src/rt/ambcomp.c

#ifndef lint
static const char       RCSid[] = "$Id: ambcomp.c,v 2.25 2014/04/11 20:31:37 greg Exp $";
#endif
/*
 * Routines to compute "ambient" values using Monte Carlo
 *
 *  Declarations of external symbols in ambient.h
 */

#include "copyright.h"

#include  "ray.h"
#include  "ambient.h"
#include  "random.h"

#ifdef NEWAMB

extern void             SDsquare2disk(double ds[2], double seedx, double seedy);

typedef struct {
        RAY     *rp;            /* originating ray sample */
        FVECT   ux, uy;         /* tangent axis directions */
        int     ns;             /* number of samples per axis */
        COLOR   acoef;          /* division contribution coefficient */
        struct s_ambsamp {
                COLOR   v;              /* hemisphere sample value */
                float   p[3];           /* intersection point */
        } sa[1];                /* sample array (extends struct) */
}  AMBHEMI;             /* ambient sample hemisphere */

#define ambsamp(h,i,j)  (h)->sa[(i)*(h)->ns + (j)]


static AMBHEMI *
inithemi(                       /* initialize sampling hemisphere */
        COLOR   ac,
        RAY     *r,
        double  wt
)
{
        AMBHEMI *hp;
        double  d;
        int     n, i;
                                        /* set number of divisions */
        if (ambacc <= FTINY &&
                        wt > (d = 0.8*intens(ac)*r->rweight/(ambdiv*minweight)))
                wt = d;                 /* avoid ray termination */
        n = sqrt(ambdiv * wt) + 0.5;
        i = 1 + 4*(ambacc > FTINY);     /* minimum number of samples */
        if (n < i)
                n = i;
                                        /* allocate sampling array */
        hp = (AMBHEMI *)malloc(sizeof(AMBHEMI) +
                                sizeof(struct s_ambsamp)*(n*n - 1));
        if (hp == NULL)
                return(NULL);
        hp->rp = r;
        hp->ns = n;
                                        /* assign coefficient */
        copycolor(hp->acoef, ac);
        d = 1.0/(n*n);
        scalecolor(hp->acoef, d);
                                        /* make tangent axes */
        hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
        for (i = 0; i < 3; i++)
                if (r->rn[i] < 0.6 && r->rn[i] > -0.6)
                        break;
        if (i >= 3)
                error(CONSISTENCY, "bad ray direction in inithemi()");
        hp->uy[i] = 1.0;
        VCROSS(hp->ux, hp->uy, r->rn);
        normalize(hp->ux);
        VCROSS(hp->uy, r->rn, hp->ux);
                                        /* we're ready to sample */
        return(hp);
}


static int
ambsample(                              /* sample an ambient direction */
        AMBHEMI *hp,
        int     i,
        int     j,
)
{
        struct s_ambsamp        *ap = &ambsamp(hp,i,j);
        RAY                     ar;
        int                     hlist[3];
        double                  spt[2], dz;
        int                     ii;
                                        /* ambient coefficient for weight */
        if (ambacc > FTINY)
                setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
        else
                copycolor(ar.rcoef, hp->acoef);
        if (rayorigin(&ar, AMBIENT, hp->rp, ar.rcoef) < 0) {
                setcolor(ap->v, 0., 0., 0.);
                ap->r = 0.;
                return(0);              /* no sample taken */
        }
        if (ambacc > FTINY) {
                multcolor(ar.rcoef, hp->acoef);
                scalecolor(ar.rcoef, 1./AVGREFL);
        }
                                        /* generate hemispherical sample */
        SDsquare2disk(spt, (i+frandom())/hp->ns, (j+frandom())/hp->ns);
        zd = sqrt(1. - spt[0]*spt[0] - spt[1]*spt[1]);
        for (ii = 3; ii--; )
                ar.rdir[ii] =   spt[0]*hp->ux[ii] +
                                spt[1]*hp->uy[ii] +
                                zd*hp->rp->ron[ii];
        checknorm(ar.rdir);
        dimlist[ndims++] = i*hp->ns + j + 90171;
        rayvalue(&ar);                  /* evaluate ray */
        ndims--;
        multcolor(ar.rcol, ar.rcoef);   /* apply coefficient */
        copycolor(ap->v, ar.rcol);
        if (ar.rt > 20.0*maxarad)       /* limit vertex distance */
                ar.rt = 20.0*maxarad;
        VSUM(ap->p, ar.rorg, ar.rdir, ar.rt);
        return(1);
}


static void
ambHessian(                             /* anisotropic radii & pos. gradient */
        AMBHEMI *hp,
        FVECT   uv[2],                  /* returned */
        float   ra[2],                  /* returned */
        float   pg[2]                   /* returned */
)
{
        if (ra != NULL) {               /* compute Hessian-derived radii */
        } else {                        /* else copy original tangent axes */
                VCOPY(uv[0], hp->ux);
                VCOPY(uv[1], hp->uy);
        }
        if (pg == NULL)                 /* no position gradient requested? */
                return;
}

int
doambient(                              /* compute ambient component */
        COLOR   rcol,                   /* input/output color */
        RAY     *r,
        double  wt,
        FVECT   uv[2],                  /* returned */
        float   ra[2],                  /* returned */
        float   pg[2],                  /* returned */
        float   dg[2]                   /* returned */
)
{
        int                     cnt = 0;
        FVECT                   my_uv[2];
        AMBHEMI                 *hp;
        double                  d, acol[3];
        struct s_ambsamp        *ap;
        int                     i, j;
                                        /* initialize */
        if ((hp = inithemi(rcol, r, wt)) == NULL)
                return(0);
        if (uv != NULL)
                memset(uv, 0, sizeof(FVECT)*2);
        if (ra != NULL)
                ra[0] = ra[1] = 0.0;
        if (pg != NULL)
                pg[0] = pg[1] = 0.0;
        if (dg != NULL)
                dg[0] = dg[1] = 0.0;
                                        /* sample the hemisphere */
        acol[0] = acol[1] = acol[2] = 0.0;
        for (i = hemi.ns; i--; )
                for (j = hemi.ns; j--; )
                        if (ambsample(hp, i, j)) {
                                ap = &ambsamp(hp,i,j);
                                addcolor(acol, ap->v);
                                ++cnt;
                        }
        if (!cnt) {
                setcolor(rcol, 0.0, 0.0, 0.0);
                free(hp);
                return(0);              /* no valid samples */
        }
        d = 1.0 / cnt;                  /* final indirect irradiance/PI */
        acol[0] *= d; acol[1] *= d; acol[2] *= d;
        copycolor(rcol, acol);
        if (cnt < hp->ns*hp->ns ||      /* incomplete sampling? */
                        (ra == NULL) & (pg == NULL) & (dg == NULL)) {
                free(hp);
                return(-1);             /* no radius or gradient calc. */
        }
        d = 0.01 * bright(rcol);        /* add in 1% before Hessian comp. */
        if (d < FTINY) d = FTINY;
        ap = hp->sa;                    /* using Y channel from here on... */
        for (i = hp->ns*hp->ns; i--; ap++)
                colval(ap->v,CIEY) = bright(ap->v) + d;

        if (uv == NULL)                 /* make sure we have axis pointers */
                uv = my_uv;
                                        /* compute radii & pos. gradient */
        ambHessian(hp, uv, ra, pg);
        if (dg != NULL)                 /* compute direction gradient */
                ambdirgrad(hp, uv, dg);
        if (ra != NULL) {               /* adjust/clamp radii */
                d = pow(wt, -0.25);
                if ((ra[0] *= d) > maxarad)
                        ra[0] = maxarad;
                if ((ra[1] *= d) > 2.0*ra[0])
                        ra[1] = 2.0*ra[0];
        }
        free(hp);                       /* clean up and return */
        return(1);
}


#else /* ! NEWAMB */


void
inithemi(                       /* initialize sampling hemisphere */
        AMBHEMI  *hp,
        COLOR ac,
        RAY  *r,
        double  wt
)
{
        double  d;
        int  i;
                                        /* set number of divisions */
        if (ambacc <= FTINY &&
                        wt > (d = 0.8*intens(ac)*r->rweight/(ambdiv*minweight)))
                wt = d;                 /* avoid ray termination */
        hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
        i = ambacc > FTINY ? 3 : 1;     /* minimum number of samples */
        if (hp->nt < i)
                hp->nt = i;
        hp->np = PI * hp->nt + 0.5;
                                        /* set number of super-samples */
        hp->ns = ambssamp * wt + 0.5;
                                        /* assign coefficient */
        copycolor(hp->acoef, ac);
        d = 1.0/(hp->nt*hp->np);
        scalecolor(hp->acoef, d);
                                        /* make axes */
        VCOPY(hp->uz, r->ron);
        hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
        for (i = 0; i < 3; i++)
                if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
                        break;
        if (i >= 3)
                error(CONSISTENCY, "bad ray direction in inithemi");
        hp->uy[i] = 1.0;
        fcross(hp->ux, hp->uy, hp->uz);
        normalize(hp->ux);
        fcross(hp->uy, hp->uz, hp->ux);
}


int
divsample(                              /* sample a division */
        AMBSAMP  *dp,
        AMBHEMI  *h,
        RAY  *r
)
{
        RAY  ar;
        int  hlist[3];
        double  spt[2];
        double  xd, yd, zd;
        double  b2;
        double  phi;
        int  i;
                                        /* ambient coefficient for weight */
        if (ambacc > FTINY)
                setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
        else
                copycolor(ar.rcoef, h->acoef);
        if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0)
                return(-1);
        if (ambacc > FTINY) {
                multcolor(ar.rcoef, h->acoef);
                scalecolor(ar.rcoef, 1./AVGREFL);
        }
        hlist[0] = r->rno;
        hlist[1] = dp->t;
        hlist[2] = dp->p;
        multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n));
        zd = sqrt((dp->t + spt[0])/h->nt);
        phi = 2.0*PI * (dp->p + spt[1])/h->np;
        xd = tcos(phi) * zd;
        yd = tsin(phi) * zd;
        zd = sqrt(1.0 - zd*zd);
        for (i = 0; i < 3; i++)
                ar.rdir[i] =    xd*h->ux[i] +
                                yd*h->uy[i] +
                                zd*h->uz[i];
        checknorm(ar.rdir);
        dimlist[ndims++] = dp->t*h->np + dp->p + 90171;
        rayvalue(&ar);
        ndims--;
        multcolor(ar.rcol, ar.rcoef);   /* apply coefficient */
        addcolor(dp->v, ar.rcol);
                                        /* use rt to improve gradient calc */
        if (ar.rt > FTINY && ar.rt < FHUGE)
                dp->r += 1.0/ar.rt;
                                        /* (re)initialize error */
        if (dp->n++) {
                b2 = bright(dp->v)/dp->n - bright(ar.rcol);
                b2 = b2*b2 + dp->k*((dp->n-1)*(dp->n-1));
                dp->k = b2/(dp->n*dp->n);
        } else
                dp->k = 0.0;
        return(0);
}


static int
ambcmp(                                 /* decreasing order */
        const void *p1,
        const void *p2
)
{
        const AMBSAMP   *d1 = (const AMBSAMP *)p1;
        const AMBSAMP   *d2 = (const AMBSAMP *)p2;

        if (d1->k < d2->k)
                return(1);
        if (d1->k > d2->k)
                return(-1);
        return(0);
}


static int
ambnorm(                                /* standard order */
        const void *p1,
        const void *p2
)
{
        const AMBSAMP   *d1 = (const AMBSAMP *)p1;
        const AMBSAMP   *d2 = (const AMBSAMP *)p2;
        int     c;

        if ( (c = d1->t - d2->t) )
                return(c);
        return(d1->p - d2->p);
}


double
doambient(                              /* compute ambient component */
        COLOR  rcol,
        RAY  *r,
        double  wt,
        FVECT  pg,
        FVECT  dg
)
{
        double  b, d=0;
        AMBHEMI  hemi;
        AMBSAMP  *div;
        AMBSAMP  dnew;
        double  acol[3];
        AMBSAMP  *dp;
        double  arad;
        int  divcnt;
        int  i, j;
                                        /* initialize hemisphere */
        inithemi(&hemi, rcol, r, wt);
        divcnt = hemi.nt * hemi.np;
                                        /* initialize */
        if (pg != NULL)
                pg[0] = pg[1] = pg[2] = 0.0;
        if (dg != NULL)
                dg[0] = dg[1] = dg[2] = 0.0;
        setcolor(rcol, 0.0, 0.0, 0.0);
        if (divcnt == 0)
                return(0.0);
                                        /* allocate super-samples */
        if (hemi.ns > 0 || pg != NULL || dg != NULL) {
                div = (AMBSAMP *)malloc(divcnt*sizeof(AMBSAMP));
                if (div == NULL)
                        error(SYSTEM, "out of memory in doambient");
        } else
                div = NULL;
                                        /* sample the divisions */
        arad = 0.0;
        acol[0] = acol[1] = acol[2] = 0.0;
        if ((dp = div) == NULL)
                dp = &dnew;
        divcnt = 0;
        for (i = 0; i < hemi.nt; i++)
                for (j = 0; j < hemi.np; j++) {
                        dp->t = i; dp->p = j;
                        setcolor(dp->v, 0.0, 0.0, 0.0);
                        dp->r = 0.0;
                        dp->n = 0;
                        if (divsample(dp, &hemi, r) < 0) {
                                if (div != NULL)
                                        dp++;
                                continue;
                        }
                        arad += dp->r;
                        divcnt++;
                        if (div != NULL)
                                dp++;
                        else
                                addcolor(acol, dp->v);
                }
        if (!divcnt) {
                if (div != NULL)
                        free((void *)div);
                return(0.0);            /* no samples taken */
        }
        if (divcnt < hemi.nt*hemi.np) {
                pg = dg = NULL;         /* incomplete sampling */
                hemi.ns = 0;
        } else if (arad > FTINY && divcnt/arad < minarad) {
                hemi.ns = 0;            /* close enough */
        } else if (hemi.ns > 0) {       /* else perform super-sampling? */
                comperrs(div, &hemi);                   /* compute errors */
                qsort(div, divcnt, sizeof(AMBSAMP), ambcmp);    /* sort divs */
                                                /* super-sample */
                for (i = hemi.ns; i > 0; i--) {
                        dnew = *div;
                        if (divsample(&dnew, &hemi, r) < 0) {
                                dp++;
                                continue;
                        }
                        dp = div;               /* reinsert */
                        j = divcnt < i ? divcnt : i;
                        while (--j > 0 && dnew.k < dp[1].k) {
                                *dp = *(dp+1);
                                dp++;
                        }
                        *dp = dnew;
                }
                if (pg != NULL || dg != NULL)   /* restore order */
                        qsort(div, divcnt, sizeof(AMBSAMP), ambnorm);
        }
                                        /* compute returned values */
        if (div != NULL) {
                arad = 0.0;             /* note: divcnt may be < nt*np */
                for (i = hemi.nt*hemi.np, dp = div; i-- > 0; dp++) {
                        arad += dp->r;
                        if (dp->n > 1) {
                                b = 1.0/dp->n;
                                scalecolor(dp->v, b);
                                dp->r *= b;
                                dp->n = 1;
                        }
                        addcolor(acol, dp->v);
                }
                b = bright(acol);
                if (b > FTINY) {
                        b = 1.0/b;      /* compute & normalize gradient(s) */
                        if (pg != NULL) {
                                posgradient(pg, div, &hemi);
                                for (i = 0; i < 3; i++)
                                        pg[i] *= b;
                        }
                        if (dg != NULL) {
                                dirgradient(dg, div, &hemi);
                                for (i = 0; i < 3; i++)
                                        dg[i] *= b;
                        }
                }
                free((void *)div);
        }
        copycolor(rcol, acol);
        if (arad <= FTINY)
                arad = maxarad;
        else
                arad = (divcnt+hemi.ns)/arad;
        if (pg != NULL) {               /* reduce radius if gradient large */
                d = DOT(pg,pg);
                if (d*arad*arad > 1.0)
                        arad = 1.0/sqrt(d);
        }
        if (arad < minarad) {
                arad = minarad;
                if (pg != NULL && d*arad*arad > 1.0) {  /* cap gradient */
                        d = 1.0/arad/sqrt(d);
                        for (i = 0; i < 3; i++)
                                pg[i] *= d;
                }
        }
        if ((arad /= sqrt(wt)) > maxarad)
                arad = maxarad;
        return(arad);
}


void
comperrs(                       /* compute initial error estimates */
        AMBSAMP  *da,   /* assumes standard ordering */
        AMBHEMI  *hp
)
{
        double  b, b2;
        int  i, j;
        AMBSAMP  *dp;
                                /* sum differences from neighbors */
        dp = da;
        for (i = 0; i < hp->nt; i++)
                for (j = 0; j < hp->np; j++) {
#ifdef  DEBUG
                        if (dp->t != i || dp->p != j)
                                error(CONSISTENCY,
                                        "division order in comperrs");
#endif
                        b = bright(dp[0].v);
                        if (i > 0) {            /* from above */
                                b2 = bright(dp[-hp->np].v) - b;
                                b2 *= b2 * 0.25;
                                dp[0].k += b2;
                                dp[-hp->np].k += b2;
                        }
                        if (j > 0) {            /* from behind */
                                b2 = bright(dp[-1].v) - b;
                                b2 *= b2 * 0.25;
                                dp[0].k += b2;
                                dp[-1].k += b2;
                        } else {                /* around */
                                b2 = bright(dp[hp->np-1].v) - b;
                                b2 *= b2 * 0.25;
                                dp[0].k += b2;
                                dp[hp->np-1].k += b2;
                        }
                        dp++;
                }
                                /* divide by number of neighbors */
        dp = da;
        for (j = 0; j < hp->np; j++)            /* top row */
                (dp++)->k *= 1.0/3.0;
        if (hp->nt < 2)
                return;
        for (i = 1; i < hp->nt-1; i++)          /* central region */
                for (j = 0; j < hp->np; j++)
                        (dp++)->k *= 0.25;
        for (j = 0; j < hp->np; j++)            /* bottom row */
                (dp++)->k *= 1.0/3.0;
}


void
posgradient(                                    /* compute position gradient */
        FVECT  gv,
        AMBSAMP  *da,                   /* assumes standard ordering */
        AMBHEMI  *hp
)
{
        int  i, j;
        double  nextsine, lastsine, b, d;
        double  mag0, mag1;
        double  phi, cosp, sinp, xd, yd;
        AMBSAMP  *dp;

        xd = yd = 0.0;
        for (j = 0; j < hp->np; j++) {
                dp = da + j;
                mag0 = mag1 = 0.0;
                lastsine = 0.0;
                for (i = 0; i < hp->nt; i++) {
#ifdef  DEBUG
                        if (dp->t != i || dp->p != j)
                                error(CONSISTENCY,
                                        "division order in posgradient");
#endif
                        b = bright(dp->v);
                        if (i > 0) {
                                d = dp[-hp->np].r;
                                if (dp[0].r > d) d = dp[0].r;
                                                        /* sin(t)*cos(t)^2 */
                                d *= lastsine * (1.0 - (double)i/hp->nt);
                                mag0 += d*(b - bright(dp[-hp->np].v));
                        }
                        nextsine = sqrt((double)(i+1)/hp->nt);
                        if (j > 0) {
                                d = dp[-1].r;
                                if (dp[0].r > d) d = dp[0].r;
                                mag1 += d * (nextsine - lastsine) *
                                                (b - bright(dp[-1].v));
                        } else {
                                d = dp[hp->np-1].r;
                                if (dp[0].r > d) d = dp[0].r;
                                mag1 += d * (nextsine - lastsine) *
                                                (b - bright(dp[hp->np-1].v));
                        }
                        dp += hp->np;
                        lastsine = nextsine;
                }
                mag0 *= 2.0*PI / hp->np;
                phi = 2.0*PI * (double)j/hp->np;
                cosp = tcos(phi); sinp = tsin(phi);
                xd += mag0*cosp - mag1*sinp;
                yd += mag0*sinp + mag1*cosp;
        }
        for (i = 0; i < 3; i++)
                gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])*(hp->nt*hp->np)/PI;
}


void
dirgradient(                                    /* compute direction gradient */
        FVECT  gv,
        AMBSAMP  *da,                   /* assumes standard ordering */
        AMBHEMI  *hp
)
{
        int  i, j;
        double  mag;
        double  phi, xd, yd;
        AMBSAMP  *dp;

        xd = yd = 0.0;
        for (j = 0; j < hp->np; j++) {
                dp = da + j;
                mag = 0.0;
                for (i = 0; i < hp->nt; i++) {
#ifdef  DEBUG
                        if (dp->t != i || dp->p != j)
                                error(CONSISTENCY,
                                        "division order in dirgradient");
#endif
                                                        /* tan(t) */
                        mag += bright(dp->v)/sqrt(hp->nt/(i+.5) - 1.0);
                        dp += hp->np;
                }
                phi = 2.0*PI * (j+.5)/hp->np + PI/2.0;
                xd += mag * tcos(phi);
                yd += mag * tsin(phi);
        }
        for (i = 0; i < 3; i++)
                gv[i] = xd*hp->ux[i] + yd*hp->uy[i];
}

#endif  /* ! NEWAMB */
Revision:	2.26
Committed:	Wed Apr 16 20:32:00 2014 UTC (10 years ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.25:	+199 -1 lines
Log Message:	Partial implementation of Hessian calculation
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.26	static const char RCSid[] = "$Id: ambcomp.c,v 2.25 2014/04/11 20:31:37 greg Exp $";
3	greg	1.1	#endif
4			/*
5			* Routines to compute "ambient" values using Monte Carlo
6	greg	2.9	*
7			* Declarations of external symbols in ambient.h
8			*/
9
10	greg	2.10	#include "copyright.h"
11	greg	1.1
12			#include "ray.h"
13	greg	2.25	#include "ambient.h"
14			#include "random.h"
15	greg	1.1
16	greg	2.25	#ifdef NEWAMB
17	greg	1.1
18	greg	2.26	extern void SDsquare2disk(double ds[2], double seedx, double seedy);
19
20			typedef struct {
21			RAY rp; / originating ray sample */
22			FVECT ux, uy; /* tangent axis directions */
23			int ns; /* number of samples per axis */
24			COLOR acoef; /* division contribution coefficient */
25			struct s_ambsamp {
26			COLOR v; /* hemisphere sample value */
27			float p[3]; /* intersection point */
28			} sa[1]; /* sample array (extends struct) */
29			} AMBHEMI; /* ambient sample hemisphere */
30
31			#define ambsamp(h,i,j) (h)->sa[(i)*(h)->ns + (j)]
32
33
34			static AMBHEMI *
35			inithemi( /* initialize sampling hemisphere */
36			COLOR ac,
37			RAY *r,
38			double wt
39			)
40			{
41			AMBHEMI *hp;
42			double d;
43			int n, i;
44			/* set number of divisions */
45			if (ambacc <= FTINY &&
46			wt > (d = 0.8intens(ac)r->rweight/(ambdiv*minweight)))
47			wt = d; /* avoid ray termination */
48			n = sqrt(ambdiv * wt) + 0.5;
49			i = 1 + 4(ambacc > FTINY); / minimum number of samples */
50			if (n < i)
51			n = i;
52			/* allocate sampling array */
53			hp = (AMBHEMI *)malloc(sizeof(AMBHEMI) +
54			sizeof(struct s_ambsamp)(nn - 1));
55			if (hp == NULL)
56			return(NULL);
57			hp->rp = r;
58			hp->ns = n;
59			/* assign coefficient */
60			copycolor(hp->acoef, ac);
61			d = 1.0/(n*n);
62			scalecolor(hp->acoef, d);
63			/* make tangent axes */
64			hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
65			for (i = 0; i < 3; i++)
66			if (r->rn[i] < 0.6 && r->rn[i] > -0.6)
67			break;
68			if (i >= 3)
69			error(CONSISTENCY, "bad ray direction in inithemi()");
70			hp->uy[i] = 1.0;
71			VCROSS(hp->ux, hp->uy, r->rn);
72			normalize(hp->ux);
73			VCROSS(hp->uy, r->rn, hp->ux);
74			/* we're ready to sample */
75			return(hp);
76			}
77
78
79			static int
80			ambsample( /* sample an ambient direction */
81			AMBHEMI *hp,
82			int i,
83			int j,
84			)
85			{
86			struct s_ambsamp *ap = &ambsamp(hp,i,j);
87			RAY ar;
88			int hlist[3];
89			double spt[2], dz;
90			int ii;
91			/* ambient coefficient for weight */
92			if (ambacc > FTINY)
93			setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
94			else
95			copycolor(ar.rcoef, hp->acoef);
96			if (rayorigin(&ar, AMBIENT, hp->rp, ar.rcoef) < 0) {
97			setcolor(ap->v, 0., 0., 0.);
98			ap->r = 0.;
99			return(0); /* no sample taken */
100			}
101			if (ambacc > FTINY) {
102			multcolor(ar.rcoef, hp->acoef);
103			scalecolor(ar.rcoef, 1./AVGREFL);
104			}
105			/* generate hemispherical sample */
106			SDsquare2disk(spt, (i+frandom())/hp->ns, (j+frandom())/hp->ns);
107			zd = sqrt(1. - spt[0]spt[0] - spt[1]spt[1]);
108			for (ii = 3; ii--; )
109			ar.rdir[ii] = spt[0]*hp->ux[ii] +
110			spt[1]*hp->uy[ii] +
111			zd*hp->rp->ron[ii];
112			checknorm(ar.rdir);
113			dimlist[ndims++] = i*hp->ns + j + 90171;
114			rayvalue(&ar); /* evaluate ray */
115			ndims--;
116			multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
117			copycolor(ap->v, ar.rcol);
118			if (ar.rt > 20.0maxarad) / limit vertex distance */
119			ar.rt = 20.0*maxarad;
120			VSUM(ap->p, ar.rorg, ar.rdir, ar.rt);
121			return(1);
122			}
123
124
125			static void
126			ambHessian( /* anisotropic radii & pos. gradient */
127			AMBHEMI *hp,
128			FVECT uv[2], /* returned */
129			float ra[2], /* returned */
130			float pg[2] /* returned */
131			)
132			{
133			if (ra != NULL) { /* compute Hessian-derived radii */
134			} else { /* else copy original tangent axes */
135			VCOPY(uv[0], hp->ux);
136			VCOPY(uv[1], hp->uy);
137			}
138			if (pg == NULL) /* no position gradient requested? */
139			return;
140			}
141
142			int
143			doambient( /* compute ambient component */
144			COLOR rcol, /* input/output color */
145			RAY *r,
146			double wt,
147			FVECT uv[2], /* returned */
148			float ra[2], /* returned */
149			float pg[2], /* returned */
150			float dg[2] /* returned */
151			)
152			{
153			int cnt = 0;
154			FVECT my_uv[2];
155			AMBHEMI *hp;
156			double d, acol[3];
157			struct s_ambsamp *ap;
158			int i, j;
159			/* initialize */
160			if ((hp = inithemi(rcol, r, wt)) == NULL)
161			return(0);
162			if (uv != NULL)
163			memset(uv, 0, sizeof(FVECT)*2);
164			if (ra != NULL)
165			ra[0] = ra[1] = 0.0;
166			if (pg != NULL)
167			pg[0] = pg[1] = 0.0;
168			if (dg != NULL)
169			dg[0] = dg[1] = 0.0;
170			/* sample the hemisphere */
171			acol[0] = acol[1] = acol[2] = 0.0;
172			for (i = hemi.ns; i--; )
173			for (j = hemi.ns; j--; )
174			if (ambsample(hp, i, j)) {
175			ap = &ambsamp(hp,i,j);
176			addcolor(acol, ap->v);
177			++cnt;
178			}
179			if (!cnt) {
180			setcolor(rcol, 0.0, 0.0, 0.0);
181			free(hp);
182			return(0); /* no valid samples */
183			}
184			d = 1.0 / cnt; /* final indirect irradiance/PI */
185			acol[0] = d; acol[1] = d; acol[2] *= d;
186			copycolor(rcol, acol);
187			if (cnt < hp->nshp->ns \|\| / incomplete sampling? */
188			(ra == NULL) & (pg == NULL) & (dg == NULL)) {
189			free(hp);
190			return(-1); /* no radius or gradient calc. */
191			}
192			d = 0.01 * bright(rcol); /* add in 1% before Hessian comp. */
193			if (d < FTINY) d = FTINY;
194			ap = hp->sa; /* using Y channel from here on... */
195			for (i = hp->ns*hp->ns; i--; ap++)
196			colval(ap->v,CIEY) = bright(ap->v) + d;
197
198			if (uv == NULL) /* make sure we have axis pointers */
199			uv = my_uv;
200			/* compute radii & pos. gradient */
201			ambHessian(hp, uv, ra, pg);
202			if (dg != NULL) /* compute direction gradient */
203			ambdirgrad(hp, uv, dg);
204			if (ra != NULL) { /* adjust/clamp radii */
205			d = pow(wt, -0.25);
206			if ((ra[0] *= d) > maxarad)
207			ra[0] = maxarad;
208			if ((ra[1] = d) > 2.0ra[0])
209			ra[1] = 2.0*ra[0];
210			}
211			free(hp); /* clean up and return */
212			return(1);
213			}
214
215
216	greg	2.25	#else /* ! NEWAMB */
217	greg	1.1
218
219	greg	2.15	void
220	greg	2.14	inithemi( /* initialize sampling hemisphere */
221	greg	2.23	AMBHEMI *hp,
222	greg	2.16	COLOR ac,
223	greg	2.14	RAY *r,
224			double wt
225			)
226	greg	1.1	{
227	greg	2.16	double d;
228	greg	2.23	int i;
229	greg	2.14	/* set number of divisions */
230	greg	2.16	if (ambacc <= FTINY &&
231	greg	2.20	wt > (d = 0.8intens(ac)r->rweight/(ambdiv*minweight)))
232	greg	2.16	wt = d; /* avoid ray termination */
233			hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
234	greg	2.14	i = ambacc > FTINY ? 3 : 1; /* minimum number of samples */
235			if (hp->nt < i)
236			hp->nt = i;
237			hp->np = PI * hp->nt + 0.5;
238			/* set number of super-samples */
239	greg	2.15	hp->ns = ambssamp * wt + 0.5;
240	greg	2.16	/* assign coefficient */
241	greg	2.14	copycolor(hp->acoef, ac);
242	greg	2.16	d = 1.0/(hp->nt*hp->np);
243			scalecolor(hp->acoef, d);
244	greg	2.14	/* make axes */
245			VCOPY(hp->uz, r->ron);
246			hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
247			for (i = 0; i < 3; i++)
248			if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
249			break;
250			if (i >= 3)
251			error(CONSISTENCY, "bad ray direction in inithemi");
252			hp->uy[i] = 1.0;
253			fcross(hp->ux, hp->uy, hp->uz);
254			normalize(hp->ux);
255			fcross(hp->uy, hp->uz, hp->ux);
256	greg	1.1	}
257
258
259	greg	2.9	int
260	greg	2.14	divsample( /* sample a division */
261	greg	2.23	AMBSAMP *dp,
262	greg	2.14	AMBHEMI *h,
263			RAY *r
264			)
265	greg	1.1	{
266			RAY ar;
267	greg	1.11	int hlist[3];
268			double spt[2];
269	greg	1.1	double xd, yd, zd;
270			double b2;
271			double phi;
272	greg	2.23	int i;
273	greg	2.15	/* ambient coefficient for weight */
274	greg	2.16	if (ambacc > FTINY)
275			setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
276			else
277			copycolor(ar.rcoef, h->acoef);
278	greg	2.14	if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0)
279	greg	1.4	return(-1);
280	greg	2.17	if (ambacc > FTINY) {
281			multcolor(ar.rcoef, h->acoef);
282			scalecolor(ar.rcoef, 1./AVGREFL);
283			}
284	greg	1.1	hlist[0] = r->rno;
285			hlist[1] = dp->t;
286			hlist[2] = dp->p;
287	greg	1.13	multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n));
288	greg	1.11	zd = sqrt((dp->t + spt[0])/h->nt);
289			phi = 2.0PI (dp->p + spt[1])/h->np;
290	gwlarson	2.8	xd = tcos(phi) * zd;
291			yd = tsin(phi) * zd;
292	greg	1.1	zd = sqrt(1.0 - zd*zd);
293	greg	1.2	for (i = 0; i < 3; i++)
294			ar.rdir[i] = xd*h->ux[i] +
295			yd*h->uy[i] +
296			zd*h->uz[i];
297	greg	2.22	checknorm(ar.rdir);
298	greg	1.2	dimlist[ndims++] = dp->t*h->np + dp->p + 90171;
299	greg	1.1	rayvalue(&ar);
300			ndims--;
301	greg	2.16	multcolor(ar.rcol, ar.rcoef); /* apply coefficient */
302	greg	1.1	addcolor(dp->v, ar.rcol);
303	greg	2.9	/* use rt to improve gradient calc */
304			if (ar.rt > FTINY && ar.rt < FHUGE)
305			dp->r += 1.0/ar.rt;
306	greg	1.1	/* (re)initialize error */
307			if (dp->n++) {
308			b2 = bright(dp->v)/dp->n - bright(ar.rcol);
309			b2 = b2b2 + dp->k((dp->n-1)*(dp->n-1));
310			dp->k = b2/(dp->n*dp->n);
311			} else
312			dp->k = 0.0;
313	greg	1.4	return(0);
314	greg	1.1	}
315
316
317	greg	2.14	static int
318			ambcmp( /* decreasing order */
319			const void *p1,
320			const void *p2
321			)
322			{
323			const AMBSAMP d1 = (const AMBSAMP )p1;
324			const AMBSAMP d2 = (const AMBSAMP )p2;
325
326			if (d1->k < d2->k)
327			return(1);
328			if (d1->k > d2->k)
329			return(-1);
330			return(0);
331			}
332
333
334			static int
335			ambnorm( /* standard order */
336			const void *p1,
337			const void *p2
338			)
339			{
340			const AMBSAMP d1 = (const AMBSAMP )p1;
341			const AMBSAMP d2 = (const AMBSAMP )p2;
342	greg	2.23	int c;
343	greg	2.14
344			if ( (c = d1->t - d2->t) )
345			return(c);
346			return(d1->p - d2->p);
347			}
348
349
350	greg	1.1	double
351	greg	2.14	doambient( /* compute ambient component */
352	greg	2.23	COLOR rcol,
353	greg	2.14	RAY *r,
354			double wt,
355			FVECT pg,
356			FVECT dg
357			)
358	greg	1.1	{
359	greg	2.24	double b, d=0;
360	greg	1.1	AMBHEMI hemi;
361			AMBSAMP *div;
362			AMBSAMP dnew;
363	greg	2.23	double acol[3];
364			AMBSAMP *dp;
365	greg	1.1	double arad;
366	greg	2.19	int divcnt;
367	greg	2.23	int i, j;
368	greg	1.1	/* initialize hemisphere */
369	greg	2.23	inithemi(&hemi, rcol, r, wt);
370	greg	2.19	divcnt = hemi.nt * hemi.np;
371	greg	2.17	/* initialize */
372			if (pg != NULL)
373			pg[0] = pg[1] = pg[2] = 0.0;
374			if (dg != NULL)
375			dg[0] = dg[1] = dg[2] = 0.0;
376	greg	2.23	setcolor(rcol, 0.0, 0.0, 0.0);
377	greg	2.19	if (divcnt == 0)
378	greg	1.1	return(0.0);
379	greg	2.14	/* allocate super-samples */
380	greg	2.15	if (hemi.ns > 0 \|\| pg != NULL \|\| dg != NULL) {
381	greg	2.19	div = (AMBSAMP )malloc(divcntsizeof(AMBSAMP));
382	greg	1.1	if (div == NULL)
383			error(SYSTEM, "out of memory in doambient");
384			} else
385			div = NULL;
386			/* sample the divisions */
387			arad = 0.0;
388	greg	2.23	acol[0] = acol[1] = acol[2] = 0.0;
389	greg	1.1	if ((dp = div) == NULL)
390			dp = &dnew;
391	greg	2.19	divcnt = 0;
392	greg	1.1	for (i = 0; i < hemi.nt; i++)
393			for (j = 0; j < hemi.np; j++) {
394			dp->t = i; dp->p = j;
395			setcolor(dp->v, 0.0, 0.0, 0.0);
396	greg	1.2	dp->r = 0.0;
397	greg	1.1	dp->n = 0;
398	greg	2.16	if (divsample(dp, &hemi, r) < 0) {
399	greg	2.19	if (div != NULL)
400			dp++;
401	greg	2.16	continue;
402			}
403	greg	2.6	arad += dp->r;
404	greg	2.19	divcnt++;
405	greg	1.1	if (div != NULL)
406			dp++;
407	greg	2.6	else
408	greg	1.1	addcolor(acol, dp->v);
409			}
410	greg	2.21	if (!divcnt) {
411			if (div != NULL)
412			free((void *)div);
413	greg	2.19	return(0.0); /* no samples taken */
414	greg	2.21	}
415	greg	2.19	if (divcnt < hemi.nt*hemi.np) {
416			pg = dg = NULL; /* incomplete sampling */
417			hemi.ns = 0;
418			} else if (arad > FTINY && divcnt/arad < minarad) {
419	greg	2.15	hemi.ns = 0; /* close enough */
420	greg	2.19	} else if (hemi.ns > 0) { /* else perform super-sampling? */
421	greg	1.4	comperrs(div, &hemi); /* compute errors */
422	greg	2.19	qsort(div, divcnt, sizeof(AMBSAMP), ambcmp); /* sort divs */
423	greg	1.1	/* super-sample */
424	greg	2.15	for (i = hemi.ns; i > 0; i--) {
425	schorsch	2.11	dnew = *div;
426	greg	2.16	if (divsample(&dnew, &hemi, r) < 0) {
427			dp++;
428			continue;
429			}
430			dp = div; /* reinsert */
431	greg	2.19	j = divcnt < i ? divcnt : i;
432	greg	1.1	while (--j > 0 && dnew.k < dp[1].k) {
433	schorsch	2.11	dp = (dp+1);
434	greg	1.1	dp++;
435			}
436	schorsch	2.11	*dp = dnew;
437	greg	1.1	}
438	greg	1.2	if (pg != NULL \|\| dg != NULL) /* restore order */
439	greg	2.19	qsort(div, divcnt, sizeof(AMBSAMP), ambnorm);
440	greg	1.1	}
441			/* compute returned values */
442	greg	1.3	if (div != NULL) {
443	greg	2.19	arad = 0.0; /* note: divcnt may be < ntnp /
444			for (i = hemi.nt*hemi.np, dp = div; i-- > 0; dp++) {
445	greg	1.3	arad += dp->r;
446			if (dp->n > 1) {
447			b = 1.0/dp->n;
448			scalecolor(dp->v, b);
449			dp->r *= b;
450			dp->n = 1;
451			}
452			addcolor(acol, dp->v);
453			}
454	greg	1.5	b = bright(acol);
455	greg	1.6	if (b > FTINY) {
456	greg	2.17	b = 1.0/b; /* compute & normalize gradient(s) */
457	greg	1.6	if (pg != NULL) {
458			posgradient(pg, div, &hemi);
459			for (i = 0; i < 3; i++)
460			pg[i] *= b;
461			}
462			if (dg != NULL) {
463			dirgradient(dg, div, &hemi);
464			for (i = 0; i < 3; i++)
465			dg[i] *= b;
466			}
467	greg	1.5	}
468	greg	2.9	free((void *)div);
469	greg	1.3	}
470	greg	2.23	copycolor(rcol, acol);
471	greg	1.1	if (arad <= FTINY)
472	greg	1.16	arad = maxarad;
473	greg	2.3	else
474	greg	2.19	arad = (divcnt+hemi.ns)/arad;
475	greg	1.15	if (pg != NULL) { /* reduce radius if gradient large */
476			d = DOT(pg,pg);
477			if (daradarad > 1.0)
478			arad = 1.0/sqrt(d);
479			}
480	greg	1.16	if (arad < minarad) {
481	greg	1.1	arad = minarad;
482	greg	1.16	if (pg != NULL && daradarad > 1.0) { /* cap gradient */
483			d = 1.0/arad/sqrt(d);
484			for (i = 0; i < 3; i++)
485			pg[i] *= d;
486			}
487			}
488	greg	2.3	if ((arad /= sqrt(wt)) > maxarad)
489			arad = maxarad;
490			return(arad);
491	greg	1.1	}
492
493
494	greg	2.9	void
495	greg	2.14	comperrs( /* compute initial error estimates */
496			AMBSAMP da, / assumes standard ordering */
497	greg	2.23	AMBHEMI *hp
498	greg	2.14	)
499	greg	1.1	{
500			double b, b2;
501			int i, j;
502	greg	2.23	AMBSAMP *dp;
503	greg	1.1	/* sum differences from neighbors */
504			dp = da;
505			for (i = 0; i < hp->nt; i++)
506			for (j = 0; j < hp->np; j++) {
507	greg	1.6	#ifdef DEBUG
508			if (dp->t != i \|\| dp->p != j)
509			error(CONSISTENCY,
510			"division order in comperrs");
511			#endif
512	greg	1.1	b = bright(dp[0].v);
513			if (i > 0) { /* from above */
514			b2 = bright(dp[-hp->np].v) - b;
515			b2 = b2 0.25;
516			dp[0].k += b2;
517			dp[-hp->np].k += b2;
518			}
519			if (j > 0) { /* from behind */
520			b2 = bright(dp[-1].v) - b;
521			b2 = b2 0.25;
522			dp[0].k += b2;
523			dp[-1].k += b2;
524	greg	1.4	} else { /* around */
525			b2 = bright(dp[hp->np-1].v) - b;
526	greg	1.1	b2 = b2 0.25;
527			dp[0].k += b2;
528	greg	1.4	dp[hp->np-1].k += b2;
529	greg	1.1	}
530			dp++;
531			}
532			/* divide by number of neighbors */
533			dp = da;
534			for (j = 0; j < hp->np; j++) /* top row */
535			(dp++)->k *= 1.0/3.0;
536			if (hp->nt < 2)
537			return;
538			for (i = 1; i < hp->nt-1; i++) /* central region */
539			for (j = 0; j < hp->np; j++)
540			(dp++)->k *= 0.25;
541			for (j = 0; j < hp->np; j++) /* bottom row */
542			(dp++)->k *= 1.0/3.0;
543			}
544
545
546	greg	2.9	void
547	greg	2.14	posgradient( /* compute position gradient */
548			FVECT gv,
549			AMBSAMP da, / assumes standard ordering */
550	greg	2.23	AMBHEMI *hp
551	greg	2.14	)
552	greg	1.1	{
553	greg	2.23	int i, j;
554	greg	2.2	double nextsine, lastsine, b, d;
555	greg	1.2	double mag0, mag1;
556			double phi, cosp, sinp, xd, yd;
557	greg	2.23	AMBSAMP *dp;
558	greg	1.2
559			xd = yd = 0.0;
560			for (j = 0; j < hp->np; j++) {
561			dp = da + j;
562			mag0 = mag1 = 0.0;
563	greg	2.2	lastsine = 0.0;
564	greg	1.2	for (i = 0; i < hp->nt; i++) {
565			#ifdef DEBUG
566			if (dp->t != i \|\| dp->p != j)
567			error(CONSISTENCY,
568			"division order in posgradient");
569			#endif
570			b = bright(dp->v);
571			if (i > 0) {
572			d = dp[-hp->np].r;
573			if (dp[0].r > d) d = dp[0].r;
574	greg	2.2	/* sin(t)cos(t)^2 /
575			d = lastsine (1.0 - (double)i/hp->nt);
576	greg	1.2	mag0 += d*(b - bright(dp[-hp->np].v));
577			}
578	greg	2.2	nextsine = sqrt((double)(i+1)/hp->nt);
579	greg	1.2	if (j > 0) {
580			d = dp[-1].r;
581			if (dp[0].r > d) d = dp[0].r;
582	greg	2.2	mag1 += d * (nextsine - lastsine) *
583			(b - bright(dp[-1].v));
584	greg	1.2	} else {
585			d = dp[hp->np-1].r;
586			if (dp[0].r > d) d = dp[0].r;
587	greg	2.2	mag1 += d * (nextsine - lastsine) *
588			(b - bright(dp[hp->np-1].v));
589	greg	1.2	}
590			dp += hp->np;
591	greg	2.2	lastsine = nextsine;
592	greg	1.2	}
593	greg	2.2	mag0 = 2.0PI / hp->np;
594	greg	1.2	phi = 2.0PI (double)j/hp->np;
595	gwlarson	2.8	cosp = tcos(phi); sinp = tsin(phi);
596	greg	1.2	xd += mag0cosp - mag1sinp;
597			yd += mag0sinp + mag1cosp;
598			}
599			for (i = 0; i < 3; i++)
600	greg	2.16	gv[i] = (xdhp->ux[i] + ydhp->uy[i])(hp->nthp->np)/PI;
601	greg	1.1	}
602
603
604	greg	2.9	void
605	greg	2.14	dirgradient( /* compute direction gradient */
606			FVECT gv,
607			AMBSAMP da, / assumes standard ordering */
608	greg	2.23	AMBHEMI *hp
609	greg	2.14	)
610	greg	1.1	{
611	greg	2.23	int i, j;
612	greg	1.2	double mag;
613			double phi, xd, yd;
614	greg	2.23	AMBSAMP *dp;
615	greg	1.2
616			xd = yd = 0.0;
617			for (j = 0; j < hp->np; j++) {
618			dp = da + j;
619			mag = 0.0;
620			for (i = 0; i < hp->nt; i++) {
621			#ifdef DEBUG
622			if (dp->t != i \|\| dp->p != j)
623			error(CONSISTENCY,
624			"division order in dirgradient");
625			#endif
626	greg	2.2	/* tan(t) */
627			mag += bright(dp->v)/sqrt(hp->nt/(i+.5) - 1.0);
628	greg	1.2	dp += hp->np;
629			}
630			phi = 2.0PI (j+.5)/hp->np + PI/2.0;
631	gwlarson	2.8	xd += mag * tcos(phi);
632			yd += mag * tsin(phi);
633	greg	1.2	}
634			for (i = 0; i < 3; i++)
635	greg	2.16	gv[i] = xdhp->ux[i] + ydhp->uy[i];
636	greg	1.1	}
637	greg	2.25
638			#endif /* ! NEWAMB */