ambient

Context(s)	displace fog surface

vector  ambient(...)

Returns the color of ambient light in the scene. Light inclusion/exclusion options

light-inclusion-exclusion-options

“categories”, string ="*"

Specifies lights to include/exclude by their “category” tags. This is the preferred include/exclude lights rather than pattern matching light names with the "lightmask" keyword argument.

For example:

diff = diffuse(nml, "lightmask", "hero | fill");

See light categories for more information.

“lightmask”, string ="*"

When evaluating light and shadow shaders, objects have pre-defined light masks. This mask is usually specified in the geometry object and specifies a list of lights which are used to illuminate a surface or fog shader. It is possible to override the default light mask by specifying a “lightmask” argument.

For example:

diff = diffuse(nml, "lightmask", "light*,^light2");

…will cause all lights whose names begin with “light” except for a light named “light2” to be considered for diffuse illumination.

All Houdini scoping patterns, excepting group expansion, are supported:

• * - wild-card match
• ? - single character match
• ^ - exclusion operator
• [list] - character list match