"shadow catcher"
Class	Reflectance
Synopsis	Allows shadows to fall upon hidden geometry in a scene. Usually the supplied geometry will follow some detail depicted by a background image. This then allows objects that have been placed in the scene to cast shadows that appear to interact with the background in a natural way.
Arguments	"catch" Type: LtEnum Default: LI_SHADOW_CATCH_ALL Range: 0, 1, 2 Hint: - "shadow colour" Type: LtColour Default: 1.0, 1.0, 1.0 Range: [ 0, inf ], [ 0, inf ], [ 0, inf ] Hint: [ 0, 1 ], [ 0, 1 ], [ 0, 1 ] "shadow brightness" Type: LtFloat Default: 0.0 Range: [ 0, 1 ] Hint: [ 0.2, 0.8 ] "reflectance" Type: LtShader Default: NULL Range: 1 Hint: -
Location	lishslte
Description	Allows shadows to fall upon hidden geometry that is placed in a scene. Usually the supplied geometry will follow some detail depicted by a background image. This then allows objects that have been placed in the scene to cast shadows that appear to interact with the background in a natural way. catch is an LtEnum parameter that allows the shadow analysis to be controlled: LI_SHADOW_CATCH_NONE Shadow analysis is not performed but the shadow catcher primitive is shaded directly with the background followed by execution of any specified reflectance shader (see below). LI_SHADOW_CATCH_ALL As above but with shadow analysis. In this mode shadows are cast by the scene geometry and the absence of light is considered as total shadow. For example, a region outside a spot light cone is determined to be in total shadow. LI_SHADOW_CATCH_SHADOWS_ONLY Shadow analysis is performed as described above but in this mode only shadow created by geometry is considered to be a true shadow. shadow colour specifies a filter colour to be applied to the shadow. Use this parameter to tint a shadow a desired colour, for example to match the ambient lighting conditions. Note that if any ambient lights are illuminating the scene then they only affect the shadowed area and not the shadow catcher geometry as a whole. The effects of ambient lighting are added to the shadow region before any filtering by shadow colour is performed. Any ambient lighting contributions to the shadow region are also clamped to ensure that this region is never brighter than its surroundings. shadow brightness limits the darkest value that a shadow can be, where 0.0 is total shadow (i.e., black) and 1.0 is total illumination. This threshold value is applied as a limiting value to the total shadow at a point. The total shadow is the sum of the individual shadow cotributions from each light source. reflectance a reflectance class shader that may be used as input to the shader to provide the geometry with the reflectance properties that match the scenery it represents. For example, a reflectance shader may be used so that background covered by a shadow catcher responds to the lighting conditions in a natural way. Previous page alphabetically (sceneryinterface) Next page alphabetically (simpleenvironmentlight) Index
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