Primitive, surface, and custom shader parameters

Use these shading parameters when the Operation setting is set to Render. Otherwise, they do not appear in the Preview/Output tab.

You can turn on the following Primitive Shader Parameters and Surface Shader Parameters to write this information into the render file so that they may be used by any shader attached to the primitive.

Primitive Shader Parameters

Specifies which parameters to pass to the shader.

Length: The length of the current primitive.
Width: The width of the current primitive (without taper applied).
T: The tangent of the current primitive at its generation point.
Stray: Flag indicating if the current primitive is considered stray.
Id: Count for the current primitive on the current face.
Descid: Description index for the current primitive.
Ri: A unique integer ID for the current primitive.
Rf: A unique float ID for the current primitive.

Surface Shader Parameters

Specifies which parameters to pass to the shader.

U: The U parameter of the face the current primitive.
V: The V parameter of the face the current primitive.
Faceid: The face ID on the surface for the current primitive.
Geomid: Geometry index for the current primitive.
P: The point on the surface for the current primitive.
Pref: The point on the reference surface for the current primitive.
Pg: The undisplaced point on the surface for the current primitive.
Prefg: The undisplaced point on the reference surface for the current primitive.
N: The normal on the surface for the current primitive.
Nref: The normal on the reference surface for the current primitive.
Ng: The undisplaced normal on the surface for the current primitive.
Nrefg: The undisplaced normal on the reference surface for the current primitive.
D Pdu: dP/du (tangent) on the surface for the current primitive.
D Pduref: dP/du on the reference surface for the current primitive.
D Pdug: The undisplaced dP/du (tangent) on the surface for the current primitive.
D Pdurefg: The undisplaced dP/du on the reference surface for the current primitive.
D Pdv: dP/dv (tangent) on the surface for the current primitive.
D Pdvref: dP/dv on the reference surface for the current primitive.
D Pdvg: The undisplaced dP/dv (tangent) on the surface for the current primitive.
D Pdvrefg: The undisplaced dP/dv on the reference surface for the current primitive.
Geo Name: A constant (string) that holds the name of the underlying geometry.

Custom Shader Parameters

Create a named shader parameter that you can set with a map or expression, and pass to the shader.

Custom Shader Parameters: Click + to create the named parameter.

Select the data type that you want to use from the list.

Click - to delete the named parameter.

Except where otherwise noted, this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License