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Improved sample pattern for AO. It used to jitter locatations within

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a UV Sphere which isn't a very uniform distribution on a sphere.
Now I itterate a evenly distributed set of points on sphere, and use that
by random rotating the entire sphere for each pixel.

http://www.blender.org/bf/samp3.jpg
http://www.blender.org/bf/samp4.jpg

Both pics same rendertime, 36 AO samples. Quite a difference, eh!

Will put html page for release up.
This commit is contained in:
Ton Roosendaal 2004-04-16 15:32:49 +00:00
parent 4e2f7baff2
commit 2cc124cf3b
1 changed files with 157 additions and 55 deletions
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212
source/blender/render/intern/source/ray.c
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@ -1860,18 +1860,147 @@ void RandomSpherical(float *v)
else v[2] = 1.f;
}
static void DS_energy(float *sphere, int tot, float *vec)
{
float *fp, fac, force[3], res[3];
int a;
res[0]= res[1]= res[2]= 0.0;
for(a=0, fp=sphere; a<tot; a++, fp+=3) {
VecSubf(force, vec, fp);
fac= force[0]*force[0] + force[1]*force[1] + force[2]*force[2];
if(fac!=0.0) {
fac= 1.0/fac;
res[0]+= fac*force[0];
res[1]+= fac*force[1];
res[2]+= fac*force[2];
}
}
VecMulf(res, 0.5);
VecAddf(vec, vec, res);
Normalise(vec);
}
static void DistributedSpherical(float *sphere, int tot, int iter)
{
float *fp;
int a;
/* init */
fp= sphere;
for(a=0; a<tot; a++, fp+= 3) {
RandomSpherical(fp);
}
while(iter--) {
for(a=0, fp= sphere; a<tot; a++, fp+= 3) {
DS_energy(sphere, tot, fp);
}
}
}
static float *sphere_sampler(int type, int resol, float *nrm)
{
static float sphere[2*3*256], sphere1[2*3*256];
static int last_distr= 0, tot;
float *vec;
if(resol>16) return sphere;
tot= 2*resol*resol;
if (type & WO_AORNDSMP) {
int a;
/* total random sampling */
vec= sphere;
for (a=0; a<tot; a++, vec+=3) {
RandomSpherical(vec);
}
}
else {
float cosf, sinf, cost, sint;
float ang, *vec1;
int a;
if(last_distr!=resol) DistributedSpherical(sphere, tot, 16);
last_distr= resol;
// random rotation
ang= BLI_frand();
sinf= sin(ang); cosf= cos(ang);
ang= BLI_frand();
sint= sin(ang); cost= cos(ang);
vec= sphere;
vec1= sphere1;
for (a=0; a<tot; a++, vec+=3, vec1+=3) {
vec1[0]= cost*cosf*vec[0] - sinf*vec[1] + sint*cosf*vec[2];
vec1[1]= cost*sinf*vec[0] + cosf*vec[1] + sint*sinf*vec[2];
vec1[2]= -sint*vec[0] + cost*vec[2];
}
return sphere1;
}
#if 0
{ /* stratified uniform sampling */
float gdiv = 1.0/resol;
float gdiv2p = gdiv*2.0*M_PI;
float d, z1, z2, sqz1, sz2, cz2;
float ru[3], rv[3];
int x, y;
last_distr= 0;
/* calculate the two perpendicular vectors */
if ((nrm[0]==0.0) && (nrm[1]==0.0)) {
if (nrm[2]<0) ru[0]=-1; else ru[0]=1;
ru[1] = ru[2] = 0;
rv[0] = rv[2] = 0;
rv[1] = 1;
}
else {
ru[0] = nrm[1];
ru[1] = -nrm[0];
ru[2] = 0.0;
d = ru[0]*ru[0] + ru[1]*ru[1];
if (d!=0) {
d = 1.0/sqrt(d);
ru[0] *= d;
ru[1] *= d;
}
Crossf(rv, nrm, ru);
}
vec= sphere;
for (x=0; x<resol; x++) {
for (y=0; y<resol; y++, vec+=3) {
z1 = (x + BLI_frand()) * gdiv;
z2 = (y + BLI_frand()) * gdiv2p;
if ((sqz1 = 1.0-z1*z1)<0) sqz1=0; else sqz1=sqrt(sqz1);
sz2 = sin(z2);
cz2 = cos(z2);
vec[0] = sqz1*(cz2*ru[0] + sz2*rv[0]) + nrm[0]*z1;
vec[1] = sqz1*(cz2*ru[1] + sz2*rv[1]) + nrm[1]*z1;
vec[2] = sqz1*(cz2*ru[2] + sz2*rv[2]) + nrm[2]*z1;
}
}
}
#endif
return sphere;
}
/* extern call from shade_lamp_loop, ambient occlusion calculus */
void ray_ao(ShadeInput *shi, World *wrld, float *shadfac)
{
Isect isec;
float nrm[3], vec[3], ru[3], rv[3];
float d, z1, z2, sqz1, sz2, cz2, sh=0;
int grid = wrld->aosamp;
float gdiv = 1.0/grid;
float gdiv2p = gdiv*2.0*M_PI;
float *vec, *nrm, div, sh=0;
float maxdist = wrld->aodist;
int x, y;
int tot, actual;
int j=0;
VECCOPY(isec.start, shi->co);
@ -1890,50 +2019,20 @@ void ray_ao(ShadeInput *shi, World *wrld, float *shadfac)
R.wrld.zeng= G.scene->world->zeng;
R.wrld.zenb= G.scene->world->zenb;
}
/* calculate the two perpendicular vectors */
VECCOPY(nrm, shi->vn);
if ((nrm[0]==0.0) && (nrm[1]==0.0)) {
if (nrm[2]<0) ru[0]=-1; else ru[0]=1;
ru[1] = ru[2] = 0;
rv[0] = rv[2] = 0;
rv[1] = 1;
}
else {
ru[0] = nrm[1];
ru[1] = -nrm[0];
ru[2] = 0.0;
d = ru[0]*ru[0] + ru[1]*ru[1];
if (d!=0) {
d = 1.0/sqrt(d);
ru[0] *= d;
ru[1] *= d;
}
Crossf(rv, nrm, ru);
}
for (x=0;x<grid;x++) {
for (y=0;y<grid;y++) {
if (wrld->aomode & WO_AORNDSMP) {
/* total random sampling */
RandomSpherical(vec);
if ((vec[0]*nrm[0] + vec[1]*nrm[1] + vec[2]*nrm[2]) < 0.0) {
vec[0] = -vec[0];
vec[1] = -vec[1];
vec[2] = -vec[2];
}
}
else {
/* stratified uniform sampling */
z1 = (x + BLI_frand()) * gdiv;
z2 = (y + BLI_frand()) * gdiv2p;
if ((sqz1 = 1.0-z1*z1)<0) sqz1=0; else sqz1=sqrt(sqz1);
sz2 = sin(z2);
cz2 = cos(z2);
vec[0] = sqz1*(cz2*ru[0] + sz2*rv[0]) + nrm[0]*z1;
vec[1] = sqz1*(cz2*ru[1] + sz2*rv[1]) + nrm[1]*z1;
vec[2] = sqz1*(cz2*ru[2] + sz2*rv[2]) + nrm[2]*z1;
}
nrm= shi->vlr->n;
vec= sphere_sampler(wrld->aomode, wrld->aosamp, nrm);
// warning: since we use full sphere now, and dotproduct is below, we do twice as much
tot= 2*wrld->aosamp*wrld->aosamp;
actual= 0;
while(tot--) {
if ((vec[0]*nrm[0] + vec[1]*nrm[1] + vec[2]*nrm[2]) > 0.0) {
actual++;
isec.end[0] = shi->co[0] - maxdist*vec[0];
isec.end[1] = shi->co[1] - maxdist*vec[1];
isec.end[2] = shi->co[2] - maxdist*vec[2];
@ -1943,6 +2042,7 @@ void ray_ao(ShadeInput *shi, World *wrld, float *shadfac)
isec.start[2]= shi->co[2] + (jit[j][0]-0.5)*O.dxco[2] + (jit[j][1]-0.5)*O.dyco[2] ;
j = ((j+1) % R.osa);
}
/* do the trace */
if (d3dda(&isec)) {
if (wrld->aomode & WO_AODIST) sh+=exp(-isec.labda*wrld->aodistfac); else sh+=1.0;
@ -1970,15 +2070,17 @@ void ray_ao(ShadeInput *shi, World *wrld, float *shadfac)
}
}
}
// samples
vec+= 3;
}
gdiv= wrld->aoenergy/(float)(wrld->aosamp*wrld->aosamp);
shadfac[3] = wrld->aoenergy - (sh*gdiv);
div= wrld->aoenergy/(float)(actual);
shadfac[3] = wrld->aoenergy - (sh*div);
if(wrld->aocolor!=WO_AOPLAIN) {
shadfac[0] *= gdiv;
shadfac[1] *= gdiv;
shadfac[2] *= gdiv;
shadfac[0] *= div;
shadfac[1] *= div;
shadfac[2] *= div;
}
}