[SItoA] More about particle shapes

For the Point, and Sphere particles shapes, you get a single Arnold points node. For example, for the Sphere shape, you’d get a points node that looked something like this:

 name pointcloud.SItoA.Sphere.5000
 points 54 1 b85POINT
 radius 54 1 b85FLOAT
 mode "sphere"
 visibility 255
 sidedness 255
 1 0 0 0
 0 1 0 0
 0 0 1 0
 0 0 0 1
 shader "Sources.Materials.DefaultLib.Material.standard.SItoA.5000.2.sta_shading_group"
 id 832

This particular node is for 54 points in sphere mode. For each point, you get the center position (the points.points parameter) and a radius (the points.radius parameter). If there’s any scaling applied to the particle in ICE, the radius is multiplied by the X scaling of the particle.

For the Point shape, you get an Arnold points node in “disk” mode, with radius = size * X scaling.

For the other supported shapes, you get the corresponding Arnold shape.

Noise, world coordinates, and offsets

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.