src/rt/srcsupp.c

/* Copyright (c) 1992 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 *  Support routines for source objects and materials
 */

#include  "ray.h"

#include  "otypes.h"

#include  "source.h"

#include  "cone.h"

#include  "face.h"

#define SRCINC          4               /* realloc increment for array */

SRCREC  *source = NULL;                 /* our list of sources */
int  nsources = 0;                      /* the number of sources */

SRCFUNC  sfun[NUMOTYPE];                /* source dispatch table */


initstypes()                    /* initialize source dispatch table */
{
        extern VSMATERIAL  mirror_vs, direct1_vs, direct2_vs;
        extern int  fsetsrc(), ssetsrc(), sphsetsrc(), cylsetsrc(), rsetsrc();
        extern int  nopart(), flatpart(), cylpart();
        extern double  fgetplaneq(), rgetplaneq();
        extern double  fgetmaxdisk(), rgetmaxdisk();
        static SOBJECT  fsobj = {fsetsrc, flatpart, fgetplaneq, fgetmaxdisk};
        static SOBJECT  ssobj = {ssetsrc, nopart};
        static SOBJECT  sphsobj = {sphsetsrc, nopart};
        static SOBJECT  cylsobj = {cylsetsrc, cylpart};
        static SOBJECT  rsobj = {rsetsrc, flatpart, rgetplaneq, rgetmaxdisk};

        sfun[MAT_MIRROR].mf = &mirror_vs;
        sfun[MAT_DIRECT1].mf = &direct1_vs;
        sfun[MAT_DIRECT2].mf = &direct2_vs;
        sfun[OBJ_FACE].of = &fsobj;
        sfun[OBJ_SOURCE].of = &ssobj;
        sfun[OBJ_SPHERE].of = &sphsobj;
        sfun[OBJ_CYLINDER].of = &cylsobj;
        sfun[OBJ_RING].of = &rsobj;
}


int
newsource()                     /* allocate new source in our array */
{
        if (nsources == 0)
                source = (SRCREC *)malloc(SRCINC*sizeof(SRCREC));
        else if (nsources%SRCINC == 0)
                source = (SRCREC *)realloc((char *)source,
                                (unsigned)(nsources+SRCINC)*sizeof(SRCREC));
        if (source == NULL)
                return(-1);
        source[nsources].sflags = 0;
        source[nsources].nhits = 1;
        source[nsources].ntests = 2;    /* initial hit probability = 1/2 */
        return(nsources++);
}


setflatss(src)                          /* set sampling for a flat source */
register SRCREC  *src;
{
        double  mult;
        register int  i;

        src->ss[SV][0] = src->ss[SV][1] = src->ss[SV][2] = 0.0;
        for (i = 0; i < 3; i++)
                if (src->snorm[i] < 0.6 && src->snorm[i] > -0.6)
                        break;
        src->ss[SV][i] = 1.0;
        fcross(src->ss[SU], src->ss[SV], src->snorm);
        mult = .5 * sqrt( src->ss2 / DOT(src->ss[SU],src->ss[SU]) );
        for (i = 0; i < 3; i++)
                src->ss[SU][i] *= mult;
        fcross(src->ss[SV], src->snorm, src->ss[SU]);
}


fsetsrc(src, so)                        /* set a face as a source */
register SRCREC  *src;
OBJREC  *so;
{
        register FACE  *f;
        register int  i, j;
        double  d;
        
        src->sa.success = 2*AIMREQT-1;          /* bitch on second failure */
        src->so = so;
                                                /* get the face */
        f = getface(so);
                                                /* find the center */
        for (j = 0; j < 3; j++) {
                src->sloc[j] = 0.0;
                for (i = 0; i < f->nv; i++)
                        src->sloc[j] += VERTEX(f,i)[j];
                src->sloc[j] /= (double)f->nv;
        }
        if (!inface(src->sloc, f))
                objerror(so, USER, "cannot hit center");
        src->sflags |= SFLAT;
        VCOPY(src->snorm, f->norm);
        src->ss2 = f->area;
                                                /* find maximum radius */
        src->srad = 0.;
        for (i = 0; i < f->nv; i++) {
                d = dist2(VERTEX(f,i), src->sloc);
                if (d > src->srad)
                        src->srad = d;
        }
        src->srad = sqrt(src->srad);
                                                /* compute size vectors */
        if (f->nv == 4 || (f->nv == 5 &&        /* parallelogram case */
                        dist2(VERTEX(f,0),VERTEX(f,4)) <= FTINY*FTINY))
                for (j = 0; j < 3; j++) {
                        src->ss[SU][j] = .5*(VERTEX(f,1)[j]-VERTEX(f,0)[j]);
                        src->ss[SV][j] = .5*(VERTEX(f,3)[j]-VERTEX(f,0)[j]);
                }
        else
                setflatss(src);
}


ssetsrc(src, so)                        /* set a source as a source */
register SRCREC  *src;
register OBJREC  *so;
{
        double  theta;
        
        src->sa.success = 2*AIMREQT-1;          /* bitch on second failure */
        src->so = so;
        if (so->oargs.nfargs != 4)
                objerror(so, USER, "bad arguments");
        src->sflags |= SDISTANT;
        VCOPY(src->sloc, so->oargs.farg);
        if (normalize(src->sloc) == 0.0)
                objerror(so, USER, "zero direction");
        theta = PI/180.0/2.0 * so->oargs.farg[3];
        if (theta <= FTINY)
                objerror(so, USER, "zero size");
        src->ss2 = 2.0*PI * (1.0 - cos(theta));
                                        /* the following is approximate */
        src->srad = sqrt(src->ss2/PI);
        VCOPY(src->snorm, src->sloc);
        setflatss(src);                 /* hey, whatever works */
        src->ss[SW][0] = src->ss[SW][1] = src->ss[SW][2] = 0.0;
}


sphsetsrc(src, so)                      /* set a sphere as a source */
register SRCREC  *src;
register OBJREC  *so;
{
        register int  i;

        src->sa.success = 2*AIMREQT-1;          /* bitch on second failure */
        src->so = so;
        if (so->oargs.nfargs != 4)
                objerror(so, USER, "bad # arguments");
        if (so->oargs.farg[3] <= FTINY)
                objerror(so, USER, "illegal radius");
        VCOPY(src->sloc, so->oargs.farg);
        src->srad = so->oargs.farg[3];
        src->ss2 = PI * src->srad * src->srad;
        for (i = 0; i < 3; i++)
                src->ss[SU][i] = src->ss[SV][i] = src->ss[SW][i] = 0.0;
        for (i = 0; i < 3; i++)
                src->ss[i][i] = .7236 * so->oargs.farg[3];
}


rsetsrc(src, so)                        /* set a ring (disk) as a source */
register SRCREC  *src;
OBJREC  *so;
{
        register CONE  *co;
        
        src->sa.success = 2*AIMREQT-1;          /* bitch on second failure */
        src->so = so;
                                                /* get the ring */
        co = getcone(so, 0);
        VCOPY(src->sloc, CO_P0(co));
        if (CO_R0(co) > 0.0)
                objerror(so, USER, "cannot hit center");
        src->sflags |= SFLAT;
        VCOPY(src->snorm, co->ad);
        src->srad = CO_R1(co);
        src->ss2 = PI * src->srad * src->srad;
        setflatss(src);
}


cylsetsrc(src, so)                      /* set a cylinder as a source */
register SRCREC  *src;
OBJREC  *so;
{
        register CONE  *co;
        register int  i;
        
        src->sa.success = 4*AIMREQT-1;          /* bitch on fourth failure */
        src->so = so;
                                                /* get the cylinder */
        co = getcone(so, 0);
        if (CO_R0(co) > .2*co->al)              /* heuristic constraint */
                objerror(so, WARNING, "source aspect too small");
        src->sflags |= SCYL;
        for (i = 0; i < 3; i++)
                src->sloc[i] = .5 * (CO_P1(co)[i] + CO_P0(co)[i]);
        src->srad = .5*co->al;
        src->ss2 = 2.*CO_R0(co)*co->al;
                                                /* set sampling vectors */
        for (i = 0; i < 3; i++)
                src->ss[SU][i] = .5 * co->al * co->ad[i];
        src->ss[SV][0] = src->ss[SV][1] = src->ss[SV][2] = 0.0;
        for (i = 0; i < 3; i++)
                if (co->ad[i] < 0.6 && co->ad[i] > -0.6)
                        break;
        src->ss[SV][i] = 1.0;
        fcross(src->ss[SW], src->ss[SV], co->ad);
        normalize(src->ss[SW]);
        for (i = 0; i < 3; i++)
                src->ss[SW][i] *= .8559 * CO_R0(co);
        fcross(src->ss[SV], src->ss[SW], co->ad);
}


SPOT *
makespot(m)                     /* make a spotlight */
register OBJREC  *m;
{
        register SPOT  *ns;

        if ((ns = (SPOT *)malloc(sizeof(SPOT))) == NULL)
                return(NULL);
        ns->siz = 2.0*PI * (1.0 - cos(PI/180.0/2.0 * m->oargs.farg[3]));
        VCOPY(ns->aim, m->oargs.farg+4);
        if ((ns->flen = normalize(ns->aim)) == 0.0)
                objerror(m, USER, "zero focus vector");
        return(ns);
}


double
fgetmaxdisk(ocent, op)          /* get center and squared radius of face */
FVECT  ocent;
OBJREC  *op;
{
        double  maxrad2;
        double  d;
        register int  i, j;
        register FACE  *f;
        
        f = getface(op);
        if (f->area == 0.)
                return(0.);
        for (i = 0; i < 3; i++) {
                ocent[i] = 0.;
                for (j = 0; j < f->nv; j++)
                        ocent[i] += VERTEX(f,j)[i];
                ocent[i] /= (double)f->nv;
        }
        d = DOT(ocent,f->norm);
        for (i = 0; i < 3; i++)
                ocent[i] += (f->offset - d)*f->norm[i];
        maxrad2 = 0.;
        for (j = 0; j < f->nv; j++) {
                d = dist2(VERTEX(f,j), ocent);
                if (d > maxrad2)
                        maxrad2 = d;
        }
        return(maxrad2);
}


double
rgetmaxdisk(ocent, op)          /* get center and squared radius of ring */
FVECT  ocent;
OBJREC  *op;
{
        register CONE  *co;
        
        co = getcone(op, 0);
        VCOPY(ocent, CO_P0(co));
        return(CO_R1(co)*CO_R1(co));
}


double
fgetplaneq(nvec, op)                    /* get plane equation for face */
FVECT  nvec;
OBJREC  *op;
{
        register FACE  *fo;

        fo = getface(op);
        VCOPY(nvec, fo->norm);
        return(fo->offset);
}


double
rgetplaneq(nvec, op)                    /* get plane equation for ring */
FVECT  nvec;
OBJREC  *op;
{
        register CONE  *co;

        co = getcone(op, 0);
        VCOPY(nvec, co->ad);
        return(DOT(nvec, CO_P0(co)));
}


commonspot(sp1, sp2, org)       /* set sp1 to intersection of sp1 and sp2 */
register SPOT  *sp1, *sp2;
FVECT  org;
{
        FVECT  cent;
        double  rad2, cos1, cos2;

        cos1 = 1. - sp1->siz/(2.*PI);
        cos2 = 1. - sp2->siz/(2.*PI);
        if (sp2->siz >= 2.*PI-FTINY)            /* BIG, just check overlap */
                return(DOT(sp1->aim,sp2->aim) >= cos1*cos2 -
                                        sqrt((1.-cos1*cos1)*(1.-cos2*cos2)));
                                /* compute and check disks */
        rad2 = intercircle(cent, sp1->aim, sp2->aim,
                        1./(cos1*cos1) - 1.,  1./(cos2*cos2) - 1.);
        if (rad2 <= FTINY || normalize(cent) == 0.)
                return(0);
        VCOPY(sp1->aim, cent);
        sp1->siz = 2.*PI*(1. - 1./sqrt(1.+rad2));
        return(1);
}


commonbeam(sp1, sp2, dir)       /* set sp1 to intersection of sp1 and sp2 */
register SPOT  *sp1, *sp2;
FVECT  dir;
{
        FVECT  cent, c1, c2;
        double  rad2, d;
        register int  i;
                                        /* move centers to common plane */
        d = DOT(sp1->aim, dir);
        for (i = 0; i < 3; i++)
                c1[i] = sp1->aim[i] - d*dir[i];
        d = DOT(sp2->aim, dir);
        for (i = 0; i < 3; i++)
                c2[i] = sp2->aim[i] - d*dir[i];
                                        /* compute overlap */
        rad2 = intercircle(cent, c1, c2, sp1->siz/PI, sp2->siz/PI);
        if (rad2 <= FTINY)
                return(0);
        VCOPY(sp1->aim, cent);
        sp1->siz = PI*rad2;
        return(1);
}


checkspot(sp, nrm)              /* check spotlight for behind source */
register SPOT  *sp;     /* spotlight */
FVECT  nrm;             /* source surface normal */
{
        double  d, d1;

        d = DOT(sp->aim, nrm);
        if (d > FTINY)                  /* center in front? */
                return(1);
                                        /* else check horizon */
        d1 = 1. - sp->siz/(2.*PI);
        return(1.-FTINY-d*d < d1*d1);
}


double
spotdisk(oc, op, sp, pos)       /* intersect spot with object op */
FVECT  oc;
OBJREC  *op;
register SPOT  *sp;
FVECT  pos;
{
        FVECT  onorm;
        double  offs, d, dist;
        register int  i;

        offs = getplaneq(onorm, op);
        d = -DOT(onorm, sp->aim);
        if (d >= -FTINY && d <= FTINY)
                return(0.);
        dist = (DOT(pos, onorm) - offs)/d;
        if (dist < 0.)
                return(0.);
        for (i = 0; i < 3; i++)
                oc[i] = pos[i] + dist*sp->aim[i];
        return(sp->siz*dist*dist/PI/(d*d));
}


double
beamdisk(oc, op, sp, dir)       /* intersect beam with object op */
FVECT  oc;
OBJREC  *op;
register SPOT  *sp;
FVECT  dir;
{
        FVECT  onorm;
        double  offs, d, dist;
        register int  i;

        offs = getplaneq(onorm, op);
        d = -DOT(onorm, dir);
        if (d >= -FTINY && d <= FTINY)
                return(0.);
        dist = (DOT(sp->aim, onorm) - offs)/d;
        for (i = 0; i < 3; i++)
                oc[i] = sp->aim[i] + dist*dir[i];
        return(sp->siz/PI/(d*d));
}


double
intercircle(cc, c1, c2, r1s, r2s)       /* intersect two circles */
FVECT  cc;                      /* midpoint (return value) */
FVECT  c1, c2;                  /* circle centers */
double  r1s, r2s;               /* radii squared */
{
        double  a2, d2, l;
        FVECT  disp;
        register int  i;

        for (i = 0; i < 3; i++)
                disp[i] = c2[i] - c1[i];
        d2 = DOT(disp,disp);
                                        /* circle within overlap? */
        if (r1s < r2s) {
                if (r2s >= r1s + d2) {
                        VCOPY(cc, c1);
                        return(r1s);
                }
        } else {
                if (r1s >= r2s + d2) {
                        VCOPY(cc, c2);
                        return(r2s);
                }
        }
        a2 = .25*(2.*(r1s+r2s) - d2 - (r2s-r1s)*(r2s-r1s)/d2);
                                        /* no overlap? */
        if (a2 <= 0.)
                return(0.);
                                        /* overlap, compute center */
        l = sqrt((r1s - a2)/d2);
        for (i = 0; i < 3; i++)
                cc[i] = c1[i] + l*disp[i];
        return(a2);
}


sourcehit(r)                    /* 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) {
                for (i = 0; i < 3; i++)
                        r->ron[i] = -r->rdir[i];
                r->rod = 1.0;
                r->rox = NULL;
                return(1);
        }
        return(0);
}


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

/* wrongillum *
 *
 * 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.
 */

#define  wrongillum(m, r)       (!(source[r->rsrc].sflags&SVIRTUAL) && \
                        objptr(source[r->rsrc].so->omod)->otype==MAT_ILLUM)

/* 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 which should be passed.
 */

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

#define  distglow(m, r)         (m->otype==MAT_GLOW && \
                                r->rot > 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 || \
                                        distglow(m, r)))

/* overcount *
 *
 * All overcounting possibilities are contained here.
 */

#define  overcount(m, r)        (badcomponent(m,r) || wrongsource(m,r))

/* 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 -di flag renders light sources invisible, and here is the test.
 */

#define  srcignore(m, r)        (directinvis && !(r->crtype&SHADOW) && \
                                !distglow(m, r))


m_light(m, r)                   /* ray hit a light source */
register OBJREC  *m;
register RAY  *r;
{
                                                /* check for over-counting */
        if (overcount(m, r))
                return;
                                                /* check for passed illum */
        if (passillum(m, r)) {
                if (m->oargs.nsargs < 1 || !strcmp(m->oargs.sarg[0], VOIDID))
                        raytrans(r);
                else
                        rayshade(r, modifier(m->oargs.sarg[0]));
                return;
        }
                                        /* otherwise treat as source */
                                                /* check for behind */
        if (r->rod < 0.0)
                return;
                                                /* check for invisibility */
        if (srcignore(m, r))
                return;
                                                /* 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);
}
Revision:	2.4
Committed:	Wed Feb 26 09:49:37 1992 UTC (33 years, 8 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.3:	+2 -1 lines
Log Message:	fixed bug in specular/ambient rays hitting back side of illums
#	User	Rev	Content
1	greg	2.2	/* Copyright (c) 1992 Regents of the University of California */
2	greg	1.1
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* Support routines for source objects and materials
9			*/
10
11			#include "ray.h"
12
13			#include "otypes.h"
14
15			#include "source.h"
16
17			#include "cone.h"
18
19			#include "face.h"
20
21	greg	1.14	#define SRCINC 4 /* realloc increment for array */
22	greg	1.1
23			SRCREC source = NULL; / our list of sources */
24			int nsources = 0; /* the number of sources */
25
26			SRCFUNC sfun[NUMOTYPE]; /* source dispatch table */
27
28
29			initstypes() /* initialize source dispatch table */
30			{
31	greg	1.9	extern VSMATERIAL mirror_vs, direct1_vs, direct2_vs;
32	greg	1.14	extern int fsetsrc(), ssetsrc(), sphsetsrc(), cylsetsrc(), rsetsrc();
33			extern int nopart(), flatpart(), cylpart();
34	greg	1.1	extern double fgetplaneq(), rgetplaneq();
35			extern double fgetmaxdisk(), rgetmaxdisk();
36	greg	1.14	static SOBJECT fsobj = {fsetsrc, flatpart, fgetplaneq, fgetmaxdisk};
37			static SOBJECT ssobj = {ssetsrc, nopart};
38			static SOBJECT sphsobj = {sphsetsrc, nopart};
39			static SOBJECT cylsobj = {cylsetsrc, cylpart};
40			static SOBJECT rsobj = {rsetsrc, flatpart, rgetplaneq, rgetmaxdisk};
41	greg	1.1
42			sfun[MAT_MIRROR].mf = &mirror_vs;
43	greg	1.9	sfun[MAT_DIRECT1].mf = &direct1_vs;
44			sfun[MAT_DIRECT2].mf = &direct2_vs;
45	greg	1.1	sfun[OBJ_FACE].of = &fsobj;
46			sfun[OBJ_SOURCE].of = &ssobj;
47			sfun[OBJ_SPHERE].of = &sphsobj;
48	greg	1.14	sfun[OBJ_CYLINDER].of = &cylsobj;
49	greg	1.1	sfun[OBJ_RING].of = &rsobj;
50			}
51
52
53	greg	1.2	int
54	greg	1.1	newsource() /* allocate new source in our array */
55			{
56			if (nsources == 0)
57	greg	1.13	source = (SRCREC )malloc(SRCINCsizeof(SRCREC));
58			else if (nsources%SRCINC == 0)
59	greg	1.1	source = (SRCREC )realloc((char )source,
60	greg	1.13	(unsigned)(nsources+SRCINC)*sizeof(SRCREC));
61	greg	1.1	if (source == NULL)
62	greg	1.2	return(-1);
63	greg	1.1	source[nsources].sflags = 0;
64			source[nsources].nhits = 1;
65			source[nsources].ntests = 2; /* initial hit probability = 1/2 */
66	greg	1.2	return(nsources++);
67	greg	1.1	}
68
69
70	greg	1.14	setflatss(src) /* set sampling for a flat source */
71			register SRCREC *src;
72			{
73			double mult;
74			register int i;
75
76			src->ss[SV][0] = src->ss[SV][1] = src->ss[SV][2] = 0.0;
77			for (i = 0; i < 3; i++)
78			if (src->snorm[i] < 0.6 && src->snorm[i] > -0.6)
79			break;
80			src->ss[SV][i] = 1.0;
81			fcross(src->ss[SU], src->ss[SV], src->snorm);
82			mult = .5 * sqrt( src->ss2 / DOT(src->ss[SU],src->ss[SU]) );
83			for (i = 0; i < 3; i++)
84			src->ss[SU][i] *= mult;
85			fcross(src->ss[SV], src->snorm, src->ss[SU]);
86			}
87
88
89	greg	1.1	fsetsrc(src, so) /* set a face as a source */
90			register SRCREC *src;
91			OBJREC *so;
92			{
93			register FACE *f;
94			register int i, j;
95	greg	1.14	double d;
96	greg	1.1
97			src->sa.success = 2AIMREQT-1; / bitch on second failure */
98			src->so = so;
99			/* get the face */
100			f = getface(so);
101			/* find the center */
102			for (j = 0; j < 3; j++) {
103			src->sloc[j] = 0.0;
104			for (i = 0; i < f->nv; i++)
105			src->sloc[j] += VERTEX(f,i)[j];
106			src->sloc[j] /= (double)f->nv;
107			}
108			if (!inface(src->sloc, f))
109			objerror(so, USER, "cannot hit center");
110			src->sflags \|= SFLAT;
111			VCOPY(src->snorm, f->norm);
112			src->ss2 = f->area;
113	greg	1.14	/* find maximum radius */
114			src->srad = 0.;
115			for (i = 0; i < f->nv; i++) {
116			d = dist2(VERTEX(f,i), src->sloc);
117			if (d > src->srad)
118			src->srad = d;
119			}
120			src->srad = sqrt(src->srad);
121			/* compute size vectors */
122			if (f->nv == 4 \|\| (f->nv == 5 && /* parallelogram case */
123			dist2(VERTEX(f,0),VERTEX(f,4)) <= FTINY*FTINY))
124			for (j = 0; j < 3; j++) {
125			src->ss[SU][j] = .5*(VERTEX(f,1)[j]-VERTEX(f,0)[j]);
126			src->ss[SV][j] = .5*(VERTEX(f,3)[j]-VERTEX(f,0)[j]);
127			}
128			else
129			setflatss(src);
130	greg	1.1	}
131
132
133			ssetsrc(src, so) /* set a source as a source */
134			register SRCREC *src;
135			register OBJREC *so;
136			{
137			double theta;
138
139			src->sa.success = 2AIMREQT-1; / bitch on second failure */
140			src->so = so;
141			if (so->oargs.nfargs != 4)
142			objerror(so, USER, "bad arguments");
143			src->sflags \|= SDISTANT;
144			VCOPY(src->sloc, so->oargs.farg);
145			if (normalize(src->sloc) == 0.0)
146			objerror(so, USER, "zero direction");
147			theta = PI/180.0/2.0 * so->oargs.farg[3];
148			if (theta <= FTINY)
149			objerror(so, USER, "zero size");
150			src->ss2 = 2.0PI (1.0 - cos(theta));
151	greg	1.14	/* the following is approximate */
152			src->srad = sqrt(src->ss2/PI);
153			VCOPY(src->snorm, src->sloc);
154			setflatss(src); /* hey, whatever works */
155			src->ss[SW][0] = src->ss[SW][1] = src->ss[SW][2] = 0.0;
156	greg	1.1	}
157
158
159			sphsetsrc(src, so) /* set a sphere as a source */
160			register SRCREC *src;
161			register OBJREC *so;
162			{
163	greg	1.14	register int i;
164
165	greg	1.1	src->sa.success = 2AIMREQT-1; / bitch on second failure */
166			src->so = so;
167			if (so->oargs.nfargs != 4)
168			objerror(so, USER, "bad # arguments");
169			if (so->oargs.farg[3] <= FTINY)
170			objerror(so, USER, "illegal radius");
171			VCOPY(src->sloc, so->oargs.farg);
172	greg	1.14	src->srad = so->oargs.farg[3];
173			src->ss2 = PI * src->srad * src->srad;
174			for (i = 0; i < 3; i++)
175			src->ss[SU][i] = src->ss[SV][i] = src->ss[SW][i] = 0.0;
176			for (i = 0; i < 3; i++)
177	greg	1.15	src->ss[i][i] = .7236 * so->oargs.farg[3];
178	greg	1.1	}
179
180
181			rsetsrc(src, so) /* set a ring (disk) as a source */
182			register SRCREC *src;
183			OBJREC *so;
184			{
185			register CONE *co;
186
187			src->sa.success = 2AIMREQT-1; / bitch on second failure */
188			src->so = so;
189			/* get the ring */
190			co = getcone(so, 0);
191			VCOPY(src->sloc, CO_P0(co));
192			if (CO_R0(co) > 0.0)
193			objerror(so, USER, "cannot hit center");
194			src->sflags \|= SFLAT;
195			VCOPY(src->snorm, co->ad);
196	greg	1.14	src->srad = CO_R1(co);
197			src->ss2 = PI * src->srad * src->srad;
198			setflatss(src);
199			}
200
201
202			cylsetsrc(src, so) /* set a cylinder as a source */
203			register SRCREC *src;
204			OBJREC *so;
205			{
206			register CONE *co;
207			register int i;
208
209			src->sa.success = 4AIMREQT-1; / bitch on fourth failure */
210			src->so = so;
211			/* get the cylinder */
212			co = getcone(so, 0);
213			if (CO_R0(co) > .2co->al) / heuristic constraint */
214			objerror(so, WARNING, "source aspect too small");
215	greg	1.15	src->sflags \|= SCYL;
216	greg	1.14	for (i = 0; i < 3; i++)
217			src->sloc[i] = .5 * (CO_P1(co)[i] + CO_P0(co)[i]);
218	greg	1.15	src->srad = .5*co->al;
219	greg	1.14	src->ss2 = 2.CO_R0(co)co->al;
220			/* set sampling vectors */
221			for (i = 0; i < 3; i++)
222			src->ss[SU][i] = .5 * co->al * co->ad[i];
223			src->ss[SV][0] = src->ss[SV][1] = src->ss[SV][2] = 0.0;
224			for (i = 0; i < 3; i++)
225			if (co->ad[i] < 0.6 && co->ad[i] > -0.6)
226			break;
227			src->ss[SV][i] = 1.0;
228			fcross(src->ss[SW], src->ss[SV], co->ad);
229			normalize(src->ss[SW]);
230			for (i = 0; i < 3; i++)
231	greg	1.15	src->ss[SW][i] = .8559 CO_R0(co);
232	greg	1.14	fcross(src->ss[SV], src->ss[SW], co->ad);
233	greg	1.1	}
234
235
236			SPOT *
237			makespot(m) /* make a spotlight */
238			register OBJREC *m;
239			{
240			register SPOT *ns;
241
242			if ((ns = (SPOT *)malloc(sizeof(SPOT))) == NULL)
243			return(NULL);
244			ns->siz = 2.0PI (1.0 - cos(PI/180.0/2.0 * m->oargs.farg[3]));
245			VCOPY(ns->aim, m->oargs.farg+4);
246			if ((ns->flen = normalize(ns->aim)) == 0.0)
247			objerror(m, USER, "zero focus vector");
248			return(ns);
249			}
250
251
252			double
253			fgetmaxdisk(ocent, op) /* get center and squared radius of face */
254			FVECT ocent;
255			OBJREC *op;
256			{
257			double maxrad2;
258	greg	1.5	double d;
259	greg	1.1	register int i, j;
260			register FACE *f;
261
262			f = getface(op);
263	greg	1.5	if (f->area == 0.)
264			return(0.);
265	greg	1.1	for (i = 0; i < 3; i++) {
266			ocent[i] = 0.;
267			for (j = 0; j < f->nv; j++)
268			ocent[i] += VERTEX(f,j)[i];
269			ocent[i] /= (double)f->nv;
270			}
271	greg	1.5	d = DOT(ocent,f->norm);
272			for (i = 0; i < 3; i++)
273			ocent[i] += (f->offset - d)*f->norm[i];
274	greg	1.1	maxrad2 = 0.;
275			for (j = 0; j < f->nv; j++) {
276	greg	1.5	d = dist2(VERTEX(f,j), ocent);
277			if (d > maxrad2)
278			maxrad2 = d;
279	greg	1.1	}
280			return(maxrad2);
281			}
282
283
284			double
285			rgetmaxdisk(ocent, op) /* get center and squared radius of ring */
286			FVECT ocent;
287			OBJREC *op;
288			{
289			register CONE *co;
290
291			co = getcone(op, 0);
292			VCOPY(ocent, CO_P0(co));
293			return(CO_R1(co)*CO_R1(co));
294			}
295
296
297			double
298			fgetplaneq(nvec, op) /* get plane equation for face */
299			FVECT nvec;
300			OBJREC *op;
301			{
302			register FACE *fo;
303
304			fo = getface(op);
305			VCOPY(nvec, fo->norm);
306			return(fo->offset);
307			}
308
309
310			double
311			rgetplaneq(nvec, op) /* get plane equation for ring */
312			FVECT nvec;
313			OBJREC *op;
314			{
315			register CONE *co;
316
317			co = getcone(op, 0);
318			VCOPY(nvec, co->ad);
319			return(DOT(nvec, CO_P0(co)));
320	greg	1.4	}
321
322
323			commonspot(sp1, sp2, org) /* set sp1 to intersection of sp1 and sp2 */
324			register SPOT sp1, sp2;
325			FVECT org;
326			{
327			FVECT cent;
328			double rad2, cos1, cos2;
329
330			cos1 = 1. - sp1->siz/(2.*PI);
331			cos2 = 1. - sp2->siz/(2.*PI);
332			if (sp2->siz >= 2.PI-FTINY) / BIG, just check overlap */
333			return(DOT(sp1->aim,sp2->aim) >= cos1*cos2 -
334			sqrt((1.-cos1cos1)(1.-cos2*cos2)));
335			/* compute and check disks */
336			rad2 = intercircle(cent, sp1->aim, sp2->aim,
337			1./(cos1cos1) - 1., 1./(cos2cos2) - 1.);
338			if (rad2 <= FTINY \|\| normalize(cent) == 0.)
339			return(0);
340			VCOPY(sp1->aim, cent);
341			sp1->siz = 2.PI(1. - 1./sqrt(1.+rad2));
342			return(1);
343			}
344
345
346			commonbeam(sp1, sp2, dir) /* set sp1 to intersection of sp1 and sp2 */
347			register SPOT sp1, sp2;
348			FVECT dir;
349			{
350			FVECT cent, c1, c2;
351			double rad2, d;
352			register int i;
353			/* move centers to common plane */
354			d = DOT(sp1->aim, dir);
355			for (i = 0; i < 3; i++)
356			c1[i] = sp1->aim[i] - d*dir[i];
357			d = DOT(sp2->aim, dir);
358			for (i = 0; i < 3; i++)
359			c2[i] = sp2->aim[i] - d*dir[i];
360			/* compute overlap */
361			rad2 = intercircle(cent, c1, c2, sp1->siz/PI, sp2->siz/PI);
362			if (rad2 <= FTINY)
363			return(0);
364			VCOPY(sp1->aim, cent);
365			sp1->siz = PI*rad2;
366			return(1);
367			}
368
369
370			checkspot(sp, nrm) /* check spotlight for behind source */
371			register SPOT sp; / spotlight */
372			FVECT nrm; /* source surface normal */
373			{
374			double d, d1;
375
376			d = DOT(sp->aim, nrm);
377			if (d > FTINY) /* center in front? */
378	greg	1.8	return(1);
379	greg	1.4	/* else check horizon */
380			d1 = 1. - sp->siz/(2.*PI);
381	greg	1.8	return(1.-FTINY-dd < d1d1);
382	greg	1.4	}
383
384
385			double
386	greg	1.6	spotdisk(oc, op, sp, pos) /* intersect spot with object op */
387			FVECT oc;
388			OBJREC *op;
389			register SPOT *sp;
390			FVECT pos;
391			{
392			FVECT onorm;
393			double offs, d, dist;
394			register int i;
395
396			offs = getplaneq(onorm, op);
397			d = -DOT(onorm, sp->aim);
398			if (d >= -FTINY && d <= FTINY)
399			return(0.);
400			dist = (DOT(pos, onorm) - offs)/d;
401			if (dist < 0.)
402			return(0.);
403			for (i = 0; i < 3; i++)
404			oc[i] = pos[i] + dist*sp->aim[i];
405			return(sp->sizdistdist/PI/(d*d));
406			}
407
408
409			double
410			beamdisk(oc, op, sp, dir) /* intersect beam with object op */
411			FVECT oc;
412			OBJREC *op;
413			register SPOT *sp;
414			FVECT dir;
415			{
416			FVECT onorm;
417			double offs, d, dist;
418			register int i;
419
420			offs = getplaneq(onorm, op);
421			d = -DOT(onorm, dir);
422			if (d >= -FTINY && d <= FTINY)
423			return(0.);
424			dist = (DOT(sp->aim, onorm) - offs)/d;
425			for (i = 0; i < 3; i++)
426			oc[i] = sp->aim[i] + dist*dir[i];
427			return(sp->siz/PI/(d*d));
428			}
429
430
431			double
432	greg	1.4	intercircle(cc, c1, c2, r1s, r2s) /* intersect two circles */
433			FVECT cc; /* midpoint (return value) */
434			FVECT c1, c2; /* circle centers */
435			double r1s, r2s; /* radii squared */
436			{
437			double a2, d2, l;
438			FVECT disp;
439			register int i;
440
441			for (i = 0; i < 3; i++)
442			disp[i] = c2[i] - c1[i];
443			d2 = DOT(disp,disp);
444			/* circle within overlap? */
445			if (r1s < r2s) {
446			if (r2s >= r1s + d2) {
447			VCOPY(cc, c1);
448			return(r1s);
449			}
450			} else {
451			if (r1s >= r2s + d2) {
452			VCOPY(cc, c2);
453			return(r2s);
454			}
455			}
456			a2 = .25(2.(r1s+r2s) - d2 - (r2s-r1s)*(r2s-r1s)/d2);
457			/* no overlap? */
458			if (a2 <= 0.)
459			return(0.);
460			/* overlap, compute center */
461			l = sqrt((r1s - a2)/d2);
462			for (i = 0; i < 3; i++)
463			cc[i] = c1[i] + l*disp[i];
464			return(a2);
465	greg	1.1	}
466
467
468			sourcehit(r) /* check to see if ray hit distant source */
469			register RAY *r;
470			{
471			int first, last;
472			register int i;
473
474			if (r->rsrc >= 0) { /* check only one if aimed */
475			first = last = r->rsrc;
476			} else { /* otherwise check all */
477			first = 0; last = nsources-1;
478			}
479			for (i = first; i <= last; i++)
480	greg	1.12	if ((source[i].sflags & (SDISTANT\|SVIRTUAL)) == SDISTANT)
481	greg	1.1	/*
482			* Check to see if ray is within
483			* solid angle of source.
484			*/
485			if (2.0PI (1.0 - DOT(source[i].sloc,r->rdir))
486			<= source[i].ss2) {
487			r->ro = source[i].so;
488			if (!(source[i].sflags & SSKIP))
489			break;
490			}
491
492			if (r->ro != NULL) {
493			for (i = 0; i < 3; i++)
494			r->ron[i] = -r->rdir[i];
495			r->rod = 1.0;
496			r->rox = NULL;
497			return(1);
498			}
499			return(0);
500			}
501
502
503	greg	1.16	/****************************************************************
504			* The following macros were separated from the m_light() routine
505			* because they are very nasty and difficult to understand.
506			*/
507	greg	1.1
508	greg	1.16	/* wrongillum *
509			*
510			* We cannot allow an illum to pass to another illum, because that
511			* would almost certainly constitute overcounting.
512			* However, we do allow an illum to pass to another illum
513			* that is actually going to relay to a virtual light source.
514			*/
515
516			#define wrongillum(m, r) (!(source[r->rsrc].sflags&SVIRTUAL) && \
517			objptr(source[r->rsrc].so->omod)->otype==MAT_ILLUM)
518
519			/* wrongsource *
520			*
521			* This source is the wrong source (ie. overcounted) if we are
522			* aimed to a different source than the one we hit and the one
523			* we hit is not an illum which should be passed.
524			*/
525
526			#define wrongsource(m, r) (r->rsrc>=0 && source[r->rsrc].so!=r->ro && \
527			(m->otype!=MAT_ILLUM \|\| wrongillum(m,r)))
528
529			/* distglow *
530			*
531			* A distant glow is an object that sometimes acts as a light source,
532			* but is too far away from the test point to be one in this case.
533			*/
534
535	greg	1.10	#define distglow(m, r) (m->otype==MAT_GLOW && \
536			r->rot > m->oargs.farg[3])
537
538	greg	2.3	/* badcomponent *
539	greg	1.16	*
540	greg	2.3	* We must avoid counting light sources in the ambient calculation,
541	greg	1.16	* since the direct component is handled separately. Therefore, any
542			* ambient ray which hits an active light source must be discarded.
543	greg	2.3	* The same is true for stray specular samples, since the specular
544			* contribution from light sources is calculated separately.
545	greg	1.16	*/
546
547	greg	2.3	#define badcomponent(m, r) (r->crtype&(AMBIENT\|SPECULAR) && \
548	greg	2.4	!(r->crtype&SHADOW \|\| r->rod < 0.0 \|\| \
549			distglow(m, r)))
550	greg	1.1
551	greg	2.2	/* overcount *
552			*
553			* All overcounting possibilities are contained here.
554			*/
555
556	greg	2.3	#define overcount(m, r) (badcomponent(m,r) \|\| wrongsource(m,r))
557	greg	2.2
558	greg	1.16	/* passillum *
559			*
560			* An illum passes to another material type when we didn't hit it
561			* on purpose (as part of a direct calculation), or it is relaying
562			* a virtual light source.
563			*/
564
565	greg	1.1	#define passillum(m, r) (m->otype==MAT_ILLUM && \
566	greg	1.16	(r->rsrc<0 \|\| source[r->rsrc].so!=r->ro \|\| \
567			source[r->rsrc].sflags&SVIRTUAL))
568
569			/* srcignore *
570			*
571			* The -di flag renders light sources invisible, and here is the test.
572			*/
573	greg	1.1
574	greg	1.10	#define srcignore(m, r) (directinvis && !(r->crtype&SHADOW) && \
575			!distglow(m, r))
576	greg	1.1
577	greg	1.10
578	greg	1.1	m_light(m, r) /* ray hit a light source */
579			register OBJREC *m;
580			register RAY *r;
581			{
582			/* check for over-counting */
583	greg	2.2	if (overcount(m, r))
584	greg	1.1	return;
585			/* check for passed illum */
586			if (passillum(m, r)) {
587			if (m->oargs.nsargs < 1 \|\| !strcmp(m->oargs.sarg[0], VOIDID))
588			raytrans(r);
589			else
590			rayshade(r, modifier(m->oargs.sarg[0]));
591	greg	1.10	return;
592			}
593			/* otherwise treat as source */
594	greg	1.1	/* check for behind */
595	greg	1.10	if (r->rod < 0.0)
596			return;
597			/* check for invisibility */
598			if (srcignore(m, r))
599			return;
600	greg	1.1	/* get distribution pattern */
601	greg	1.10	raytexture(r, m->omod);
602	greg	1.1	/* get source color */
603	greg	1.10	setcolor(r->rcol, m->oargs.farg[0],
604			m->oargs.farg[1],
605			m->oargs.farg[2]);
606	greg	1.1	/* modify value */
607	greg	1.10	multcolor(r->rcol, r->pcol);
608	greg	1.1	}