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** Contents**

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10.4 Other Lighting Models

Up to this point we have largely discussed the Phong lighting model.
The diffuse and specular terms for a single light are given by the
following equation:

Section 10.1.1 discusses the use of sphere mapping to
replace the OpenGL per-vertex specular illumination computation with
one performed at each pixel. The specular contribution in the
texture map is computed using the Phong formulation above. However,
the Phong model can be substituted with other bi-directional reflectance
functions to achieve other lighting effects. Since the texture coordinates
are computed with a sphere mapping function, the resulting texture
mapping operation accurately approximates view-dependent specular
reflectance distributions.

**Subsections**

2001-01-10