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 */
{
        if (nsources == 0)
                source = (SRCREC *)malloc(sizeof(SRCREC));
        else
                source = (SRCREC *)realloc((char *)source,
                                (unsigned)(nsources+1)*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++);
}


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)
                        /*
                         * 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)      (m->otype!=MAT_ILLUM && \
                                r->rsrc>=0 && \
                                source[r->rsrc].so!=r->ro)

#define  badambient(m, r)       ((r->crtype&(AMBIENT|SHADOW))==AMBIENT && \
                                !(m->otype==MAT_GLOW&&r->rot>m->oargs.farg[3]))

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


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]));

                                                /* otherwise treat as source */
        } else {
                                                /* check for behind */
                if (r->rod < 0.0)
                        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:	1.9
Committed:	Tue Jul 16 15:56:48 1991 UTC (32 years, 9 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.8:	+3 -1 lines
Log Message:	added redirecting materials
#	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			if (nsources == 0)
53			source = (SRCREC *)malloc(sizeof(SRCREC));
54			else
55			source = (SRCREC )realloc((char )source,
56			(unsigned)(nsources+1)*sizeof(SRCREC));
57			if (source == NULL)
58	greg	1.2	return(-1);
59	greg	1.1	source[nsources].sflags = 0;
60			source[nsources].nhits = 1;
61			source[nsources].ntests = 2; /* initial hit probability = 1/2 */
62	greg	1.2	return(nsources++);
63	greg	1.1	}
64
65
66			fsetsrc(src, so) /* set a face as a source */
67			register SRCREC *src;
68			OBJREC *so;
69			{
70			register FACE *f;
71			register int i, j;
72
73			src->sa.success = 2AIMREQT-1; / bitch on second failure */
74			src->so = so;
75			/* get the face */
76			f = getface(so);
77			/* find the center */
78			for (j = 0; j < 3; j++) {
79			src->sloc[j] = 0.0;
80			for (i = 0; i < f->nv; i++)
81			src->sloc[j] += VERTEX(f,i)[j];
82			src->sloc[j] /= (double)f->nv;
83			}
84			if (!inface(src->sloc, f))
85			objerror(so, USER, "cannot hit center");
86			src->sflags \|= SFLAT;
87			VCOPY(src->snorm, f->norm);
88			src->ss = sqrt(f->area / PI);
89			src->ss2 = f->area;
90			}
91
92
93			ssetsrc(src, so) /* set a source as a source */
94			register SRCREC *src;
95			register OBJREC *so;
96			{
97			double theta;
98
99			src->sa.success = 2AIMREQT-1; / bitch on second failure */
100			src->so = so;
101			if (so->oargs.nfargs != 4)
102			objerror(so, USER, "bad arguments");
103			src->sflags \|= SDISTANT;
104			VCOPY(src->sloc, so->oargs.farg);
105			if (normalize(src->sloc) == 0.0)
106			objerror(so, USER, "zero direction");
107			theta = PI/180.0/2.0 * so->oargs.farg[3];
108			if (theta <= FTINY)
109			objerror(so, USER, "zero size");
110	greg	1.7	src->ss = theta >= PI/4.0 ? 1.0 : tan(theta);
111	greg	1.1	src->ss2 = 2.0PI (1.0 - cos(theta));
112			}
113
114
115			sphsetsrc(src, so) /* set a sphere as a source */
116			register SRCREC *src;
117			register OBJREC *so;
118			{
119			src->sa.success = 2AIMREQT-1; / bitch on second failure */
120			src->so = so;
121			if (so->oargs.nfargs != 4)
122			objerror(so, USER, "bad # arguments");
123			if (so->oargs.farg[3] <= FTINY)
124			objerror(so, USER, "illegal radius");
125			VCOPY(src->sloc, so->oargs.farg);
126			src->ss = so->oargs.farg[3];
127			src->ss2 = PI * src->ss * src->ss;
128			}
129
130
131			rsetsrc(src, so) /* set a ring (disk) as a source */
132			register SRCREC *src;
133			OBJREC *so;
134			{
135			register CONE *co;
136
137			src->sa.success = 2AIMREQT-1; / bitch on second failure */
138			src->so = so;
139			/* get the ring */
140			co = getcone(so, 0);
141			VCOPY(src->sloc, CO_P0(co));
142			if (CO_R0(co) > 0.0)
143			objerror(so, USER, "cannot hit center");
144			src->sflags \|= SFLAT;
145			VCOPY(src->snorm, co->ad);
146			src->ss = CO_R1(co);
147			src->ss2 = PI * src->ss * src->ss;
148			}
149
150
151			SPOT *
152			makespot(m) /* make a spotlight */
153			register OBJREC *m;
154			{
155			register SPOT *ns;
156
157			if ((ns = (SPOT *)malloc(sizeof(SPOT))) == NULL)
158			return(NULL);
159			ns->siz = 2.0PI (1.0 - cos(PI/180.0/2.0 * m->oargs.farg[3]));
160			VCOPY(ns->aim, m->oargs.farg+4);
161			if ((ns->flen = normalize(ns->aim)) == 0.0)
162			objerror(m, USER, "zero focus vector");
163			return(ns);
164			}
165
166
167			double
168			fgetmaxdisk(ocent, op) /* get center and squared radius of face */
169			FVECT ocent;
170			OBJREC *op;
171			{
172			double maxrad2;
173	greg	1.5	double d;
174	greg	1.1	register int i, j;
175			register FACE *f;
176
177			f = getface(op);
178	greg	1.5	if (f->area == 0.)
179			return(0.);
180	greg	1.1	for (i = 0; i < 3; i++) {
181			ocent[i] = 0.;
182			for (j = 0; j < f->nv; j++)
183			ocent[i] += VERTEX(f,j)[i];
184			ocent[i] /= (double)f->nv;
185			}
186	greg	1.5	d = DOT(ocent,f->norm);
187			for (i = 0; i < 3; i++)
188			ocent[i] += (f->offset - d)*f->norm[i];
189	greg	1.1	maxrad2 = 0.;
190			for (j = 0; j < f->nv; j++) {
191	greg	1.5	d = dist2(VERTEX(f,j), ocent);
192			if (d > maxrad2)
193			maxrad2 = d;
194	greg	1.1	}
195			return(maxrad2);
196			}
197
198
199			double
200			rgetmaxdisk(ocent, op) /* get center and squared radius of ring */
201			FVECT ocent;
202			OBJREC *op;
203			{
204			register CONE *co;
205
206			co = getcone(op, 0);
207			VCOPY(ocent, CO_P0(co));
208			return(CO_R1(co)*CO_R1(co));
209			}
210
211
212			double
213			fgetplaneq(nvec, op) /* get plane equation for face */
214			FVECT nvec;
215			OBJREC *op;
216			{
217			register FACE *fo;
218
219			fo = getface(op);
220			VCOPY(nvec, fo->norm);
221			return(fo->offset);
222			}
223
224
225			double
226			rgetplaneq(nvec, op) /* get plane equation for ring */
227			FVECT nvec;
228			OBJREC *op;
229			{
230			register CONE *co;
231
232			co = getcone(op, 0);
233			VCOPY(nvec, co->ad);
234			return(DOT(nvec, CO_P0(co)));
235	greg	1.4	}
236
237
238			commonspot(sp1, sp2, org) /* set sp1 to intersection of sp1 and sp2 */
239			register SPOT sp1, sp2;
240			FVECT org;
241			{
242			FVECT cent;
243			double rad2, cos1, cos2;
244
245			cos1 = 1. - sp1->siz/(2.*PI);
246			cos2 = 1. - sp2->siz/(2.*PI);
247			if (sp2->siz >= 2.PI-FTINY) / BIG, just check overlap */
248			return(DOT(sp1->aim,sp2->aim) >= cos1*cos2 -
249			sqrt((1.-cos1cos1)(1.-cos2*cos2)));
250			/* compute and check disks */
251			rad2 = intercircle(cent, sp1->aim, sp2->aim,
252			1./(cos1cos1) - 1., 1./(cos2cos2) - 1.);
253			if (rad2 <= FTINY \|\| normalize(cent) == 0.)
254			return(0);
255			VCOPY(sp1->aim, cent);
256			sp1->siz = 2.PI(1. - 1./sqrt(1.+rad2));
257			return(1);
258			}
259
260
261			commonbeam(sp1, sp2, dir) /* set sp1 to intersection of sp1 and sp2 */
262			register SPOT sp1, sp2;
263			FVECT dir;
264			{
265			FVECT cent, c1, c2;
266			double rad2, d;
267			register int i;
268			/* move centers to common plane */
269			d = DOT(sp1->aim, dir);
270			for (i = 0; i < 3; i++)
271			c1[i] = sp1->aim[i] - d*dir[i];
272			d = DOT(sp2->aim, dir);
273			for (i = 0; i < 3; i++)
274			c2[i] = sp2->aim[i] - d*dir[i];
275			/* compute overlap */
276			rad2 = intercircle(cent, c1, c2, sp1->siz/PI, sp2->siz/PI);
277			if (rad2 <= FTINY)
278			return(0);
279			VCOPY(sp1->aim, cent);
280			sp1->siz = PI*rad2;
281			return(1);
282			}
283
284
285			checkspot(sp, nrm) /* check spotlight for behind source */
286			register SPOT sp; / spotlight */
287			FVECT nrm; /* source surface normal */
288			{
289			double d, d1;
290
291			d = DOT(sp->aim, nrm);
292			if (d > FTINY) /* center in front? */
293	greg	1.8	return(1);
294	greg	1.4	/* else check horizon */
295			d1 = 1. - sp->siz/(2.*PI);
296	greg	1.8	return(1.-FTINY-dd < d1d1);
297	greg	1.4	}
298
299
300			double
301	greg	1.6	spotdisk(oc, op, sp, pos) /* intersect spot with object op */
302			FVECT oc;
303			OBJREC *op;
304			register SPOT *sp;
305			FVECT pos;
306			{
307			FVECT onorm;
308			double offs, d, dist;
309			register int i;
310
311			offs = getplaneq(onorm, op);
312			d = -DOT(onorm, sp->aim);
313			if (d >= -FTINY && d <= FTINY)
314			return(0.);
315			dist = (DOT(pos, onorm) - offs)/d;
316			if (dist < 0.)
317			return(0.);
318			for (i = 0; i < 3; i++)
319			oc[i] = pos[i] + dist*sp->aim[i];
320			return(sp->sizdistdist/PI/(d*d));
321			}
322
323
324			double
325			beamdisk(oc, op, sp, dir) /* intersect beam with object op */
326			FVECT oc;
327			OBJREC *op;
328			register SPOT *sp;
329			FVECT dir;
330			{
331			FVECT onorm;
332			double offs, d, dist;
333			register int i;
334
335			offs = getplaneq(onorm, op);
336			d = -DOT(onorm, dir);
337			if (d >= -FTINY && d <= FTINY)
338			return(0.);
339			dist = (DOT(sp->aim, onorm) - offs)/d;
340			for (i = 0; i < 3; i++)
341			oc[i] = sp->aim[i] + dist*dir[i];
342			return(sp->siz/PI/(d*d));
343			}
344
345
346			double
347	greg	1.4	intercircle(cc, c1, c2, r1s, r2s) /* intersect two circles */
348			FVECT cc; /* midpoint (return value) */
349			FVECT c1, c2; /* circle centers */
350			double r1s, r2s; /* radii squared */
351			{
352			double a2, d2, l;
353			FVECT disp;
354			register int i;
355
356			for (i = 0; i < 3; i++)
357			disp[i] = c2[i] - c1[i];
358			d2 = DOT(disp,disp);
359			/* circle within overlap? */
360			if (r1s < r2s) {
361			if (r2s >= r1s + d2) {
362			VCOPY(cc, c1);
363			return(r1s);
364			}
365			} else {
366			if (r1s >= r2s + d2) {
367			VCOPY(cc, c2);
368			return(r2s);
369			}
370			}
371			a2 = .25(2.(r1s+r2s) - d2 - (r2s-r1s)*(r2s-r1s)/d2);
372			/* no overlap? */
373			if (a2 <= 0.)
374			return(0.);
375			/* overlap, compute center */
376			l = sqrt((r1s - a2)/d2);
377			for (i = 0; i < 3; i++)
378			cc[i] = c1[i] + l*disp[i];
379			return(a2);
380	greg	1.1	}
381
382
383			sourcehit(r) /* check to see if ray hit distant source */
384			register RAY *r;
385			{
386			int first, last;
387			register int i;
388
389			if (r->rsrc >= 0) { /* check only one if aimed */
390			first = last = r->rsrc;
391			} else { /* otherwise check all */
392			first = 0; last = nsources-1;
393			}
394			for (i = first; i <= last; i++)
395			if (source[i].sflags & SDISTANT)
396			/*
397			* Check to see if ray is within
398			* solid angle of source.
399			*/
400			if (2.0PI (1.0 - DOT(source[i].sloc,r->rdir))
401			<= source[i].ss2) {
402			r->ro = source[i].so;
403			if (!(source[i].sflags & SSKIP))
404			break;
405			}
406
407			if (r->ro != NULL) {
408			for (i = 0; i < 3; i++)
409			r->ron[i] = -r->rdir[i];
410			r->rod = 1.0;
411			r->rox = NULL;
412			return(1);
413			}
414			return(0);
415			}
416
417
418			#define wrongsource(m, r) (m->otype!=MAT_ILLUM && \
419			r->rsrc>=0 && \
420			source[r->rsrc].so!=r->ro)
421
422			#define badambient(m, r) ((r->crtype&(AMBIENT\|SHADOW))==AMBIENT && \
423			!(m->otype==MAT_GLOW&&r->rot>m->oargs.farg[3]))
424
425			#define passillum(m, r) (m->otype==MAT_ILLUM && \
426			!(r->rsrc>=0&&source[r->rsrc].so==r->ro))
427
428
429			m_light(m, r) /* ray hit a light source */
430			register OBJREC *m;
431			register RAY *r;
432			{
433			/* check for over-counting */
434			if (wrongsource(m, r) \|\| badambient(m, r))
435			return;
436			/* check for passed illum */
437			if (passillum(m, r)) {
438
439			if (m->oargs.nsargs < 1 \|\| !strcmp(m->oargs.sarg[0], VOIDID))
440			raytrans(r);
441			else
442			rayshade(r, modifier(m->oargs.sarg[0]));
443
444			/* otherwise treat as source */
445			} else {
446			/* check for behind */
447			if (r->rod < 0.0)
448			return;
449			/* get distribution pattern */
450			raytexture(r, m->omod);
451			/* get source color */
452			setcolor(r->rcol, m->oargs.farg[0],
453			m->oargs.farg[1],
454			m->oargs.farg[2]);
455			/* modify value */
456			multcolor(r->rcol, r->pcol);
457			}
458			}