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The following diagram illustrates several fundamental builtin variables: the surface position P, the normalized shading normal Nn and the normalized shading tangent Tn, the geometric normal Ngn, and the parametric derivatives dPdu and dPdv, as well as Vlen and Vn which provide information about the incoming ray.
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The following diagram illustrates the incidentRaySpread and incidentRayRadius properties of the ray which are related to ray differentials, and are important to the computation of filter widths for antialiasing.
Anchor getprimvar getprimvar
Primitive Variables
| getprimvar | |
| getprimvar |
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