Projected Textures

Projected textures use a Q texture coordinate, along with the S, T, & R coordinates.

Texture projection works similarly to a 3D rendering projection.

A rendering projection takes the (X, Y, Z, W) coordinates of vertices, and converts them into (X, Y) screen positions.

A projection loaded in the GL_TEXTURE matrix can take (S, T, R, Q) texture coordinates and transform them into different (S, T) texture coordinates.

Projecting a texture thus involves 2 major steps:

• Use texgen to generate (S, T, R, Q) coordinates that correspond to vertices' (X, Y, Z) position in space.
• Apply a camera-like transformation to the GL_TEXTURE matrix

Example: projector.cpp