Using multiple illumination maps using-multiple-illumination-maps

Some applications may require a different illumination map for different kinds of materials.

Up to three illumination maps can be authored for each vignette. The illumination map for a render operation is selected with the illum= and or gloss= commands.

Default selection - If illum= or gloss= are not specified, the renderer uses the first authored illumination map (typically map A, aka the ‘Flat’ illumination map).

Automatic selection with gloss= - If illum= is not specified or is set to -1, the renderer compares the specified gloss= value with the gloss values associated with each illumination map in the vignette. It chooses the illumination map whose gloss value is closest to the specified gloss=.

Explicit selection with illum= - If illum= is specified and set to 0, 1, or 2, the renderer uses the corresponding illumination map; gloss= is ignored for selecting the illumination map.

If the vignette contains only one illumination map, the renderer uses that map and ignore the illum= and gloss= commands.