// Returns index of triangle intersected by central axis of lightfield cell's beam
// Returns -1 if no triangle is intersected
private int BeamTriangleSimpleIntersect(Coord4D lfCoord, RenderContext context)
{
// switch to tracing the canonical ray associated with this lightfield entry, instead of the original ray (to avoid biasing values in lightfield)
Vector cellRayStart;
Vector cellRayDir;
lightFieldCache.Coord4DToRay(lfCoord, out cellRayStart, out cellRayDir);
// TODO: once the light field cache 'fills up', do we cease tracing rays? Prove/measure this!
// trace a primary ray against all triangles in scene
// TODO: trace multiple rays to find the triangle with largest cross-section in the beam corresponding to this lightfield cell?
// This may also avoid incorrectly storing 'missing triangle' value when primary ray misses because there are no triangles along central axis of cell's beam.
IntersectionInfo intersection = geometry_subdivided.IntersectRay(cellRayStart, cellRayDir, context);
if (intersection == null)
{
return(-1);
}
else
{
Contract.Assert(intersection.triIndex >= 0);
return(intersection.triIndex);
}
}
private uint CalcColorForCoord(Coord4D lfCoord, RenderContext context)
{
// Index into light field cache using 4D spherical coordinates
uint lfCacheEntry = lightFieldCache.ReadCache(lfCoord.Item1, lfCoord.Item2, lfCoord.Item3, lfCoord.Item4);
if (lfCacheEntry != lightFieldCache.EmptyCacheEntry)
{
// lightfield stores colors, and we found a color entry to return
return(lfCacheEntry);
}
// switch to tracing the ray associated with this lightfield entry, instead of the original ray (to avoid biasing values in lightfield)
Vector rayStart;
Vector rayDir;
lightFieldCache.Coord4DToRay(lfCoord, out rayStart, out rayDir);
// TODO: once the light field cache 'fills up', do we cease tracing rays? Prove/measure this!
// we did not find a color in the light field corresponding to this ray, so trace this ray against the geometry
// TODO: this line is the major performance bottleneck!
IntersectionInfo info = geometry.IntersectRay(rayStart, rayDir, context);
if (info == null)
{
// ray did not hit the geometry, so cache background color into the 4D light field
lightFieldCache.WriteCache(lfCoord.Item1, lfCoord.Item2, lfCoord.Item3, lfCoord.Item4, backgroundColor);
return(backgroundColor);
}
// TODO: this is where lots of other AO, shadow code etc used to execute
// cache ray colors in a 4D light field?
lightFieldCache.WriteCache(lfCoord.Item1, lfCoord.Item2, lfCoord.Item3, lfCoord.Item4, info.color);
return(info.color);
}
