Houdini 20.0 Nodes VOP nodes

MtlX Fake Caustics for Karma VOP node

This node type is deprecated. It is scheduled to be deleted in an upcoming revision of Houdini.

Karma Fake Caustics is no longer necessary; Karma does fake caustics by default now.

(Since version 20.0.)

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This node takes an incoming MaterialX surface shader and adds fake caustics to the shader for rendering with Karma. This has no effect when used in other renderers.

This node will output a different opacity value based on whether or not the ray used is a shadow ray.



Surface Shader The input surface shader.


Bool Whether to enable fake caustics.


Float Relative index of refraction between the surface and the exterior.


Float Scaling factor of transmission color.


Color3 Fake transmission color of the shaded object, used to tint the shadow ray.


Float Minimum opacity of the object.


Float Instead specifying the shadow color explicitly, with XPU, it’s possible to compute the shadow opacity from the BSDF. This mixes between the explicit parameters in the VOP (toward 0) and the shadow opacity from the transmission lobes of BSDF (toward 1).


Vector Normal vector to use. If this is not connected, the shader uses the geometry’s world-space normal.



Surface Surface shader with fake caustics applied.

See also

VOP nodes