Hardware bump mapping demo

Bump mapping in Direct3D can be accurately described as "per-pixel texture coordinate perturbation of specular or diffuse environment maps," because you provide information about the contour of the bump map in terms of delta-values, which the system applies to the u and v texture coordinates of an environment map in the next texture stage. The delta values are encoded in the pixel format of the bump map surface.

I'd rather you came up with a useable solution for DOT 3. You can still work on this too - just come up with a better implementation of DOT 3 too.

Bump Mapping

This is a method where the flat image of a texture map is altered to give the impression of being non-smooth but without changing the physical shape of the surface. Bump mapping is becoming more popular in 3D games because it can be used to add small scale detail (such as wrinkles, creases, scuff marks, etc) without the need to add extra polygons.

It does this by using another texture map (sometimes called a bump map) to change the brightness of the pixel in the main texture on the surface. There are various methods of bump mapping - 3 such popular ones are:

Emboss:
the bump map is called a height map - it is a simple greyscale version of the texture to be bumped, whereby the texel values are used to alter the colour of the original pixel. The height map is rendered twice, with the second one moved slightly. The two maps are then combined together, in such a way that the resulting new bump map is the difference between the two. This is then multiplied with the required base texture.

DOT Product 3:
the bump map is called a normal map - this texture contains values that alter the surface normals of the original pixels. A surface normal is like an arrow that points in the direction that the surface is facing in; as it angles away from a light source, the colour of the pixel gets darker (and vice versa). This method generally gives better results than embossing but at a greater cost to performance.
Direct3D offers a "set" dot 3 bump mapping routine but a more general method exists too; normal mapping basically uses the same process but it is done via a programmable pixel shader.

Environmental:
this method uses a mixture of techniques, embossing, and environment mapping. A height map is created (as described above) and then blended with the original base texture; this is then followed by blending this result with an environment map (which can be anything from a simple lightmap to a complex cubic map) to give the final bumped surface.
It should be noted that bump mapping never alters the position or amount of vertices in the surface. Edge-on views and shadows can spoil the illusion but more complex bump mapping procedures can help to reduce this problem.