public override void Render(Scene scene)
{
this.scene = scene;
if (NumLightPaths <= 0)
{
NumLightPaths = scene.FrameBuffer.Width * scene.FrameBuffer.Height;
}
lightPaths = new LightPathCache {
MaxDepth = MaxDepth, NumPaths = NumLightPaths, Scene = scene
};
for (uint iter = 0; iter < NumIterations; ++iter)
{
scene.FrameBuffer.StartIteration();
lightPaths.TraceAllPaths(iter, null);
ProcessPathCache();
TraceAllCameraPaths(iter);
scene.FrameBuffer.EndIteration();
}
}
protected virtual void AssemblePhotons(LightPathCache paths)
{
if (photons == null || photons.Length < paths.MaxDepth * paths.NumPaths)
{
photons = new PhotonReference[paths.MaxDepth * paths.NumPaths];
}
photonCount = 0;
for (int i = 0; i < paths.NumPaths; ++i)
{
for (int k = 1; k < paths.PathCache.Length(i); ++k)
{
if (Filter(paths.PathCache[i, k]))
{
photons[photonCount++] = new PhotonReference {
PathIndex = i,
VertexIndex = k,
Position = paths.PathCache[i, k].Point.Position
};
}
}
}
}
public void Build(LightPathCache paths, float averageRadius)
{
inverseBinSize = 0.5f / averageRadius;
AssemblePhotons(paths);
// Compute the bounding box of all photons
bounds = BoundingBox.Empty;
for (int i = 0; i < photonCount; ++i)
{
var p = photons[i];
bounds = bounds.GrowToContain(p.Position);
}
// Add an offset for numerical stability
var extents = bounds.Max - bounds.Min;
bounds = new BoundingBox(
max: bounds.Max + extents * 0.001f,
min: bounds.Min - extents * 0.001f
);
// Count the number of photons per grid cell
cellCounts = new int[NextPowerOfTwo(photonCount)];
Parallel.For(0, photonCount, i => {
var p = photons[i];
var hash = HashPhoton(p.Position);
Interlocked.Increment(ref cellCounts[hash]);
});
// Compute the insertion position for each cell
int sum = 0;
for (int i = 0; i < cellCounts.Length; ++i)
{
cellCounts[i] = sum += cellCounts[i];
}
Debug.Assert(cellCounts[^ 1] == photonCount);
