I have been using the Direct3D mesh intersection function and it seems that it must internally use some kind of acceleration structure--it is way faster than the unaccelerated mesh intersect functions I have written, but I have not been able to find any documentation about this.
I am using it in a raytracer and was wondering if using bounding boxes and an acceleration structure internally in the mesh would do any good or if it already uses these.
Direct3D mesh intersection function
thewizster
AFAIK it simply interates through the triangles and does a ray/triangle intersection test.
Really the only early out that it could do is to calculate a bounding sphere and reject the whole shape. But I suspect it does not do that becuase most game engines code this themselves and would not appreciate the time wasted due to duplication.
What algorithm are you using for your ray/triangle test
You should almost always use some kind of early rejection either through space partitioning or bounding shapes before calling any mesh intersection function.
Sammu
I have used barycentric coordinates for past raytracers I have written, which pretty much seems to be the standard, although I hear there are faster algorithms.
I am using D3D to read and store meshes that I have exported from Maya as .x files, so I figured I might be able to get away with just using the built in mesh intersect function, which might possibly be faster than one I could write myself.
I guess I'll probably experiment with bounding boxes and BSP trees to see if I can get some speedup over just intersecting the mesh.