Advanced users can directly set the blending destinination and source factors using these commands. These commands affect the colour components of the current layer. This may not hold true for all combinations of blend styles however, so it's best to experiment. This will only affect blend styles that use alphachannel information. Tells the current layer to use alpha testing for transparency.
Alpha testing is off by default.
Sets the depth function used for the current layer. LESS Replaces pixels that are closer than the current layer's depth. The texture coordinates in the BSP file are ignored. The texture is projected relative to the viewer to producing false reflections. Good for shiny metal, glass or liquids.