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This node is similar to the Point SOP. It supports two inputs, and will inherit the first input source by default.
There are currently four vertex attributes supported: Diffuse Color, Alpha, Texture Coordinates, and Normal.
When the attribute is defined, it can only occur on either points or vertices, but not both. Thus, if the input geometry has a point attribute for diffuse color, the attribute will automatically be "elevated" to be a vertex attribute (if diffuse colors are added in the Vertex op).
The op processes every vertex of every primitive. For each vertex processed, there are variables which allow you to know the:
a) Vertex number of the primitive being processed b) The number of vertices in the primitive being processed c) The point which is referenced by the vertex d) The primitive which contains the vertex e) The total number of points f) The total number of primitives
Set the "Cusp Normal" parameter in order for a cusp operation similar to that of the Facet SOP, without uniquing shared points, to be applied based on the Angle parameter as threshold. This can also be done with the Normal node.
There are also local variables to find out the value of the point attribute position. See Locals section below.
Example of manipulation:
vertex/cr = $BBX vertex/cg = $CG2 vertex/cb = $CB - $CB2
Subset of primitives whose vertices are to be affected.
Diffuse color (RGB)
Crease weight for polygonal subdivision Use the Primitive operation to create a crease of constant weight for the entire primitive.
The threshold angle to cusp at.
Point number and total number of points.
Primitive number & total number of primitives.
Vertex number & total number of vertices.
CEX, CEY, CEZ
Centroid of the geometry.
BBX, BBY, BBZ
Relative position of point within bounding box. Values are mapped between 0 and 1.
TX, TY, TZ
NX, NY, NZ
Point or vertex normal directions.
MAPU, MAPV, MAPW
Point or vertex texture coordinates.
CR, CG, CB
Diffuse point or vertex color.
Point or vertex alpha value.
Point or vertex crease weight value.
PT2, NPT2, etc
Append 2 for the second source.
The following examples include this node.
This example shows how to set up the indirectlight object for indirect diffuse lighting. The scene consists of a box that has been extruded several times, containing a light source and the camera. The light has been placed so that all light reaching the camera must bounce more than once inside the scene before reaching the camera. The indirectlight object is configured to generate 1000000 photons. To visualize the photon map, change the rendering mode on the light to "Direct Global Photon Map". To adjust the sampling quality, modify the pixel samples or ray samples on the mantra ROP. The rendering engine used in this example is PBR.
This demonstration contains four different examples of applying the creaseweight attribute to polygonal geometry utilizing the Crease SOP, Vertex SOP, Attribute Create SOP, and Subdivide SOP.
It also points out some of the differences between rendering with Mantra vs. RenderMan. It is important to know that Mantra can not render the creases due to Copyright laws.
Rendering creases with Mantra requires the addition of a Subdivision SOP for calculating the geometry. The Render tab’s Geometry parameter at the object level should be set to: Geometry As Is.
If Renderman is being used, the Subdivide SOP is only for previewing the result. Renderman calculates creases during the render. The Render tab’s Geometry parameter at the object level should be set to: Polygons as Subdivision Surfaces.