So what happens if a color is assigned to the points instead of the primitives? What is the difference between assigning color to points versus assigning color to primitives? Sometimes we experience color bleeding onto other primitives of the geometry, this article explains why.

Houdini expressions are functions available to help you calculate values in the parameters of the nodes. You may have seen $HIPNAME which returns the name of the current hip file. Or the centroid one that I use most often for procedural modeling, $CEX $CEY $CEZ, which returns the centroid vector component.

Procedural Modeling has infinite possible ways of doing things, and the way Houdini does its point number assignment makes it very convenient to write VEX code to automate things. Using VEX into your procedural modeling workflow is a huge advantage.