/* mix two colors according to weights given -- cres may be c1 or c2 */
void
c_cmix(C_COLOR *cres, double w1, C_COLOR *c1, double w2, C_COLOR *c2)
{
double scale;
int i;
if (w1 == 0) {
*cres = *c2;
return;
}
if (w2 == 0) {
*cres = *c1;
return;
}
if ((c1->flags|c2->flags) & C_CDSPEC) { /* spectral mixing */
float cmix[C_CNSS];
c_ccvt(c1, C_CSSPEC|C_CSEFF);
c_ccvt(c2, C_CSSPEC|C_CSEFF);
if (c1->ssum*c2->ssum == 0) {
*cres = c_dfcolor;
return;
}
w1 /= c1->eff*c1->ssum;
w2 /= c2->eff*c2->ssum;
scale = 0.;
for (i = 0; i < C_CNSS; i++) {
cmix[i] = w1*c1->ssamp[i] + w2*c2->ssamp[i];
if (cmix[i] > scale)
scale = cmix[i];
else if (cmix[i] < -scale)
scale = -cmix[i];
}
scale = C_CMAXV / scale;
cres->ssum = 0;
for (i = 0; i < C_CNSS; i++)
cres->ssum += cres->ssamp[i] = scale*cmix[i] + frand();
cres->flags = C_CDSPEC|C_CSSPEC;
} else { /* CIE xy mixing */
c_ccvt(c1, C_CSXY);
c_ccvt(c2, C_CSXY);
w1 *= c2->cy;
w2 *= c1->cy;
scale = w1 + w2;
if (scale == 0.) {
*cres = c_dfcolor;
return;
}
scale = 1. / scale;
cres->cx = (w1*c1->cx + w2*c2->cx) * scale;
cres->cy = (w1*c1->cy + w2*c2->cy) * scale;
cres->flags = C_CDXY|C_CSXY;
}
}
/* multiply two colors -- cres may be c1 or c2 */
double
c_cmult(C_COLOR *cres, C_COLOR *c1, double y1, C_COLOR *c2, double y2)
{
double yres;
int i;
if ((c1->flags|c2->flags) & C_CDSPEC) {
long cmix[C_CNSS], cmax = 0; /* spectral multiply */
c_ccvt(c1, C_CSSPEC|C_CSEFF);
c_ccvt(c2, C_CSSPEC|C_CSEFF);
for (i = 0; i < C_CNSS; i++) {
cmix[i] = c1->ssamp[i] * c2->ssamp[i];
if (cmix[i] > cmax)
cmax = cmix[i];
else if (cmix[i] < -cmax)
cmax = -cmix[i];
}
cmax /= C_CMAXV;
if (!cmax) {
*cres = c_dfcolor;
return(0.);
}
cres->ssum = 0;
for (i = 0; i < C_CNSS; i++)
cres->ssum += cres->ssamp[i] = cmix[i] / cmax;
cres->flags = C_CDSPEC|C_CSSPEC;
c_ccvt(cres, C_CSEFF); /* below is correct */
yres = y1 * y2 * c_y31.ssum * C_CLPWM /
(c1->eff*c1->ssum * c2->eff*c2->ssum) *
cres->eff*( cres->ssum*(double)cmax +
C_CNSS/2.0*(cmax-1) );
} else {
float rgb1[3], rgb2[3]; /* CIE xy multiply */
c_toSharpRGB(c1, y1, rgb1);
c_toSharpRGB(c2, y2, rgb2);
rgb2[0] *= rgb1[0]; rgb2[1] *= rgb1[1]; rgb2[2] *= rgb1[2];
yres = c_fromSharpRGB(rgb2, cres);
}
return(yres);
}
/* check if color is grey */
int
c_isgrey(C_COLOR *clr)
{
if (!(clr->flags & (C_CSXY|C_CSSPEC)))
return(1); /* no settings == grey */
c_ccvt(clr, C_CSXY);
return(clr->cx >= .323 && clr->cx <= .343 &&
clr->cy >= .323 && clr->cy <= .343);
}
void
cvtcolor( /* convert a CIE XYZ color to RGB */
COLOR radrgb,
register C_COLOR *ciec,
double intensity
)
{
static COLOR ciexyz;
c_ccvt(ciec, C_CSXY); /* get xy representation */
ciexyz[1] = intensity;
ciexyz[0] = ciec->cx/ciec->cy*ciexyz[1];
ciexyz[2] = ciexyz[1]*(1./ciec->cy - 1.) - ciexyz[0];
cie_rgb(radrgb, ciexyz);
}
/* encode (x,y) chromaticity */
C_CHROMA
c_encodeChroma(C_COLOR *clr)
{
double df;
int ub, vb;
c_ccvt(clr, C_CSXY);
df = UV_NORMF/(-2.*clr->cx + 12.*clr->cy + 3.);
ub = 4.*clr->cx*df + frand();
if (ub > 0xff) ub = 0xff;
else ub *= (ub > 0);
vb = 9.*clr->cy*df + frand();
if (vb > 0xff) vb = 0xff;
else vb *= (vb > 0);
return(vb<<8 | ub);
}
void
ccy2rgb( /* convert MGF color to RGB */
C_COLOR *cin, /* input MGF chrominance */
double cieY, /* input luminance or reflectance */
COLOR cout /* output RGB color */
)
{
double d;
COLOR xyz;
/* get CIE XYZ representation */
c_ccvt(cin, C_CSXY);
d = cin->cx/cin->cy;
xyz[CIEX] = d * cieY;
xyz[CIEY] = cieY;
xyz[CIEZ] = (1./cin->cy - d - 1.) * cieY;
cie_rgb(cout, xyz);
}
/* convert to sharpened RGB color for low-error operations */
void
c_toSharpRGB(C_COLOR *cin, double cieY, float cout[3])
{
double xyz[3];
c_ccvt(cin, C_CSXY);
xyz[0] = cin->cx/cin->cy * cieY;
xyz[1] = cieY;
xyz[2] = (1. - cin->cx - cin->cy)/cin->cy * cieY;
cout[0] = XYZtoSharp[0][0]*xyz[0] + XYZtoSharp[0][1]*xyz[1] +
XYZtoSharp[0][2]*xyz[2];
cout[1] = XYZtoSharp[1][0]*xyz[0] + XYZtoSharp[1][1]*xyz[1] +
XYZtoSharp[1][2]*xyz[2];
cout[2] = XYZtoSharp[2][0]*xyz[0] + XYZtoSharp[2][1]*xyz[1] +
XYZtoSharp[2][2]*xyz[2];
}
/* Sample an individual BSDF component */
SDError
SDsampComponent(SDValue *sv, FVECT ioVec, double randX, SDComponent *sdc)
{
float coef[SDmaxCh];
SDError ec;
FVECT inVec;
const SDCDst *cd;
double d;
int n;
/* check arguments */
if ((sv == NULL) | (ioVec == NULL) | (sdc == NULL))
return SDEargument;
/* get cumulative distribution */
VCOPY(inVec, ioVec);
cd = (*sdc->func->getCDist)(inVec, sdc);
if (cd == NULL)
return SDEmemory;
if (cd->cTotal <= 1e-6) { /* anything to sample? */
sv->spec = c_dfcolor;
sv->cieY = .0;
memset(ioVec, 0, 3*sizeof(double));
return SDEnone;
}
sv->cieY = cd->cTotal;
/* compute sample direction */
ec = (*sdc->func->sampCDist)(ioVec, randX, cd);
if (ec)
return ec;
/* get BSDF color */
n = (*sdc->func->getBSDFs)(coef, ioVec, inVec, sdc);
if (n <= 0) {
strcpy(SDerrorDetail, "BSDF sample value error");
return SDEinternal;
}
sv->spec = sdc->cspec[0];
d = coef[0];
while (--n) {
c_cmix(&sv->spec, d, &sv->spec, coef[n], &sdc->cspec[n]);
d += coef[n];
}
/* make sure everything is set */
c_ccvt(&sv->spec, C_CSXY+C_CSSPEC);
return SDEnone;
}
/* Return BSDF for the given incident and scattered ray vectors */
SDError
SDevalBSDF(SDValue *sv, const FVECT outVec, const FVECT inVec, const SDData *sd)
{
int inFront, outFront;
SDSpectralDF *sdf;
float coef[SDmaxCh];
int nch, i;
/* check arguments */
if ((sv == NULL) | (outVec == NULL) | (inVec == NULL) | (sd == NULL))
return SDEargument;
/* whose side are we on? */
inFront = (inVec[2] > 0);
outFront = (outVec[2] > 0);
/* start with diffuse portion */
if (inFront & outFront) {
*sv = sd->rLambFront;
sdf = sd->rf;
} else if (!(inFront | outFront)) {
*sv = sd->rLambBack;
sdf = sd->rb;
} else if (inFront) {
*sv = sd->tLamb;
sdf = (sd->tf != NULL) ? sd->tf : sd->tb;
} else /* inBack */ {
*sv = sd->tLamb;
sdf = (sd->tb != NULL) ? sd->tb : sd->tf;
}
sv->cieY *= 1./M_PI;
/* add non-diffuse components */
i = (sdf != NULL) ? sdf->ncomp : 0;
while (i-- > 0) {
nch = (*sdf->comp[i].func->getBSDFs)(coef, outVec, inVec,
&sdf->comp[i]);
while (nch-- > 0) {
c_cmix(&sv->spec, sv->cieY, &sv->spec,
coef[nch], &sdf->comp[i].cspec[nch]);
sv->cieY += coef[nch];
}
}
/* make sure everything is set */
c_ccvt(&sv->spec, C_CSXY+C_CSSPEC);
return SDEnone;
}
/* Sample BSDF direction based on the given random variable */
SDError
SDsampBSDF(SDValue *sv, FVECT ioVec, double randX, int sflags, const SDData *sd)
{
SDError ec;
FVECT inVec;
int inFront;
SDSpectralDF *rdf, *tdf;
double rdiff;
float coef[SDmaxCh];
int i, j, n, nr;
SDComponent *sdc;
const SDCDst **cdarr = NULL;
/* check arguments */
if ((sv == NULL) | (ioVec == NULL) | (sd == NULL) |
(randX < 0) | (randX >= 1.))
return SDEargument;
/* whose side are we on? */
VCOPY(inVec, ioVec);
inFront = (inVec[2] > 0);
/* remember diffuse portions */
if (inFront) {
*sv = sd->rLambFront;
rdf = sd->rf;
tdf = (sd->tf != NULL) ? sd->tf : sd->tb;
} else /* !inFront */ {
*sv = sd->rLambBack;
rdf = sd->rb;
tdf = (sd->tb != NULL) ? sd->tb : sd->tf;
}
if ((sflags & SDsampDf+SDsampR) != SDsampDf+SDsampR)
sv->cieY = .0;
rdiff = sv->cieY;
if ((sflags & SDsampDf+SDsampT) == SDsampDf+SDsampT)
sv->cieY += sd->tLamb.cieY;
/* gather non-diffuse components */
i = nr = (((sflags & SDsampSp+SDsampR) == SDsampSp+SDsampR) &
(rdf != NULL)) ? rdf->ncomp : 0;
j = (((sflags & SDsampSp+SDsampT) == SDsampSp+SDsampT) &
(tdf != NULL)) ? tdf->ncomp : 0;
n = i + j;
if (n > 0 && (cdarr = (const SDCDst **)malloc(n*sizeof(SDCDst *))) == NULL)
return SDEmemory;
while (j-- > 0) { /* non-diffuse transmission */
cdarr[i+j] = (*tdf->comp[j].func->getCDist)(inVec, &tdf->comp[j]);
if (cdarr[i+j] == NULL) {
free(cdarr);
return SDEmemory;
}
sv->cieY += cdarr[i+j]->cTotal;
}
while (i-- > 0) { /* non-diffuse reflection */
cdarr[i] = (*rdf->comp[i].func->getCDist)(inVec, &rdf->comp[i]);
if (cdarr[i] == NULL) {
free(cdarr);
return SDEmemory;
}
sv->cieY += cdarr[i]->cTotal;
}
if (sv->cieY <= 1e-6) { /* anything to sample? */
sv->cieY = .0;
memset(ioVec, 0, 3*sizeof(double));
return SDEnone;
}
/* scale random variable */
randX *= sv->cieY;
/* diffuse reflection? */
if (randX < rdiff) {
SDdiffuseSamp(ioVec, inFront, randX/rdiff);
goto done;
}
randX -= rdiff;
/* diffuse transmission? */
if ((sflags & SDsampDf+SDsampT) == SDsampDf+SDsampT) {
if (randX < sd->tLamb.cieY) {
sv->spec = sd->tLamb.spec;
SDdiffuseSamp(ioVec, !inFront, randX/sd->tLamb.cieY);
goto done;
}
randX -= sd->tLamb.cieY;
}
/* else one of cumulative dist. */
for (i = 0; i < n && randX < cdarr[i]->cTotal; i++)
randX -= cdarr[i]->cTotal;
if (i >= n)
return SDEinternal;
/* compute sample direction */
sdc = (i < nr) ? &rdf->comp[i] : &tdf->comp[i-nr];
ec = (*sdc->func->sampCDist)(ioVec, randX/cdarr[i]->cTotal, cdarr[i]);
if (ec)
return ec;
/* compute color */
j = (*sdc->func->getBSDFs)(coef, ioVec, inVec, sdc);
if (j <= 0) {
sprintf(SDerrorDetail, "BSDF \"%s\" sampling value error",
sd->name);
return SDEinternal;
}
sv->spec = sdc->cspec[0];
rdiff = coef[0];
while (--j) {
c_cmix(&sv->spec, rdiff, &sv->spec, coef[j], &sdc->cspec[j]);
rdiff += coef[j];
}
done:
if (cdarr != NULL)
free(cdarr);
/* make sure everything is set */
c_ccvt(&sv->spec, C_CSXY+C_CSSPEC);
return SDEnone;
}
