Shader Type: State (Tool)
Output: Scalar value
Makes scalar-type parameters available in the raytracing state structure. This node is intended for Shader developers who require low-level information during the raytracing process.
You should have some shader-writing knowledge in either mental ray 1.9, 2.0, or 2.1 in order to use this tool properly.
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Name |
The shader’s name. Enter any name you like, or leave the default. |
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State |
Lets you choose one of the following scalar-type parameters: Ray Length -- Returns the length of the last ray to intersect the surface being evaluated. Screen Position: Raster X -- Returns the X coordinate in raster space of the pixel being evaluated, ranging from [0..RESX-1]. Screen Position: Raster Y -- Returns the Y coordinate in raster space of the pixel being evaluated, ranging from [0..RESY-1]. Motion Blur Time -- Returns the shutter time of the evaluated pixel. This is useful for making a texture appear or disappear as motion blur is applied to an object. Express as [0..shutter_speed]. Index of Refraction of Outgoing Ray -- Returns the IOR of the ray leaving the surface being evaluated. Index of Refraction of Incoming Ray -- Returns the IOR of the ray entering/hitting the surface being evaluated. Dot of Surface Normal -- Returns the dot product of the surface normal and eye camera ray (incidence). Barycentric A / Crosswise Hair returns values from 0 to 1 along the width of the hair (from one edge to the other: 0 > 1 > 0). Barycentric B / Lengthwise Hair returns values from 0 to 1 along the length of the hair, with 0 being the root and 1 being the tip. Barycentric C / Spline Hair Interpolant assigns a number to each hair created from curves. This number is based on where it originates within the collection of guide hairs (curves). If you have three curves, a hair that is generated between curve 1 and 2 gets assigned a number between 0 and 0.5 depending on its proximity to either curve. Barycentric hair parameters let you define more accurate specular color along a hair strand, as well as map custom values over hair or create a surface for curve hairs upon which you can apply textures. Barycentric coordinates give the coordinates of a point relative to the triangle it is on as a weight of the three corner vertices, normalized so that the sum is 1. That means that from the barycentric coordinates of a point, you can get the “real” coordinates of the point. |
This shader is usually used at the left end of a render tree effect to define a scalar’s input value for a shader. In a simple example, you could use this shader to define the Factor of the Intensity shader. You can also use the Barycentric B and C states to extract the surface interpolation value of the hair between curves to create a surface for mapping.
Autodesk Softimage v.7.5