Texture Environment

Textures provide color information, but so does glColor or lighting.

The texture environment controls how these colors interact.

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, mode)

A "GL_REPLACE" environment uses just the texture color, and ignores everything else.
    Color = C_t

A "GL_MODULATE" environment combines the texture and other color, multiplying them together.
    Color = C_t * C_f

Example: texenv.py