Bump mapping (aka normal mapping) is technique for simulating bumps and wrinkles on the surface of an object.

It is achieved by perturbing the surface normal for each fragment being rendered.  The new normal is used in per-fragment lighting calculations.

The result is a surface that appears bumpy, even though the underlying position of points on the surface is unchanged.


Source:Paul's Projects

Bump mapping can be implemented using multi-texturing.  A texture representing the normal displacement can be loaded.

Displacements are represented as RGB in the texture, in the tangent space of the surface.

When rendering, the surface normals are displaced based on the texture.  The displaced normal is used for calculating lighting.

See the Cookbook for a recipe.

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