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shaderhlsldirectx-9

Reflection off curved surface - HLSL

Let's say I have a flat, perfect mirror. How do I find what it's reflecting? Easy, move the camera to a position which looks back up at the angle of incidence.

Now what if that flat mirror was curved or spherical? How would I find the reflection of Object A if Object B was a non-flat, perfect mirror.

Presumably this would need some kind of ray-tracing (not sure how to do in HLSL ... yet), but I'm guessing this will be a performance killer. So has anyone done this before and know what to do now? If so, is there an easier way? How did you do it?

EDIT: This has to work in DX9

Solution

  • You could at first render an environment map and then use an environment mapping shader to project it onto your curved surface. This is called Dynamic Environment Mapping or in the case of this tutorial: Dynamic Cube Mapping. This will result in something like this: Dynamic Cube Mapping UDK