/** \brief Compute occlusion from the current view direction to the
* given sample region.
*
* \param sampleRegion - parallelogram region over which to sample the map
* \param sampleOpts - set of sampling options
* \param numSamples - number of samples to take for the region.
* \param outSamps[0] - Return parameter; amount of occlusion over the
* sample region in the viewing direction for this map.
*/
void sample(const Sq3DSamplePllgram& sampleRegion,
const CqShadowSampleOptions& sampleOpts,
const TqInt numSamples, TqFloat* outSamps)
{
// filter weights
CqConstFilter filterWeights;
// Use constant depth approximation for the surface for maximum
// sampling speed. We use the depth from the camera to the centre
// of the sample region.
CqConstDepthApprox depthFunc((m_currToLight*sampleRegion.c).z());
// Determine rough filter support. This results in a
// texture-aligned box, so doesn't do proper anisotropic filtering.
// For occlusion this isn't visible anyway because of the large
// amount of averaging. We also want the filter setup to be as
// fast as possible.
// CqVector3D side1 = m_currToRasterVec*sampleRegion.s1;
// CqVector3D side2 = m_currToRasterVec*sampleRegion.s2;
// CqVector3D center = m_currToRaster*sampleRegion.c;
// TqFloat sWidthOn2 = max(side1.x(), side2.x())*m_pixels.width()/2;
// TqFloat tWidthOn2 = max(side1.y(), side2.y())*m_pixels.height()/2;
// TODO: Fix the above calculation so that the width is actually
// taken into account properly.
CqVector3D center = m_currToRaster*sampleRegion.c;
TqFloat sWidthOn2 = 0.5*(sampleOpts.sBlur()*m_pixels.width());
TqFloat tWidthOn2 = 0.5*(sampleOpts.tBlur()*m_pixels.height());
SqFilterSupport support(
lround(center.x()-sWidthOn2), lround(center.x()+sWidthOn2) + 1,
lround(center.y()-tWidthOn2), lround(center.y()+tWidthOn2) + 1);
// percentage closer accumulator
CqPcfAccum<CqConstFilter, CqConstDepthApprox> accumulator(
filterWeights, depthFunc, sampleOpts.startChannel(),
sampleOpts.biasLow(), sampleOpts.biasHigh(), outSamps);
// accumulate occlusion over the filter support.
filterTextureNowrapStochastic(accumulator, m_pixels, support, numSamples);
}
