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/* Copyright (c) 1986 Regents of the University of California */
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#ifndef lint
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static char SCCSid[] = "$SunId$ LBL";
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#endif
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/*
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* raytrace.c - routines for tracing and shading rays.
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*
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* 8/7/85
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*/
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#include "ray.h"
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#include "octree.h"
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#include "otypes.h"
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extern CUBE thescene; /* our scene */
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extern int maxdepth; /* maximum recursion depth */
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extern double minweight; /* minimum ray weight */
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long nrays = 0L; /* number of rays traced */
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#define MAXLOOP 128 /* modifier loop detection */
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#define RAYHIT (-1) /* return value for intercepted ray */
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rayorigin(r, ro, rt, rw) /* start new ray from old one */
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register RAY *r, *ro;
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int rt;
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double rw;
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{
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if ((r->parent = ro) == NULL) { /* primary ray */
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r->rlvl = 0;
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r->rweight = rw;
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r->crtype = r->rtype = rt;
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r->rsrc = -1;
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r->clipset = NULL;
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} else { /* spawned ray */
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r->rlvl = ro->rlvl;
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if (rt & RAYREFL) {
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r->rlvl++;
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r->rsrc = -1;
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r->clipset = ro->clipset;
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} else {
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r->rsrc = ro->rsrc;
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r->clipset = ro->newcset;
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}
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r->rweight = ro->rweight * rw;
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r->crtype = ro->crtype | (r->rtype = rt);
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VCOPY(r->rorg, ro->rop);
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}
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r->rno = nrays;
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r->newcset = r->clipset;
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r->ro = NULL;
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r->rot = FHUGE;
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r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
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setcolor(r->pcol, 1.0, 1.0, 1.0);
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setcolor(r->rcol, 0.0, 0.0, 0.0);
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r->rt = 0.0;
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return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
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}
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rayvalue(r) /* compute a ray's value */
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RAY *r;
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{
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extern int (*trace)();
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if (localhit(r, &thescene) || sourcehit(r))
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raycont(r);
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if (trace != NULL)
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(*trace)(r); /* trace execution */
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}
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raycont(r) /* check for clipped object and continue */
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register RAY *r;
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{
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if (r->clipset != NULL && inset(r->clipset, r->ro->omod))
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raytrans(r);
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else
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rayshade(r, r->ro->omod);
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}
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raytrans(r) /* transmit ray as is */
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register RAY *r;
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{
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RAY tr;
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if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
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VCOPY(tr.rdir, r->rdir);
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rayvalue(&tr);
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copycolor(r->rcol, tr.rcol);
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r->rt = r->rot + tr.rt;
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}
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}
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rayshade(r, mod) /* shade ray r with material mod */
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register RAY *r;
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int mod;
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{
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static int depth = 0;
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register OBJREC *m;
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/* check for infinite loop */
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if (depth++ >= MAXLOOP)
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objerror(r->ro, USER, "possible modifier loop");
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for ( ; mod != OVOID; mod = m->omod) {
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m = objptr(mod);
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/****** unnecessary test since modifier() is always called
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if (!ismodifier(m->otype)) {
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sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
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error(USER, errmsg);
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}
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******/
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(*ofun[m->otype].funp)(m, r); /* execute function */
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m->lastrno = r->rno;
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if (ismaterial(m->otype)) { /* materials call raytexture */
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depth--;
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return; /* we're done */
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}
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}
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objerror(r->ro, USER, "material not found");
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}
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raytexture(r, mod) /* get material modifiers */
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RAY *r;
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int mod;
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{
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static int depth = 0;
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register OBJREC *m;
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/* check for infinite loop */
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if (depth++ >= MAXLOOP)
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objerror(r->ro, USER, "modifier loop");
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/* execute textures and patterns */
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for ( ; mod != OVOID; mod = m->omod) {
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m = objptr(mod);
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if (!istexture(m->otype)) {
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sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
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error(USER, errmsg);
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}
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(*ofun[m->otype].funp)(m, r);
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m->lastrno = r->rno;
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}
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depth--; /* end here */
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}
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raymixture(r, fore, back, coef) /* mix modifiers */
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register RAY *r;
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OBJECT fore, back;
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double coef;
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{
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FVECT curpert, forepert, backpert;
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COLOR curpcol, forepcol, backpcol;
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register int i;
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/* clip coefficient */
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if (coef > 1.0)
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coef = 1.0;
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else if (coef < 0.0)
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coef = 0.0;
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/* save current mods */
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VCOPY(curpert, r->pert);
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copycolor(curpcol, r->pcol);
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/* compute new mods */
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/* foreground */
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r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
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setcolor(r->pcol, 1.0, 1.0, 1.0);
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if (fore != OVOID && coef > FTINY)
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raytexture(r, fore);
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VCOPY(forepert, r->pert);
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copycolor(forepcol, r->pcol);
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/* background */
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r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
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setcolor(r->pcol, 1.0, 1.0, 1.0);
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if (back != OVOID && coef < 1.0-FTINY)
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raytexture(r, back);
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VCOPY(backpert, r->pert);
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copycolor(backpcol, r->pcol);
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/* sum perturbations */
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for (i = 0; i < 3; i++)
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r->pert[i] = curpert[i] + coef*forepert[i] +
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(1.0-coef)*backpert[i];
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/* multiply colors */
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setcolor(r->pcol, coef*colval(forepcol,RED) +
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(1.0-coef)*colval(backpcol,RED),
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coef*colval(forepcol,GRN) +
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(1.0-coef)*colval(backpcol,GRN),
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coef*colval(forepcol,BLU) +
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(1.0-coef)*colval(backpcol,BLU));
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multcolor(r->pcol, curpcol);
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}
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double
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raynormal(norm, r) /* compute perturbed normal for ray */
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FVECT norm;
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register RAY *r;
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{
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double newdot;
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register int i;
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/* The perturbation is added to the surface normal to obtain
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* the new normal. If the new normal would affect the surface
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* orientation wrt. the ray, a correction is made. The method is
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* still fraught with problems since reflected rays and similar
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* directions calculated from the surface normal may spawn rays behind
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* the surface. The only solution is to curb textures at high
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* incidence (namely, keep DOT(rdir,pert) < Rdot).
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*/
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for (i = 0; i < 3; i++)
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norm[i] = r->ron[i] + r->pert[i];
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if (normalize(norm) == 0.0) {
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objerror(r->ro, WARNING, "illegal normal perturbation");
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VCOPY(norm, r->ron);
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return(r->rod);
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}
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newdot = -DOT(norm, r->rdir);
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if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
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for (i = 0; i < 3; i++)
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norm[i] += 2.0*newdot*r->rdir[i];
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newdot = -newdot;
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}
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return(newdot);
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}
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flipsurface(r) /* reverse surface orientation */
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register RAY *r;
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{
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r->rod = -r->rod;
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r->ron[0] = -r->ron[0];
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r->ron[1] = -r->ron[1];
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r->ron[2] = -r->ron[2];
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r->pert[0] = -r->pert[0];
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r->pert[1] = -r->pert[1];
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r->pert[2] = -r->pert[2];
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}
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localhit(r, scene) /* check for hit in the octree */
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register RAY *r;
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register CUBE *scene;
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{
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FVECT curpos; /* current cube position */
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int mpos, mneg; /* sign flags */
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double t, dt;
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register int i;
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nrays++; /* increment trace counter */
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mpos = mneg = 0;
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for (i = 0; i < 3; i++) {
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curpos[i] = r->rorg[i];
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if (r->rdir[i] > FTINY)
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mpos |= 1 << i;
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else if (r->rdir[i] < -FTINY)
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mneg |= 1 << i;
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}
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t = 0.0;
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if (!incube(scene, curpos)) {
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/* find distance to entry */
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for (i = 0; i < 3; i++) {
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/* plane in our direction */
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if (mpos & 1<<i)
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dt = scene->cuorg[i];
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else if (mneg & 1<<i)
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dt = scene->cuorg[i] + scene->cusize;
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else
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continue;
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/* distance to the plane */
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dt = (dt - r->rorg[i])/r->rdir[i];
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if (dt > t)
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t = dt; /* farthest face is the one */
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}
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t += FTINY; /* fudge to get inside cube */
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/* advance position */
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for (i = 0; i < 3; i++)
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curpos[i] += r->rdir[i]*t;
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if (!incube(scene, curpos)) /* non-intersecting ray */
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return(0);
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}
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return(raymove(curpos, mpos, mneg, r, scene) == RAYHIT);
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}
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static int
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raymove(pos, plus, minus, r, cu) /* check for hit as we move */
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FVECT pos; /* modified */
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int plus, minus; /* direction indicators to speed tests */
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register RAY *r;
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register CUBE *cu;
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{
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int ax;
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double dt, t;
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register int sgn;
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if (istree(cu->cutree)) { /* recurse on subcubes */
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CUBE cukid;
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register int br;
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cukid.cusize = cu->cusize * 0.5; /* find subcube */
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VCOPY(cukid.cuorg, cu->cuorg);
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br = 0;
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if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
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cukid.cuorg[0] += cukid.cusize;
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br |= 1;
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}
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if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
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cukid.cuorg[1] += cukid.cusize;
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br |= 2;
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}
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if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
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cukid.cuorg[2] += cukid.cusize;
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br |= 4;
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}
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for ( ; ; ) {
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cukid.cutree = octkid(cu->cutree, br);
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if ((ax = raymove(pos,plus,minus,r,&cukid)) == RAYHIT)
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return(RAYHIT);
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sgn = 1 << ax;
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if (sgn & minus) /* negative axis? */
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if (sgn & br) {
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cukid.cuorg[ax] -= cukid.cusize;
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br &= ~sgn;
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} else
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return(ax); /* underflow */
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else
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if (sgn & br)
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return(ax); /* overflow */
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else {
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cukid.cuorg[ax] += cukid.cusize;
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br |= sgn;
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}
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}
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/*NOTREACHED*/
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}
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if (isfull(cu->cutree) && checkhit(r, cu))
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return(RAYHIT);
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/* advance to next cube */
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sgn = plus | minus;
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if (sgn&1) {
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dt = plus&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
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t = (dt - pos[0])/r->rdir[0];
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ax = 0;
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} else
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t = FHUGE;
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if (sgn&2) {
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dt = plus&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
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dt = (dt - pos[1])/r->rdir[1];
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if (dt < t) {
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t = dt;
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ax = 1;
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}
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}
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if (sgn&4) {
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dt = plus&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
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dt = (dt - pos[2])/r->rdir[2];
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if (dt < t) {
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t = dt;
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ax = 2;
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}
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}
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pos[0] += r->rdir[0]*t;
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pos[1] += r->rdir[1]*t;
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pos[2] += r->rdir[2]*t;
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return(ax);
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}
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static
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checkhit(r, cu) /* check for hit in full cube */
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register RAY *r;
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CUBE *cu;
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{
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OBJECT oset[MAXSET+1];
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register OBJREC *o;
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register int i;
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objset(oset, cu->cutree);
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for (i = oset[0]; i > 0; i--) {
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o = objptr(oset[i]);
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if (o->lastrno == r->rno) /* checked already? */
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continue;
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(*ofun[o->otype].funp)(o, r);
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o->lastrno = r->rno;
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}
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if (r->ro == NULL)
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return(0); /* no scores yet */
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return(incube(cu, r->rop)); /* hit OK if in current cube */
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}
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