src/gen/mkillum2.c

#ifndef lint
static const char       RCSid[] = "$Id: mkillum2.c,v 2.9 2003/02/22 02:07:24 greg Exp $";
#endif
/*
 * Routines to do the actual calculation for mkillum
 */

#include  "mkillum.h"
#include  "face.h"
#include  "cone.h"
#include  "random.h"


o_default(ob, il, rt, nm)       /* default illum action */
OBJREC  *ob;
struct illum_args  *il;
struct rtproc  *rt;
char  *nm;
{
        sprintf(errmsg, "(%s): cannot make illum for %s \"%s\"",
                        nm, ofun[ob->otype].funame, ob->oname);
        error(WARNING, errmsg);
        printobj(il->altmat, ob);
}


o_face(ob, il, rt, nm)          /* make an illum face */
OBJREC  *ob;
struct illum_args  *il;
struct rtproc  *rt;
char  *nm;
{
#define MAXMISS         (5*n*il->nsamps)
        int  dim[3];
        int  n, nalt, nazi, h;
        float  *distarr;
        double  sp[2], r1, r2;
        FVECT  dn, org, dir;
        FVECT  u, v;
        double  ur[2], vr[2];
        int  nmisses;
        register FACE  *fa;
        register int  i, j;
                                /* get/check arguments */
        fa = getface(ob);
        if (fa->area == 0.0) {
                freeface(ob);
                o_default(ob, il, rt, nm);
                return;
        }
                                /* set up sampling */
        if (il->sampdens <= 0)
                nalt = nazi = 1;
        else {
                n = PI * il->sampdens;
                nalt = sqrt(n/PI) + .5;
                nazi = PI*nalt + .5;
        }
        n = nalt*nazi;
        distarr = (float *)calloc(n, 3*sizeof(float));
        if (distarr == NULL)
                error(SYSTEM, "out of memory in o_face");
                                /* take first edge longer than sqrt(area) */
        for (j = fa->nv-1, i = 0; i < fa->nv; j = i++) {
                u[0] = VERTEX(fa,i)[0] - VERTEX(fa,j)[0];
                u[1] = VERTEX(fa,i)[1] - VERTEX(fa,j)[1];
                u[2] = VERTEX(fa,i)[2] - VERTEX(fa,j)[2];
                if ((r1 = DOT(u,u)) >= fa->area-FTINY)
                        break;
        }
        if (i < fa->nv) {       /* got one! -- let's align our axes */
                r2 = 1.0/sqrt(r1);
                u[0] *= r2; u[1] *= r2; u[2] *= r2;
                fcross(v, fa->norm, u);
        } else                  /* oh well, we'll just have to wing it */
                mkaxes(u, v, fa->norm);
                                /* now, find limits in (u,v) coordinates */
        ur[0] = vr[0] = FHUGE;
        ur[1] = vr[1] = -FHUGE;
        for (i = 0; i < fa->nv; i++) {
                r1 = DOT(VERTEX(fa,i),u);
                if (r1 < ur[0]) ur[0] = r1;
                if (r1 > ur[1]) ur[1] = r1;
                r2 = DOT(VERTEX(fa,i),v);
                if (r2 < vr[0]) vr[0] = r2;
                if (r2 > vr[1]) vr[1] = r2;
        }
        dim[0] = random();
                                /* sample polygon */
        nmisses = 0;
        for (dim[1] = 0; dim[1] < nalt; dim[1]++)
            for (dim[2] = 0; dim[2] < nazi; dim[2]++)
                for (i = 0; i < il->nsamps; i++) {
                                        /* random direction */
                    h = ilhash(dim, 3) + i;
                    multisamp(sp, 2, urand(h));
                    r1 = (dim[1] + sp[0])/nalt;
                    r2 = (dim[2] + sp[1] - .5)/nazi;
                    flatdir(dn, r1, r2);
                    for (j = 0; j < 3; j++)
                        dir[j] = -dn[0]*u[j] - dn[1]*v[j] - dn[2]*fa->norm[j];
                                        /* random location */
                    do {
                        multisamp(sp, 2, urand(h+4862+nmisses));
                        r1 = ur[0] + (ur[1]-ur[0]) * sp[0];
                        r2 = vr[0] + (vr[1]-vr[0]) * sp[1];
                        for (j = 0; j < 3; j++)
                            org[j] = r1*u[j] + r2*v[j]
                                        + fa->offset*fa->norm[j];
                    } while (!inface(org, fa) && nmisses++ < MAXMISS);
                    if (nmisses > MAXMISS) {
                        objerror(ob, WARNING, "bad aspect");
                        rt->nrays = 0;
                        freeface(ob);
                        free((void *)distarr);
                        o_default(ob, il, rt, nm);
                        return;
                    }
                    for (j = 0; j < 3; j++)
                        org[j] += .001*fa->norm[j];
                                        /* send sample */
                    raysamp(distarr+3*(dim[1]*nazi+dim[2]), org, dir, rt);
                }
        rayflush(rt);
                                /* write out the face and its distribution */
        if (average(il, distarr, nalt*nazi)) {
                if (il->sampdens > 0)
                        flatout(il, distarr, nalt, nazi, u, v, fa->norm);
                illumout(il, ob);
        } else
                printobj(il->altmat, ob);
                                /* clean up */
        freeface(ob);
        free((void *)distarr);
#undef MAXMISS
}


o_sphere(ob, il, rt, nm)        /* make an illum sphere */
register OBJREC  *ob;
struct illum_args  *il;
struct rtproc  *rt;
char  *nm;
{
        int  dim[3];
        int  n, nalt, nazi;
        float  *distarr;
        double  sp[4], r1, r2, r3;
        FVECT  org, dir;
        FVECT  u, v;
        register int  i, j;
                                /* check arguments */
        if (ob->oargs.nfargs != 4)
                objerror(ob, USER, "bad # of arguments");
                                /* set up sampling */
        if (il->sampdens <= 0)
                nalt = nazi = 1;
        else {
                n = 4.*PI * il->sampdens;
                nalt = sqrt(2./PI*n) + .5;
                nazi = PI/2.*nalt + .5;
        }
        n = nalt*nazi;
        distarr = (float *)calloc(n, 3*sizeof(float));
        if (distarr == NULL)
                error(SYSTEM, "out of memory in o_sphere");
        dim[0] = random();
                                /* sample sphere */
        for (dim[1] = 0; dim[1] < nalt; dim[1]++)
            for (dim[2] = 0; dim[2] < nazi; dim[2]++)
                for (i = 0; i < il->nsamps; i++) {
                                        /* next sample point */
                    multisamp(sp, 4, urand(ilhash(dim,3)+i));
                                        /* random direction */
                    r1 = (dim[1] + sp[0])/nalt;
                    r2 = (dim[2] + sp[1] - .5)/nazi;
                    rounddir(dir, r1, r2);
                                        /* random location */
                    mkaxes(u, v, dir);          /* yuck! */
                    r3 = sqrt(sp[2]);
                    r2 = 2.*PI*sp[3];
                    r1 = r3*ob->oargs.farg[3]*cos(r2);
                    r2 = r3*ob->oargs.farg[3]*sin(r2);
                    r3 = ob->oargs.farg[3]*sqrt(1.01-r3*r3);
                    for (j = 0; j < 3; j++) {
                        org[j] = ob->oargs.farg[j] + r1*u[j] + r2*v[j] +
                                        r3*dir[j];
                        dir[j] = -dir[j];
                    }
                                        /* send sample */
                    raysamp(distarr+3*(dim[1]*nazi+dim[2]), org, dir, rt);
                }
        rayflush(rt);
                                /* write out the sphere and its distribution */
        if (average(il, distarr, nalt*nazi)) {
                if (il->sampdens > 0)
                        roundout(il, distarr, nalt, nazi);
                else
                        objerror(ob, WARNING, "diffuse distribution");
                illumout(il, ob);
        } else
                printobj(il->altmat, ob);
                                /* clean up */
        free((void *)distarr);
}


o_ring(ob, il, rt, nm)          /* make an illum ring */
OBJREC  *ob;
struct illum_args  *il;
struct rtproc  *rt;
char  *nm;
{
        int  dim[3];
        int  n, nalt, nazi;
        float  *distarr;
        double  sp[4], r1, r2, r3;
        FVECT  dn, org, dir;
        FVECT  u, v;
        register CONE  *co;
        register int  i, j;
                                /* get/check arguments */
        co = getcone(ob, 0);
                                /* set up sampling */
        if (il->sampdens <= 0)
                nalt = nazi = 1;
        else {
                n = PI * il->sampdens;
                nalt = sqrt(n/PI) + .5;
                nazi = PI*nalt + .5;
        }
        n = nalt*nazi;
        distarr = (float *)calloc(n, 3*sizeof(float));
        if (distarr == NULL)
                error(SYSTEM, "out of memory in o_ring");
        mkaxes(u, v, co->ad);
        dim[0] = random();
                                /* sample disk */
        for (dim[1] = 0; dim[1] < nalt; dim[1]++)
            for (dim[2] = 0; dim[2] < nazi; dim[2]++)
                for (i = 0; i < il->nsamps; i++) {
                                        /* next sample point */
                    multisamp(sp, 4, urand(ilhash(dim,3)+i));
                                        /* random direction */
                    r1 = (dim[1] + sp[0])/nalt;
                    r2 = (dim[2] + sp[1] - .5)/nazi;
                    flatdir(dn, r1, r2);
                    for (j = 0; j < 3; j++)
                        dir[j] = -dn[0]*u[j] - dn[1]*v[j] - dn[2]*co->ad[j];
                                        /* random location */
                    r3 = sqrt(CO_R0(co)*CO_R0(co) +
                            sp[2]*(CO_R1(co)*CO_R1(co) - CO_R0(co)*CO_R0(co)));
                    r2 = 2.*PI*sp[3];
                    r1 = r3*cos(r2);
                    r2 = r3*sin(r2);
                    for (j = 0; j < 3; j++)
                        org[j] = CO_P0(co)[j] + r1*u[j] + r2*v[j] +
                                        .001*co->ad[j];

                                        /* send sample */
                    raysamp(distarr+3*(dim[1]*nazi+dim[2]), org, dir, rt);
                }
        rayflush(rt);
                                /* write out the ring and its distribution */
        if (average(il, distarr, nalt*nazi)) {
                if (il->sampdens > 0)
                        flatout(il, distarr, nalt, nazi, u, v, co->ad);
                illumout(il, ob);
        } else
                printobj(il->altmat, ob);
                                /* clean up */
        freecone(ob);
        free((void *)distarr);
}


raysamp(res, org, dir, rt)      /* compute a ray sample */
float  res[3];
FVECT  org, dir;
register struct rtproc  *rt;
{
        register float  *fp;

        if (rt->nrays == rt->bsiz)
                rayflush(rt);
        rt->dest[rt->nrays] = res;
        fp = rt->buf + 6*rt->nrays++;
        *fp++ = org[0]; *fp++ = org[1]; *fp++ = org[2];
        *fp++ = dir[0]; *fp++ = dir[1]; *fp = dir[2];
}


rayflush(rt)                    /* flush buffered rays */
register struct rtproc  *rt;
{
        register int  i;

        if (rt->nrays <= 0)
                return;
        bzero(rt->buf+6*rt->nrays, 6*sizeof(float));
        errno = 0;
        if ( process(&(rt->pd), (char *)rt->buf, (char *)rt->buf,
                        3*sizeof(float)*(rt->nrays+1),
                        6*sizeof(float)*(rt->nrays+1)) <
                        3*sizeof(float)*(rt->nrays+1) )
                error(SYSTEM, "error reading from rtrace process");
        i = rt->nrays;
        while (i--) {
                rt->dest[i][0] += rt->buf[3*i];
                rt->dest[i][1] += rt->buf[3*i+1];
                rt->dest[i][2] += rt->buf[3*i+2];
        }
        rt->nrays = 0;
}


mkaxes(u, v, n)                 /* compute u and v to go with n */
FVECT  u, v, n;
{
        register int  i;

        v[0] = v[1] = v[2] = 0.0;
        for (i = 0; i < 3; i++)
                if (n[i] < 0.6 && n[i] > -0.6)
                        break;
        v[i] = 1.0;
        fcross(u, v, n);
        normalize(u);
        fcross(v, n, u);
}


rounddir(dv, alt, azi)          /* compute uniform spherical direction */
register FVECT  dv;
double  alt, azi;
{
        double  d1, d2;

        dv[2] = 1. - 2.*alt;
        d1 = sqrt(1. - dv[2]*dv[2]);
        d2 = 2.*PI * azi;
        dv[0] = d1*cos(d2);
        dv[1] = d1*sin(d2);
}


flatdir(dv, alt, azi)           /* compute uniform hemispherical direction */
register FVECT  dv;
double  alt, azi;
{
        double  d1, d2;

        d1 = sqrt(alt);
        d2 = 2.*PI * azi;
        dv[0] = d1*cos(d2);
        dv[1] = d1*sin(d2);
        dv[2] = sqrt(1. - alt);
}
Revision:	2.10
Committed:	Thu Jun 26 00:58:09 2003 UTC (20 years, 9 months ago) by schorsch
Content type:	text/plain
Branch:	MAIN
Changes since 2.9:	+2 -5 lines
Log Message:	Abstracted process and path handling for Windows. Renamed FLOAT to RREAL because of conflict on Windows. Added conditional compiles for some signal handlers.
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	schorsch	2.10	static const char RCSid[] = "$Id: mkillum2.c,v 2.9 2003/02/22 02:07:24 greg Exp $";
3	greg	1.1	#endif
4			/*
5	greg	1.4	* Routines to do the actual calculation for mkillum
6	greg	1.1	*/
7
8			#include "mkillum.h"
9			#include "face.h"
10			#include "cone.h"
11	greg	1.2	#include "random.h"
12	greg	1.1
13	greg	1.2
14			o_default(ob, il, rt, nm) /* default illum action */
15	greg	1.1	OBJREC *ob;
16			struct illum_args *il;
17			struct rtproc *rt;
18	greg	1.2	char *nm;
19	greg	1.1	{
20	greg	1.2	sprintf(errmsg, "(%s): cannot make illum for %s \"%s\"",
21			nm, ofun[ob->otype].funame, ob->oname);
22			error(WARNING, errmsg);
23	greg	2.2	printobj(il->altmat, ob);
24	greg	1.2	}
25
26
27			o_face(ob, il, rt, nm) /* make an illum face */
28			OBJREC *ob;
29			struct illum_args *il;
30			struct rtproc *rt;
31			char *nm;
32			{
33	greg	1.3	#define MAXMISS (5nil->nsamps)
34	greg	1.10	int dim[3];
35			int n, nalt, nazi, h;
36	greg	1.3	float *distarr;
37	greg	1.10	double sp[2], r1, r2;
38	greg	1.4	FVECT dn, org, dir;
39	greg	1.3	FVECT u, v;
40			double ur[2], vr[2];
41			int nmisses;
42			register FACE *fa;
43			register int i, j;
44			/* get/check arguments */
45			fa = getface(ob);
46			if (fa->area == 0.0) {
47			freeface(ob);
48			o_default(ob, il, rt, nm);
49			return;
50			}
51			/* set up sampling */
52	greg	1.11	if (il->sampdens <= 0)
53			nalt = nazi = 1;
54			else {
55			n = PI * il->sampdens;
56			nalt = sqrt(n/PI) + .5;
57			nazi = PI*nalt + .5;
58			}
59	greg	1.3	n = nalt*nazi;
60			distarr = (float )calloc(n, 3sizeof(float));
61			if (distarr == NULL)
62			error(SYSTEM, "out of memory in o_face");
63	greg	2.3	/* take first edge longer than sqrt(area) */
64	greg	2.4	for (j = fa->nv-1, i = 0; i < fa->nv; j = i++) {
65			u[0] = VERTEX(fa,i)[0] - VERTEX(fa,j)[0];
66			u[1] = VERTEX(fa,i)[1] - VERTEX(fa,j)[1];
67			u[2] = VERTEX(fa,i)[2] - VERTEX(fa,j)[2];
68	greg	2.5	if ((r1 = DOT(u,u)) >= fa->area-FTINY)
69	greg	2.3	break;
70			}
71			if (i < fa->nv) { /* got one! -- let's align our axes */
72	greg	2.5	r2 = 1.0/sqrt(r1);
73			u[0] = r2; u[1] = r2; u[2] *= r2;
74	greg	2.3	fcross(v, fa->norm, u);
75			} else /* oh well, we'll just have to wing it */
76			mkaxes(u, v, fa->norm);
77			/* now, find limits in (u,v) coordinates */
78	greg	1.3	ur[0] = vr[0] = FHUGE;
79			ur[1] = vr[1] = -FHUGE;
80			for (i = 0; i < fa->nv; i++) {
81			r1 = DOT(VERTEX(fa,i),u);
82			if (r1 < ur[0]) ur[0] = r1;
83			if (r1 > ur[1]) ur[1] = r1;
84			r2 = DOT(VERTEX(fa,i),v);
85			if (r2 < vr[0]) vr[0] = r2;
86			if (r2 > vr[1]) vr[1] = r2;
87			}
88			dim[0] = random();
89			/* sample polygon */
90			nmisses = 0;
91			for (dim[1] = 0; dim[1] < nalt; dim[1]++)
92			for (dim[2] = 0; dim[2] < nazi; dim[2]++)
93			for (i = 0; i < il->nsamps; i++) {
94			/* random direction */
95	greg	1.10	h = ilhash(dim, 3) + i;
96	greg	1.11	multisamp(sp, 2, urand(h));
97	greg	1.10	r1 = (dim[1] + sp[0])/nalt;
98	greg	1.13	r2 = (dim[2] + sp[1] - .5)/nazi;
99	greg	1.3	flatdir(dn, r1, r2);
100			for (j = 0; j < 3; j++)
101	greg	1.5	dir[j] = -dn[0]u[j] - dn[1]v[j] - dn[2]*fa->norm[j];
102	greg	1.3	/* random location */
103			do {
104	greg	1.11	multisamp(sp, 2, urand(h+4862+nmisses));
105	greg	1.10	r1 = ur[0] + (ur[1]-ur[0]) * sp[0];
106			r2 = vr[0] + (vr[1]-vr[0]) * sp[1];
107	greg	1.3	for (j = 0; j < 3; j++)
108			org[j] = r1u[j] + r2v[j]
109			+ fa->offset*fa->norm[j];
110			} while (!inface(org, fa) && nmisses++ < MAXMISS);
111			if (nmisses > MAXMISS) {
112			objerror(ob, WARNING, "bad aspect");
113			rt->nrays = 0;
114			freeface(ob);
115	greg	2.9	free((void *)distarr);
116	greg	1.3	o_default(ob, il, rt, nm);
117			return;
118			}
119			for (j = 0; j < 3; j++)
120			org[j] += .001*fa->norm[j];
121			/* send sample */
122	greg	1.7	raysamp(distarr+3(dim[1]nazi+dim[2]), org, dir, rt);
123	greg	1.3	}
124			rayflush(rt);
125	greg	1.11	/* write out the face and its distribution */
126	greg	1.12	if (average(il, distarr, nalt*nazi)) {
127			if (il->sampdens > 0)
128			flatout(il, distarr, nalt, nazi, u, v, fa->norm);
129			illumout(il, ob);
130	greg	2.2	} else
131	greg	1.12	printobj(il->altmat, ob);
132	greg	1.3	/* clean up */
133			freeface(ob);
134	greg	2.9	free((void *)distarr);
135	greg	1.3	#undef MAXMISS
136	greg	1.2	}
137
138
139			o_sphere(ob, il, rt, nm) /* make an illum sphere */
140	greg	1.3	register OBJREC *ob;
141	greg	1.2	struct illum_args *il;
142			struct rtproc *rt;
143			char *nm;
144			{
145	greg	1.10	int dim[3];
146	greg	1.2	int n, nalt, nazi;
147			float *distarr;
148	greg	1.10	double sp[4], r1, r2, r3;
149	greg	1.4	FVECT org, dir;
150	greg	1.2	FVECT u, v;
151			register int i, j;
152			/* check arguments */
153			if (ob->oargs.nfargs != 4)
154			objerror(ob, USER, "bad # of arguments");
155			/* set up sampling */
156	greg	1.11	if (il->sampdens <= 0)
157			nalt = nazi = 1;
158			else {
159			n = 4.PI il->sampdens;
160	greg	2.7	nalt = sqrt(2./PI*n) + .5;
161			nazi = PI/2.*nalt + .5;
162	greg	1.11	}
163	greg	1.2	n = nalt*nazi;
164			distarr = (float )calloc(n, 3sizeof(float));
165			if (distarr == NULL)
166			error(SYSTEM, "out of memory in o_sphere");
167			dim[0] = random();
168			/* sample sphere */
169			for (dim[1] = 0; dim[1] < nalt; dim[1]++)
170	greg	1.8	for (dim[2] = 0; dim[2] < nazi; dim[2]++)
171	greg	1.2	for (i = 0; i < il->nsamps; i++) {
172	greg	1.10	/* next sample point */
173	greg	1.11	multisamp(sp, 4, urand(ilhash(dim,3)+i));
174	greg	1.2	/* random direction */
175	greg	1.10	r1 = (dim[1] + sp[0])/nalt;
176	greg	1.13	r2 = (dim[2] + sp[1] - .5)/nazi;
177	greg	1.2	rounddir(dir, r1, r2);
178			/* random location */
179	greg	1.8	mkaxes(u, v, dir); /* yuck! */
180	greg	1.10	r3 = sqrt(sp[2]);
181			r2 = 2.PIsp[3];
182	greg	1.5	r1 = r3ob->oargs.farg[3]cos(r2);
183			r2 = r3ob->oargs.farg[3]sin(r2);
184			r3 = ob->oargs.farg[3]sqrt(1.01-r3r3);
185			for (j = 0; j < 3; j++) {
186			org[j] = ob->oargs.farg[j] + r1u[j] + r2v[j] +
187			r3*dir[j];
188			dir[j] = -dir[j];
189			}
190	greg	1.2	/* send sample */
191	greg	1.7	raysamp(distarr+3(dim[1]nazi+dim[2]), org, dir, rt);
192	greg	1.2	}
193			rayflush(rt);
194	greg	1.11	/* write out the sphere and its distribution */
195	greg	1.12	if (average(il, distarr, nalt*nazi)) {
196			if (il->sampdens > 0)
197			roundout(il, distarr, nalt, nazi);
198			else
199			objerror(ob, WARNING, "diffuse distribution");
200			illumout(il, ob);
201	greg	2.2	} else
202	greg	1.12	printobj(il->altmat, ob);
203	greg	1.2	/* clean up */
204	greg	2.9	free((void *)distarr);
205	greg	1.2	}
206
207
208			o_ring(ob, il, rt, nm) /* make an illum ring */
209			OBJREC *ob;
210			struct illum_args *il;
211			struct rtproc *rt;
212			char *nm;
213			{
214	greg	1.10	int dim[3];
215	greg	1.3	int n, nalt, nazi;
216			float *distarr;
217	greg	1.10	double sp[4], r1, r2, r3;
218	greg	1.4	FVECT dn, org, dir;
219	greg	1.3	FVECT u, v;
220			register CONE *co;
221			register int i, j;
222			/* get/check arguments */
223			co = getcone(ob, 0);
224			/* set up sampling */
225	greg	1.11	if (il->sampdens <= 0)
226			nalt = nazi = 1;
227			else {
228			n = PI * il->sampdens;
229			nalt = sqrt(n/PI) + .5;
230			nazi = PI*nalt + .5;
231			}
232	greg	1.3	n = nalt*nazi;
233			distarr = (float )calloc(n, 3sizeof(float));
234			if (distarr == NULL)
235			error(SYSTEM, "out of memory in o_ring");
236			mkaxes(u, v, co->ad);
237			dim[0] = random();
238			/* sample disk */
239			for (dim[1] = 0; dim[1] < nalt; dim[1]++)
240			for (dim[2] = 0; dim[2] < nazi; dim[2]++)
241			for (i = 0; i < il->nsamps; i++) {
242	greg	1.10	/* next sample point */
243	greg	1.11	multisamp(sp, 4, urand(ilhash(dim,3)+i));
244	greg	1.3	/* random direction */
245	greg	1.10	r1 = (dim[1] + sp[0])/nalt;
246	greg	1.13	r2 = (dim[2] + sp[1] - .5)/nazi;
247	greg	1.3	flatdir(dn, r1, r2);
248			for (j = 0; j < 3; j++)
249	greg	1.5	dir[j] = -dn[0]u[j] - dn[1]v[j] - dn[2]*co->ad[j];
250	greg	1.3	/* random location */
251	greg	1.5	r3 = sqrt(CO_R0(co)*CO_R0(co) +
252	greg	1.10	sp[2](CO_R1(co)CO_R1(co) - CO_R0(co)*CO_R0(co)));
253			r2 = 2.PIsp[3];
254	greg	1.5	r1 = r3*cos(r2);
255			r2 = r3*sin(r2);
256	greg	1.3	for (j = 0; j < 3; j++)
257	greg	2.6	org[j] = CO_P0(co)[j] + r1u[j] + r2v[j] +
258	greg	1.5	.001*co->ad[j];
259	greg	1.3
260			/* send sample */
261	greg	1.7	raysamp(distarr+3(dim[1]nazi+dim[2]), org, dir, rt);
262	greg	1.3	}
263			rayflush(rt);
264	greg	1.11	/* write out the ring and its distribution */
265	greg	1.12	if (average(il, distarr, nalt*nazi)) {
266			if (il->sampdens > 0)
267			flatout(il, distarr, nalt, nazi, u, v, co->ad);
268			illumout(il, ob);
269	greg	2.2	} else
270	greg	1.12	printobj(il->altmat, ob);
271	greg	1.3	/* clean up */
272			freecone(ob);
273	greg	2.9	free((void *)distarr);
274	greg	1.2	}
275
276
277			raysamp(res, org, dir, rt) /* compute a ray sample */
278			float res[3];
279			FVECT org, dir;
280			register struct rtproc *rt;
281			{
282			register float *fp;
283
284			if (rt->nrays == rt->bsiz)
285			rayflush(rt);
286			rt->dest[rt->nrays] = res;
287			fp = rt->buf + 6*rt->nrays++;
288			fp++ = org[0]; fp++ = org[1]; *fp++ = org[2];
289			fp++ = dir[0]; fp++ = dir[1]; *fp = dir[2];
290			}
291
292
293			rayflush(rt) /* flush buffered rays */
294			register struct rtproc *rt;
295			{
296			register int i;
297
298			if (rt->nrays <= 0)
299			return;
300	greg	1.9	bzero(rt->buf+6rt->nrays, 6sizeof(float));
301	greg	1.14	errno = 0;
302	schorsch	2.10	if ( process(&(rt->pd), (char )rt->buf, (char )rt->buf,
303	gregl	2.8	3sizeof(float)(rt->nrays+1),
304	greg	1.2	6sizeof(float)(rt->nrays+1)) <
305	gregl	2.8	3sizeof(float)(rt->nrays+1) )
306	greg	1.2	error(SYSTEM, "error reading from rtrace process");
307			i = rt->nrays;
308			while (i--) {
309			rt->dest[i][0] += rt->buf[3*i];
310			rt->dest[i][1] += rt->buf[3*i+1];
311			rt->dest[i][2] += rt->buf[3*i+2];
312			}
313			rt->nrays = 0;
314	greg	1.4	}
315
316
317			mkaxes(u, v, n) /* compute u and v to go with n */
318			FVECT u, v, n;
319			{
320			register int i;
321
322			v[0] = v[1] = v[2] = 0.0;
323			for (i = 0; i < 3; i++)
324			if (n[i] < 0.6 && n[i] > -0.6)
325			break;
326			v[i] = 1.0;
327			fcross(u, v, n);
328			normalize(u);
329			fcross(v, n, u);
330			}
331
332
333			rounddir(dv, alt, azi) /* compute uniform spherical direction */
334			register FVECT dv;
335			double alt, azi;
336			{
337			double d1, d2;
338
339			dv[2] = 1. - 2.*alt;
340			d1 = sqrt(1. - dv[2]*dv[2]);
341			d2 = 2.PI azi;
342			dv[0] = d1*cos(d2);
343			dv[1] = d1*sin(d2);
344			}
345
346
347			flatdir(dv, alt, azi) /* compute uniform hemispherical direction */
348			register FVECT dv;
349			double alt, azi;
350			{
351			double d1, d2;
352
353			d1 = sqrt(alt);
354			d2 = 2.PI azi;
355			dv[0] = d1*cos(d2);
356			dv[1] = d1*sin(d2);
357	greg	1.6	dv[2] = sqrt(1. - alt);
358	greg	1.1	}