src/rt/srcsupp.c

#ifndef lint
static const char       RCSid[] = "$Id: srcsupp.c,v 2.13 2003/12/31 02:03:08 greg Exp $";
#endif
/*
 *  Support routines for source objects and materials
 *
 *  External symbols declared in source.h
 */

#include "copyright.h"

#include  "ray.h"

#include  "otypes.h"

#include  "source.h"

#include  "cone.h"

#include  "face.h"

#define SRCINC          8               /* realloc increment for array */

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

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


void
initstypes()                    /* initialize source dispatch table */
{
        extern VSMATERIAL  mirror_vs, direct1_vs, direct2_vs;
        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((void *)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 = 50% */
#if SHADCACHE
        source[nsources].obscache = NULL;
#endif
        return(nsources++);
}


void
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]);
}


void
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)                         /* parallelogram case */
                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);
}


void
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;
}


void
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];
}


void
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);
}


void
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 *)m->os) != NULL)
                return(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");
        m->os = (char *)ns;
        return(ns);
}


int
spotout(r, s)                   /* check if we're outside spot region */
register RAY  *r;
register SPOT  *s;
{
        double  d;
        FVECT  vd;
        
        if (s == NULL)
                return(0);
        if (s->flen < -FTINY) {         /* distant source */
                vd[0] = s->aim[0] - r->rorg[0];
                vd[1] = s->aim[1] - r->rorg[1];
                vd[2] = s->aim[2] - r->rorg[2];
                d = DOT(r->rdir,vd);
                /*                      wrong side?
                if (d <= FTINY)
                        return(1);      */
                d = DOT(vd,vd) - d*d;
                if (PI*d > s->siz)
                        return(1);      /* out */
                return(0);      /* OK */
        }
                                        /* local source */
        if (s->siz < 2.0*PI * (1.0 + DOT(s->aim,r->rdir)))
                return(1);      /* out */
        return(0);      /* OK */
}


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)));
}


int
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);
}


int
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);
}


int
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);
}
Revision:	2.14
Committed:	Wed Dec 31 19:38:27 2003 UTC (21 years, 9 months ago) by greg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rad3R7P2, rad3R7P1, rad3R6, rad3R6P1
Changes since 2.13:	+3 -3 lines
Log Message:	Added shadow casting algorithm and separated occlusion cache routines
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.14	static const char RCSid[] = "$Id: srcsupp.c,v 2.13 2003/12/31 02:03:08 greg Exp $";
3	greg	1.1	#endif
4			/*
5			* Support routines for source objects and materials
6	greg	2.9	*
7			* External symbols declared in source.h
8			*/
9
10	greg	2.10	#include "copyright.h"
11	greg	1.1
12			#include "ray.h"
13
14			#include "otypes.h"
15
16			#include "source.h"
17
18			#include "cone.h"
19
20			#include "face.h"
21
22	greg	2.12	#define SRCINC 8 /* realloc increment for array */
23	greg	1.1
24			SRCREC source = NULL; / our list of sources */
25			int nsources = 0; /* the number of sources */
26
27			SRCFUNC sfun[NUMOTYPE]; /* source dispatch table */
28
29
30	greg	2.9	void
31	greg	1.1	initstypes() /* initialize source dispatch table */
32			{
33	greg	1.9	extern VSMATERIAL mirror_vs, direct1_vs, direct2_vs;
34	greg	1.14	static SOBJECT fsobj = {fsetsrc, flatpart, fgetplaneq, fgetmaxdisk};
35			static SOBJECT ssobj = {ssetsrc, nopart};
36			static SOBJECT sphsobj = {sphsetsrc, nopart};
37			static SOBJECT cylsobj = {cylsetsrc, cylpart};
38			static SOBJECT rsobj = {rsetsrc, flatpart, rgetplaneq, rgetmaxdisk};
39	greg	1.1
40			sfun[MAT_MIRROR].mf = &mirror_vs;
41	greg	1.9	sfun[MAT_DIRECT1].mf = &direct1_vs;
42			sfun[MAT_DIRECT2].mf = &direct2_vs;
43	greg	1.1	sfun[OBJ_FACE].of = &fsobj;
44			sfun[OBJ_SOURCE].of = &ssobj;
45			sfun[OBJ_SPHERE].of = &sphsobj;
46	greg	1.14	sfun[OBJ_CYLINDER].of = &cylsobj;
47	greg	1.1	sfun[OBJ_RING].of = &rsobj;
48			}
49
50
51	greg	1.2	int
52	greg	1.1	newsource() /* allocate new source in our array */
53			{
54			if (nsources == 0)
55	greg	1.13	source = (SRCREC )malloc(SRCINCsizeof(SRCREC));
56			else if (nsources%SRCINC == 0)
57	greg	2.11	source = (SRCREC )realloc((void )source,
58	greg	1.13	(unsigned)(nsources+SRCINC)*sizeof(SRCREC));
59	greg	1.1	if (source == NULL)
60	greg	1.2	return(-1);
61	greg	1.1	source[nsources].sflags = 0;
62	greg	2.14	source[nsources].nhits = 1;
63			source[nsources].ntests = 2; /* initial hit probability = 50% */
64	greg	2.12	#if SHADCACHE
65			source[nsources].obscache = NULL;
66			#endif
67	greg	1.2	return(nsources++);
68	greg	1.1	}
69
70
71	greg	2.9	void
72	greg	1.14	setflatss(src) /* set sampling for a flat source */
73			register SRCREC *src;
74			{
75			double mult;
76			register int i;
77
78			src->ss[SV][0] = src->ss[SV][1] = src->ss[SV][2] = 0.0;
79			for (i = 0; i < 3; i++)
80			if (src->snorm[i] < 0.6 && src->snorm[i] > -0.6)
81			break;
82			src->ss[SV][i] = 1.0;
83			fcross(src->ss[SU], src->ss[SV], src->snorm);
84			mult = .5 * sqrt( src->ss2 / DOT(src->ss[SU],src->ss[SU]) );
85			for (i = 0; i < 3; i++)
86			src->ss[SU][i] *= mult;
87			fcross(src->ss[SV], src->snorm, src->ss[SU]);
88			}
89
90
91	greg	2.9	void
92	greg	1.1	fsetsrc(src, so) /* set a face as a source */
93			register SRCREC *src;
94			OBJREC *so;
95			{
96			register FACE *f;
97			register int i, j;
98	greg	1.14	double d;
99	greg	1.1
100			src->sa.success = 2AIMREQT-1; / bitch on second failure */
101			src->so = so;
102			/* get the face */
103			f = getface(so);
104			/* find the center */
105			for (j = 0; j < 3; j++) {
106			src->sloc[j] = 0.0;
107			for (i = 0; i < f->nv; i++)
108			src->sloc[j] += VERTEX(f,i)[j];
109			src->sloc[j] /= (double)f->nv;
110			}
111			if (!inface(src->sloc, f))
112			objerror(so, USER, "cannot hit center");
113			src->sflags \|= SFLAT;
114			VCOPY(src->snorm, f->norm);
115			src->ss2 = f->area;
116	greg	1.14	/* find maximum radius */
117			src->srad = 0.;
118			for (i = 0; i < f->nv; i++) {
119			d = dist2(VERTEX(f,i), src->sloc);
120			if (d > src->srad)
121			src->srad = d;
122			}
123			src->srad = sqrt(src->srad);
124			/* compute size vectors */
125	greg	2.7	if (f->nv == 4) /* parallelogram case */
126	greg	1.14	for (j = 0; j < 3; j++) {
127			src->ss[SU][j] = .5*(VERTEX(f,1)[j]-VERTEX(f,0)[j]);
128			src->ss[SV][j] = .5*(VERTEX(f,3)[j]-VERTEX(f,0)[j]);
129			}
130			else
131			setflatss(src);
132	greg	1.1	}
133
134
135	greg	2.9	void
136	greg	1.1	ssetsrc(src, so) /* set a source as a source */
137			register SRCREC *src;
138			register OBJREC *so;
139			{
140			double theta;
141
142			src->sa.success = 2AIMREQT-1; / bitch on second failure */
143			src->so = so;
144			if (so->oargs.nfargs != 4)
145			objerror(so, USER, "bad arguments");
146			src->sflags \|= SDISTANT;
147			VCOPY(src->sloc, so->oargs.farg);
148			if (normalize(src->sloc) == 0.0)
149			objerror(so, USER, "zero direction");
150			theta = PI/180.0/2.0 * so->oargs.farg[3];
151			if (theta <= FTINY)
152			objerror(so, USER, "zero size");
153			src->ss2 = 2.0PI (1.0 - cos(theta));
154	greg	1.14	/* the following is approximate */
155			src->srad = sqrt(src->ss2/PI);
156			VCOPY(src->snorm, src->sloc);
157			setflatss(src); /* hey, whatever works */
158			src->ss[SW][0] = src->ss[SW][1] = src->ss[SW][2] = 0.0;
159	greg	1.1	}
160
161
162	greg	2.9	void
163	greg	1.1	sphsetsrc(src, so) /* set a sphere as a source */
164			register SRCREC *src;
165			register OBJREC *so;
166			{
167	greg	1.14	register int i;
168
169	greg	1.1	src->sa.success = 2AIMREQT-1; / bitch on second failure */
170			src->so = so;
171			if (so->oargs.nfargs != 4)
172			objerror(so, USER, "bad # arguments");
173			if (so->oargs.farg[3] <= FTINY)
174			objerror(so, USER, "illegal radius");
175			VCOPY(src->sloc, so->oargs.farg);
176	greg	1.14	src->srad = so->oargs.farg[3];
177			src->ss2 = PI * src->srad * src->srad;
178			for (i = 0; i < 3; i++)
179			src->ss[SU][i] = src->ss[SV][i] = src->ss[SW][i] = 0.0;
180			for (i = 0; i < 3; i++)
181	greg	1.15	src->ss[i][i] = .7236 * so->oargs.farg[3];
182	greg	1.1	}
183
184
185	greg	2.9	void
186	greg	1.1	rsetsrc(src, so) /* set a ring (disk) as a source */
187			register SRCREC *src;
188			OBJREC *so;
189			{
190			register CONE *co;
191
192			src->sa.success = 2AIMREQT-1; / bitch on second failure */
193			src->so = so;
194			/* get the ring */
195			co = getcone(so, 0);
196			VCOPY(src->sloc, CO_P0(co));
197			if (CO_R0(co) > 0.0)
198			objerror(so, USER, "cannot hit center");
199			src->sflags \|= SFLAT;
200			VCOPY(src->snorm, co->ad);
201	greg	1.14	src->srad = CO_R1(co);
202			src->ss2 = PI * src->srad * src->srad;
203			setflatss(src);
204			}
205
206
207	greg	2.9	void
208	greg	1.14	cylsetsrc(src, so) /* set a cylinder as a source */
209			register SRCREC *src;
210			OBJREC *so;
211			{
212			register CONE *co;
213			register int i;
214
215			src->sa.success = 4AIMREQT-1; / bitch on fourth failure */
216			src->so = so;
217			/* get the cylinder */
218			co = getcone(so, 0);
219			if (CO_R0(co) > .2co->al) / heuristic constraint */
220			objerror(so, WARNING, "source aspect too small");
221	greg	1.15	src->sflags \|= SCYL;
222	greg	1.14	for (i = 0; i < 3; i++)
223			src->sloc[i] = .5 * (CO_P1(co)[i] + CO_P0(co)[i]);
224	greg	1.15	src->srad = .5*co->al;
225	greg	1.14	src->ss2 = 2.CO_R0(co)co->al;
226			/* set sampling vectors */
227			for (i = 0; i < 3; i++)
228			src->ss[SU][i] = .5 * co->al * co->ad[i];
229			src->ss[SV][0] = src->ss[SV][1] = src->ss[SV][2] = 0.0;
230			for (i = 0; i < 3; i++)
231			if (co->ad[i] < 0.6 && co->ad[i] > -0.6)
232			break;
233			src->ss[SV][i] = 1.0;
234			fcross(src->ss[SW], src->ss[SV], co->ad);
235			normalize(src->ss[SW]);
236			for (i = 0; i < 3; i++)
237	greg	1.15	src->ss[SW][i] = .8559 CO_R0(co);
238	greg	1.14	fcross(src->ss[SV], src->ss[SW], co->ad);
239	greg	1.1	}
240
241
242			SPOT *
243			makespot(m) /* make a spotlight */
244			register OBJREC *m;
245			{
246			register SPOT *ns;
247
248	greg	2.5	if ((ns = (SPOT *)m->os) != NULL)
249			return(ns);
250	greg	1.1	if ((ns = (SPOT *)malloc(sizeof(SPOT))) == NULL)
251			return(NULL);
252			ns->siz = 2.0PI (1.0 - cos(PI/180.0/2.0 * m->oargs.farg[3]));
253			VCOPY(ns->aim, m->oargs.farg+4);
254			if ((ns->flen = normalize(ns->aim)) == 0.0)
255			objerror(m, USER, "zero focus vector");
256	greg	2.5	m->os = (char *)ns;
257	greg	1.1	return(ns);
258			}
259
260
261	greg	2.9	int
262	greg	2.8	spotout(r, s) /* check if we're outside spot region */
263	greg	2.5	register RAY *r;
264			register SPOT *s;
265			{
266			double d;
267			FVECT vd;
268
269			if (s == NULL)
270			return(0);
271	greg	2.8	if (s->flen < -FTINY) { /* distant source */
272	greg	2.5	vd[0] = s->aim[0] - r->rorg[0];
273			vd[1] = s->aim[1] - r->rorg[1];
274			vd[2] = s->aim[2] - r->rorg[2];
275			d = DOT(r->rdir,vd);
276			/* wrong side?
277			if (d <= FTINY)
278			return(1); */
279			d = DOT(vd,vd) - d*d;
280			if (PI*d > s->siz)
281			return(1); /* out */
282			return(0); /* OK */
283			}
284			/* local source */
285			if (s->siz < 2.0PI (1.0 + DOT(s->aim,r->rdir)))
286			return(1); /* out */
287			return(0); /* OK */
288			}
289
290
291	greg	1.1	double
292			fgetmaxdisk(ocent, op) /* get center and squared radius of face */
293			FVECT ocent;
294			OBJREC *op;
295			{
296			double maxrad2;
297	greg	1.5	double d;
298	greg	1.1	register int i, j;
299			register FACE *f;
300
301			f = getface(op);
302	greg	1.5	if (f->area == 0.)
303			return(0.);
304	greg	1.1	for (i = 0; i < 3; i++) {
305			ocent[i] = 0.;
306			for (j = 0; j < f->nv; j++)
307			ocent[i] += VERTEX(f,j)[i];
308			ocent[i] /= (double)f->nv;
309			}
310	greg	1.5	d = DOT(ocent,f->norm);
311			for (i = 0; i < 3; i++)
312			ocent[i] += (f->offset - d)*f->norm[i];
313	greg	1.1	maxrad2 = 0.;
314			for (j = 0; j < f->nv; j++) {
315	greg	1.5	d = dist2(VERTEX(f,j), ocent);
316			if (d > maxrad2)
317			maxrad2 = d;
318	greg	1.1	}
319			return(maxrad2);
320			}
321
322
323			double
324			rgetmaxdisk(ocent, op) /* get center and squared radius of ring */
325			FVECT ocent;
326			OBJREC *op;
327			{
328			register CONE *co;
329
330			co = getcone(op, 0);
331			VCOPY(ocent, CO_P0(co));
332			return(CO_R1(co)*CO_R1(co));
333			}
334
335
336			double
337			fgetplaneq(nvec, op) /* get plane equation for face */
338			FVECT nvec;
339			OBJREC *op;
340			{
341			register FACE *fo;
342
343			fo = getface(op);
344			VCOPY(nvec, fo->norm);
345			return(fo->offset);
346			}
347
348
349			double
350			rgetplaneq(nvec, op) /* get plane equation for ring */
351			FVECT nvec;
352			OBJREC *op;
353			{
354			register CONE *co;
355
356			co = getcone(op, 0);
357			VCOPY(nvec, co->ad);
358			return(DOT(nvec, CO_P0(co)));
359	greg	1.4	}
360
361
362	greg	2.9	int
363	greg	1.4	commonspot(sp1, sp2, org) /* set sp1 to intersection of sp1 and sp2 */
364			register SPOT sp1, sp2;
365			FVECT org;
366			{
367			FVECT cent;
368			double rad2, cos1, cos2;
369
370			cos1 = 1. - sp1->siz/(2.*PI);
371			cos2 = 1. - sp2->siz/(2.*PI);
372			if (sp2->siz >= 2.PI-FTINY) / BIG, just check overlap */
373			return(DOT(sp1->aim,sp2->aim) >= cos1*cos2 -
374			sqrt((1.-cos1cos1)(1.-cos2*cos2)));
375			/* compute and check disks */
376			rad2 = intercircle(cent, sp1->aim, sp2->aim,
377			1./(cos1cos1) - 1., 1./(cos2cos2) - 1.);
378			if (rad2 <= FTINY \|\| normalize(cent) == 0.)
379			return(0);
380			VCOPY(sp1->aim, cent);
381			sp1->siz = 2.PI(1. - 1./sqrt(1.+rad2));
382			return(1);
383			}
384
385
386	greg	2.9	int
387	greg	1.4	commonbeam(sp1, sp2, dir) /* set sp1 to intersection of sp1 and sp2 */
388			register SPOT sp1, sp2;
389			FVECT dir;
390			{
391			FVECT cent, c1, c2;
392			double rad2, d;
393			register int i;
394			/* move centers to common plane */
395			d = DOT(sp1->aim, dir);
396			for (i = 0; i < 3; i++)
397			c1[i] = sp1->aim[i] - d*dir[i];
398			d = DOT(sp2->aim, dir);
399			for (i = 0; i < 3; i++)
400			c2[i] = sp2->aim[i] - d*dir[i];
401			/* compute overlap */
402			rad2 = intercircle(cent, c1, c2, sp1->siz/PI, sp2->siz/PI);
403			if (rad2 <= FTINY)
404			return(0);
405			VCOPY(sp1->aim, cent);
406			sp1->siz = PI*rad2;
407			return(1);
408			}
409
410
411	greg	2.9	int
412	greg	1.4	checkspot(sp, nrm) /* check spotlight for behind source */
413			register SPOT sp; / spotlight */
414			FVECT nrm; /* source surface normal */
415			{
416			double d, d1;
417
418			d = DOT(sp->aim, nrm);
419			if (d > FTINY) /* center in front? */
420	greg	1.8	return(1);
421	greg	1.4	/* else check horizon */
422			d1 = 1. - sp->siz/(2.*PI);
423	greg	1.8	return(1.-FTINY-dd < d1d1);
424	greg	1.4	}
425
426
427			double
428	greg	1.6	spotdisk(oc, op, sp, pos) /* intersect spot with object op */
429			FVECT oc;
430			OBJREC *op;
431			register SPOT *sp;
432			FVECT pos;
433			{
434			FVECT onorm;
435			double offs, d, dist;
436			register int i;
437
438			offs = getplaneq(onorm, op);
439			d = -DOT(onorm, sp->aim);
440			if (d >= -FTINY && d <= FTINY)
441			return(0.);
442			dist = (DOT(pos, onorm) - offs)/d;
443			if (dist < 0.)
444			return(0.);
445			for (i = 0; i < 3; i++)
446			oc[i] = pos[i] + dist*sp->aim[i];
447			return(sp->sizdistdist/PI/(d*d));
448			}
449
450
451			double
452			beamdisk(oc, op, sp, dir) /* intersect beam with object op */
453			FVECT oc;
454			OBJREC *op;
455			register SPOT *sp;
456			FVECT dir;
457			{
458			FVECT onorm;
459			double offs, d, dist;
460			register int i;
461
462			offs = getplaneq(onorm, op);
463			d = -DOT(onorm, dir);
464			if (d >= -FTINY && d <= FTINY)
465			return(0.);
466			dist = (DOT(sp->aim, onorm) - offs)/d;
467			for (i = 0; i < 3; i++)
468			oc[i] = sp->aim[i] + dist*dir[i];
469			return(sp->siz/PI/(d*d));
470			}
471
472
473			double
474	greg	1.4	intercircle(cc, c1, c2, r1s, r2s) /* intersect two circles */
475			FVECT cc; /* midpoint (return value) */
476			FVECT c1, c2; /* circle centers */
477			double r1s, r2s; /* radii squared */
478			{
479			double a2, d2, l;
480			FVECT disp;
481			register int i;
482
483			for (i = 0; i < 3; i++)
484			disp[i] = c2[i] - c1[i];
485			d2 = DOT(disp,disp);
486			/* circle within overlap? */
487			if (r1s < r2s) {
488			if (r2s >= r1s + d2) {
489			VCOPY(cc, c1);
490			return(r1s);
491			}
492			} else {
493			if (r1s >= r2s + d2) {
494			VCOPY(cc, c2);
495			return(r2s);
496			}
497			}
498			a2 = .25(2.(r1s+r2s) - d2 - (r2s-r1s)*(r2s-r1s)/d2);
499			/* no overlap? */
500			if (a2 <= 0.)
501			return(0.);
502			/* overlap, compute center */
503			l = sqrt((r1s - a2)/d2);
504			for (i = 0; i < 3; i++)
505			cc[i] = c1[i] + l*disp[i];
506			return(a2);
507	greg	1.1	}