src/gen/mkillum2.c

#ifndef lint
static const char       RCSid[] = "$Id: mkillum2.c,v 2.17 2004/09/19 08:42:22 greg 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"


static void mkaxes(FVECT u, FVECT v, FVECT n);
static void rounddir(FVECT dv, double alt, double azi);
static void flatdir(FVECT dv, double alt, double azi);


static COLORV * distarr = NULL;         /* distribution array */
static int      distsiz = 0;


static void
newdist(                        /* allocate & clear distribution array */
        int siz
)
{
        if (siz == 0) {
                if (distsiz > 0)
                        free((void *)distarr);
                distarr = NULL;
                distsiz = 0;
                return;
        }
        if (distsiz < siz) {
                free((void *)distarr);
                distarr = (COLORV *)malloc(sizeof(COLORV)*3*siz);
                if (distarr == NULL)
                        error(SYSTEM, "Out of memory in distalloc");
                distsiz = siz;
        }
        memset(distarr, '\0', sizeof(COLORV)*3*siz);
}


static int
process_ray(RAY *r, int rv)
{
        COLORV  *colp;

        if (rv == 0)
                return(0);
        if (rv < 0)
                error(USER, "Ray tracing process died");
        if (r->rno >= distsiz)
                error(INTERNAL, "Bad returned index in process_ray");
        colp = &distarr[r->rno * 3];
        addcolor(colp, r->rcol);
        return(1);
}


static void
raysamp(        /* queue a ray sample */
        int  ndx,
        FVECT  org,
        FVECT  dir
)
{
        RAY     myRay;
        int     rv;

        if ((ndx < 0) | (ndx >= distsiz))
                error(INTERNAL, "Bad index in raysamp");
        VCOPY(myRay.rorg, org);
        VCOPY(myRay.rdir, dir);
        myRay.rmax = .0;
        rayorigin(&myRay, PRIMARY, NULL, NULL);
        myRay.rno = ndx;
                                        /* queue ray, check result */
        process_ray(&myRay, ray_pqueue(&myRay));
}


static void
rayclean()                      /* finish all pending rays */
{
        RAY     myRay;

        while (process_ray(&myRay, ray_presult(&myRay, 0)))
                ;
}


int /* XXX type conflict with otypes.h */
my_default(     /* default illum action */
        OBJREC  *ob,
        struct illum_args  *il,
        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
my_face(                /* make an illum face */
        OBJREC  *ob,
        struct illum_args  *il,
        char  *nm
)
{
#define MAXMISS         (5*n*il->nsamps)
        int  dim[3];
        int  n, nalt, nazi, h;
        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, 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;
        newdist(n);
                                /* 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");
                        rayclean();
                        freeface(ob);
                        free((void *)distarr);
                        return(o_default(ob, il, nm));
                    }
                    for (j = 0; j < 3; j++)
                        org[j] += .001*fa->norm[j];
                                        /* send sample */
                    raysamp(dim[1]*nazi+dim[2], org, dir);
                }
        rayclean();
                                /* 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);
        return(0);
#undef MAXMISS
}


int
my_sphere(      /* make an illum sphere */
        register OBJREC  *ob,
        struct illum_args  *il,
        char  *nm
)
{
        int  dim[3];
        int  n, nalt, nazi;
        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;
        newdist(n);
        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(dim[1]*nazi+dim[2], org, dir);
                }
        rayclean();
                                /* 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 */
        return(1);
}


int
my_ring(                /* make an illum ring */
        OBJREC  *ob,
        struct illum_args  *il,
        char  *nm
)
{
        int  dim[3];
        int  n, nalt, nazi;
        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;
        newdist(n);
        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(dim[1]*nazi+dim[2], org, dir);
                }
        rayclean();
                                /* 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);
        return(1);
}


static 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);
}


static 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);
}


static 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:	2.18
Committed:	Thu Sep 13 06:31:21 2007 UTC (18 years, 1 month ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.17:	+86 -138 lines
Log Message:	Changed mkillum from calling rtrace to calling Radiance library (raypcalls.o)
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.18	static const char RCSid[] = "$Id: mkillum2.c,v 2.17 2004/09/19 08:42:22 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	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	greg	2.16	static void mkaxes(FVECT u, FVECT v, FVECT n);
17			static void rounddir(FVECT dv, double alt, double azi);
18			static void flatdir(FVECT dv, double alt, double azi);
19
20
21	greg	2.18	static COLORV * distarr = NULL; /* distribution array */
22			static int distsiz = 0;
23
24
25			static void
26			newdist( /* allocate & clear distribution array */
27			int siz
28			)
29			{
30			if (siz == 0) {
31			if (distsiz > 0)
32			free((void *)distarr);
33			distarr = NULL;
34			distsiz = 0;
35			return;
36			}
37			if (distsiz < siz) {
38			free((void *)distarr);
39			distarr = (COLORV )malloc(sizeof(COLORV)3*siz);
40			if (distarr == NULL)
41			error(SYSTEM, "Out of memory in distalloc");
42			distsiz = siz;
43			}
44			memset(distarr, '\0', sizeof(COLORV)3siz);
45			}
46
47
48			static int
49			process_ray(RAY *r, int rv)
50			{
51			COLORV *colp;
52
53			if (rv == 0)
54			return(0);
55			if (rv < 0)
56			error(USER, "Ray tracing process died");
57			if (r->rno >= distsiz)
58			error(INTERNAL, "Bad returned index in process_ray");
59			colp = &distarr[r->rno * 3];
60			addcolor(colp, r->rcol);
61			return(1);
62			}
63
64
65	greg	2.16	static void
66	greg	2.18	raysamp( /* queue a ray sample */
67			int ndx,
68			FVECT org,
69			FVECT dir
70	greg	2.16	)
71			{
72	greg	2.18	RAY myRay;
73			int rv;
74
75			if ((ndx < 0) \| (ndx >= distsiz))
76			error(INTERNAL, "Bad index in raysamp");
77			VCOPY(myRay.rorg, org);
78			VCOPY(myRay.rdir, dir);
79			myRay.rmax = .0;
80			rayorigin(&myRay, PRIMARY, NULL, NULL);
81			myRay.rno = ndx;
82			/* queue ray, check result */
83			process_ray(&myRay, ray_pqueue(&myRay));
84			}
85
86
87			static void
88			rayclean() /* finish all pending rays */
89			{
90			RAY myRay;
91
92			while (process_ray(&myRay, ray_presult(&myRay, 0)))
93	greg	2.16	;
94			}
95	schorsch	2.12
96
97			int /* XXX type conflict with otypes.h */
98	greg	2.18	my_default( /* default illum action */
99	schorsch	2.12	OBJREC *ob,
100			struct illum_args *il,
101			char *nm
102			)
103	greg	1.1	{
104	greg	1.2	sprintf(errmsg, "(%s): cannot make illum for %s \"%s\"",
105			nm, ofun[ob->otype].funame, ob->oname);
106			error(WARNING, errmsg);
107	greg	2.2	printobj(il->altmat, ob);
108	greg	2.13	return(1);
109	greg	1.2	}
110
111
112	greg	2.13	int
113	greg	2.18	my_face( /* make an illum face */
114	schorsch	2.12	OBJREC *ob,
115			struct illum_args *il,
116			char *nm
117			)
118	greg	1.2	{
119	greg	1.3	#define MAXMISS (5nil->nsamps)
120	greg	1.10	int dim[3];
121			int n, nalt, nazi, h;
122			double sp[2], r1, r2;
123	greg	1.4	FVECT dn, org, dir;
124	greg	1.3	FVECT u, v;
125			double ur[2], vr[2];
126			int nmisses;
127			register FACE *fa;
128			register int i, j;
129			/* get/check arguments */
130			fa = getface(ob);
131			if (fa->area == 0.0) {
132			freeface(ob);
133	greg	2.18	return(o_default(ob, il, nm));
134	greg	1.3	}
135			/* set up sampling */
136	greg	1.11	if (il->sampdens <= 0)
137			nalt = nazi = 1;
138			else {
139			n = PI * il->sampdens;
140			nalt = sqrt(n/PI) + .5;
141			nazi = PI*nalt + .5;
142			}
143	greg	1.3	n = nalt*nazi;
144	greg	2.18	newdist(n);
145	greg	2.3	/* take first edge longer than sqrt(area) */
146	greg	2.4	for (j = fa->nv-1, i = 0; i < fa->nv; j = i++) {
147			u[0] = VERTEX(fa,i)[0] - VERTEX(fa,j)[0];
148			u[1] = VERTEX(fa,i)[1] - VERTEX(fa,j)[1];
149			u[2] = VERTEX(fa,i)[2] - VERTEX(fa,j)[2];
150	greg	2.5	if ((r1 = DOT(u,u)) >= fa->area-FTINY)
151	greg	2.3	break;
152			}
153			if (i < fa->nv) { /* got one! -- let's align our axes */
154	greg	2.5	r2 = 1.0/sqrt(r1);
155			u[0] = r2; u[1] = r2; u[2] *= r2;
156	greg	2.3	fcross(v, fa->norm, u);
157			} else /* oh well, we'll just have to wing it */
158			mkaxes(u, v, fa->norm);
159			/* now, find limits in (u,v) coordinates */
160	greg	1.3	ur[0] = vr[0] = FHUGE;
161			ur[1] = vr[1] = -FHUGE;
162			for (i = 0; i < fa->nv; i++) {
163			r1 = DOT(VERTEX(fa,i),u);
164			if (r1 < ur[0]) ur[0] = r1;
165			if (r1 > ur[1]) ur[1] = r1;
166			r2 = DOT(VERTEX(fa,i),v);
167			if (r2 < vr[0]) vr[0] = r2;
168			if (r2 > vr[1]) vr[1] = r2;
169			}
170			dim[0] = random();
171			/* sample polygon */
172			nmisses = 0;
173			for (dim[1] = 0; dim[1] < nalt; dim[1]++)
174			for (dim[2] = 0; dim[2] < nazi; dim[2]++)
175			for (i = 0; i < il->nsamps; i++) {
176			/* random direction */
177	greg	1.10	h = ilhash(dim, 3) + i;
178	greg	1.11	multisamp(sp, 2, urand(h));
179	greg	1.10	r1 = (dim[1] + sp[0])/nalt;
180	greg	1.13	r2 = (dim[2] + sp[1] - .5)/nazi;
181	greg	1.3	flatdir(dn, r1, r2);
182			for (j = 0; j < 3; j++)
183	greg	1.5	dir[j] = -dn[0]u[j] - dn[1]v[j] - dn[2]*fa->norm[j];
184	greg	1.3	/* random location */
185			do {
186	greg	1.11	multisamp(sp, 2, urand(h+4862+nmisses));
187	greg	1.10	r1 = ur[0] + (ur[1]-ur[0]) * sp[0];
188			r2 = vr[0] + (vr[1]-vr[0]) * sp[1];
189	greg	1.3	for (j = 0; j < 3; j++)
190			org[j] = r1u[j] + r2v[j]
191			+ fa->offset*fa->norm[j];
192			} while (!inface(org, fa) && nmisses++ < MAXMISS);
193			if (nmisses > MAXMISS) {
194			objerror(ob, WARNING, "bad aspect");
195	greg	2.18	rayclean();
196	greg	1.3	freeface(ob);
197	greg	2.9	free((void *)distarr);
198	greg	2.18	return(o_default(ob, il, nm));
199	greg	1.3	}
200			for (j = 0; j < 3; j++)
201			org[j] += .001*fa->norm[j];
202			/* send sample */
203	greg	2.18	raysamp(dim[1]*nazi+dim[2], org, dir);
204	greg	1.3	}
205	greg	2.18	rayclean();
206	greg	1.11	/* write out the face and its distribution */
207	greg	1.12	if (average(il, distarr, nalt*nazi)) {
208			if (il->sampdens > 0)
209			flatout(il, distarr, nalt, nazi, u, v, fa->norm);
210			illumout(il, ob);
211	greg	2.2	} else
212	greg	1.12	printobj(il->altmat, ob);
213	greg	1.3	/* clean up */
214			freeface(ob);
215	greg	2.15	return(0);
216	greg	1.3	#undef MAXMISS
217	greg	1.2	}
218
219
220	greg	2.13	int
221	greg	2.18	my_sphere( /* make an illum sphere */
222	schorsch	2.12	register OBJREC *ob,
223			struct illum_args *il,
224			char *nm
225			)
226	greg	1.2	{
227	greg	1.10	int dim[3];
228	greg	1.2	int n, nalt, nazi;
229	greg	1.10	double sp[4], r1, r2, r3;
230	greg	1.4	FVECT org, dir;
231	greg	1.2	FVECT u, v;
232			register int i, j;
233			/* check arguments */
234			if (ob->oargs.nfargs != 4)
235			objerror(ob, USER, "bad # of arguments");
236			/* set up sampling */
237	greg	1.11	if (il->sampdens <= 0)
238			nalt = nazi = 1;
239			else {
240			n = 4.PI il->sampdens;
241	greg	2.7	nalt = sqrt(2./PI*n) + .5;
242			nazi = PI/2.*nalt + .5;
243	greg	1.11	}
244	greg	1.2	n = nalt*nazi;
245	greg	2.18	newdist(n);
246	greg	1.2	dim[0] = random();
247			/* sample sphere */
248			for (dim[1] = 0; dim[1] < nalt; dim[1]++)
249	greg	1.8	for (dim[2] = 0; dim[2] < nazi; dim[2]++)
250	greg	1.2	for (i = 0; i < il->nsamps; i++) {
251	greg	1.10	/* next sample point */
252	greg	1.11	multisamp(sp, 4, urand(ilhash(dim,3)+i));
253	greg	1.2	/* random direction */
254	greg	1.10	r1 = (dim[1] + sp[0])/nalt;
255	greg	1.13	r2 = (dim[2] + sp[1] - .5)/nazi;
256	greg	1.2	rounddir(dir, r1, r2);
257			/* random location */
258	greg	1.8	mkaxes(u, v, dir); /* yuck! */
259	greg	1.10	r3 = sqrt(sp[2]);
260			r2 = 2.PIsp[3];
261	greg	1.5	r1 = r3ob->oargs.farg[3]cos(r2);
262			r2 = r3ob->oargs.farg[3]sin(r2);
263			r3 = ob->oargs.farg[3]sqrt(1.01-r3r3);
264			for (j = 0; j < 3; j++) {
265			org[j] = ob->oargs.farg[j] + r1u[j] + r2v[j] +
266			r3*dir[j];
267			dir[j] = -dir[j];
268			}
269	greg	1.2	/* send sample */
270	greg	2.18	raysamp(dim[1]*nazi+dim[2], org, dir);
271	greg	1.2	}
272	greg	2.18	rayclean();
273	greg	1.11	/* write out the sphere and its distribution */
274	greg	1.12	if (average(il, distarr, nalt*nazi)) {
275			if (il->sampdens > 0)
276			roundout(il, distarr, nalt, nazi);
277			else
278			objerror(ob, WARNING, "diffuse distribution");
279			illumout(il, ob);
280	greg	2.2	} else
281	greg	1.12	printobj(il->altmat, ob);
282	greg	1.2	/* clean up */
283	greg	2.13	return(1);
284	greg	1.2	}
285
286
287	greg	2.13	int
288	greg	2.18	my_ring( /* make an illum ring */
289	schorsch	2.12	OBJREC *ob,
290			struct illum_args *il,
291			char *nm
292			)
293	greg	1.2	{
294	greg	1.10	int dim[3];
295	greg	1.3	int n, nalt, nazi;
296	greg	1.10	double sp[4], r1, r2, r3;
297	greg	1.4	FVECT dn, org, dir;
298	greg	1.3	FVECT u, v;
299			register CONE *co;
300			register int i, j;
301			/* get/check arguments */
302			co = getcone(ob, 0);
303			/* set up sampling */
304	greg	1.11	if (il->sampdens <= 0)
305			nalt = nazi = 1;
306			else {
307			n = PI * il->sampdens;
308			nalt = sqrt(n/PI) + .5;
309			nazi = PI*nalt + .5;
310			}
311	greg	1.3	n = nalt*nazi;
312	greg	2.18	newdist(n);
313	greg	1.3	mkaxes(u, v, co->ad);
314			dim[0] = random();
315			/* sample disk */
316			for (dim[1] = 0; dim[1] < nalt; dim[1]++)
317			for (dim[2] = 0; dim[2] < nazi; dim[2]++)
318			for (i = 0; i < il->nsamps; i++) {
319	greg	1.10	/* next sample point */
320	greg	1.11	multisamp(sp, 4, urand(ilhash(dim,3)+i));
321	greg	1.3	/* random direction */
322	greg	1.10	r1 = (dim[1] + sp[0])/nalt;
323	greg	1.13	r2 = (dim[2] + sp[1] - .5)/nazi;
324	greg	1.3	flatdir(dn, r1, r2);
325			for (j = 0; j < 3; j++)
326	greg	1.5	dir[j] = -dn[0]u[j] - dn[1]v[j] - dn[2]*co->ad[j];
327	greg	1.3	/* random location */
328	greg	1.5	r3 = sqrt(CO_R0(co)*CO_R0(co) +
329	greg	1.10	sp[2](CO_R1(co)CO_R1(co) - CO_R0(co)*CO_R0(co)));
330			r2 = 2.PIsp[3];
331	greg	1.5	r1 = r3*cos(r2);
332			r2 = r3*sin(r2);
333	greg	1.3	for (j = 0; j < 3; j++)
334	greg	2.6	org[j] = CO_P0(co)[j] + r1u[j] + r2v[j] +
335	greg	1.5	.001*co->ad[j];
336	greg	1.3
337			/* send sample */
338	greg	2.18	raysamp(dim[1]*nazi+dim[2], org, dir);
339	greg	1.3	}
340	greg	2.18	rayclean();
341	greg	1.11	/* write out the ring and its distribution */
342	greg	1.12	if (average(il, distarr, nalt*nazi)) {
343			if (il->sampdens > 0)
344			flatout(il, distarr, nalt, nazi, u, v, co->ad);
345			illumout(il, ob);
346	greg	2.2	} else
347	greg	1.12	printobj(il->altmat, ob);
348	greg	1.3	/* clean up */
349			freecone(ob);
350	greg	2.13	return(1);
351	greg	1.2	}
352
353
354	greg	2.16	static void
355	schorsch	2.12	mkaxes( /* compute u and v to go with n */
356			FVECT u,
357			FVECT v,
358			FVECT n
359			)
360	greg	1.4	{
361			register int i;
362
363			v[0] = v[1] = v[2] = 0.0;
364			for (i = 0; i < 3; i++)
365			if (n[i] < 0.6 && n[i] > -0.6)
366			break;
367			v[i] = 1.0;
368			fcross(u, v, n);
369			normalize(u);
370			fcross(v, n, u);
371			}
372
373
374	greg	2.16	static void
375	schorsch	2.12	rounddir( /* compute uniform spherical direction */
376			register FVECT dv,
377			double alt,
378			double azi
379			)
380	greg	1.4	{
381			double d1, d2;
382
383			dv[2] = 1. - 2.*alt;
384			d1 = sqrt(1. - dv[2]*dv[2]);
385			d2 = 2.PI azi;
386			dv[0] = d1*cos(d2);
387			dv[1] = d1*sin(d2);
388			}
389
390
391	greg	2.16	static void
392	schorsch	2.12	flatdir( /* compute uniform hemispherical direction */
393			register FVECT dv,
394			double alt,
395			double azi
396			)
397	greg	1.4	{
398			double d1, d2;
399
400			d1 = sqrt(alt);
401			d2 = 2.PI azi;
402			dv[0] = d1*cos(d2);
403			dv[1] = d1*sin(d2);
404	greg	1.6	dv[2] = sqrt(1. - alt);
405	greg	1.1	}