Graphics Runner did a tutorial three years ago on dual paraboloid reflection mapping, and it used an older version of XNA for the sample code. I’ve ported it completely to XNA 4.0, using the current conventions for graphics rendering and pixel shaders.
Dual paraboloid maps are simpler to implement and more efficient than traditional cube maps for reflections. Like cube maps, they are a view-independent method of rendering reflections. The tradeoff is that you get lower quality reflections for an increase in speed, but the results are still pretty good. The original blog article does a good job explaining the math behind applying the mapping effect.
Here are some of the notable differences with the updated version:
- Simple quad mesh used in place of quad rendering class
- The ColorClamp sampler state is deprecated, this was removed