src/rt/srcsupp.c

/* Copyright (c) 1991 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"


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(), rsetsrc();
        extern double  fgetplaneq(), rgetplaneq();
        extern double  fgetmaxdisk(), rgetmaxdisk();
        static SOBJECT  fsobj = {fsetsrc, fgetplaneq, fgetmaxdisk};
        static SOBJECT  ssobj = {ssetsrc};
        static SOBJECT  sphsobj = {sphsetsrc};
        static SOBJECT  rsobj = {rsetsrc, 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_RING].of = &rsobj;
}


int
newsource()                     /* allocate new source in our array */
{
#define SRCINC  4
        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++);
#undef SRCINC
}


fsetsrc(src, so)                        /* set a face as a source */
register SRCREC  *src;
OBJREC  *so;
{
        register FACE  *f;
        register int  i, j;
        
        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->ss = sqrt(f->area / PI);
        src->ss2 = f->area;
}


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->ss = theta >= PI/4.0 ? 1.0 : tan(theta);
        src->ss2 = 2.0*PI * (1.0 - cos(theta));
}


sphsetsrc(src, so)                      /* set a sphere as a source */
register SRCREC  *src;
register OBJREC  *so;
{
        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->ss = so->oargs.farg[3];
        src->ss2 = PI * src->ss * src->ss;
}


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->ss = CO_R1(co);
        src->ss2 = PI * src->ss * src->ss;
}


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);
}


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

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

#define  badambient(m, r)       ((r->crtype&(AMBIENT|SHADOW))==AMBIENT && \
                                !distglow(m, r))

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

#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 (wrongsource(m, r) || badambient(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:	1.13
Committed:	Fri Sep 13 13:44:10 1991 UTC (32 years, 7 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.12:	+5 -3 lines
Log Message:	made source array allocation incremental
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1991 Regents of the University of California */
2
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
22			SRCREC source = NULL; / our list of sources */
23			int nsources = 0; /* the number of sources */
24
25			SRCFUNC sfun[NUMOTYPE]; /* source dispatch table */
26
27
28			initstypes() /* initialize source dispatch table */
29			{
30	greg	1.9	extern VSMATERIAL mirror_vs, direct1_vs, direct2_vs;
31	greg	1.1	extern int fsetsrc(), ssetsrc(), sphsetsrc(), rsetsrc();
32			extern double fgetplaneq(), rgetplaneq();
33			extern double fgetmaxdisk(), rgetmaxdisk();
34			static SOBJECT fsobj = {fsetsrc, fgetplaneq, fgetmaxdisk};
35			static SOBJECT ssobj = {ssetsrc};
36			static SOBJECT sphsobj = {sphsetsrc};
37			static SOBJECT rsobj = {rsetsrc, rgetplaneq, rgetmaxdisk};
38
39			sfun[MAT_MIRROR].mf = &mirror_vs;
40	greg	1.9	sfun[MAT_DIRECT1].mf = &direct1_vs;
41			sfun[MAT_DIRECT2].mf = &direct2_vs;
42	greg	1.1	sfun[OBJ_FACE].of = &fsobj;
43			sfun[OBJ_SOURCE].of = &ssobj;
44			sfun[OBJ_SPHERE].of = &sphsobj;
45			sfun[OBJ_RING].of = &rsobj;
46			}
47
48
49	greg	1.2	int
50	greg	1.1	newsource() /* allocate new source in our array */
51			{
52	greg	1.13	#define SRCINC 4
53	greg	1.1	if (nsources == 0)
54	greg	1.13	source = (SRCREC )malloc(SRCINCsizeof(SRCREC));
55			else if (nsources%SRCINC == 0)
56	greg	1.1	source = (SRCREC )realloc((char )source,
57	greg	1.13	(unsigned)(nsources+SRCINC)*sizeof(SRCREC));
58	greg	1.1	if (source == NULL)
59	greg	1.2	return(-1);
60	greg	1.1	source[nsources].sflags = 0;
61			source[nsources].nhits = 1;
62			source[nsources].ntests = 2; /* initial hit probability = 1/2 */
63	greg	1.2	return(nsources++);
64	greg	1.13	#undef SRCINC
65	greg	1.1	}
66
67
68			fsetsrc(src, so) /* set a face as a source */
69			register SRCREC *src;
70			OBJREC *so;
71			{
72			register FACE *f;
73			register int i, j;
74
75			src->sa.success = 2AIMREQT-1; / bitch on second failure */
76			src->so = so;
77			/* get the face */
78			f = getface(so);
79			/* find the center */
80			for (j = 0; j < 3; j++) {
81			src->sloc[j] = 0.0;
82			for (i = 0; i < f->nv; i++)
83			src->sloc[j] += VERTEX(f,i)[j];
84			src->sloc[j] /= (double)f->nv;
85			}
86			if (!inface(src->sloc, f))
87			objerror(so, USER, "cannot hit center");
88			src->sflags \|= SFLAT;
89			VCOPY(src->snorm, f->norm);
90			src->ss = sqrt(f->area / PI);
91			src->ss2 = f->area;
92			}
93
94
95			ssetsrc(src, so) /* set a source as a source */
96			register SRCREC *src;
97			register OBJREC *so;
98			{
99			double theta;
100
101			src->sa.success = 2AIMREQT-1; / bitch on second failure */
102			src->so = so;
103			if (so->oargs.nfargs != 4)
104			objerror(so, USER, "bad arguments");
105			src->sflags \|= SDISTANT;
106			VCOPY(src->sloc, so->oargs.farg);
107			if (normalize(src->sloc) == 0.0)
108			objerror(so, USER, "zero direction");
109			theta = PI/180.0/2.0 * so->oargs.farg[3];
110			if (theta <= FTINY)
111			objerror(so, USER, "zero size");
112	greg	1.7	src->ss = theta >= PI/4.0 ? 1.0 : tan(theta);
113	greg	1.1	src->ss2 = 2.0PI (1.0 - cos(theta));
114			}
115
116
117			sphsetsrc(src, so) /* set a sphere as a source */
118			register SRCREC *src;
119			register OBJREC *so;
120			{
121			src->sa.success = 2AIMREQT-1; / bitch on second failure */
122			src->so = so;
123			if (so->oargs.nfargs != 4)
124			objerror(so, USER, "bad # arguments");
125			if (so->oargs.farg[3] <= FTINY)
126			objerror(so, USER, "illegal radius");
127			VCOPY(src->sloc, so->oargs.farg);
128			src->ss = so->oargs.farg[3];
129			src->ss2 = PI * src->ss * src->ss;
130			}
131
132
133			rsetsrc(src, so) /* set a ring (disk) as a source */
134			register SRCREC *src;
135			OBJREC *so;
136			{
137			register CONE *co;
138
139			src->sa.success = 2AIMREQT-1; / bitch on second failure */
140			src->so = so;
141			/* get the ring */
142			co = getcone(so, 0);
143			VCOPY(src->sloc, CO_P0(co));
144			if (CO_R0(co) > 0.0)
145			objerror(so, USER, "cannot hit center");
146			src->sflags \|= SFLAT;
147			VCOPY(src->snorm, co->ad);
148			src->ss = CO_R1(co);
149			src->ss2 = PI * src->ss * src->ss;
150			}
151
152
153			SPOT *
154			makespot(m) /* make a spotlight */
155			register OBJREC *m;
156			{
157			register SPOT *ns;
158
159			if ((ns = (SPOT *)malloc(sizeof(SPOT))) == NULL)
160			return(NULL);
161			ns->siz = 2.0PI (1.0 - cos(PI/180.0/2.0 * m->oargs.farg[3]));
162			VCOPY(ns->aim, m->oargs.farg+4);
163			if ((ns->flen = normalize(ns->aim)) == 0.0)
164			objerror(m, USER, "zero focus vector");
165			return(ns);
166			}
167
168
169			double
170			fgetmaxdisk(ocent, op) /* get center and squared radius of face */
171			FVECT ocent;
172			OBJREC *op;
173			{
174			double maxrad2;
175	greg	1.5	double d;
176	greg	1.1	register int i, j;
177			register FACE *f;
178
179			f = getface(op);
180	greg	1.5	if (f->area == 0.)
181			return(0.);
182	greg	1.1	for (i = 0; i < 3; i++) {
183			ocent[i] = 0.;
184			for (j = 0; j < f->nv; j++)
185			ocent[i] += VERTEX(f,j)[i];
186			ocent[i] /= (double)f->nv;
187			}
188	greg	1.5	d = DOT(ocent,f->norm);
189			for (i = 0; i < 3; i++)
190			ocent[i] += (f->offset - d)*f->norm[i];
191	greg	1.1	maxrad2 = 0.;
192			for (j = 0; j < f->nv; j++) {
193	greg	1.5	d = dist2(VERTEX(f,j), ocent);
194			if (d > maxrad2)
195			maxrad2 = d;
196	greg	1.1	}
197			return(maxrad2);
198			}
199
200
201			double
202			rgetmaxdisk(ocent, op) /* get center and squared radius of ring */
203			FVECT ocent;
204			OBJREC *op;
205			{
206			register CONE *co;
207
208			co = getcone(op, 0);
209			VCOPY(ocent, CO_P0(co));
210			return(CO_R1(co)*CO_R1(co));
211			}
212
213
214			double
215			fgetplaneq(nvec, op) /* get plane equation for face */
216			FVECT nvec;
217			OBJREC *op;
218			{
219			register FACE *fo;
220
221			fo = getface(op);
222			VCOPY(nvec, fo->norm);
223			return(fo->offset);
224			}
225
226
227			double
228			rgetplaneq(nvec, op) /* get plane equation for ring */
229			FVECT nvec;
230			OBJREC *op;
231			{
232			register CONE *co;
233
234			co = getcone(op, 0);
235			VCOPY(nvec, co->ad);
236			return(DOT(nvec, CO_P0(co)));
237	greg	1.4	}
238
239
240			commonspot(sp1, sp2, org) /* set sp1 to intersection of sp1 and sp2 */
241			register SPOT sp1, sp2;
242			FVECT org;
243			{
244			FVECT cent;
245			double rad2, cos1, cos2;
246
247			cos1 = 1. - sp1->siz/(2.*PI);
248			cos2 = 1. - sp2->siz/(2.*PI);
249			if (sp2->siz >= 2.PI-FTINY) / BIG, just check overlap */
250			return(DOT(sp1->aim,sp2->aim) >= cos1*cos2 -
251			sqrt((1.-cos1cos1)(1.-cos2*cos2)));
252			/* compute and check disks */
253			rad2 = intercircle(cent, sp1->aim, sp2->aim,
254			1./(cos1cos1) - 1., 1./(cos2cos2) - 1.);
255			if (rad2 <= FTINY \|\| normalize(cent) == 0.)
256			return(0);
257			VCOPY(sp1->aim, cent);
258			sp1->siz = 2.PI(1. - 1./sqrt(1.+rad2));
259			return(1);
260			}
261
262
263			commonbeam(sp1, sp2, dir) /* set sp1 to intersection of sp1 and sp2 */
264			register SPOT sp1, sp2;
265			FVECT dir;
266			{
267			FVECT cent, c1, c2;
268			double rad2, d;
269			register int i;
270			/* move centers to common plane */
271			d = DOT(sp1->aim, dir);
272			for (i = 0; i < 3; i++)
273			c1[i] = sp1->aim[i] - d*dir[i];
274			d = DOT(sp2->aim, dir);
275			for (i = 0; i < 3; i++)
276			c2[i] = sp2->aim[i] - d*dir[i];
277			/* compute overlap */
278			rad2 = intercircle(cent, c1, c2, sp1->siz/PI, sp2->siz/PI);
279			if (rad2 <= FTINY)
280			return(0);
281			VCOPY(sp1->aim, cent);
282			sp1->siz = PI*rad2;
283			return(1);
284			}
285
286
287			checkspot(sp, nrm) /* check spotlight for behind source */
288			register SPOT sp; / spotlight */
289			FVECT nrm; /* source surface normal */
290			{
291			double d, d1;
292
293			d = DOT(sp->aim, nrm);
294			if (d > FTINY) /* center in front? */
295	greg	1.8	return(1);
296	greg	1.4	/* else check horizon */
297			d1 = 1. - sp->siz/(2.*PI);
298	greg	1.8	return(1.-FTINY-dd < d1d1);
299	greg	1.4	}
300
301
302			double
303	greg	1.6	spotdisk(oc, op, sp, pos) /* intersect spot with object op */
304			FVECT oc;
305			OBJREC *op;
306			register SPOT *sp;
307			FVECT pos;
308			{
309			FVECT onorm;
310			double offs, d, dist;
311			register int i;
312
313			offs = getplaneq(onorm, op);
314			d = -DOT(onorm, sp->aim);
315			if (d >= -FTINY && d <= FTINY)
316			return(0.);
317			dist = (DOT(pos, onorm) - offs)/d;
318			if (dist < 0.)
319			return(0.);
320			for (i = 0; i < 3; i++)
321			oc[i] = pos[i] + dist*sp->aim[i];
322			return(sp->sizdistdist/PI/(d*d));
323			}
324
325
326			double
327			beamdisk(oc, op, sp, dir) /* intersect beam with object op */
328			FVECT oc;
329			OBJREC *op;
330			register SPOT *sp;
331			FVECT dir;
332			{
333			FVECT onorm;
334			double offs, d, dist;
335			register int i;
336
337			offs = getplaneq(onorm, op);
338			d = -DOT(onorm, dir);
339			if (d >= -FTINY && d <= FTINY)
340			return(0.);
341			dist = (DOT(sp->aim, onorm) - offs)/d;
342			for (i = 0; i < 3; i++)
343			oc[i] = sp->aim[i] + dist*dir[i];
344			return(sp->siz/PI/(d*d));
345			}
346
347
348			double
349	greg	1.4	intercircle(cc, c1, c2, r1s, r2s) /* intersect two circles */
350			FVECT cc; /* midpoint (return value) */
351			FVECT c1, c2; /* circle centers */
352			double r1s, r2s; /* radii squared */
353			{
354			double a2, d2, l;
355			FVECT disp;
356			register int i;
357
358			for (i = 0; i < 3; i++)
359			disp[i] = c2[i] - c1[i];
360			d2 = DOT(disp,disp);
361			/* circle within overlap? */
362			if (r1s < r2s) {
363			if (r2s >= r1s + d2) {
364			VCOPY(cc, c1);
365			return(r1s);
366			}
367			} else {
368			if (r1s >= r2s + d2) {
369			VCOPY(cc, c2);
370			return(r2s);
371			}
372			}
373			a2 = .25(2.(r1s+r2s) - d2 - (r2s-r1s)*(r2s-r1s)/d2);
374			/* no overlap? */
375			if (a2 <= 0.)
376			return(0.);
377			/* overlap, compute center */
378			l = sqrt((r1s - a2)/d2);
379			for (i = 0; i < 3; i++)
380			cc[i] = c1[i] + l*disp[i];
381			return(a2);
382	greg	1.1	}
383
384
385			sourcehit(r) /* check to see if ray hit distant source */
386			register RAY *r;
387			{
388			int first, last;
389			register int i;
390
391			if (r->rsrc >= 0) { /* check only one if aimed */
392			first = last = r->rsrc;
393			} else { /* otherwise check all */
394			first = 0; last = nsources-1;
395			}
396			for (i = first; i <= last; i++)
397	greg	1.12	if ((source[i].sflags & (SDISTANT\|SVIRTUAL)) == SDISTANT)
398	greg	1.1	/*
399			* Check to see if ray is within
400			* solid angle of source.
401			*/
402			if (2.0PI (1.0 - DOT(source[i].sloc,r->rdir))
403			<= source[i].ss2) {
404			r->ro = source[i].so;
405			if (!(source[i].sflags & SSKIP))
406			break;
407			}
408
409			if (r->ro != NULL) {
410			for (i = 0; i < 3; i++)
411			r->ron[i] = -r->rdir[i];
412			r->rod = 1.0;
413			r->rox = NULL;
414			return(1);
415			}
416			return(0);
417			}
418
419
420	greg	1.11	#define wrongsource(m, r) (r->rsrc>=0 && \
421			source[r->rsrc].so!=r->ro && \
422			(m->otype!=MAT_ILLUM \|\| \
423			objptr(source[r->rsrc].so->omod)->otype==MAT_ILLUM))
424	greg	1.1
425	greg	1.10	#define distglow(m, r) (m->otype==MAT_GLOW && \
426			r->rot > m->oargs.farg[3])
427
428	greg	1.1	#define badambient(m, r) ((r->crtype&(AMBIENT\|SHADOW))==AMBIENT && \
429	greg	1.10	!distglow(m, r))
430	greg	1.1
431			#define passillum(m, r) (m->otype==MAT_ILLUM && \
432			!(r->rsrc>=0&&source[r->rsrc].so==r->ro))
433
434	greg	1.10	#define srcignore(m, r) (directinvis && !(r->crtype&SHADOW) && \
435			!distglow(m, r))
436	greg	1.1
437	greg	1.10
438	greg	1.1	m_light(m, r) /* ray hit a light source */
439			register OBJREC *m;
440			register RAY *r;
441			{
442			/* check for over-counting */
443			if (wrongsource(m, r) \|\| badambient(m, r))
444			return;
445			/* check for passed illum */
446			if (passillum(m, r)) {
447			if (m->oargs.nsargs < 1 \|\| !strcmp(m->oargs.sarg[0], VOIDID))
448			raytrans(r);
449			else
450			rayshade(r, modifier(m->oargs.sarg[0]));
451	greg	1.10	return;
452			}
453			/* otherwise treat as source */
454	greg	1.1	/* check for behind */
455	greg	1.10	if (r->rod < 0.0)
456			return;
457			/* check for invisibility */
458			if (srcignore(m, r))
459			return;
460	greg	1.1	/* get distribution pattern */
461	greg	1.10	raytexture(r, m->omod);
462	greg	1.1	/* get source color */
463	greg	1.10	setcolor(r->rcol, m->oargs.farg[0],
464			m->oargs.farg[1],
465			m->oargs.farg[2]);
466	greg	1.1	/* modify value */
467	greg	1.10	multcolor(r->rcol, r->pcol);
468	greg	1.1	}