src/gen/mkillum2.c

#ifndef lint
static const char       RCSid[] = "$Id: mkillum2.c,v 2.12 2003/11/16 10:29:38 schorsch Exp $";
#endif
/*
 * Routines to do the actual calculation for mkillum
 */

#include <string.h>

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


int o_default(FUN_ARGLIST);
int o_face(FUN_ARGLIST);
int o_sphere(FUN_ARGLIST);
int o_ring(FUN_ARGLIST);
void raysamp(float res[3], FVECT org, FVECT dir, struct rtproc *rt);
void rayflush(struct rtproc *rt);
void mkaxes(FVECT u, FVECT v, FVECT n);
void rounddir(FVECT dv, double alt, double azi);
void flatdir(FVECT dv, double alt, double azi);


int /* XXX type conflict with otypes.h */
o_default(      /* 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);
        return(1);
}


int
o_face(         /* 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);
                return(o_default(ob, il, rt, nm));
        }
                                /* 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);
                        return(o_default(ob, il, rt, nm));
                    }
                    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
}


int
o_sphere(       /* 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);
        return(1);
}


int
o_ring(         /* 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);
        return(1);
}


void
raysamp(        /* compute a ray sample */
        float  res[3],
        FVECT  org,
        FVECT  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];
}


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

        if (rt->nrays <= 0)
                return;
        memset(rt->buf+6*rt->nrays, '\0', 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;
}


void
mkaxes(                 /* compute u and v to go with n */
        FVECT  u,
        FVECT  v,
        FVECT  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);
}


void
rounddir(               /* compute uniform spherical direction */
        register FVECT  dv,
        double  alt,
        double  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);
}


void
flatdir(                /* compute uniform hemispherical direction */
        register FVECT  dv,
        double  alt,
        double  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:	2.13
Committed:	Fri Nov 21 07:15:30 2003 UTC (20 years, 5 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.12:	+14 -12 lines
Log Message:	Fixed prototyping in mkillum and eliminated compile error in lookup.c
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.13	static const char RCSid[] = "$Id: mkillum2.c,v 2.12 2003/11/16 10:29:38 schorsch 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	schorsch	2.11	#include <string.h>
9
10	greg	1.1	#include "mkillum.h"
11			#include "face.h"
12			#include "cone.h"
13	greg	1.2	#include "random.h"
14	greg	1.1
15	greg	2.13
16			int o_default(FUN_ARGLIST);
17			int o_face(FUN_ARGLIST);
18			int o_sphere(FUN_ARGLIST);
19			int o_ring(FUN_ARGLIST);
20	schorsch	2.12	void raysamp(float res[3], FVECT org, FVECT dir, struct rtproc *rt);
21			void rayflush(struct rtproc *rt);
22			void mkaxes(FVECT u, FVECT v, FVECT n);
23			void rounddir(FVECT dv, double alt, double azi);
24			void flatdir(FVECT dv, double alt, double azi);
25
26
27			int /* XXX type conflict with otypes.h */
28			o_default( /* default illum action */
29			OBJREC *ob,
30			struct illum_args *il,
31			struct rtproc *rt,
32			char *nm
33			)
34	greg	1.1	{
35	greg	1.2	sprintf(errmsg, "(%s): cannot make illum for %s \"%s\"",
36			nm, ofun[ob->otype].funame, ob->oname);
37			error(WARNING, errmsg);
38	greg	2.2	printobj(il->altmat, ob);
39	greg	2.13	return(1);
40	greg	1.2	}
41
42
43	greg	2.13	int
44	schorsch	2.12	o_face( /* make an illum face */
45			OBJREC *ob,
46			struct illum_args *il,
47			struct rtproc *rt,
48			char *nm
49			)
50	greg	1.2	{
51	greg	1.3	#define MAXMISS (5nil->nsamps)
52	greg	1.10	int dim[3];
53			int n, nalt, nazi, h;
54	greg	1.3	float *distarr;
55	greg	1.10	double sp[2], r1, r2;
56	greg	1.4	FVECT dn, org, dir;
57	greg	1.3	FVECT u, v;
58			double ur[2], vr[2];
59			int nmisses;
60			register FACE *fa;
61			register int i, j;
62			/* get/check arguments */
63			fa = getface(ob);
64			if (fa->area == 0.0) {
65			freeface(ob);
66	greg	2.13	return(o_default(ob, il, rt, nm));
67	greg	1.3	}
68			/* set up sampling */
69	greg	1.11	if (il->sampdens <= 0)
70			nalt = nazi = 1;
71			else {
72			n = PI * il->sampdens;
73			nalt = sqrt(n/PI) + .5;
74			nazi = PI*nalt + .5;
75			}
76	greg	1.3	n = nalt*nazi;
77			distarr = (float )calloc(n, 3sizeof(float));
78			if (distarr == NULL)
79			error(SYSTEM, "out of memory in o_face");
80	greg	2.3	/* take first edge longer than sqrt(area) */
81	greg	2.4	for (j = fa->nv-1, i = 0; i < fa->nv; j = i++) {
82			u[0] = VERTEX(fa,i)[0] - VERTEX(fa,j)[0];
83			u[1] = VERTEX(fa,i)[1] - VERTEX(fa,j)[1];
84			u[2] = VERTEX(fa,i)[2] - VERTEX(fa,j)[2];
85	greg	2.5	if ((r1 = DOT(u,u)) >= fa->area-FTINY)
86	greg	2.3	break;
87			}
88			if (i < fa->nv) { /* got one! -- let's align our axes */
89	greg	2.5	r2 = 1.0/sqrt(r1);
90			u[0] = r2; u[1] = r2; u[2] *= r2;
91	greg	2.3	fcross(v, fa->norm, u);
92			} else /* oh well, we'll just have to wing it */
93			mkaxes(u, v, fa->norm);
94			/* now, find limits in (u,v) coordinates */
95	greg	1.3	ur[0] = vr[0] = FHUGE;
96			ur[1] = vr[1] = -FHUGE;
97			for (i = 0; i < fa->nv; i++) {
98			r1 = DOT(VERTEX(fa,i),u);
99			if (r1 < ur[0]) ur[0] = r1;
100			if (r1 > ur[1]) ur[1] = r1;
101			r2 = DOT(VERTEX(fa,i),v);
102			if (r2 < vr[0]) vr[0] = r2;
103			if (r2 > vr[1]) vr[1] = r2;
104			}
105			dim[0] = random();
106			/* sample polygon */
107			nmisses = 0;
108			for (dim[1] = 0; dim[1] < nalt; dim[1]++)
109			for (dim[2] = 0; dim[2] < nazi; dim[2]++)
110			for (i = 0; i < il->nsamps; i++) {
111			/* random direction */
112	greg	1.10	h = ilhash(dim, 3) + i;
113	greg	1.11	multisamp(sp, 2, urand(h));
114	greg	1.10	r1 = (dim[1] + sp[0])/nalt;
115	greg	1.13	r2 = (dim[2] + sp[1] - .5)/nazi;
116	greg	1.3	flatdir(dn, r1, r2);
117			for (j = 0; j < 3; j++)
118	greg	1.5	dir[j] = -dn[0]u[j] - dn[1]v[j] - dn[2]*fa->norm[j];
119	greg	1.3	/* random location */
120			do {
121	greg	1.11	multisamp(sp, 2, urand(h+4862+nmisses));
122	greg	1.10	r1 = ur[0] + (ur[1]-ur[0]) * sp[0];
123			r2 = vr[0] + (vr[1]-vr[0]) * sp[1];
124	greg	1.3	for (j = 0; j < 3; j++)
125			org[j] = r1u[j] + r2v[j]
126			+ fa->offset*fa->norm[j];
127			} while (!inface(org, fa) && nmisses++ < MAXMISS);
128			if (nmisses > MAXMISS) {
129			objerror(ob, WARNING, "bad aspect");
130			rt->nrays = 0;
131			freeface(ob);
132	greg	2.9	free((void *)distarr);
133	greg	2.13	return(o_default(ob, il, rt, nm));
134	greg	1.3	}
135			for (j = 0; j < 3; j++)
136			org[j] += .001*fa->norm[j];
137			/* send sample */
138	greg	1.7	raysamp(distarr+3(dim[1]nazi+dim[2]), org, dir, rt);
139	greg	1.3	}
140			rayflush(rt);
141	greg	1.11	/* write out the face and its distribution */
142	greg	1.12	if (average(il, distarr, nalt*nazi)) {
143			if (il->sampdens > 0)
144			flatout(il, distarr, nalt, nazi, u, v, fa->norm);
145			illumout(il, ob);
146	greg	2.2	} else
147	greg	1.12	printobj(il->altmat, ob);
148	greg	1.3	/* clean up */
149			freeface(ob);
150	greg	2.9	free((void *)distarr);
151	greg	1.3	#undef MAXMISS
152	greg	1.2	}
153
154
155	greg	2.13	int
156	schorsch	2.12	o_sphere( /* make an illum sphere */
157			register OBJREC *ob,
158			struct illum_args *il,
159			struct rtproc *rt,
160			char *nm
161			)
162	greg	1.2	{
163	greg	1.10	int dim[3];
164	greg	1.2	int n, nalt, nazi;
165			float *distarr;
166	greg	1.10	double sp[4], r1, r2, r3;
167	greg	1.4	FVECT org, dir;
168	greg	1.2	FVECT u, v;
169			register int i, j;
170			/* check arguments */
171			if (ob->oargs.nfargs != 4)
172			objerror(ob, USER, "bad # of arguments");
173			/* set up sampling */
174	greg	1.11	if (il->sampdens <= 0)
175			nalt = nazi = 1;
176			else {
177			n = 4.PI il->sampdens;
178	greg	2.7	nalt = sqrt(2./PI*n) + .5;
179			nazi = PI/2.*nalt + .5;
180	greg	1.11	}
181	greg	1.2	n = nalt*nazi;
182			distarr = (float )calloc(n, 3sizeof(float));
183			if (distarr == NULL)
184			error(SYSTEM, "out of memory in o_sphere");
185			dim[0] = random();
186			/* sample sphere */
187			for (dim[1] = 0; dim[1] < nalt; dim[1]++)
188	greg	1.8	for (dim[2] = 0; dim[2] < nazi; dim[2]++)
189	greg	1.2	for (i = 0; i < il->nsamps; i++) {
190	greg	1.10	/* next sample point */
191	greg	1.11	multisamp(sp, 4, urand(ilhash(dim,3)+i));
192	greg	1.2	/* random direction */
193	greg	1.10	r1 = (dim[1] + sp[0])/nalt;
194	greg	1.13	r2 = (dim[2] + sp[1] - .5)/nazi;
195	greg	1.2	rounddir(dir, r1, r2);
196			/* random location */
197	greg	1.8	mkaxes(u, v, dir); /* yuck! */
198	greg	1.10	r3 = sqrt(sp[2]);
199			r2 = 2.PIsp[3];
200	greg	1.5	r1 = r3ob->oargs.farg[3]cos(r2);
201			r2 = r3ob->oargs.farg[3]sin(r2);
202			r3 = ob->oargs.farg[3]sqrt(1.01-r3r3);
203			for (j = 0; j < 3; j++) {
204			org[j] = ob->oargs.farg[j] + r1u[j] + r2v[j] +
205			r3*dir[j];
206			dir[j] = -dir[j];
207			}
208	greg	1.2	/* send sample */
209	greg	1.7	raysamp(distarr+3(dim[1]nazi+dim[2]), org, dir, rt);
210	greg	1.2	}
211			rayflush(rt);
212	greg	1.11	/* write out the sphere and its distribution */
213	greg	1.12	if (average(il, distarr, nalt*nazi)) {
214			if (il->sampdens > 0)
215			roundout(il, distarr, nalt, nazi);
216			else
217			objerror(ob, WARNING, "diffuse distribution");
218			illumout(il, ob);
219	greg	2.2	} else
220	greg	1.12	printobj(il->altmat, ob);
221	greg	1.2	/* clean up */
222	greg	2.9	free((void *)distarr);
223	greg	2.13	return(1);
224	greg	1.2	}
225
226
227	greg	2.13	int
228	schorsch	2.12	o_ring( /* make an illum ring */
229			OBJREC *ob,
230			struct illum_args *il,
231			struct rtproc *rt,
232			char *nm
233			)
234	greg	1.2	{
235	greg	1.10	int dim[3];
236	greg	1.3	int n, nalt, nazi;
237			float *distarr;
238	greg	1.10	double sp[4], r1, r2, r3;
239	greg	1.4	FVECT dn, org, dir;
240	greg	1.3	FVECT u, v;
241			register CONE *co;
242			register int i, j;
243			/* get/check arguments */
244			co = getcone(ob, 0);
245			/* set up sampling */
246	greg	1.11	if (il->sampdens <= 0)
247			nalt = nazi = 1;
248			else {
249			n = PI * il->sampdens;
250			nalt = sqrt(n/PI) + .5;
251			nazi = PI*nalt + .5;
252			}
253	greg	1.3	n = nalt*nazi;
254			distarr = (float )calloc(n, 3sizeof(float));
255			if (distarr == NULL)
256			error(SYSTEM, "out of memory in o_ring");
257			mkaxes(u, v, co->ad);
258			dim[0] = random();
259			/* sample disk */
260			for (dim[1] = 0; dim[1] < nalt; dim[1]++)
261			for (dim[2] = 0; dim[2] < nazi; dim[2]++)
262			for (i = 0; i < il->nsamps; i++) {
263	greg	1.10	/* next sample point */
264	greg	1.11	multisamp(sp, 4, urand(ilhash(dim,3)+i));
265	greg	1.3	/* random direction */
266	greg	1.10	r1 = (dim[1] + sp[0])/nalt;
267	greg	1.13	r2 = (dim[2] + sp[1] - .5)/nazi;
268	greg	1.3	flatdir(dn, r1, r2);
269			for (j = 0; j < 3; j++)
270	greg	1.5	dir[j] = -dn[0]u[j] - dn[1]v[j] - dn[2]*co->ad[j];
271	greg	1.3	/* random location */
272	greg	1.5	r3 = sqrt(CO_R0(co)*CO_R0(co) +
273	greg	1.10	sp[2](CO_R1(co)CO_R1(co) - CO_R0(co)*CO_R0(co)));
274			r2 = 2.PIsp[3];
275	greg	1.5	r1 = r3*cos(r2);
276			r2 = r3*sin(r2);
277	greg	1.3	for (j = 0; j < 3; j++)
278	greg	2.6	org[j] = CO_P0(co)[j] + r1u[j] + r2v[j] +
279	greg	1.5	.001*co->ad[j];
280	greg	1.3
281			/* send sample */
282	greg	1.7	raysamp(distarr+3(dim[1]nazi+dim[2]), org, dir, rt);
283	greg	1.3	}
284			rayflush(rt);
285	greg	1.11	/* write out the ring and its distribution */
286	greg	1.12	if (average(il, distarr, nalt*nazi)) {
287			if (il->sampdens > 0)
288			flatout(il, distarr, nalt, nazi, u, v, co->ad);
289			illumout(il, ob);
290	greg	2.2	} else
291	greg	1.12	printobj(il->altmat, ob);
292	greg	1.3	/* clean up */
293			freecone(ob);
294	greg	2.9	free((void *)distarr);
295	greg	2.13	return(1);
296	greg	1.2	}
297
298
299	schorsch	2.12	void
300			raysamp( /* compute a ray sample */
301			float res[3],
302			FVECT org,
303			FVECT dir,
304			register struct rtproc *rt
305			)
306	greg	1.2	{
307			register float *fp;
308
309			if (rt->nrays == rt->bsiz)
310			rayflush(rt);
311			rt->dest[rt->nrays] = res;
312			fp = rt->buf + 6*rt->nrays++;
313			fp++ = org[0]; fp++ = org[1]; *fp++ = org[2];
314			fp++ = dir[0]; fp++ = dir[1]; *fp = dir[2];
315			}
316
317
318	schorsch	2.12	void
319			rayflush( /* flush buffered rays */
320			register struct rtproc *rt
321			)
322	greg	1.2	{
323			register int i;
324
325			if (rt->nrays <= 0)
326			return;
327	schorsch	2.11	memset(rt->buf+6rt->nrays, '\0', 6sizeof(float));
328	greg	1.14	errno = 0;
329	schorsch	2.10	if ( process(&(rt->pd), (char )rt->buf, (char )rt->buf,
330	gregl	2.8	3sizeof(float)(rt->nrays+1),
331	greg	1.2	6sizeof(float)(rt->nrays+1)) <
332	gregl	2.8	3sizeof(float)(rt->nrays+1) )
333	greg	1.2	error(SYSTEM, "error reading from rtrace process");
334			i = rt->nrays;
335			while (i--) {
336			rt->dest[i][0] += rt->buf[3*i];
337			rt->dest[i][1] += rt->buf[3*i+1];
338			rt->dest[i][2] += rt->buf[3*i+2];
339			}
340			rt->nrays = 0;
341	greg	1.4	}
342
343
344	schorsch	2.12	void
345			mkaxes( /* compute u and v to go with n */
346			FVECT u,
347			FVECT v,
348			FVECT n
349			)
350	greg	1.4	{
351			register int i;
352
353			v[0] = v[1] = v[2] = 0.0;
354			for (i = 0; i < 3; i++)
355			if (n[i] < 0.6 && n[i] > -0.6)
356			break;
357			v[i] = 1.0;
358			fcross(u, v, n);
359			normalize(u);
360			fcross(v, n, u);
361			}
362
363
364	schorsch	2.12	void
365			rounddir( /* compute uniform spherical direction */
366			register FVECT dv,
367			double alt,
368			double azi
369			)
370	greg	1.4	{
371			double d1, d2;
372
373			dv[2] = 1. - 2.*alt;
374			d1 = sqrt(1. - dv[2]*dv[2]);
375			d2 = 2.PI azi;
376			dv[0] = d1*cos(d2);
377			dv[1] = d1*sin(d2);
378			}
379
380
381	schorsch	2.12	void
382			flatdir( /* compute uniform hemispherical direction */
383			register FVECT dv,
384			double alt,
385			double azi
386			)
387	greg	1.4	{
388			double d1, d2;
389
390			d1 = sqrt(alt);
391			d2 = 2.PI azi;
392			dv[0] = d1*cos(d2);
393			dv[1] = d1*sin(d2);
394	greg	1.6	dv[2] = sqrt(1. - alt);
395	greg	1.1	}