There’s a lot of literature on collision detection, and I’ve read at least a big enough portion of it to be fairly familiar with most techniques. However, there’s something that has eluded me for a while, and I figured, since StackOverflow provides access to a large group of brilliant minds at once, I’d ask here first before digging around in the bookshelf.
In this day and age, more and more work is being delegated to GPU rather than CPU, and in a lot of cases this is a good thing. For example, there are geometry shaders to create new geometry, or (slightly less new, but still quite fascinating) vertex shaders to which you can through a bunch of vertexes at, and something elegant will come out of it. What I was considering though, as these primitives exists only on the graphics hardware, how would you perform reliable collision detection with these primitives? Let’s assume I have some kind of extremely simplified mesh which is displaced in a vertex shader (I don’t have a concrete problem, I’m more playing with the idea, and I haven’t gotten very deep into geometry shaders yet).
What I’ve considered so far is separate ‘rendering’ passes from suitable angles with shading more or less turned off, and perhaps lower resolution mesh, rendering the inside (with faces flipped inward) of my second primitive along with the mesh I want to test against, and executing an occlusion query for the mesh. If the mesh is completely occluded there’d be no intersection. This would of course require that my second primitive is convex.
Somehow I get the feeling that this kind of test will be extremely expensive as the number of primitives increase (even if a large portion can be culled directly). Does anyone else have another idea or technique? I’m more familiar with opengl and cg than directx, but if you have some examples or so in directx, I guess I’ll be able to figure out the opengl counterparts.
All ideas are appreciated, so please brainstorm. 🙂
It sounds like Dan Horn’s article “Stream Reduction Operations for GPGPU Applications” in GPU Gems 2 is exactly what you want. Like all chapters, it’s freely available online.