mirror of
https://git.code.sf.net/p/quake/quakeforge
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189 lines
4.3 KiB
C
189 lines
4.3 KiB
C
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/*
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trace.c
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BSP line tracing
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Copyright (C) 2004 Bill Currie
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Author: Bill Currie <bill@taniwha.org>
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Date: 2004/9/25
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to:
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Free Software Foundation, Inc.
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59 Temple Place - Suite 330
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Boston, MA 02111-1307, USA
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#ifdef HAVE_STRING_H
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# include <string.h>
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#endif
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#ifdef HAVE_STRINGS_H
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# include <strings.h>
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#endif
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#include "QF/model.h"
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#include "QF/sys.h"
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#include "compat.h"
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#include "world.h"
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/* LINE TESTING IN HULLS */
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// 1/32 epsilon to keep floating point happy
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#ifndef DIST_EPSILON
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#define DIST_EPSILON (0.03125)
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#endif
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typedef struct {
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vec3_t end;
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int side;
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int num;
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mplane_t *plane;
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} tracestack_t;
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static inline void
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calc_impact (trace_t *trace, const vec3_t start, const vec3_t end,
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mplane_t *plane)
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{
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vec_t t1, t2, frac;
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vec3_t dist;
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t1 = PlaneDiff (start, plane);
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t2 = PlaneDiff (end, plane);
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if (t1 < 0) {
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frac = (t1 + DIST_EPSILON) / (t1 - t2);
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// invert plane paramterers
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VectorNegate (plane->normal, trace->plane.normal);
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trace->plane.dist = -plane->dist;
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} else {
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frac = (t1 - DIST_EPSILON) / (t1 - t2);
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VectorCopy (plane->normal, trace->plane.normal);
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trace->plane.dist = plane->dist;
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}
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frac = bound (0, frac, 1);
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trace->fraction = frac;
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VectorSubtract (end, start, dist);
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VectorMultAdd (start, frac, dist, trace->endpos);
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}
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VISIBLE void
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MOD_TraceLine (hull_t *hull, int num,
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const vec3_t start_point, const vec3_t end_point,
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trace_t *trace)
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{
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vec_t start_dist, end_dist, frac;
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vec3_t start, end, dist;
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int side, empty, solid;
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tracestack_t *tstack;
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tracestack_t tracestack[256];
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mclipnode_t *node;
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mplane_t *plane, *split_plane;
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VectorCopy (start_point, start);
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VectorCopy (end_point, end);
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tstack = tracestack;
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empty = 0;
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solid = 0;
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split_plane = 0;
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while (1) {
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while (num < 0) {
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if (!solid && num != CONTENTS_SOLID) {
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empty = 1;
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if (num == CONTENTS_EMPTY)
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trace->inopen = true;
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else
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trace->inwater = true;
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} else if (!empty && num == CONTENTS_SOLID) {
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solid = 1;
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} else if (solid && num != CONTENTS_SOLID) {
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//FIXME not sure what I want
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//made it out of the solid and into open space, continue
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//on as if we were always in empty space
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empty = 1;
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solid = 0;
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trace->startsolid = 1;
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if (num == CONTENTS_EMPTY)
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trace->inopen = true;
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else
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trace->inwater = true;
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} else if (empty/* || solid*/) {//FIXME not sure what I want
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// DONE!
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trace->allsolid = solid & (num == CONTENTS_SOLID);
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trace->startsolid = solid;
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calc_impact (trace, start_point, end_point, split_plane);
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return;
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}
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// pop up the stack for a back side
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if (tstack-- == tracestack) {
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// we've finished.
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trace->allsolid = solid & (num == CONTENTS_SOLID);
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trace->startsolid = solid;
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return;
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}
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// set the hit point for this plane
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VectorCopy (end, start);
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// go down the back side
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VectorCopy (tstack->end, end);
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side = tstack->side;
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split_plane = tstack->plane;
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num = hull->clipnodes[tstack->num].children[side ^ 1];
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}
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node = hull->clipnodes + num;
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plane = hull->planes + node->planenum;
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start_dist = PlaneDiff (start, plane);
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end_dist = PlaneDiff (end, plane);
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if (start_dist >= 0 && end_dist >= 0) {
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// entirely in front of the plane
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num = node->children[0];
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continue;
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}
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if (start_dist < 0 && end_dist < 0) {
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// entirely behind the plane
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num = node->children[1];
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continue;
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}
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side = start_dist < 0;
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frac = start_dist / (start_dist - end_dist);
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frac = bound (0, frac, 1);
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tstack->num = num;
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tstack->side = side;
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tstack->plane = plane;
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VectorCopy (end, tstack->end);
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tstack++;
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VectorSubtract (end, start, dist);
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VectorMultAdd (start, frac, dist, end);
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num = node->children[side];
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}
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}
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