ref: 746f429371aa0d6e03a62d6c00e97ccbffd5acea
dir: /src/heretic/p_sight.c/
// // Copyright(C) 1993-1996 Id Software, Inc. // Copyright(C) 1993-2008 Raven Software // Copyright(C) 2005-2014 Simon Howard // // This program is free software; you can redistribute it and/or // modify it under the terms of the GNU General Public License // as published by the Free Software Foundation; either version 2 // of the License, or (at your option) any later version. // // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // P_sight.c #include <stdlib.h> #include "doomdef.h" #include "p_local.h" /* ============================================================================== P_CheckSight This uses specialized forms of the maputils routines for optimized performance ============================================================================== */ fixed_t sightzstart; // eye z of looker fixed_t topslope, bottomslope; // slopes to top and bottom of target int sightcounts[3]; /* ============== = = PTR_SightTraverse = ============== */ boolean PTR_SightTraverse(intercept_t * in) { line_t *li; fixed_t slope; li = in->d.line; // // crosses a two sided line // P_LineOpening(li); if (openbottom >= opentop) // quick test for totally closed doors return false; // stop if (li->frontsector->floorheight != li->backsector->floorheight) { slope = FixedDiv(openbottom - sightzstart, in->frac); if (slope > bottomslope) bottomslope = slope; } if (li->frontsector->ceilingheight != li->backsector->ceilingheight) { slope = FixedDiv(opentop - sightzstart, in->frac); if (slope < topslope) topslope = slope; } if (topslope <= bottomslope) return false; // stop return true; // keep going } /* ================== = = P_SightBlockLinesIterator = =================== */ boolean P_SightBlockLinesIterator(int x, int y) { int offset; short *list; line_t *ld; int s1, s2; divline_t dl; offset = y * bmapwidth + x; offset = *(blockmap + offset); for (list = blockmaplump + offset; *list != -1; list++) { ld = &lines[*list]; if (ld->validcount == validcount) continue; // line has already been checked ld->validcount = validcount; s1 = P_PointOnDivlineSide(ld->v1->x, ld->v1->y, &trace); s2 = P_PointOnDivlineSide(ld->v2->x, ld->v2->y, &trace); if (s1 == s2) continue; // line isn't crossed P_MakeDivline(ld, &dl); s1 = P_PointOnDivlineSide(trace.x, trace.y, &dl); s2 = P_PointOnDivlineSide(trace.x + trace.dx, trace.y + trace.dy, &dl); if (s1 == s2) continue; // line isn't crossed // try to early out the check if (!ld->backsector) return false; // stop checking // store the line for later intersection testing intercept_p->d.line = ld; intercept_p++; } return true; // everything was checked } /* ==================== = = P_SightTraverseIntercepts = = Returns true if the traverser function returns true for all lines ==================== */ boolean P_SightTraverseIntercepts(void) { int count; fixed_t dist; intercept_t *scan, *in; divline_t dl; count = intercept_p - intercepts; // // calculate intercept distance // for (scan = intercepts; scan < intercept_p; scan++) { P_MakeDivline(scan->d.line, &dl); scan->frac = P_InterceptVector(&trace, &dl); } // // go through in order // in = 0; // shut up compiler warning while (count--) { dist = INT_MAX; for (scan = intercepts; scan < intercept_p; scan++) if (scan->frac < dist) { dist = scan->frac; in = scan; } if (!PTR_SightTraverse(in)) return false; // don't bother going farther in->frac = INT_MAX; } return true; // everything was traversed } /* ================== = = P_SightPathTraverse = = Traces a line from x1,y1 to x2,y2, calling the traverser function for each = Returns true if the traverser function returns true for all lines ================== */ boolean P_SightPathTraverse(fixed_t x1, fixed_t y1, fixed_t x2, fixed_t y2) { fixed_t xt1, yt1, xt2, yt2; fixed_t xstep, ystep; fixed_t partial; fixed_t xintercept, yintercept; int mapx, mapy, mapxstep, mapystep; int count; validcount++; intercept_p = intercepts; if (((x1 - bmaporgx) & (MAPBLOCKSIZE - 1)) == 0) x1 += FRACUNIT; // don't side exactly on a line if (((y1 - bmaporgy) & (MAPBLOCKSIZE - 1)) == 0) y1 += FRACUNIT; // don't side exactly on a line trace.x = x1; trace.y = y1; trace.dx = x2 - x1; trace.dy = y2 - y1; x1 -= bmaporgx; y1 -= bmaporgy; xt1 = x1 >> MAPBLOCKSHIFT; yt1 = y1 >> MAPBLOCKSHIFT; x2 -= bmaporgx; y2 -= bmaporgy; xt2 = x2 >> MAPBLOCKSHIFT; yt2 = y2 >> MAPBLOCKSHIFT; // points should never be out of bounds, but check once instead of // each block if (xt1 < 0 || yt1 < 0 || xt1 >= bmapwidth || yt1 >= bmapheight || xt2 < 0 || yt2 < 0 || xt2 >= bmapwidth || yt2 >= bmapheight) return false; if (xt2 > xt1) { mapxstep = 1; partial = FRACUNIT - ((x1 >> MAPBTOFRAC) & (FRACUNIT - 1)); ystep = FixedDiv(y2 - y1, abs(x2 - x1)); } else if (xt2 < xt1) { mapxstep = -1; partial = (x1 >> MAPBTOFRAC) & (FRACUNIT - 1); ystep = FixedDiv(y2 - y1, abs(x2 - x1)); } else { mapxstep = 0; partial = FRACUNIT; ystep = 256 * FRACUNIT; } yintercept = (y1 >> MAPBTOFRAC) + FixedMul(partial, ystep); if (yt2 > yt1) { mapystep = 1; partial = FRACUNIT - ((y1 >> MAPBTOFRAC) & (FRACUNIT - 1)); xstep = FixedDiv(x2 - x1, abs(y2 - y1)); } else if (yt2 < yt1) { mapystep = -1; partial = (y1 >> MAPBTOFRAC) & (FRACUNIT - 1); xstep = FixedDiv(x2 - x1, abs(y2 - y1)); } else { mapystep = 0; partial = FRACUNIT; xstep = 256 * FRACUNIT; } xintercept = (x1 >> MAPBTOFRAC) + FixedMul(partial, xstep); // // step through map blocks // Count is present to prevent a round off error from skipping the break mapx = xt1; mapy = yt1; for (count = 0; count < 64; count++) { if (!P_SightBlockLinesIterator(mapx, mapy)) { sightcounts[1]++; return false; // early out } if (mapx == xt2 && mapy == yt2) break; if ((yintercept >> FRACBITS) == mapy) { yintercept += ystep; mapx += mapxstep; } else if ((xintercept >> FRACBITS) == mapx) { xintercept += xstep; mapy += mapystep; } } // // couldn't early out, so go through the sorted list // sightcounts[2]++; return P_SightTraverseIntercepts(); } /* ===================== = = P_CheckSight = = Returns true if a straight line between t1 and t2 is unobstructed = look from eyes of t1 to any part of t2 = ===================== */ boolean P_CheckSight(mobj_t * t1, mobj_t * t2) { int s1, s2; int pnum, bytenum, bitnum; // // check for trivial rejection // s1 = (t1->subsector->sector - sectors); s2 = (t2->subsector->sector - sectors); pnum = s1 * numsectors + s2; bytenum = pnum >> 3; bitnum = 1 << (pnum & 7); if (rejectmatrix[bytenum] & bitnum) { sightcounts[0]++; return false; // can't possibly be connected } // // check precisely // sightzstart = t1->z + t1->height - (t1->height >> 2); topslope = (t2->z + t2->height) - sightzstart; bottomslope = (t2->z) - sightzstart; return P_SightPathTraverse(t1->x, t1->y, t2->x, t2->y); }