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closure color vray_hair(normal N, color diffuse_color, color transparency, color primary_specular_color, float primary_glossiness, float secondary_glossiness, color transmission_color, float transmission_glossiness_length, float transmission_glossiness_width);
Closure that is primarily designed for rendering hair and fur. See VRayHairMtl for in depth parameter explanation and examples. An OSL shader that simulates the VRayHairMtl is available in the Examples section. This shader also demonstrates how the VRayHairMtl's parameters translate to the vray_hair closure ones.

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color secondary_specular_color;
The color of the secondary specular component corresponding to light that is reflected off the back surface of the hair strands. The default value is locked to the transmission_color parameter of the vary_hair closure. See VRayHairMtl for more information.

int opaque_for_shadows;
If set to 1 makes the hair closure opaque for shadow calculations. Default value is 0. See VRayHairMtl for more information.

int opaque_for_gi;
Use a value of 1 to make the hair material opaque for GI calculations. Default value is 0. See VRayHairMtl for more information.

int simplify_for_gi;
Use 1 to apply a simplified diffuse version of the closure for GI calculations. Default value is 0. See VRayHairMtl for more information.

int use_cached_gi;
If set to 1, an irradiance map will be used to approximate diffuse indirect illumination. Otherwise the hair closure will always be calculated with brute force GI. Default value is 1. See VRayHairMtl for more information.

float light_multiplier;
A multiplier for the effect of direct illumination on the current hair closure. Default value is 1.0. See VRayHairMtl for more information.

vector hair_direction;
If provided, overrides the internally derived hair strand direction. Default value is vector(0.0, 0.0, 1.0).

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