Fog parameters are controlled through device render states. Both pixel and vertex fog types support all the fog formulas introduced in Fog Formulas. The CONST_D3DFOGMODE enumeration defines constants that you can use to identify the fog formula you want Microsoft® Direct3D® to use. The D3DRS_FOGTABLEMODE render state controls the fog mode that Direct3D uses for pixel fog, and the D3DRS_FOGVERTEXMODE render state controls the mode for vertex fog.

The D3DRS_FOGDENSITY render state controls the fog density applied when an exponential fog formula is enabled. Fog density is essentially a weighting factor, ranging from 0.0 to 1.0 (inclusive), that scales the distance value in the exponent.

The color that the system uses for fog blending is controlled through the D3DRS_FOGCOLOR device render state. Use the D3DColorXRGB function to generate valid values for this render state. For more information, see Fog Color and Fog Blending.