SLfloat SLLightRect::shadowTestMC(SLRay* ray, // ray of hit point
const SLVec3f& L, // vector from hit point to light
const SLfloat lightDist) // distance to light
{
SLVec3f SP; // vector hit point to sample point in world coords
SLfloat randX = rnd01();
SLfloat randY = rnd01();
// choose random point on rect as sample
SP.set(updateAndGetWM().multVec(SLVec3f((randX*_width)-(_width*0.5f), (randY*_height)-(_height*0.5f), 0)) - ray->hitPoint);
SLfloat SPDist = SP.length();
SP.normalize();
SLRay shadowRay(SPDist, SP, ray);
SLScene::current->root3D()->hitRec(&shadowRay);
if (shadowRay.length >= SPDist - FLT_EPSILON)
return 1.0f;
else
return 0.0f;
}
/*!
SLLightRect::shadowTest returns 0.0 if the hit point is completely shaded and
1.0 if it is 100% lighted. A return value inbetween is calculate by the ratio
of the shadow rays not blocked to the total number of casted shadow rays.
*/
SLfloat SLLightRect::shadowTest(SLRay* ray, // ray of hit point
const SLVec3f& L, // vector from hit point to light
const SLfloat lightDist) // distance to light
{
if (_samples.x==1 && _samples.y==1)
{
// define shadow ray
SLRay shadowRay(lightDist, L, ray);
SLScene::current->root3D()->hitRec(&shadowRay);
return (shadowRay.length < lightDist) ? 0.0f : 1.0f;
}
else // do light sampling for soft shadows
{ SLfloat dw = (SLfloat)_width/(SLfloat)_samples.x; // width of a sample cell
SLfloat dl = (SLfloat)_height/(SLfloat)_samples.y;// length of a sample cell
SLint x, y, hx=_samples.x/2, hy=_samples.y/2;
SLint samples = _samples.x*_samples.y;
SLbool* isSampled = new SLbool[samples];
SLbool importantPointsAreLighting = true;
SLfloat lighted = 0.0f; // return value
SLfloat invSamples = 1.0f/(SLfloat)(samples);
SLVec3f SP; // vector hitpoint to samplepoint in world coords
for (y=0; y<_samples.y; ++y)
{ for (x=0; x<_samples.x; ++x)
{ SLint iSP = y*_samples.x + x;
isSampled[iSP]=false;
}
}
/*
Important sample points (X) on a 7 by 5 rectangular light.
If all of them are lighting the hitpoint the sample points
in between (O) are not tested anymore.
0 1 2 3 4 5 6
+---+---+---+---+---+---+---+
0 | X | . | . | X | . | . | X |
+---+---+---+---+---+---+---+
1 | . | . | . | . | . | . | . |
+---+---+---+---+---+---+---+
2 | X | . | . | X | . | . | X |
+---+---+---+---+---+---+---+
3 | . | . | . | . | . | . | . |
+---+---+---+---+---+---+---+
4 | X | . | . | X | . | . | X |
+---+---+---+---+---+---+---+
*/
// Double loop for the important sample points
for (y=-hy; y<=hy; y+=hy)
{ for (x=-hx; x<=hx; x+=hx)
{ SLint iSP = (y+hy)*_samples.x + x+hx;
isSampled[iSP]=true;
SP.set(updateAndGetWM().multVec(SLVec3f(x*dw, y*dl, 0)) - ray->hitPoint);
SLfloat SPDist = SP.length();
SP.normalize();
SLRay shadowRay(SPDist, SP, ray);
SLScene::current->root3D()->hitRec(&shadowRay);
if (shadowRay.length >= SPDist-FLT_EPSILON)
lighted += invSamples; // sum up the light
else
importantPointsAreLighting = false;
}
}
if (importantPointsAreLighting)
lighted = 1.0f;
else
{ // Double loop for the samplepoints inbetween
for (y=-hy; y<=hy; ++y)
{ for (x=-hx; x<=hx; ++x)
{ SLint iSP = (y+hy)*_samples.x + x+hx;
if (!isSampled[iSP])
{ SP.set(updateAndGetWM().multVec(SLVec3f(x*dw, y*dl, 0)) - ray->hitPoint);
SLfloat SPDist = SP.length();
SP.normalize();
SLRay shadowRay(SPDist, SP, ray);
SLScene::current->root3D()->hitRec(&shadowRay);
// sum up the light
if (shadowRay.length >= SPDist-FLT_EPSILON)
lighted += invSamples;
}
}
}
}
if (isSampled) delete [] isSampled;
return lighted;
}
}
