x--;					\ 1217. 		err -= dys;				\ 1218. 	   }						\  1219. 	    y--;					\ 1220. 	   err += dxs;					\ 1221. 	   if (!is_clear(y,x)) goto label;/* blocked */\ 1222. 	}						\ 1223.     } else {						\ 1224. 	err = dys - dx;					\ 1225. 							\ 1226. 	for (k = dx-1; k; k--) {			\ 1227. 	   if (err >= 0) {				\ 1228. 		y--;					\ 1229. 		err -= dxs;				\ 1230. 	   }						\  1231. 	    x--;					\ 1232. 	   err += dys;					\ 1233. 	   if (!is_clear(y,x)) goto label;/* blocked */\ 1234. 	}						\ 1235.     }							\  1236. 							\  1237.     result = 1;						\ 1238. } 1239.  1240. /*  1241.  * Quadrant III (step > 0). 1242. */  1243. #define q3_path(srow,scol,y2,x2,label)			\ 1244. {							\ 1245.     int dx, dy;						\ 1246.    register int k, err, x, y, dxs, dys;		\ 1247. 							\ 1248.     x  = (scol);	y  = (srow);			\ 1249.    dx = x - (x2);	dy = (y2) - y;			\ 1250. 							\ 1251.     result = 0;		 /* default to a blocked path */\ 1252. 							\ 1253.     dxs = dx << 1;	   /* save the shifted values */\ 1254.    dys = dy << 1;					\ 1255.    if (dy > dx) {					\ 1256. 	err = dxs - dy;					\ 1257. 							\ 1258. 	for (k = dy-1; k; k--) {			\ 1259. 	   if (err >= 0) {				\ 1260. 		x--;					\ 1261. 		err -= dys;				\ 1262. 	   }						\  1263. 	    y++;					\ 1264. 	   err += dxs;					\ 1265. 	   if (!is_clear(y,x)) goto label;/* blocked */\ 1266. 	}						\ 1267. 							\  1268.     } else {						\ 1269. 	err = dys - dx;					\ 1270. 							\ 1271. 	for (k = dx-1; k; k--) {			\ 1272. 	   if (err >= 0) {				\ 1273. 		y++;					\ 1274. 		err -= dxs;				\ 1275. 	   }						\  1276. 	    x--;					\ 1277. 	   err += dys;					\ 1278. 	   if (!is_clear(y,x)) goto label;/* blocked */\ 1279. 	}						\ 1280.     }							\  1281. 							\  1282.     result = 1;						\ 1283. } 1284.  1285. #else   /* quadrants are really functions */ 1286. 1287. STATIC_DCL int FDECL(_q1_path, (int,int,int,int)); 1288. STATIC_DCL int FDECL(_q2_path, (int,int,int,int)); 1289. STATIC_DCL int FDECL(_q3_path, (int,int,int,int)); 1290. STATIC_DCL int FDECL(_q4_path, (int,int,int,int)); 1291. 1292. #define q1_path(sy,sx,y,x,dummy) result = _q1_path(sy,sx,y,x) 1293. #define q2_path(sy,sx,y,x,dummy) result = _q2_path(sy,sx,y,x) 1294. #define q3_path(sy,sx,y,x,dummy) result = _q3_path(sy,sx,y,x) 1295. #define q4_path(sy,sx,y,x,dummy) result = _q4_path(sy,sx,y,x) 1296. 1297. /*  1298.  * Quadrant I (step < 0). 1299. */  1300. STATIC_OVL int 1301. _q1_path(srow,scol,y2,x2) 1302.    int scol, srow, y2, x2; 1303. { 1304.     int dx, dy; 1305.    register int k, err, x, y, dxs, dys; 1306. 1307.     x  = scol;		y  = srow; 1308.    dx = x2 - x;	dy = y - y2; 1309. 1310.     dxs = dx << 1;	   /* save the shifted values */ 1311.    dys = dy << 1; 1312.    if (dy > dx) { 1313. 	err = dxs - dy; 1314. 1315. 	for (k = dy-1; k; k--) { 1316. 	   if (err >= 0) { 1317. 		x++; 1318. 		err -= dys; 1319. 	   }  1320. 	    y--; 1321. 	   err += dxs; 1322. 	   if (!is_clear(y,x)) return 0; /* blocked */ 1323. 	} 1324.     } else { 1325. 	err = dys - dx; 1326. 1327. 	for (k = dx-1; k; k--) { 1328. 	   if (err >= 0) { 1329. 		y--; 1330. 		err -= dxs; 1331. 	   }  1332. 	    x++; 1333. 	   err += dys; 1334. 	   if (!is_clear(y,x)) return 0;/* blocked */ 1335. 	} 1336.     }  1337.  1338.     return 1; 1339. } 1340.  1341. /*  1342.  * Quadrant IV (step > 0). 1343. */  1344. STATIC_OVL int 1345. _q4_path(srow,scol,y2,x2) 1346.    int scol, srow, y2, x2; 1347. { 1348.     int dx, dy; 1349.    register int k, err, x, y, dxs, dys; 1350. 1351.     x  = scol;		y  = srow; 1352.    dx = x2 - x;	dy = y2 - y;  1353. 1354.    dxs = dx << 1;	   /* save the shifted values */ 1355.    dys = dy << 1; 1356.    if (dy > dx) { 1357. 	err = dxs - dy; 1358. 1359. 	for (k = dy-1; k; k--) { 1360. 	   if (err >= 0) { 1361. 		x++; 1362. 		err -= dys; 1363. 	   }  1364. 	    y++; 1365. 	   err += dxs; 1366. 	   if (!is_clear(y,x)) return 0; /* blocked */ 1367. 	} 1368.     } else { 1369. 	err = dys - dx; 1370. 1371. 	for (k = dx-1; k; k--) { 1372. 	   if (err >= 0) { 1373. 		y++; 1374. 		err -= dxs; 1375. 	   }  1376. 	    x++; 1377. 	   err += dys; 1378. 	   if (!is_clear(y,x)) return 0;/* blocked */ 1379. 	} 1380.     }  1381.  1382.     return 1; 1383. } 1384.  1385. /*  1386.  * Quadrant II (step < 0). 1387. */  1388. STATIC_OVL int 1389. _q2_path(srow,scol,y2,x2) 1390.    int scol, srow, y2, x2; 1391. { 1392.     int dx, dy; 1393.    register int k, err, x, y, dxs, dys; 1394. 1395.     x  = scol;		y  = srow; 1396.    dx = x - x2;	dy = y - y2; 1397. 1398.     dxs = dx << 1;	   /* save the shifted values */ 1399.    dys = dy << 1; 1400.    if (dy > dx) { 1401. 	err = dxs - dy; 1402. 1403. 	for (k = dy-1; k; k--) { 1404. 	   if (err >= 0) { 1405. 		x--; 1406. 		err -= dys; 1407. 	   }  1408. 	    y--; 1409. 	   err += dxs; 1410. 	   if (!is_clear(y,x)) return 0; /* blocked */ 1411. 	} 1412.     } else { 1413. 	err = dys - dx; 1414. 1415. 	for (k = dx-1; k; k--) { 1416. 	   if (err >= 0) { 1417. 		y--; 1418. 		err -= dxs; 1419. 	   }  1420. 	    x--; 1421. 	   err += dys; 1422. 	   if (!is_clear(y,x)) return 0;/* blocked */ 1423. 	} 1424.     }  1425.  1426.     return 1; 1427. } 1428.  1429. /*  1430.  * Quadrant III (step > 0). 1431. */  1432. STATIC_OVL int 1433. _q3_path(srow,scol,y2,x2) 1434.    int scol, srow, y2, x2; 1435. { 1436.     int dx, dy; 1437.    register int k, err, x, y, dxs, dys; 1438. 1439.     x  = scol;		y  = srow; 1440.    dx = x - x2;	dy = y2 - y;  1441. 1442.    dxs = dx << 1;	   /* save the shifted values */ 1443.    dys = dy << 1; 1444.    if (dy > dx) { 1445. 	err = dxs - dy; 1446. 1447. 	for (k = dy-1; k; k--) { 1448. 	   if (err >= 0) { 1449. 		x--; 1450. 		err -= dys; 1451. 	   }  1452. 	    y++; 1453. 	   err += dxs; 1454. 	   if (!is_clear(y,x)) return 0; /* blocked */ 1455. 	} 1456.     } else { 1457. 	err = dys - dx; 1458. 1459. 	for (k = dx-1; k; k--) { 1460. 	   if (err >= 0) { 1461. 		y++; 1462. 		err -= dxs; 1463. 	   }  1464. 	    x--; 1465. 	   err += dys; 1466. 	   if (!is_clear(y,x)) return 0;/* blocked */ 1467. 	} 1468.     }  1469.  1470.     return 1; 1471. } 1472.  1473. #endif	/* quadrants are functions */ 1474. 1475. /*  1476.  * Use vision tables to determine if there is a clear path from 1477. * (col1,row1) to (col2,row2). This is used by: 1478. *		m_cansee 1479. *		m_canseeu 1480. *		do_light_sources 1481. */  1482. boolean 1483. clear_path(col1,row1,col2,row2) 1484.    int col1, row1, col2, row2; 1485. { 1486.     int result; 1487. 1488.     if(col1 < col2) { 1489. 	if(row1 > row2) { 1490. 	   q1_path(row1,col1,row2,col2,cleardone); 1491. 	} else { 1492. 	   q4_path(row1,col1,row2,col2,cleardone); 1493. 	} 1494.     } else { 1495. 	if(row1 > row2) { 1496. 	   q2_path(row1,col1,row2,col2,cleardone); 1497. 	} else if(row1 == row2 && col1 == col2) { 1498. 	   result = 1; 1499. 	} else { 1500. 	   q3_path(row1,col1,row2,col2,cleardone); 1501. 	} 1502.     }  1503. cleardone: 1504.    return((boolean)result); 1505. } 1506.  1507. #ifdef VISION_TABLES 1508. /*===========================================================================*\ 1509. 			    GENERAL LINE OF SIGHT 1510. 				Algorithm D 1511. \*===========================================================================*/ 1512.  1513.  1514. /*  1515.  * Indicate caller for the shadow routines. 1516. */  1517. #define FROM_RIGHT 0 1518. #define FROM_LEFT 1 1519. 1520.  1521. /*  1522.  * Include the table definitions. 1523. */  1524. #include "vis_tab.h"  1525. 1526. 1527. /* 3D table pointers. */ 1528. static close2d *close_dy[CLOSE_MAX_BC_DY]; 1529. static far2d  *far_dy[FAR_MAX_BC_DY]; 1530. 1531. STATIC_DCL void FDECL(right_side, (int,int,int,int,int,int,int,char*)); 1532. STATIC_DCL void FDECL(left_side, (int,int,int,int,int,int,int,char*)); 1533. STATIC_DCL int FDECL(close_shadow, (int,int,int,int)); 1534. STATIC_DCL int FDECL(far_shadow, (int,int,int,int)); 1535. 1536. /*  1537.  * Initialize algorithm D's table pointers. If we don't have these, 1538. * then we do 3D table lookups. Verrrry slow. 1539. */  1540. STATIC_OVL void 1541. view_init 1542. { 1543.     int i;  1544. 1545.    for (i = 0; i < CLOSE_MAX_BC_DY; i++) 1546. 	close_dy[i] = &close_table[i]; 1547. 1548.     for (i = 0; i < FAR_MAX_BC_DY; i++) 1549. 	far_dy[i] = &far_table[i]; 1550. } 1551.  1552.  1553. /*  1554.  * If the far table has an entry of OFF_TABLE, then the far block prevents 1555. * us from seeing the location just above/below it. I.e. the first visible 1556. * location is one *before* the block. 1557. */  1558. #define OFF_TABLE 0xff 1559. 1560. STATIC_OVL int 1561. close_shadow(side,this_row,block_row,block_col) 1562.    int side,this_row,block_row,block_col; 1563. { 1564.     register int sdy, sdx, pdy, offset; 1565. 1566.     /*  1567.      * If on the same column (block_row = -1), then we can see it. 1568.     */  1569.     if (block_row < 0) return block_col; 1570. 1571.     /* Take explicit absolute values. Adjust. */ 1572.     if ((sdy = (start_row-block_row)) < 0) sdy = -sdy; --sdy;	/* src   dy */ 1573.    if ((sdx = (start_col-block_col)) < 0) sdx = -sdx;		/* src   dx */ 1574.    if ((pdy = (block_row-this_row))  < 0) pdy = -pdy;		/* point dy */ 1575. 1576.     if (sdy < 0 || sdy >= CLOSE_MAX_SB_DY || sdx >= CLOSE_MAX_SB_DX ||  1577. 						    pdy >= CLOSE_MAX_BC_DY) { 1578. 	impossible("close_shadow: bad value"); 1579. 	return block_col; 1580.    }  1581.     offset = close_dy[sdy]->close[sdx][pdy]; 1582.    if (side == FROM_RIGHT) 1583. 	return block_col + offset; 1584. 1585.     return block_col - offset; 1586. } 1587.  1588.  1589. STATIC_OVL int 1590. far_shadow(side,this_row,block_row,block_col) 1591.    int side,this_row,block_row,block_col; 1592. { 1593.     register int sdy, sdx, pdy, offset; 1594. 1595.     /*  1596.      * Take care of a bug that shows up only on the borders. 1597.     *  1598.      * If the block is beyond the border, then the row is negative. Return 1599.     * the block's column number (should be 0 or COLNO-1). 1600.     *  1601.      * Could easily have the column be -1, but then wouldn't know if it was 1602.     * the left or right border. 1603.     */  1604.     if (block_row < 0) return block_col; 1605. 1606.     /* Take explicit absolute values. Adjust. */ 1607.     if ((sdy = (start_row-block_row)) < 0) sdy = -sdy;		/* src   dy */ 1608.    if ((sdx = (start_col-block_col)) < 0) sdx = -sdx; --sdx;	/* src   dx */ 1609.    if ((pdy = (block_row-this_row))  < 0) pdy = -pdy; --pdy;	/* point dy */ 1610. 1611.     if (sdy >= FAR_MAX_SB_DY || sdx < 0 || sdx >= FAR_MAX_SB_DX ||  1612. 					    pdy < 0 || pdy >= FAR_MAX_BC_DY) { 1613. 	impossible("far_shadow: bad value"); 1614. 	return block_col; 1615.    }  1616.     if ((offset = far_dy[sdy]->far_q[sdx][pdy]) == OFF_TABLE) offset = -1; 1617.    if (side == FROM_RIGHT) 1618. 	return block_col + offset; 1619. 1620.     return block_col - offset; 1621. } 1622.  1623.  1624. /*  1625.  * right_side 1626. *  1627.  * Figure out what could be seen on the right side of the source. 1628. */  1629. STATIC_OVL void 1630. right_side(row, cb_row, cb_col, fb_row, fb_col, left, right_mark, limits) 1631.    int row;		/* current row */ 1632.    int	cb_row, cb_col;	/* close block row and col */ 1633.    int	fb_row, fb_col;	/* far block row and col */ 1634.    int left;		/* left mark of the previous row */ 1635.    int	right_mark;	/* right mark of previous row */ 1636.    char *limits;	/* points at range limit for current row, or NULL */ 1637. { 1638.     register int  i;  1639. register char *rowp; 1640.    int  hit_stone = 0; 1641.    int  left_shadow, right_shadow, loc_right; 1642.    int  lblock_col;		/* local block column (current row) */ 1643.    int  nrow, deeper; 1644.    char *row_min;		/* left most */ 1645.    char *row_max;		/* right most */ 1646.    int		  lim_max;	/* right most limit of circle */ 1647. 1648.     nrow    = row + step; 1649.    deeper  = good_row(nrow) && (!limits || (*limits >= *(limits+1))); 1650.    if(!vis_func) { 1651. 	rowp   = cs_rows[row]; 1652. 	row_min = &cs_left[row]; 1653. 	row_max = &cs_right[row]; 1654.    }  1655.     if(limits) { 1656. 	lim_max = start_col + *limits; 1657. 	if(lim_max > COLNO-1) lim_max = COLNO-1; 1658. 	if(right_mark > lim_max) right_mark = lim_max; 1659. 	limits++; /* prepare for next row */ 1660.    } else 1661. 	lim_max = COLNO-1; 1662. 1663.     /*  1664.      * Get the left shadow from the close block. This value could be 1665. * illegal. 1666.     */  1667.     left_shadow = close_shadow(FROM_RIGHT,row,cb_row,cb_col); 1668. 1669.     /*  1670.      * Mark all stone walls as seen before the left shadow. All this work 1671.     * for a special case. 1672.     *  1673.      * NOTE. With the addition of this code in here, it is now *required* 1674.     * for the algorithm to work correctly. If this is commented out, 1675.     * change the above assignment so that left and not left_shadow is the 1676.     * variable that gets the shadow. 1677.     */  1678.     while (left <= right_mark) { 1679. 	loc_right = right_ptrs[row][left]; 1680. 	if(loc_right > lim_max) loc_right = lim_max; 1681. 	if (viz_clear_rows[row][left]) { 1682. 	   if (loc_right >= left_shadow) { 1683. 		left = left_shadow;	/* opening ends beyond shadow */ 1684. 		break; 1685. 	   }  1686. 	    left = loc_right; 1687. 	   loc_right = right_ptrs[row][left]; 1688. 	   if(loc_right > lim_max) loc_right = lim_max; 1689. 	   if (left == loc_right) return;	/* boundary */ 1690. 1691. 	    /* Shadow covers opening, beyond right mark */ 1692. 	   if (left == right_mark && left_shadow > right_mark) return; 1693. 	} 1694.  1695. 	if (loc_right > right_mark)	/* can't see stone beyond the mark */ 1696. 	   loc_right = right_mark; 1697. 1698. 	if(vis_func) { 1699. 	   for (i = left; i <= loc_right; i++) (*vis_func)(i, row, varg); 1700. 	} else { 1701. 	   for (i = left; i <= loc_right; i++) set_cs(rowp,i); 1702. 	   set_min(left);	set_max(loc_right); 1703. 	} 1704.  1705. 	if (loc_right == right_mark) return;	/* all stone */ 1706. 	if (loc_right >= left_shadow) hit_stone = 1; 1707. 	left = loc_right + 1; 1708.    }  1709.  1710.     /*  1711.      * At this point we are at the first visible clear spot on or beyond 1712.     * the left shadow, unless the left shadow is an illegal value. If we 1713. * have "hit stone" then we have a stone wall just to our left. 1714.     */  1715.  1716.     /*  1717.      * Get the right shadow. Make sure that it is a legal value. 1718.     */  1719.     if ((right_shadow = far_shadow(FROM_RIGHT,row,fb_row,fb_col)) >= COLNO) 1720. 	right_shadow = COLNO-1; 1721.    /*  1722.      * Make vertical walls work the way we want them. In this case, we 1723. * note when the close block blocks the column just above/beneath 1724.     * it (right_shadow < fb_col [actually right_shadow == fb_col-1]). If 1725. * the location is filled, then we want to see it, so we put the 1726.     * right shadow back (same as fb_col). 1727.     */  1728.     if (right_shadow < fb_col && !viz_clear_rows[row][fb_col]) 1729. 	right_shadow = fb_col; 1730.    if(right_shadow > lim_max) right_shadow = lim_max; 1731. 1732.     /*  1733.      * Main loop. Within the range of sight of the previous row, mark all 1734.     * stone walls as seen. Follow open areas recursively. 1735.     */  1736.     while (left <= right_mark) { 1737. 	/* Get the far right of the opening or wall */ 1738. 	loc_right = right_ptrs[row][left]; 1739. 	if(loc_right > lim_max) loc_right = lim_max; 1740. 1741. 	if (!viz_clear_rows[row][left]) { 1742. 	   hit_stone = 1;	/* use stone on this row as close block */ 1743. 	   /*  1744. 	     * We can see all of the wall until the next open spot or the 1745. 	    * start of the shadow caused by the far block (right). 1746. 	    *  1747. 	     * Can't see stone beyond the right mark. 1748. 	    */  1749. 	    if (loc_right > right_mark) loc_right = right_mark; 1750. 1751. 	    if(vis_func) { 1752. 		for (i = left; i <= loc_right; i++) (*vis_func)(i, row, varg); 1753. 	   } else { 1754. 		for (i = left; i <= loc_right; i++) set_cs(rowp,i); 1755. 		set_min(left);	set_max(loc_right); 1756. 	   }  1757.  1758. 	    if (loc_right == right_mark) return;	/* hit the end */ 1759. 	   left = loc_right + 1; 1760. 	   loc_right = right_ptrs[row][left]; 1761. 	   if(loc_right > lim_max) loc_right = lim_max; 1762. 	   /* fall through... we know at least one position is visible */ 1763. 	} 1764.  1765. 	/*  1766. 	 * We are in an opening. 1767. 	 * 1768. 	 * If this is the first open spot since the could see area  (this is  1769. 	 * true if we have hit stone), get the shadow generated by the wall 1770. 	 * just to our left. 1771. 	 */ 1772. 	if (hit_stone) { 1773. 	   lblock_col = left-1;	/* local block column */ 1774. 	   left = close_shadow(FROM_RIGHT,row,row,lblock_col); 1775. 	   if (left > lim_max) break;		/* off the end */ 1776. 	} 1777.  1778. 	/*  1779. 	 * Check if the shadow covers the opening. If it does, then 1780. 	 * move to end of the opening. A shadow generated on from a 1781. * wall on this row does *not* cover the wall on the right 1782. 	 * of the opening. 1783. 	 */ 1784. 	if (left >= loc_right) { 1785. 	   if (loc_right == lim_max) {		/* boundary */ 1786. 		if (left == lim_max) { 1787. 		   if(vis_func) (*vis_func)(lim_max, row, varg); 1788. 		   else { 1789. 			set_cs(rowp,lim_max);	/* last pos */ 1790. 			set_max(lim_max); 1791. 		   }  1792. 		}  1793. 		return;					/* done */ 1794. 	   }  1795. 	    left = loc_right; 1796. 	   continue; 1797. 	} 1798.  1799. 	/*  1800. 	 * If the far wall of the opening (loc_right) is closer than the 1801. 	 * shadow limit imposed by the far block (right) then use the far 1802. 	 * wall as our new far block when we recurse. 1803. 	 * 1804. 	 * If the limits are the the same, and the far block really exists 1805. 	 * (fb_row >= 0) then do the same as above. 1806. 	 * 1807. 	 * Normally, the check would be for the far wall being closer OR EQUAL 1808. 	 * to the shadow limit. However, there is a bug that arises from the 1809. 	 * fact that the clear area pointers end in an open space (if it 1810. 	 * exists) on a boundary. This then makes a far block exist where it 1811. * shouldn't --- on a boundary. To get around that, I had to 1812. * introduce the concept of a non-existent far block (when the 1813. 	 * row < 0). Next I have to check for it. Here is where that check 1814. 	 * exists. 1815. 	 */ 1816. 	if ((loc_right < right_shadow) ||  1817. 				(fb_row >= 0 && loc_right == right_shadow)) { 1818. 	   if(vis_func) { 1819. 		for (i = left; i <= loc_right; i++) (*vis_func)(i, row, varg); 1820. 	   } else { 1821. 		for (i = left; i <= loc_right; i++) set_cs(rowp,i); 1822. 		set_min(left);	set_max(loc_right); 1823. 	   }  1824.  1825. 	    if (deeper) { 1826. 		if (hit_stone) 1827. 		   right_side(nrow,row,lblock_col,row,loc_right,  1828. 							left,loc_right,limits); 1829. 		else 1830. 		   right_side(nrow,cb_row,cb_col,row,loc_right,  1831. 							left,loc_right,limits); 1832. 	   }  1833.  1834. 	    /*  1835. 	     * The following line, setting hit_stone, is needed for those 1836. 	    * walls that are only 1 wide. If hit stone is *not* set and 1837. 	    * the stone is only one wide, then the close block is the old 1838. 	    * one instead one on the current row. A way around having to 1839. * set it here is to make left = loc_right (not loc_right+1) and 1840. 	    * let the outer loop take care of it. However, if we do that 1841. 	    * then we then have to check for boundary conditions here as  1842. * well. 1843. 	    */  1844. 	    hit_stone = 1; 1845. 1846. 	    left = loc_right+1; 1847. 	} 1848. 	/*  1849. 	 * The opening extends beyond the right mark. This means that 1850. 	 * the next far block is the current far block. 1851. 	 */ 1852. 	else { 1853. 	   if(vis_func) { 1854. 		for (i=left; i <= right_shadow; i++) (*vis_func)(i, row, varg); 1855. 	   } else { 1856. 		for (i = left; i <= right_shadow; i++) set_cs(rowp,i); 1857. 		set_min(left);	set_max(right_shadow); 1858. 	   }  1859.  1860. 	    if (deeper) { 1861. 		if (hit_stone) 1862. 		   right_side(nrow,   row,lblock_col,fb_row,fb_col,  1863. 						     left,right_shadow,limits); 1864. 		else 1865. 		   right_side(nrow,cb_row,    cb_col,fb_row,fb_col,  1866. 						     left,right_shadow,limits); 1867. 	   }  1868.  1869. 	    return;	/* we're outta here */ 1870. 	} 1871.     }  1872. }  1873.  1874.  1875. /*  1876.  * left_side 1877. *  1878.  * This routine is the mirror image of right_side. Please see right_side 1879. * for blow by blow comments. 1880. */  1881. STATIC_OVL void 1882. left_side(row, cb_row, cb_col, fb_row, fb_col, left_mark, right, limits) 1883.    int row;		/* the current row */ 1884.    int	cb_row, cb_col;	/* close block row and col */ 1885.    int	fb_row, fb_col;	/* far block row and col */ 1886.    int	left_mark;	/* left mark of previous row */ 1887.    int right;		/* right mark of the previous row */ 1888.    char *limits; 1889. { 1890.     register int  i;  1891. register char *rowp; 1892.    int  hit_stone = 0; 1893.    int  left_shadow, right_shadow, loc_left; 1894.    int  lblock_col;		/* local block column (current row) */ 1895.    int  nrow, deeper; 1896.    char *row_min;		/* left most */ 1897.    char *row_max;		/* right most */ 1898.    int		  lim_min; 1899. 1900.     nrow    = row + step; 1901.    deeper  = good_row(nrow) && (!limits || (*limits >= *(limits+1))); 1902.    if(!vis_func) { 1903. 	rowp   = cs_rows[row]; 1904. 	row_min = &cs_left[row]; 1905. 	row_max = &cs_right[row]; 1906.    }  1907.     if(limits) { 1908. 	lim_min = start_col - *limits; 1909. 	if(lim_min < 0) lim_min = 0; 1910. 	if(left_mark < lim_min) left_mark = lim_min; 1911. 	limits++; /* prepare for next row */ 1912.    } else 1913. 	lim_min = 0; 1914. 1915.     /* This value could be illegal. */ 1916.     right_shadow = close_shadow(FROM_LEFT,row,cb_row,cb_col); 1917. 1918.     while ( right >= left_mark ) { 1919. 	loc_left = left_ptrs[row][right]; 1920. 	if(loc_left < lim_min) loc_left = lim_min; 1921. 	if (viz_clear_rows[row][right]) { 1922. 	   if (loc_left <= right_shadow) { 1923. 		right = right_shadow;	/* opening ends beyond shadow */ 1924. 		break; 1925. 	   }  1926. 	    right = loc_left; 1927. 	   loc_left = left_ptrs[row][right]; 1928. 	   if(loc_left < lim_min) loc_left = lim_min; 1929. 	   if (right == loc_left) return;	/* boundary */ 1930. 	} 1931.  1932. 	if (loc_left < left_mark)	/* can't see beyond the left mark */ 1933. 	   loc_left = left_mark; 1934. 1935. 	if(vis_func) { 1936. 	   for (i = loc_left; i <= right; i++) (*vis_func)(i, row, varg); 1937. 	} else { 1938. 	   for (i = loc_left; i <= right; i++) set_cs(rowp,i); 1939. 	   set_min(loc_left);	set_max(right); 1940. 	} 1941.  1942. 	if (loc_left == left_mark) return;	/* all stone */ 1943. 	if (loc_left <= right_shadow) hit_stone = 1; 1944. 	right = loc_left - 1; 1945.    }  1946.  1947.     /* At first visible clear spot on or beyond the right shadow. */ 1948.  1949.     if ((left_shadow = far_shadow(FROM_LEFT,row,fb_row,fb_col)) < 0) 1950. 	left_shadow = 0; 1951. 1952.     /* Do vertical walls as we want. */ 1953.     if (left_shadow > fb_col && !viz_clear_rows[row][fb_col]) 1954. 	left_shadow = fb_col; 1955.    if(left_shadow < lim_min) left_shadow = lim_min; 1956. 1957.     while (right >= left_mark) { 1958. 	loc_left = left_ptrs[row][right]; 1959. 1960. 	if (!viz_clear_rows[row][right]) { 1961. 	   hit_stone = 1;	/* use stone on this row as close block */ 1962. 1963. 	    /* We can only see walls until the left mark */ 1964. 	   if (loc_left < left_mark) loc_left = left_mark; 1965. 1966. 	    if(vis_func) { 1967. 		for (i = loc_left; i <= right; i++) (*vis_func)(i, row, varg); 1968. 	   } else { 1969. 		for (i = loc_left; i <= right; i++) set_cs(rowp,i); 1970. 		set_min(loc_left);	set_max(right); 1971. 	   }  1972.  1973. 	    if (loc_left == left_mark) return;	/* hit end */ 1974. 	   right = loc_left - 1; 1975. 	   loc_left = left_ptrs[row][right]; 1976. 	   if (loc_left < lim_min) loc_left = lim_min; 1977. 	   /* fall through...*/ 1978. 	} 1979.  1980. 	/* We are in an opening. */ 1981. 	if (hit_stone) { 1982. 	   lblock_col = right+1;	/* stone block (local) */ 1983. 	   right = close_shadow(FROM_LEFT,row,row,lblock_col); 1984. 	   if (right < lim_min) return;	/* off the end */ 1985. 	} 1986.  1987. 	/*  Check if the shadow covers the opening. */ 1988. 	if (right <= loc_left) { 1989. 	   /*  Make a boundary condition work. */ 1990. 	    if (loc_left == lim_min) {	/* at boundary */ 1991. 		if (right == lim_min) { 1992. 		   if(vis_func) (*vis_func)(lim_min, row, varg); 1993. 		   else { 1994. 			set_cs(rowp,lim_min);	/* caught the last pos */ 1995. 			set_min(lim_min); 1996. 		   }  1997. 		}  1998. 		return;			/* and break out the loop */ 1999. 	   }  2000.  2001. 	    right = loc_left; 2002. 	   continue; 2003. 	} 2004.  2005. 	/* If the far wall of the opening is closer than the shadow limit. */ 2006. 	if ((loc_left > left_shadow) ||  2007. 				    (fb_row >= 0 && loc_left == left_shadow)) { 2008. 	   if(vis_func) { 2009. 		for (i = loc_left; i <= right; i++) (*vis_func)(i, row, varg); 2010. 	   } else { 2011. 		for (i = loc_left; i <= right; i++) set_cs(rowp,i); 2012. 		set_min(loc_left);	set_max(right); 2013. 	   }  2014.  2015. 	    if (deeper) { 2016. 		if (hit_stone) 2017. 		   left_side(nrow,row,lblock_col,row,loc_left,  2018. 							loc_left,right,limits); 2019. 		else 2020. 		   left_side(nrow,cb_row,cb_col,row,loc_left,  2021. 							loc_left,right,limits); 2022. 	   }  2023.  2024. 	    hit_stone = 1;	/* needed for walls of width 1 */ 2025. 	   right = loc_left-1; 2026. 	} 2027. 	/*  The opening extends beyond the left mark. */ 2028. 	else { 2029. 	   if(vis_func) { 2030. 		for (i=left_shadow; i <= right; i++) (*vis_func)(i, row, varg); 2031. 	   } else { 2032. 		for (i = left_shadow; i <= right; i++) set_cs(rowp,i); 2033. 		set_min(left_shadow);	set_max(right); 2034. 	   }  2035.  2036. 	    if (deeper) { 2037. 		if (hit_stone) 2038. 		   left_side(nrow,row,lblock_col,fb_row,fb_col,  2039. 						     left_shadow,right,limits); 2040. 		else 2041. 		   left_side(nrow,cb_row,cb_col,fb_row,fb_col,  2042. 						     left_shadow,right,limits); 2043. 	   }  2044.  2045. 	    return;	/* we're outta here */ 2046. 	} 2047.  2048.     }  2049. }  2050.  2051. /*  2052.  * view_from 2053. *  2054.  * Calculate a view from the given location. Initialize and fill a 2055. * ROWNOxCOLNO array (could_see) with all the locations that could be 2056. * seen from the source location. Initialize and fill the left most 2057. * and right most boundaries of what could be seen. 2058. */  2059. STATIC_OVL void 2060. view_from(srow,scol,loc_cs_rows,left_most,right_most, range, func, arg) 2061.    int  srow, scol;			/* source row and column */ 2062.    char **loc_cs_rows;			/* could_see array (row pointers) */ 2063.    char *left_most, *right_most;	/* limits of what could be seen */ 2064.    int range;		/* 0 if unlimited */ 2065.    void FDECL((*func), (int,int,genericptr_t)); 2066.    genericptr_t arg; 2067. { 2068.     register int i;  2069. char	 *rowp; 2070.    int		 nrow, left, right, left_row, right_row; 2071.    char	 *limits; 2072. 2073.     /* Set globals for near_shadow, far_shadow, etc. to use. */ 2074.     start_col = scol; 2075.    start_row = srow; 2076.    cs_rows   = loc_cs_rows; 2077.    cs_left   = left_most; 2078.    cs_right  = right_most; 2079.    vis_func = func; 2080.    varg = arg; 2081. 2082.     /*  Find the left and right limits of sight on the starting row. */ 2083.     if (viz_clear_rows[srow][scol]) { 2084. 	left = left_ptrs[srow][scol]; 2085. 	right = right_ptrs[srow][scol]; 2086.    } else { 2087. 	left = (!scol) ? 0 : 2088. 	    (viz_clear_rows[srow][scol-1] ?  left_ptrs[srow][scol-1] : scol-1); 2089. 	right = (scol == COLNO-1) ? COLNO-1 : 2090. 	   (viz_clear_rows[srow][scol+1] ? right_ptrs[srow][scol+1] : scol+1); 2091.    }  2092.  2093.     if(range) { 2094. 	if(range > MAX_RADIUS || range < 1) 2095. 	   panic("view_from called with range %d", range); 2096. 	limits = circle_ptr(range) + 1; /* start at next row */ 2097. 	if(left < scol - range) left = scol - range; 2098. 	if(right > scol + range) right = scol + range; 2099.    } else 2100. 	limits = (char*) 0; 2101. 2102.     if(func) { 2103. 	for (i = left; i <= right; i++) (*func)(i, srow, arg); 2104.    } else { 2105. 	/* Row optimization */ 2106. 	rowp = cs_rows[srow]; 2107. 2108. 	/* We know that we can see our row. */ 2109. 	for (i = left; i <= right; i++) set_cs(rowp,i); 2110. 	cs_left[srow] = left; 2111. 	cs_right[srow] = right; 2112.    }  2113.  2114.     /* The far block has a row number of -1 if we are on an edge. */ 2115.     right_row = (right == COLNO-1) ? -1 : srow; 2116.    left_row  = (!left)		   ? -1 : srow; 2117. 2118.     /*  2119.      *  Check what could be seen in quadrants. 2120.     */  2121.     if ( (nrow = srow+1) < ROWNO ) { 2122. 	step = 1;	/* move down */ 2123. 	if (scol= 0 ) { 2130. 	step = -1;	/* move up */ 2131. 	if (scol<COLNO-1) 2132. 	   right_side(nrow,-1,scol,right_row,right,scol,right,limits); 2133. 	if (scol) 2134. 	   left_side(nrow,-1,scol,left_row, left, left, scol,limits); 2135.    }  2136. }  2137.  2138.  2139. #else	/*===== End of algorithm D =====*/ 2140. 2141.  2142. /*===========================================================================*\  2143. 			    GENERAL LINE OF SIGHT 2144. 				Algorithm C 2145. \*===========================================================================*/ 2146.  2147. /*  2148.  * Defines local to Algorithm C.  2149. */ 2150. STATIC_DCL void FDECL(right_side, (int,int,int,char*)); 2151. STATIC_DCL void FDECL(left_side, (int,int,int,char*)); 2152. 2153. /* Initialize algorithm C (nothing). */ 2154. STATIC_OVL void 2155. view_init 2156. { 2157. }  2158.  2159. /*  2160.  * Mark positions as visible on one quadrant of the right side. The 2161. * quadrant is determined by the value of the global variable step. 2162. */  2163. STATIC_OVL void 2164. right_side(row, left, right_mark, limits) 2165.    int row;		/* current row */ 2166.    int left;		/* first (left side) visible spot on prev row */ 2167.    int right_mark;	/* last (right side) visible spot on prev row */ 2168.    char *limits;	/* points at range limit for current row, or NULL */ 2169. { 2170.     int		  right;	/* right limit of "could see" */ 2171.    int		  right_edge;	/* right edge of an opening */ 2172.    int		  nrow;		/* new row (calculate once) */ 2173.    int		  deeper;	/* if TRUE, call self as needed */ 2174.    int		  result;	/* set by q?_path */ 2175.    register int  i;		/* loop counter */ 2176.    register char *rowp;	/* row optimization */ 2177.    char	  *row_min;	/* left most  [used by macro set_min] */ 2178.    char	  *row_max;	/* right most [used by macro set_max] */ 2179.    int		  lim_max;	/* right most limit of circle */ 2180. 2181. #ifdef GCC_WARN 2182.    rowp = row_min = row_max = 0; 2183. #endif 2184.    nrow    = row + step; 2185.    /*  2186.      * Can go deeper if the row is in bounds and the next row is within 2187.     * the circle's limit. We tell the latter by checking to see if the next 2188.     * limit value is the start of a new circle radius (meaning we depend  2189.      * on the structure of circle_data[]). 2190.     */  2191.     deeper  = good_row(nrow) && (!limits || (*limits >= *(limits+1))); 2192.    if(!vis_func) { 2193. 	rowp   = cs_rows[row];	/* optimization */ 2194. 	row_min = &cs_left[row]; 2195. 	row_max = &cs_right[row]; 2196.    }  2197.     if(limits) { 2198. 	lim_max = start_col + *limits; 2199. 	if(lim_max > COLNO-1) lim_max = COLNO-1; 2200. 	if(right_mark > lim_max) right_mark = lim_max; 2201. 	limits++; /* prepare for next row */ 2202.    } else 2203. 	lim_max = COLNO-1; 2204. 2205.     while (left <= right_mark) { 2206. 	right_edge = right_ptrs[row][left]; 2207. 	if(right_edge > lim_max) right_edge = lim_max; 2208. 2209. 	if (!is_clear(row,left)) { 2210. 	   /*  2211. 	     * Jump to the far side of a stone wall. We can set all 2212. 	    * the points in between as seen. 2213. 	    *  2214. 	     * If the right edge goes beyond the right mark, check to see 2215. 	    * how much we can see. 2216. 	    */  2217. 	    if (right_edge > right_mark) { 2218. 		/* 2219. 		 * If the mark on the previous row was a clear position, 2220. 		 * the odds are that we can actually see part of the wall 2221. 		 * beyond the mark on this row. If so, then see one beyond 2222. 		 * the mark. Otherwise don't. This is a kludge so corners 2223. 		 * with an adjacent doorway show up in nethack. 2224. 		 */ 2225. 		right_edge = is_clear(row-step,right_mark) ? 2226. 						   right_mark+1 : right_mark; 2227. 	   }  2228. 	    if(vis_func) { 2229. 		for (i = left; i <= right_edge; i++) (*vis_func)(i, row, varg); 2230. 	   } else { 2231. 		for (i = left; i <= right_edge; i++) set_cs(rowp,i); 2232. 		set_min(left);     set_max(right_edge); 2233. 	   }  2234. 	    left = right_edge + 1; /* no limit check necessary */ 2235. 	   continue; 2236. 	} 2237.  2238. 	/* No checking needed if our left side is the start column. */ 2239. 	if (left != start_col) { 2240. 	   /*  2241. 	     * Find the left side. Move right until we can see it or we run 2242. 	    * into a wall. 2243. 	    */  2244. 	    for (left <= right_edge; left++) { 2245. 		if (step < 0) { 2246. 		   q1_path(start_row,start_col,row,left,rside1); 2247. 		} else { 2248. 		   q4_path(start_row,start_col,row,left,rside1); 2249. 		} 2250. rside1:					/* used if q?_path is a macro */ 2251. 		if (result) break; 2252. 	   }  2253.  2254. 	    /*  2255. 	     * Check for boundary conditions. We *need* check (2) to break 2256. 	    * an infinite loop where: 2257. 	    *  2258. 	     *		left == right_edge == right_mark == lim_max. 2259. 	    *  2260. 	     */  2261. 	    if (left > lim_max) return;	/* check (1) */ 2262. 	   if (left == lim_max) {	/* check (2) */ 2263. 		if(vis_func) (*vis_func)(lim_max, row, varg); 2264. 		else { 2265. 		   set_cs(rowp,lim_max); 2266. 		   set_max(lim_max); 2267. 		} 2268. 		return; 2269. 	   }  2270. 	    /*  2271. 	     * Check if we can see any spots in the opening. We might 2272. 	    * (left == right_edge) or might not (left == right_edge+1) have 2273. 	    * been able to see the far wall. Make sure we *can* see the 2274. 	    * wall (remember, we can see the spot above/below this one) 2275. 	    * by backing up. 2276. 	    */  2277. 	    if (left >= right_edge) { 2278. 		left = right_edge;	/* for the case left == right_edge+1 */ 2279. 		continue; 2280. 	   }  2281. 	}  2282.  2283. 	/*  2284. 	 * Find the right side. If the marker from the previous row is 2285. * closer than the edge on this row, then we have to check 2286. 	 * how far we can see around the corner (under the overhang). Stop 2287. 	 * at the first non-visible spot or we actually hit the far wall. 2288. 	 * 2289. 	 * Otherwise, we know we can see the right edge of the current row. 2290. 	 * 2291. 	 * This must be a strict less than so that we can always see a  2292. * horizontal wall, even if it is adjacent to us. 2293. 	 */ 2294. 	if (right_mark < right_edge) { 2295. 	   for (right = right_mark; right <= right_edge; right++) { 2296. 		if (step < 0) { 2297. 		   q1_path(start_row,start_col,row,right,rside2); 2298. 		} else { 2299. 		   q4_path(start_row,start_col,row,right,rside2); 2300. 		} 2301. rside2:					/* used if q?_path is a macro */ 2302. 		if (!result) break; 2303. 	   }  2304. 	    --right;	/* get rid of the last increment */ 2305. 	} 2306. 	else 2307. 	   right = right_edge; 2308. 2309. 	/*  2310. 	 * We have the range that we want. Set the bits. Note that 2311. 	 * there is no else --- we no longer handle splinters. 2312. 	 */ 2313. 	if (left <= right) { 2314. 	   /*  2315. 	     * An ugly special case. If you are adjacent to a vertical wall 2316. 	    * and it has a break in it, then the right mark is set to be  2317. * start_col. We *want* to be able to see adjacent vertical 2318. 	    * walls, so we have to set it back. 2319. 	    */  2320. 	    if (left == right && left == start_col &&  2321. 			start_col < (COLNO-1) && !is_clear(row,start_col+1)) 2322. 		right = start_col+1; 2323. 2324. 	    if(right > lim_max) right = lim_max; 2325. 	   /* set the bits */ 2326. 	   if(vis_func) 2327. 		for (i = left; i <= right; i++) (*vis_func)(i, row, varg); 2328. 	   else { 2329. 		for (i = left; i <= right; i++) set_cs(rowp,i); 2330. 		set_min(left);     set_max(right); 2331. 	   }  2332.  2333. 	    /* recursive call for next finger of light */ 2334. 	   if (deeper) right_side(nrow,left,right,limits); 2335. 	   left = right + 1; /* no limit check necessary */ 2336. 	} 2337.     }  2338. }  2339.  2340.  2341. /*  2342.  * This routine is the mirror image of right_side. See right_side for 2343. * extensive comments. 2344. */  2345. STATIC_OVL void 2346. left_side(row, left_mark, right, limits) 2347.    int row, left_mark, right; 2348.    char *limits; 2349. { 2350.     int		  left, left_edge, nrow, deeper, result; 2351.    register int  i;  2352. register char *rowp; 2353.    char	  *row_min, *row_max; 2354.    int		  lim_min; 2355. 2356. #ifdef GCC_WARN 2357.    rowp = row_min = row_max = 0; 2358. #endif 2359.    nrow    = row+step; 2360.    deeper  = good_row(nrow) && (!limits || (*limits >= *(limits+1))); 2361.    if(!vis_func) { 2362. 	rowp   = cs_rows[row]; 2363. 	row_min = &cs_left[row]; 2364. 	row_max = &cs_right[row]; 2365.    }  2366.     if(limits) { 2367. 	lim_min = start_col - *limits; 2368. 	if(lim_min < 0) lim_min = 0; 2369. 	if(left_mark < lim_min) left_mark = lim_min; 2370. 	limits++; /* prepare for next row */ 2371.    } else 2372. 	lim_min = 0; 2373. 2374.     while (right >= left_mark) { 2375. 	left_edge = left_ptrs[row][right]; 2376. 	if(left_edge < lim_min) left_edge = lim_min; 2377. 2378. 	if (!is_clear(row,right)) { 2379. 	   /* Jump to the far side of a stone wall. */ 2380. 	    if (left_edge < left_mark) { 2381. 		/* Maybe see more (kludge). */ 2382. 		left_edge = is_clear(row-step,left_mark) ? 2383. 						   left_mark-1 : left_mark; 2384. 	   }  2385. 	    if(vis_func) { 2386. 		for (i = left_edge; i <= right; i++) (*vis_func)(i, row, varg); 2387. 	   } else { 2388. 		for (i = left_edge; i <= right; i++) set_cs(rowp,i); 2389. 		set_min(left_edge); set_max(right); 2390. 	   }  2391. 	    right = left_edge - 1; /* no limit check necessary */ 2392. 	   continue; 2393. 	} 2394.  2395. 	if (right != start_col) { 2396. 	   /* Find the right side. */ 2397. 	    for (right >= left_edge; right--) { 2398. 		if (step < 0) { 2399. 		   q2_path(start_row,start_col,row,right,lside1); 2400. 		} else { 2401. 		   q3_path(start_row,start_col,row,right,lside1); 2402. 		} 2403. lside1:					/* used if q?_path is a macro */ 2404. 		if (result) break; 2405. 	   }  2406.  2407. 	    /* Check for boundary conditions. */ 2408. 	    if (right < lim_min) return; 2409. 	   if (right == lim_min) { 2410. 		if(vis_func) (*vis_func)(lim_min, row, varg); 2411. 		else { 2412. 		   set_cs(rowp,lim_min); 2413. 		   set_min(lim_min); 2414. 		} 2415. 		return; 2416. 	   }  2417. 	    /* Check if we can see any spots in the opening. */ 2418. 	    if (right <= left_edge) { 2419. 		right = left_edge; 2420. 		continue; 2421. 	   }  2422. 	}  2423.  2424. 	/* Find the left side. */ 2425. 	if (left_mark > left_edge) { 2426. 	   for (left = left_mark; left >= left_edge; --left) { 2427. 		if (step < 0) { 2428. 		   q2_path(start_row,start_col,row,left,lside2); 2429. 		} else { 2430. 		   q3_path(start_row,start_col,row,left,lside2); 2431. 		} 2432. lside2:					/* used if q?_path is a macro */ 2433. 		if (!result) break; 2434. 	   }  2435. 	    left++;	/* get rid of the last decrement */ 2436. 	} 2437. 	else 2438. 	   left = left_edge; 2439. 2440. 	if (left <= right) { 2441. 	   /* An ugly special case. */ 2442. 	    if (left == right && right == start_col &&  2443. 			    start_col > 0 && !is_clear(row,start_col-1)) 2444. 		left = start_col-1; 2445. 2446. 	    if(left < lim_min) left = lim_min; 2447. 	   if(vis_func) 2448. 		for (i = left; i <= right; i++) (*vis_func)(i, row, varg); 2449. 	   else { 2450. 		for (i = left; i <= right; i++) set_cs(rowp,i); 2451. 		set_min(left);     set_max(right); 2452. 	   }  2453.  2454. 	    /* Recurse */ 2455. 	   if (deeper) left_side(nrow,left,right,limits); 2456. 	   right = left - 1; /* no limit check necessary */ 2457. 	} 2458.     }  2459. }  2460.  2461.  2462. /*  2463.  * Calculate all possible visible locations from the given location 2464. * (srow,scol). NOTE this is (y,x)! Mark the visible locations in the 2465. * array provided. 2466. */  2467. STATIC_OVL void 2468. view_from(srow, scol, loc_cs_rows, left_most, right_most, range, func, arg) 2469.    int  srow, scol;	/* starting row and column */ 2470.    char **loc_cs_rows;	/* pointers to the rows of the could_see array */ 2471.    char *left_most;	/* min mark on each row */ 2472.    char *right_most;	/* max mark on each row */ 2473.    int range;		/* 0 if unlimited */ 2474.    void FDECL((*func), (int,int,genericptr_t)); 2475.    genericptr_t arg; 2476. { 2477.     register int i;		/* loop counter */ 2478.    char         *rowp;		/* optimization for setting could_see */ 2479.    int		 nrow;		/* the next row */ 2480.    int		 left;		/* the left-most visible column */ 2481.    int		 right;		/* the right-most visible column */ 2482.    char	 *limits;	/* range limit for next row */ 2483. 2484.     /* Set globals for q?_path, left_side, and right_side to use. */ 2485.     start_col = scol; 2486.    start_row = srow; 2487.    cs_rows   = loc_cs_rows;	/* 'could see' rows */ 2488.    cs_left   = left_most; 2489.    cs_right  = right_most; 2490.    vis_func = func; 2491.    varg = arg; 2492. 2493.     /*  2494.      * Determine extent of sight on the starting row. 2495.     */  2496.     if (is_clear(srow,scol)) { 2497. 	left = left_ptrs[srow][scol]; 2498. 	right = right_ptrs[srow][scol]; 2499.    } else { 2500. 	/* 2501. 	 * When in stone, you can only see your adjacent squares, unless 2502. 	 * you are on an array boundary or a stone/clear boundary. 2503. 	 */ 2504. 	left  = (!scol) ? 0 : 2505. 		(is_clear(srow,scol-1) ? left_ptrs[srow][scol-1] : scol-1); 2506. 	right = (scol == COLNO-1) ? COLNO-1 : 2507. 		(is_clear(srow,scol+1) ? right_ptrs[srow][scol+1] : scol+1); 2508.    }  2509.  2510.     if(range) { 2511. 	if(range > MAX_RADIUS || range < 1) 2512. 	   panic("view_from called with range %d", range); 2513. 	limits = circle_ptr(range) + 1; /* start at next row */ 2514. 	if(left < scol - range) left = scol - range; 2515. 	if(right > scol + range) right = scol + range; 2516.    } else 2517. 	limits = (char*) 0; 2518. 2519.     if(func) { 2520. 	for (i = left; i <= right; i++) (*func)(i, srow, arg); 2521.    } else { 2522. 	/* Row pointer optimization. */ 2523. 	rowp = cs_rows[srow]; 2524. 2525. 	/* We know that we can see our row. */ 2526. 	for (i = left; i <= right; i++) set_cs(rowp,i); 2527. 	cs_left[srow] = left; 2528. 	cs_right[srow] = right; 2529.    }  2530.  2531.     /*  2532.      * Check what could be seen in quadrants. We need to check for valid 2533.     * rows here, since we don't do it in the routines right_side and 2534.     * left_side [ugliness to remove extra routine calls]. 2535.     */  2536.     if ( (nrow = srow+1) < ROWNO ) {	/* move down */ 2537. 	step = 1; 2538. 	if (scol < COLNO-1) right_side(nrow, scol, right, limits); 2539. 	if (scol)	   left_side (nrow, left,  scol, limits); 2540.    }  2541.  2542.     if ( (nrow = srow-1) >= 0 ) {	/* move up */ 2543. 	step = -1; 2544. 	if (scol < COLNO-1) right_side(nrow, scol, right, limits); 2545. 	if (scol)	   left_side (nrow, left,  scol, limits); 2546.    }  2547. }  2548.  2549. #endif	/*===== End of algorithm C =====*/ 2550. 2551. /*  2552.  * AREA OF EFFECT "ENGINE" 2553. *  2554.  * Calculate all possible visible locations as viewed from the given location 2555. * (srow,scol) within the range specified. Perform "func" with (x, y) args and 2556. * additional argument "arg" for each square. 2557. *  2558.  * If not centered on the hero, just forward arguments to view_from; it  2559. * will call "func" when necessary. If the hero is the center, use the 2560. * vision matrix and reduce extra work. 2561. */  2562. void 2563. do_clear_area(scol,srow,range,func,arg) 2564.    int scol, srow, range; 2565.    void FDECL((*func), (int,int,genericptr_t)); 2566.    genericptr_t arg; 2567. { 2568. 	/* If not centered on hero, do the hard work of figuring the area */ 2569. 	if (scol != u.ux || srow != u.uy) 2570. 	   view_from(srow, scol, (char **)0, (char *)0, (char *)0,  2571. 							range, func, arg); 2572. 	else { 2573. 	   register int x;  2574. int y, min_x, max_x, max_y, offset; 2575. 	   char *limits; 2576. 2577. 	    if (range > MAX_RADIUS || range < 1) 2578. 		panic("do_clear_area: illegal range %d", range); 2579. 	   if(vision_full_recalc) 2580. 		vision_recalc(0);	/* recalc vision if dirty */ 2581. 	   limits = circle_ptr(range); 2582. 	   if ((max_y = (srow + range)) >= ROWNO) max_y = ROWNO-1; 2583. 	   if ((y = (srow - range)) < 0) y = 0; 2584. 	   for (y <= max_y; y++) { 2585. 		offset = limits[v_abs(y-srow)]; 2586. 		if((min_x = (scol - offset)) < 0) min_x = 0; 2587. 		if((max_x = (scol + offset)) >= COLNO) max_x = COLNO-1; 2588. 		for (x = min_x; x <= max_x; x++) 2589. 		   if (couldsee(x, y)) 2590. 			(*func)(x, y, arg); 2591. 	   }  2592. 	}  2593. }  2594.  2595. /*vision.c*/