src/rt/source.c

#ifndef lint
static const char RCSid[] = "$Id: source.c,v 2.38 2003/12/31 01:50:02 greg Exp $";
#endif
/*
 *  source.c - routines dealing with illumination sources.
 *
 *  External symbols declared in source.h
 */

#include "copyright.h"

#include  "ray.h"

#include  "otypes.h"

#include  "otspecial.h"

#include  "source.h"

#include  "random.h"

extern double  ssampdist;               /* scatter sampling distance */

#ifndef MAXSSAMP
#define MAXSSAMP        16              /* maximum samples per ray */
#endif

/*
 * Structures used by direct()
 */

typedef struct {
        int  sno;               /* source number */
        FVECT  dir;             /* source direction */
        COLOR  coef;            /* material coefficient */
        COLOR  val;             /* contribution */
}  CONTRIB;             /* direct contribution */

typedef struct {
        int  sndx;              /* source index (to CONTRIB array) */
        float  brt;             /* brightness (for comparison) */
}  CNTPTR;              /* contribution pointer */

static CONTRIB  *srccnt;                /* source contributions in direct() */
static CNTPTR  *cntord;                 /* source ordering in direct() */
static int  maxcntr = 0;                /* size of contribution arrays */


OBJREC *                        /* find an object's actual material */
findmaterial(register OBJREC *o)
{
        while (!ismaterial(o->otype)) {
                if (ismixture(o->otype))
                        return(NULL);   /* reject mixed materials */
                if (o->otype == MOD_ALIAS && o->oargs.nsargs) {
                        OBJECT  aobj;
                        OBJREC  *ao;
                        aobj = lastmod(objndx(o), o->oargs.sarg[0]);
                        if (aobj < 0)
                                objerror(o, USER, "bad reference");
                        ao = objptr(aobj);
                        if (ismaterial(ao->otype))
                                return(ao);
                }
                if (o->omod == OVOID)
                        return(NULL);
                o = objptr(o->omod);
        }
        return(o);
}


void
marksources()                   /* find and mark source objects */
{
        int  foundsource = 0;
        int  i;
        register OBJREC  *o, *m;
        register int  ns;
                                        /* initialize dispatch table */
        initstypes();
                                        /* find direct sources */
        for (i = 0; i < nsceneobjs; i++) {
        
                o = objptr(i);

                if (!issurface(o->otype) || o->omod == OVOID)
                        continue;
                                        /* find material */
                m = findmaterial(o);
                if (m == NULL || !islight(m->otype))
                        continue;       /* not source modifier */
        
                if (m->oargs.nfargs != (m->otype == MAT_GLOW ? 4 :
                                m->otype == MAT_SPOT ? 7 : 3))
                        objerror(m, USER, "bad # arguments");

                if (m->otype == MAT_GLOW &&
                                o->otype != OBJ_SOURCE &&
                                m->oargs.farg[3] <= FTINY)
                        continue;                       /* don't bother */
                if (m->oargs.farg[0] <= FTINY && m->oargs.farg[1] <= FTINY &&
                                m->oargs.farg[2] <= FTINY)
                        continue;                       /* don't bother */

                if (sfun[o->otype].of == NULL ||
                                sfun[o->otype].of->setsrc == NULL)
                        objerror(o, USER, "illegal material");

                if ((ns = newsource()) < 0)
                        goto memerr;

                setsource(&source[ns], o);

                if (m->otype == MAT_GLOW) {
                        source[ns].sflags |= SPROX;
                        source[ns].sl.prox = m->oargs.farg[3];
                        if (source[ns].sflags & SDISTANT)
                                source[ns].sflags |= SSKIP;
                } else if (m->otype == MAT_SPOT) {
                        source[ns].sflags |= SSPOT;
                        if ((source[ns].sl.s = makespot(m)) == NULL)
                                goto memerr;
                        if (source[ns].sflags & SFLAT &&
                                !checkspot(source[ns].sl.s,source[ns].snorm)) {
                                objerror(o, WARNING,
                                        "invalid spotlight direction");
                                source[ns].sflags |= SSKIP;
                        }
                }
#if  SHADCACHE
                source[ns].obscache = NULL;
#endif
                if (!(source[ns].sflags & SSKIP))
                        foundsource++;
        }
        if (!foundsource) {
                error(WARNING, "no light sources found");
                return;
        }
        markvirtuals();                 /* find and add virtual sources */
                                /* allocate our contribution arrays */
        maxcntr = nsources + MAXSPART;  /* start with this many */
        srccnt = (CONTRIB *)malloc(maxcntr*sizeof(CONTRIB));
        cntord = (CNTPTR *)malloc(maxcntr*sizeof(CNTPTR));
        if ((srccnt == NULL) | (cntord == NULL))
                goto memerr;
        return;
memerr:
        error(SYSTEM, "out of memory in marksources");
}


void
freesources()                   /* free all source structures */
{
        if (nsources > 0) {
#if SHADCACHE
                while (nsources--)
                        freeobscache(&source[nsources]);
#endif
                free((void *)source);
                source = NULL;
                nsources = 0;
        }
        if (maxcntr <= 0)
                return;
        free((void *)srccnt);
        srccnt = NULL;
        free((void *)cntord);
        cntord = NULL;
        maxcntr = 0;
}


int
srcray(                         /* send a ray to a source, return domega */
register RAY  *sr,              /* returned source ray */
RAY  *r,                        /* ray which hit object */
SRCINDEX  *si                   /* source sample index */
)
{
    double  d;                          /* distance to source */
    register SRCREC  *srcp;

    rayorigin(sr, r, SHADOW, 1.0);              /* ignore limits */

    while ((d = nextssamp(sr, si)) != 0.0) {
        sr->rsrc = si->sn;                      /* remember source */
        srcp = source + si->sn;
        if (srcp->sflags & SDISTANT) {
                if (srcp->sflags & SSPOT && spotout(sr, srcp->sl.s))
                        continue;
                return(1);              /* sample OK */
        }
                                /* local source */
                                                /* check proximity */
        if (srcp->sflags & SPROX && d > srcp->sl.prox)
                continue;
                                                /* check angle */
        if (srcp->sflags & SSPOT) {
                if (spotout(sr, srcp->sl.s))
                        continue;
                                        /* adjust solid angle */
                si->dom *= d*d;
                d += srcp->sl.s->flen;
                si->dom /= d*d;
        }
        return(1);                      /* sample OK */
    }
    return(0);                  /* no more samples */
}


void
srcvalue(                       /* punch ray to source and compute value */
register RAY  *r
)
{
        register SRCREC  *sp;

        sp = &source[r->rsrc];
        if (sp->sflags & SVIRTUAL) {    /* virtual source */
                                        /* check intersection */
                if (!(*ofun[sp->so->otype].funp)(sp->so, r))
                        return;
                if (!rayshade(r, r->ro->omod))  /* compute contribution */
                        goto nomat;
                rayparticipate(r);
                return;
        }
                                        /* compute intersection */
        if (sp->sflags & SDISTANT ? sourcehit(r) :
                        (*ofun[sp->so->otype].funp)(sp->so, r)) {
                if (sp->sa.success >= 0)
                        sp->sa.success++;
                if (!rayshade(r, r->ro->omod))  /* compute contribution */
                        goto nomat;
                rayparticipate(r);
                return;
        }
                                        /* we missed our mark! */
        if (sp->sa.success < 0)
                return;                 /* bitched already */
        sp->sa.success -= AIMREQT;
        if (sp->sa.success >= 0)
                return;                 /* leniency */
        sprintf(errmsg, "aiming failure for light source \"%s\"",
                        sp->so->oname);
        error(WARNING, errmsg);         /* issue warning */
        return;
nomat:
        objerror(r->ro, USER, "material not found");
}


int
sourcehit(                      /* check to see if ray hit distant source */
register RAY  *r
)
{
        int  first, last;
        register int  i;

        if (r->rsrc >= 0) {             /* check only one if aimed */
                first = last = r->rsrc;
        } else {                        /* otherwise check all */
                first = 0; last = nsources-1;
        }
        for (i = first; i <= last; i++)
                if ((source[i].sflags & (SDISTANT|SVIRTUAL)) == SDISTANT)
                        /*
                         * Check to see if ray is within
                         * solid angle of source.
                         */
                        if (2.0*PI * (1.0 - DOT(source[i].sloc,r->rdir))
                                        <= source[i].ss2) {
                                r->ro = source[i].so;
                                if (!(source[i].sflags & SSKIP))
                                        break;
                        }

        if (r->ro != NULL) {
                r->robj = objndx(r->ro);
                for (i = 0; i < 3; i++)
                        r->ron[i] = -r->rdir[i];
                r->rod = 1.0;
                r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
                r->uv[0] = r->uv[1] = 0.0;
                r->rox = NULL;
                return(1);
        }
        return(0);
}


#if  SHADCACHE                  /* preemptive shadow checking */
#define ABS(x)  ((x)>0 ? (x) : -(x))

static void                             /* find closest blockers to source */
initobscache(SRCREC *srcp)
{
        int     i;
        int     cachelen;

        if (srcp->sflags & SDISTANT)
                cachelen = 4*SHADCACHE*SHADCACHE;
        else if (srcp->sflags & SFLAT)
                cachelen = SHADCACHE*SHADCACHE*3 + (SHADCACHE&1)*SHADCACHE*4;
        else /* spherical distribution */
                cachelen = SHADCACHE*SHADCACHE*6;
                                        /* allocate cache */
        DCHECK(srcp->obscache != NULL,
                        CONSISTENCY, "initobscache() called twice");
        srcp->obscache = (OBSCACHE *)malloc(sizeof(OBSCACHE) +
                                                sizeof(OBJECT)*(cachelen-1));
        if (srcp->obscache == NULL)
                error(SYSTEM, "out of memory in initobscache()");
                                        /* set parameters */
        if (srcp->sflags & SDISTANT) {
                int     ax, ax1, ax2;
                RREAL   amax = 0;
                for (ax1 = 3; ax1--; )
                        if (ABS(srcp->sloc[ax1]) > amax) {
                                amax = ABS(srcp->sloc[ax1]);
                                ax = ax1;
                        }
                srcp->obscache->p.d.ax = ax;
                ax1 = (ax+1)%3;
                ax2 = (ax+2)%3;
                VCOPY(srcp->obscache->p.d.o, thescene.cuorg);
                if (srcp->sloc[ax] > 0)
                        srcp->obscache->p.d.o[ax] += thescene.cusize;
                if (srcp->sloc[ax1] < 0)
                        srcp->obscache->p.d.o[ax1] += thescene.cusize *
                                        srcp->sloc[ax1] / ABS(srcp->sloc[ax]);
                if (srcp->sloc[ax2] < 0)
                        srcp->obscache->p.d.o[ax2] += thescene.cusize *
                                        srcp->sloc[ax2] / ABS(srcp->sloc[ax]);
                srcp->obscache->p.d.e1 = (1.-FTINY) / (thescene.cusize*(1. +
                                fabs(srcp->sloc[ax1]/srcp->sloc[ax])));
                srcp->obscache->p.d.e2 = (1.-FTINY) / (thescene.cusize*(1. +
                                fabs(srcp->sloc[ax2]/srcp->sloc[ax])));
        } else if (srcp->sflags & SFLAT) {
                VCOPY(srcp->obscache->p.f.u, srcp->ss[SU]);
                normalize(srcp->obscache->p.f.u);
                fcross(srcp->obscache->p.f.v,
                                srcp->snorm, srcp->obscache->p.f.u);
        }
                                        /* XXX Should cast rays from source */
        for (i = cachelen; i--; )
                srcp->obscache->obs[i] = OVOID;
}


static OBJECT *                 /* return occluder cache entry */
srcobstructp(register RAY *r)
{
        static OBJECT   noobs;
        SRCREC          *srcp;
        int             ondx;

        DCHECK(r->rsrc < 0, CONSISTENCY,
                        "srcobstructp() called with unaimed ray");
        noobs = OVOID;
        srcp = &source[r->rsrc];
        if (srcp->obscache == NULL)     /* initialize cache */
                initobscache(srcp);
                                        /* compute cache index */
        if (srcp->sflags & SDISTANT) {
                int     ax, ax1, ax2;
                double  t;
                ax = srcp->obscache->p.d.ax;
                if ((ax1 = ax+1) >= 3) ax1 -= 3;
                if ((ax2 = ax+2) >= 3) ax2 -= 3;
                t = (srcp->obscache->p.d.o[ax] - r->rorg[ax]) / srcp->sloc[ax];
                if (t <= FTINY)
                        return &noobs;  /* could happen if ray is outside */
                ondx = 2*SHADCACHE*(int)(2*SHADCACHE*srcp->obscache->p.d.e1 *
                                (r->rorg[ax1] + t*srcp->sloc[ax1] -
                                        srcp->obscache->p.d.o[ax1]));
                ondx += (int)(2*SHADCACHE*srcp->obscache->p.d.e2 *
                                (r->rorg[ax2] + t*srcp->sloc[ax2] -
                                        srcp->obscache->p.d.o[ax2]));
                if (ondx < 0 | ondx >= 4*SHADCACHE*SHADCACHE)
                        return &nobs;   /* could happen if ray is outside */
        } else if (srcp->sflags & SFLAT) {
                FVECT   sd;
                RREAL   sd0m, sd1m;
                sd[0] = -DOT(r->rdir, srcp->obscache->p.f.u);
                sd[1] = -DOT(r->rdir, srcp->obscache->p.f.v);
                sd[2] = -DOT(r->rdir, srcp->snorm);
                if (sd[2] < 0)
                        return &noobs;  /* shouldn't happen */
                sd0m = ABS(sd[0]);
                sd1m = ABS(sd[1]);
                if (sd[2] >= sd0m && sd[2] >= sd1m) {
                        ondx = SHADCACHE*(int)(SHADCACHE*(.5-FTINY) *
                                        (1. + sd[0]/sd[2]));
                        ondx += (int)(SHADCACHE*(.5-FTINY) *
                                        (1. + sd[1]/sd[2]));
                } else if (sd0m >= sd1m) {
                        ondx = SHADCACHE*SHADCACHE;
                        if (sd[0] < 0)
                                ondx += ((SHADCACHE+1)>>1)*SHADCACHE;
                        ondx += SHADCACHE*(int)(SHADCACHE*(.5-FTINY) *
                                        sd[2]/sd0m);
                        ondx += (int)(SHADCACHE*(.5-FTINY) *
                                        (1. + sd[1]/sd0m));
                } else /* sd1m > sd0m */ {
                        ondx = SHADCACHE*SHADCACHE +
                                        ((SHADCACHE+1)>>1)*SHADCACHE*2;
                        if (sd[1] < 0)
                                ondx += ((SHADCACHE+1)>>1)*SHADCACHE;
                        ondx += SHADCACHE*(int)(SHADCACHE*(.5-FTINY) *
                                        sd[2]/sd1m);
                        ondx += (int)(SHADCACHE*(.5-FTINY) *
                                        (1. + sd[0]/sd1m));
                }
        } else /* spherical distribution */ {
                int     ax, ax1, ax2;
                RREAL   amax = 0;
                for (ax1 = 3; ax1--; )
                        if (ABS(r->rdir[ax1]) > amax) {
                                amax = ABS(r->rdir[ax1]);
                                ax = ax1;
                        }
                if ((ax1 = ax+1) >= 3) ax1 -= 3;
                if ((ax2 = ax+2) >= 3) ax2 -= 3;
                ondx = 2*SHADCACHE*SHADCACHE * ax;
                if (r->rdir[ax] < 0)
                        ondx += SHADCACHE*SHADCACHE;
                ondx += SHADCACHE*(int)(SHADCACHE*(.5-FTINY) *
                                        (1. + r->rdir[ax1]/amax));
                ondx += (int)(SHADCACHE*(.5-FTINY) *
                                (1. + r->rdir[ax2]/amax));
        }
                                        /* return cache pointer */
        return(&srcp->obscache->obs[ondx]);
}


void                            /* free obstruction cache */
freeobscache(SRCREC *srcp)
{
        if (srcp->obscache == NULL)
                return;
        free((void *)srcp->obscache);
        srcp->obscache = NULL;
}

        
void                            /* record a source blocker */
srcblocker(register RAY *r)
{
        OBJREC  *m;

        if (r->robj == OVOID || objptr(r->robj) != r->ro ||
                        isvolume(r->ro->otype))
                return;                 /* don't record complex blockers */
        m = findmaterial(r->ro);
        if (m == NULL)
                return;                 /* no material?! */
        if (!(ofun[m->otype].flags & T_OPAQUE))
                return;                 /* material not a reliable blocker */

        *srcobstructp(r) = r->robj;     /* else record obstructor */
}


int                             /* check ray against cached blocker */
srcblocked(RAY *r)
{
        OBJECT  obs = *srcobstructp(r);
        OBJREC  *op;

        if (obs == OVOID)
                return(0);
        op = objptr(obs);               /* check for intersection */
        return ((*ofun[op->otype].funp)(op, r));
}

#endif


static int
cntcmp(                         /* contribution compare (descending) */
const void *p1,
const void *p2
)
{
        register const CNTPTR  *sc1 = (const CNTPTR *)p1;
        register const CNTPTR  *sc2 = (const CNTPTR *)p2;

        if (sc1->brt > sc2->brt)
                return(-1);
        if (sc1->brt < sc2->brt)
                return(1);
        return(0);
}


void
direct(                                 /* add direct component */
RAY  *r,                        /* ray that hit surface */
void  (*f)(),                   /* direct component coefficient function */
char  *p                        /* data for f */
)
{
        extern void  (*trace)();
        register int  sn;
        register CONTRIB  *scp;
        SRCINDEX  si;
        int  nshadcheck, ncnts;
        int  nhits;
        double  prob, ourthresh, hwt;
        RAY  sr;
                        /* NOTE: srccnt and cntord global so no recursion */
        if (nsources <= 0)
                return;         /* no sources?! */
                                                /* potential contributions */
        initsrcindex(&si);
        for (sn = 0; srcray(&sr, r, &si); sn++) {
                if (sn >= maxcntr) {
                        maxcntr = sn + MAXSPART;
                        srccnt = (CONTRIB *)realloc((void *)srccnt,
                                        maxcntr*sizeof(CONTRIB));
                        cntord = (CNTPTR *)realloc((void *)cntord,
                                        maxcntr*sizeof(CNTPTR));
                        if ((srccnt == NULL) | (cntord == NULL))
                                error(SYSTEM, "out of memory in direct");
                }
                cntord[sn].sndx = sn;
                scp = srccnt + sn;
                scp->sno = sr.rsrc;
                                                /* compute coefficient */
                (*f)(scp->coef, p, sr.rdir, si.dom);
                cntord[sn].brt = bright(scp->coef);
                if (cntord[sn].brt <= 0.0)
                        continue;
#if SHADCACHE
                                                /* check shadow cache */
                if (si.np == 1 && srcblocked(&sr)) {
                        cntord[sn].brt = 0.0;
                        continue;
                }
#endif
                VCOPY(scp->dir, sr.rdir);
                                                /* compute potential */
                sr.revf = srcvalue;
                rayvalue(&sr);
                copycolor(scp->val, sr.rcol);
                multcolor(scp->val, scp->coef);
                cntord[sn].brt = bright(scp->val);
        }
                                                /* sort contributions */
        qsort(cntord, sn, sizeof(CNTPTR), cntcmp);
        {                                       /* find last */
                register int  l, m;

                ncnts = l = sn;
                sn = 0;
                while ((m = (sn + ncnts) >> 1) != l) {
                        if (cntord[m].brt > 0.0)
                                sn = m;
                        else
                                ncnts = m;
                        l = m;
                }
        }
        if (ncnts == 0)
                return;         /* no contributions! */
                                                /* accumulate tail */
        for (sn = ncnts-1; sn > 0; sn--)
                cntord[sn-1].brt += cntord[sn].brt;
                                                /* compute number to check */
        nshadcheck = pow((double)ncnts, shadcert) + .5;
                                                /* modify threshold */
        ourthresh = shadthresh / r->rweight;
                                                /* test for shadows */
        for (nhits = 0, hwt = 0.0, sn = 0; sn < ncnts;
                        hwt += (double)source[scp->sno].nhits /
                                (double)source[scp->sno].ntests,
                        sn++) {
                                                /* check threshold */
                if ((sn+nshadcheck>=ncnts ? cntord[sn].brt :
                                cntord[sn].brt-cntord[sn+nshadcheck].brt)
                                < ourthresh*bright(r->rcol))
                        break;
                scp = srccnt + cntord[sn].sndx;
                                                /* test for hit */
                rayorigin(&sr, r, SHADOW, 1.0);
                VCOPY(sr.rdir, scp->dir);
                sr.rsrc = scp->sno;
                                                /* keep statistics */
                if (source[scp->sno].ntests++ > 0xfffffff0) {
                        source[scp->sno].ntests >>= 1;
                        source[scp->sno].nhits >>= 1;
                }
                if (localhit(&sr, &thescene) &&
                                ( sr.ro != source[scp->sno].so ||
                                source[scp->sno].sflags & SFOLLOW )) {
                                                /* follow entire path */
                        raycont(&sr);
                        rayparticipate(&sr);
                        if (trace != NULL)
                                (*trace)(&sr);  /* trace execution */
                        if (bright(sr.rcol) <= FTINY) {
#if SHADCACHE
                                if ((scp <= srccnt || scp[-1].sno != scp->sno)
                                                && (scp >= srccnt+ncnts ||
                                                    scp[1].sno != scp->sno))
                                        srcblocker(&sr);
#endif
                                continue;       /* missed! */
                        }
                        copycolor(scp->val, sr.rcol);
                        multcolor(scp->val, scp->coef);
                }
                                                /* add contribution if hit */
                addcolor(r->rcol, scp->val);
                nhits++;
                source[scp->sno].nhits++;
        }
                                        /* source hit rate */
        if (hwt > FTINY)
                hwt = (double)nhits / hwt;
        else
                hwt = 0.5;
#ifdef DEBUG
        sprintf(errmsg, "%d tested, %d untested, %f conditional hit rate\n",
                        sn, ncnts-sn, hwt);
        eputs(errmsg);
#endif
                                        /* add in untested sources */
        for ( ; sn < ncnts; sn++) {
                scp = srccnt + cntord[sn].sndx;
                prob = hwt * (double)source[scp->sno].nhits /
                                (double)source[scp->sno].ntests;
                if (prob > 1.0)
                        prob = 1.0;
                scalecolor(scp->val, prob);
                addcolor(r->rcol, scp->val);
        }
}


void
srcscatter(                     /* compute source scattering into ray */
register RAY  *r
)
{
        int  oldsampndx;
        int  nsamps;
        RAY  sr;
        SRCINDEX  si;
        double  t, d;
        double  re, ge, be;
        COLOR  cvext;
        int  i, j;

        if (r->slights == NULL || r->slights[0] == 0
                        || r->gecc >= 1.-FTINY || r->rot >= FHUGE)
                return;
        if (ssampdist <= FTINY || (nsamps = r->rot/ssampdist + .5) < 1)
                nsamps = 1;
#if MAXSSAMP
        else if (nsamps > MAXSSAMP)
                nsamps = MAXSSAMP;
#endif
        oldsampndx = samplendx;
        samplendx = random()&0x7fff;            /* randomize */
        for (i = r->slights[0]; i > 0; i--) {   /* for each source */
                for (j = 0; j < nsamps; j++) {  /* for each sample position */
                        samplendx++;
                        t = r->rot * (j+frandom())/nsamps;
                                                        /* extinction */
                        re = t*colval(r->cext,RED);
                        ge = t*colval(r->cext,GRN);
                        be = t*colval(r->cext,BLU);
                        setcolor(cvext, re > 92. ? 0. : exp(-re),
                                        ge > 92. ? 0. : exp(-ge),
                                        be > 92. ? 0. : exp(-be));
                        if (intens(cvext) <= FTINY)
                                break;                  /* too far away */
                        sr.rorg[0] = r->rorg[0] + r->rdir[0]*t;
                        sr.rorg[1] = r->rorg[1] + r->rdir[1]*t;
                        sr.rorg[2] = r->rorg[2] + r->rdir[2]*t;
                        sr.rmax = 0.;
                        initsrcindex(&si);      /* sample ray to this source */
                        si.sn = r->slights[i];
                        nopart(&si, &sr);
                        if (!srcray(&sr, NULL, &si) ||
                                        sr.rsrc != r->slights[i])
                                continue;               /* no path */
                        copycolor(sr.cext, r->cext);
                        copycolor(sr.albedo, r->albedo);
                        sr.gecc = r->gecc;
                        sr.slights = r->slights;
                        rayvalue(&sr);                  /* eval. source ray */
                        if (bright(sr.rcol) <= FTINY)
                                continue;
                        if (r->gecc <= FTINY)           /* compute P(theta) */
                                d = 1.;
                        else {
                                d = DOT(r->rdir, sr.rdir);
                                d = 1. + r->gecc*r->gecc - 2.*r->gecc*d;
                                d = (1. - r->gecc*r->gecc) / (d*sqrt(d));
                        }
                                                        /* other factors */
                        d *= si.dom * r->rot / (4.*PI*nsamps);
                        multcolor(sr.rcol, r->cext);
                        multcolor(sr.rcol, r->albedo);
                        scalecolor(sr.rcol, d);
                        multcolor(sr.rcol, cvext);
                        addcolor(r->rcol, sr.rcol);     /* add it in */
                }
        }
        samplendx = oldsampndx;
}


/****************************************************************
 * The following macros were separated from the m_light() routine
 * because they are very nasty and difficult to understand.
 */

/* illumblock *
 *
 * We cannot allow an illum to pass to another illum, because that
 * would almost certainly constitute overcounting.
 * However, we do allow an illum to pass to another illum
 * that is actually going to relay to a virtual light source.
 * We also prevent an illum from passing to a glow; this provides a
 * convenient mechanism for defining detailed light source
 * geometry behind (or inside) an effective radiator.
 */

static int
weaksrcmat(int obj)             /* identify material */
{
        register OBJREC *o = objptr(obj);
        
        while (!ismaterial(o->otype))   /* find material */
                o = objptr(o->omod);
        return((o->otype==MAT_ILLUM)|(o->otype==MAT_GLOW));
}

#define  illumblock(m, r)       (!(source[r->rsrc].sflags&SVIRTUAL) && \
                                r->rod > 0.0 && \
                                weaksrcmat(source[r->rsrc].so->omod))

/* wrongsource *
 *
 * This source is the wrong source (ie. overcounted) if we are
 * aimed to a different source than the one we hit and the one
 * we hit is not an illum that should be passed.
 */

#define  wrongsource(m, r)      (r->rsrc>=0 && source[r->rsrc].so!=r->ro && \
                                (m->otype!=MAT_ILLUM || illumblock(m,r)))

/* distglow *
 *
 * A distant glow is an object that sometimes acts as a light source,
 * but is too far away from the test point to be one in this case.
 * (Glows with negative radii should NEVER participate in illumination.)
 */

#define  distglow(m, r, d)      (m->otype==MAT_GLOW && \
                                m->oargs.farg[3] >= -FTINY && \
                                d > m->oargs.farg[3])

/* badcomponent *
 *
 * We must avoid counting light sources in the ambient calculation,
 * since the direct component is handled separately.  Therefore, any
 * ambient ray which hits an active light source must be discarded.
 * The same is true for stray specular samples, since the specular
 * contribution from light sources is calculated separately.
 */

#define  badcomponent(m, r)     (r->crtype&(AMBIENT|SPECULAR) && \
                                !(r->crtype&SHADOW || r->rod < 0.0 || \
                /* not 100% correct */  distglow(m, r, r->rot)))

/* passillum *
 *
 * An illum passes to another material type when we didn't hit it
 * on purpose (as part of a direct calculation), or it is relaying
 * a virtual light source.
 */

#define  passillum(m, r)        (m->otype==MAT_ILLUM && \
                                (r->rsrc<0 || source[r->rsrc].so!=r->ro || \
                                source[r->rsrc].sflags&SVIRTUAL))

/* srcignore *
 *
 * The -dv flag is normally on for sources to be visible.
 */

#define  srcignore(m, r)        !(directvis || r->crtype&SHADOW || \
                                distglow(m, r, raydist(r,PRIMARY)))


int
m_light(                                /* ray hit a light source */
register OBJREC  *m,
register RAY  *r
)
{
                                                /* check for over-counting */
        if (badcomponent(m, r))
                return(1);
        if (wrongsource(m, r))
                return(1);
                                                /* check for passed illum */
        if (passillum(m, r)) {
                if (m->oargs.nsargs && strcmp(m->oargs.sarg[0], VOIDID))
                        return(rayshade(r,lastmod(objndx(m),m->oargs.sarg[0])));
                raytrans(r);
                return(1);
        }
                                        /* otherwise treat as source */
                                                /* check for behind */
        if (r->rod < 0.0)
                return(1);
                                                /* check for invisibility */
        if (srcignore(m, r))
                return(1);
                                                /* check for outside spot */
        if (m->otype==MAT_SPOT && spotout(r, makespot(m)))
                return(1);
                                                /* get distribution pattern */
        raytexture(r, m->omod);
                                                /* get source color */
        setcolor(r->rcol, m->oargs.farg[0],
                          m->oargs.farg[1],
                          m->oargs.farg[2]);
                                                /* modify value */
        multcolor(r->rcol, r->pcol);
        return(1);
}
Revision:	2.39
Committed:	Wed Dec 31 02:03:08 2003 UTC (20 years, 4 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.38:	+3 -1 lines
Log Message:	Minor fixes to source occlusion cache