If you need to change the same Arnold attributes on many nodes, use the Attribute Spreadsheet. For example, suppose you wanted to turn off the Opaque attribute on a number of objects in your scene. Here’s how to do it:
If you’re using world coordinates for your noise, then obviously as an object moves in global space, the noise will change. Here I’ve extracted a polygon and moved it: same shader tree that uses noise, but different noise because I’m using world coordinates.
You could keep the same noise by applying an offset equal to the translation:
Note that I’ve assumed that there’s no scaling of the noise. If there was, I’d have to multiply my offset by the same scaling.
You can add attributes to shape nodes in Maya, and MTOA will export those extra attributes as user data in Arnold shape nodes. For example, you use this mechanism to add user data to a procedural node.
Add some extra attributes to a shape node, using the naming convention mtoa_constant_parameter-name. That is, the attribute name must always start with “mtoa_constant_”.
Export to ASS. In the .ass file, your extra attributes will be declared as user parameters:
procedural
{
name ArnoldStandInShape
dso "C:/Users/SOLIDANGLE/Dev/MyProcedural.dll"
min -9.63329697 0 0.861843109
max -6.73797035 3.62841082 9.87797546
matrix
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
declare MyVector constant VECTOR
MyVector 0 0 0
declare MyFloat constant FLOAT
MyFloat 0
declare MyInteger constant INT
MyInteger 0
declare MyBoolean constant BOOL
MyBoolean off
declare MyString constant STRING
MyString ""
}
Arnold Support Corner 