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| Name | Type | Default | Description |
|---|---|---|---|
| grouping:membership | string | null | Grouping membership used for linking |
| identifier:id | integer | 0 | Lower 32 bits of 64 bit object id |
| identifier:id2 | integer | 0 | Upper 32 bits of 64 bit object id |
| identifier:lpegroup | string | null | Grouping membership used for light path expressions, example, keylight |
| identifier:name | string | null | Instance path name |
| lightfilter:subset | string | null | Active light filter groups in lighting |
| lighting:excludesubset | string | null | Exclude light groups from lighting |
| lighting:mute | integer | 0 | Mutes light emission |
| lighting:subset | string | null | Light groups active in lighting |
| Ri:Matte | integer | 0 | Indicates a matte object |
| Ri:ReverseOrientation | integer | 0 | Flip shading normals |
| Ri:Sides | integer | 2 | Geometry can be one or two sided |
| shade:relativepixelvariance | float | 1 | PixelVariance multiplier for camera visible objects, allows you to alter the samples relative to the global setting |
| shade:indexofrefraction | float | -1.3 | Set an index of refraction used in nested dielectrics, we use the bxdf result, this is used as an override |
| trace:holdout | integer | 0 | Indicates holdout object, useful in holdout workflow |
| trace:intersectpriority | integer | 0 | Raytrace intersection priority for nested dielectrics |
| trace:maxdiffusedepth | integer | 1 | Maximum diffuse light bounces |
| trace:maxspeculardepth | integer | 2 | Maximum specular light bounces |
| trace:reflectexcludesubset | string | null | Exclude object groups from reflections |
| trace:reflectsubset | string | null | Object groups visible to reflections |
| trace:shadowexcludesubset | string | null | Exclude object groups from casting shadows |
| trace:shadowsubset | string | null | Object groups active in shadows |
| attributes trace:transmitexcludesubset | string | null | Exclude object groups from transmission/refractions |
| trace:transmitsubset | string | null | Object groups visible to transmission/refractions |
| user:<name> <type> <value> | any | null | Arbitrary instance user data |
| visibility:camera | integer | 1 | Indicates if object is visible to the camera |
| visibility:indirect | integer | 1 | Indicates if object is visible to indirect (reflection and specular refraction) rays |
| visibility:transmission | integer | 1 | Indicates if object is visible to shadow rays |
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Primvars can be set and manipulated on different types of geometry (as available for that type of geometry). This can allow pattern networks and shaders to retrieve this information at render time.
User Primvars
Class Specifiers: There are several types of Primvars
Constant: One value remains constant over the entire surface primitive.
Uniform: One value remains constant for each uv patch segment of the surface primitive.
Varying: Four values are interpolated over each uv patch segment of the surface. Bilinear interpolation is used for interpolation between the four values.
Vertex: Values are interpolated between each vertex in the surface primitive. The basis function of the surface is used for interpolation between vertices.
Facevarying: For polygons and subdivision surfaces, four values are interpolated over each face of the mesh. Bilinear interpolation is used for interpolation between the four values.
A variable's class and the surface primitive determine how many samples must be included when a primitive variable is attached to a surface primitive. The following two tables identify the correct number of values that must be included for each combination of class specifier and surface primitive.
| Surface Primitive | Constant | Uniform | Varying | Vertex | Facevarying |
|---|---|---|---|---|---|
| Quadrics | 1 | 1 | 4 | 4 | 4 |
| Polygon | 1 | 1 | nverts | nverts | nverts |
| General Polygon | 1 | 1 | nverts | nverts | nverts |
| Points Polygons | 1 | npolys | nverts | nverts | sum(nverticesi) |
| Points General Polygons | 1 | npolys | nverts | nverts | sum(nverticesi) |
| Points | 1 | 1 | npoints | npoints | npoints |
| Subdivision Mesh | 1 | nfaces | nverts | nverts | sum(nverticesi) |
| Surface Primitive | Constant | Uniform | Varying and Facevarying | Vertex |
|---|---|---|---|---|
| Patch Bilinear | 1 | 1 | 4 | 4 |
| Patch Bicubic | 1 | 1 | 4 | 16 |
| PatchMesh Bilinear | 1 | (nu-unowrap)* (nv-vnowrap) | nu*nv | nu*nv |
| PatchMesh Bicubic | 1 | usegs*vsegs | (usegs+unowrap)* (vsegs+vnowrap) | nu*nv |
| NuPatch | 1 | (nu-uorder+1)* (nv-vorder+1) | (nu-uorder+2)* (nv-vorder+2) | nu*nv |
| Curves Linear | 1 | sum(nsegsi-nowrap) | sum(nverticesi) | sum(nverticesi) |
| Curves Cubic | 1 | sum(nsegsi) | sum(nsegsi+nowrap) | sum(nverticesi) |
| Blobby | 1 | 1 | nleaf | nleaf |
Note, in the above table for parametric surface primitives, unowrap, vnowrap, and nowrap are assumed to be a boolean value of either 0 = periodic or 1 = nonperiodic. This is NOT how uwrap, vwrap, and wrap are used in the RenderMan interface.
For a bicubic patch mesh the number of values for the uniform and varying classes is determined by the number of patch segments in the u and v direction (usegs, vsegs, and nsegsi in the above table). This is determined by the u and v basis functions of the patch mesh. The following table gives the formula for calculating the number of patch segments, in the u or v direction, of a patch mesh. N is the number of control vertices in the u or v direction (nu or nv in the above table).
User Primvars
| Name | Type | Default | Description |
|---|---|---|---|
| <name> <type> <value> | Any | null | Arbitrary primitive user data |
| identifier:object | string | null | |
| Name | Type | Default | Description |
| <name> <type> <value> | Any | null | Arbitrary primitive user data |
| identifier:object | string | null | Object name |
Dicing and Approximating geometry
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| Name | Type | Default | Description |
|---|---|---|---|
| trace:autobias | integer | 1 | Allow the renderer to automatially adjust ray bias, 0 is off |
| trace:bias | float | 0.01 | The user-set bias amount, typically small values to offset a ray to avoid artifacts such as shadow acne |
| trace:displacements | integer | 1 | Trace displacements (seen in reflections and refractions, etc) 0 is off |
| trace:samplemotion | integer | 0 | Whether motion blurred objects appear in ray-traced results. When 0, the motion blur of other objects hit by rays launched from the motion blur of other objects hit object with this attribute will be ignored. When non-zero, motion blur will be taken into account by rays launched from the object with this attribute will be ignored. When non-zero, motion blur will be taken into account by rays launched from an object with this attribute |
Primvars based on geometry type
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| an object with this attribute |
Primvars based on geometry type
Blobbies
| Name | Type | Default | Description |
|---|---|---|---|
| primvars:Blobby Ri:code | integer | null (required) | |
| primvars:Blobby Ri:floats | float | null | |
| primvars:Blobby Ri:nleaf | integer | null (required) | |
| primvars:Blobby Ri:strings |
primvars:Blobby Ri:code integer[n] [required] Description
primvars:Blobby Ri:floats float[n] [] Description
primvars:Blobby Ri:nleaf integer [required] Description
primvars:Blobby Ri:strings integer[n] [] Description
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