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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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* source.c - routines dealing with illumination sources.
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*
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* 8/20/85
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*/
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#include "ray.h"
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#include "source.h"
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#include "otypes.h"
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#include "cone.h"
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#include "face.h"
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#include "random.h"
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extern double dstrsrc; /* source distribution amount */
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SOURCE srcval[MAXSOURCE]; /* our array of sources */
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int nsources = 0; /* the number of sources */
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marksources() /* find and mark source objects */
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{
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register OBJREC *o, *m;
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register int i;
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for (i = 0; i < nobjects; i++) {
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o = objptr(i);
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if (o->omod == OVOID)
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continue;
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m = objptr(o->omod);
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if (m->otype != MAT_LIGHT &&
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m->otype != MAT_ILLUM &&
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m->otype != MAT_GLOW &&
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m->otype != MAT_SPOT)
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continue;
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if (m->oargs.nfargs != (m->otype == MAT_GLOW ? 4 :
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m->otype == MAT_SPOT ? 7 : 3))
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objerror(m, USER, "bad # arguments");
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if (m->otype == MAT_GLOW &&
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o->otype != OBJ_SOURCE &&
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m->oargs.farg[3] <= FTINY)
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continue; /* don't bother */
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if (nsources >= MAXSOURCE)
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error(INTERNAL, "too many sources in marksources");
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newsource(&srcval[nsources], o);
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if (m->otype == MAT_GLOW) {
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srcval[nsources].sflags |= SPROX;
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srcval[nsources].sl.prox = m->oargs.farg[3];
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if (o->otype == OBJ_SOURCE)
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srcval[nsources].sflags |= SSKIP;
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} else if (m->otype == MAT_SPOT) {
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srcval[nsources].sflags |= SSPOT;
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srcval[nsources].sl.s = makespot(m);
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}
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nsources++;
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}
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}
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newsource(src, so) /* add a source to the array */
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register SOURCE *src;
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register OBJREC *so;
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{
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double cos(), tan(), sqrt();
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double theta;
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FACE *f;
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CONE *co;
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int j;
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register int i;
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src->sflags = 0;
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src->so = so;
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switch (so->otype) {
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case OBJ_SOURCE:
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if (so->oargs.nfargs != 4)
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objerror(so, USER, "bad arguments");
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src->sflags |= SDISTANT;
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VCOPY(src->sloc, so->oargs.farg);
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if (normalize(src->sloc) == 0.0)
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objerror(so, USER, "zero direction");
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theta = PI/180.0/2.0 * so->oargs.farg[3];
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if (theta <= FTINY)
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objerror(so, USER, "zero size");
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src->ss = theta >= PI/4 ? 1.0 : tan(theta);
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src->ss2 = 2.0*PI * (1.0 - cos(theta));
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break;
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case OBJ_SPHERE:
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VCOPY(src->sloc, so->oargs.farg);
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src->ss = so->oargs.farg[3];
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src->ss2 = PI * src->ss * src->ss;
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break;
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case OBJ_FACE:
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/* get the face */
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f = getface(so);
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/* find the center */
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for (j = 0; j < 3; j++) {
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src->sloc[j] = 0.0;
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for (i = 0; i < f->nv; i++)
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src->sloc[j] += VERTEX(f,i)[j];
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src->sloc[j] /= f->nv;
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}
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if (!inface(src->sloc, f))
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objerror(so, USER, "cannot hit center");
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src->ss = sqrt(f->area / PI);
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src->ss2 = f->area;
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break;
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case OBJ_RING:
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/* get the ring */
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co = getcone(so, 0);
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VCOPY(src->sloc, CO_P0(co));
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if (CO_R0(co) > 0.0)
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objerror(so, USER, "cannot hit center");
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src->ss = CO_R1(co);
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src->ss2 = PI * src->ss * src->ss;
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break;
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default:
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objerror(so, USER, "illegal material");
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}
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}
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SPOT *
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makespot(m) /* make a spotlight */
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register OBJREC *m;
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{
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extern double cos();
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register SPOT *ns;
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if ((ns = (SPOT *)malloc(sizeof(SPOT))) == NULL)
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error(SYSTEM, "out of memory in makespot");
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ns->siz = 2.0*PI * (1.0 - cos(PI/180.0/2.0 * m->oargs.farg[3]));
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VCOPY(ns->aim, m->oargs.farg+4);
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if ((ns->flen = normalize(ns->aim)) == 0.0)
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objerror(m, USER, "zero focus vector");
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return(ns);
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}
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double
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srcray(sr, r, sn) /* send a ray to a source, return domega */
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register RAY *sr; /* returned source ray */
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RAY *r; /* ray which hit object */
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register int sn; /* source number */
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{
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register double *norm = NULL; /* plane normal */
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double ddot; /* (distance times) cosine */
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FVECT vd;
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double d;
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register int i;
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if (srcval[sn].sflags & SSKIP)
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return(0.0); /* skip this source */
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rayorigin(sr, r, SHADOW, 1.0); /* ignore limits */
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sr->rsrc = sn; /* remember source */
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/* get source direction */
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if (srcval[sn].sflags & SDISTANT)
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/* constant direction */
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VCOPY(sr->rdir, srcval[sn].sloc);
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else { /* compute direction */
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for (i = 0; i < 3; i++)
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sr->rdir[i] = srcval[sn].sloc[i] - sr->rorg[i];
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if (srcval[sn].so->otype == OBJ_FACE)
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norm = getface(srcval[sn].so)->norm;
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else if (srcval[sn].so->otype == OBJ_RING)
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norm = getcone(srcval[sn].so,0)->ad;
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if (norm != NULL && (ddot = -DOT(sr->rdir, norm)) <= 0.0)
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return(0.0); /* behind surface! */
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}
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if (dstrsrc > FTINY) {
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/* distribute source direction */
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for (i = 0; i < 3; i++)
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vd[i] = dstrsrc * srcval[sn].ss * (1.0 - 2.0*frandom());
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if (norm != NULL) { /* project offset */
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d = DOT(vd, norm);
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for (i = 0; i < 3; i++)
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vd[i] -= d * norm[i];
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}
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for (i = 0; i < 3; i++) /* offset source direction */
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sr->rdir[i] += vd[i];
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} else if (srcval[sn].sflags & SDISTANT)
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/* already normalized */
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return(srcval[sn].ss2);
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if ((d = normalize(sr->rdir)) == 0.0)
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/* at source! */
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return(0.0);
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if (srcval[sn].sflags & SDISTANT)
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/* domega constant */
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return(srcval[sn].ss2);
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else {
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/* check proximity */
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if (srcval[sn].sflags & SPROX &&
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d > srcval[sn].sl.prox)
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return(0.0);
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if (norm != NULL)
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ddot /= d;
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else
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ddot = 1.0;
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/* check angle */
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if (srcval[sn].sflags & SSPOT) {
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if (srcval[sn].sl.s->siz < 2.0*PI *
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(1.0 + DOT(srcval[sn].sl.s->aim,sr->rdir)))
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return(0.0);
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d += srcval[sn].sl.s->flen;
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}
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/* return domega */
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return(ddot*srcval[sn].ss2/(d*d));
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}
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}
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sourcehit(r) /* check to see if ray hit distant source */
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register RAY *r;
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{
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int first, last;
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register int i;
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if (r->rsrc >= 0) { /* check only one if aimed */
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first = last = r->rsrc;
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} else { /* otherwise check all */
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first = 0; last = nsources-1;
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}
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for (i = first; i <= last; i++)
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if (srcval[i].sflags & SDISTANT)
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/*
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* Check to see if ray is within
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* solid angle of source.
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*/
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if (2.0*PI * (1.0 - DOT(srcval[i].sloc,r->rdir))
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<= srcval[i].ss2) {
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r->ro = srcval[i].so;
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if (!(srcval[i].sflags & SSKIP))
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break;
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}
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if (r->ro != NULL) {
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for (i = 0; i < 3; i++)
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r->ron[i] = -r->rdir[i];
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r->rod = 1.0;
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return(1);
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}
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return(0);
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}
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#define wrongsource(m, r) (m->otype!=MAT_ILLUM && \
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r->rsrc>=0 && \
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srcval[r->rsrc].so!=r->ro)
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#define badambient(m, r) ((r->crtype&(AMBIENT|SHADOW))==AMBIENT && \
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!(r->rtype&REFLECTED) && /* hack! */\
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!(m->otype==MAT_GLOW&&r->rot>m->oargs.farg[3]))
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#define passillum(m, r) (m->otype==MAT_ILLUM && \
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!(r->rsrc>=0&&srcval[r->rsrc].so==r->ro))
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m_light(m, r) /* ray hit a light source */
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register OBJREC *m;
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register RAY *r;
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{
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/* check for behind */
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if (r->rod < 0.0)
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return;
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/* check for over-counting */
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if (wrongsource(m, r) || badambient(m, r))
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return;
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/* check for passed illum */
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if (passillum(m, r)) {
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if (m->oargs.nsargs < 1 || !strcmp(m->oargs.sarg[0], VOIDID))
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raytrans(r);
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else
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rayshade(r, modifier(m->oargs.sarg[0]));
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/* otherwise treat as source */
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} else {
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/* get distribution pattern */
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raytexture(r, m->omod);
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/* get source color */
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setcolor(r->rcol, m->oargs.farg[0],
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m->oargs.farg[1],
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m->oargs.farg[2]);
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/* modify value */
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multcolor(r->rcol, r->pcol);
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}
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}
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o_source() {} /* intersection with a source is done elsewhere */
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