Fog State Structure Structure fog_state contains the following: double start GL_FOG_START - starting distance of the fog double end GL_FOG_END - ending distance of the fog double density GL_FOG_DENSITY - density of the fog GLint mode GL_FOG_MODE - fog function: GL_EXP, GL_EXP2, or GL_LINEAR Color fcolor GL_FOG_COLOR - fog color See OpenGL function glFog.