Texture Environment

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, mode)

mode can be one of GL_MODULATE, GL_REPLACE, GL_DECAL, GL_BLEND

If C_t is the texture color, and C_f is the "fragment" color:

  For GL_MODULATE, Color = C_t * C_f

  For GL_REPLACE, Color = C_t