This final installment of building a custom VOP looks at writing the help for our operator. Writing help is now a simple task given the new wiki style and should not be overlooked.

Here we take a look at creating a new VOP operator and build the parameter inputs and outputs to support the transpose functions two different forms: 4x4 matrix input and a 3x3 matrix input.

The main parts covered are the actual creation of a VOP operator, adding input parameters, adding support for the two forms as signatures and explaining what a signature is, adding the parameter interface and finally adding an output to match the input.

In this entry I take a look at point instancing and the new instancepoint() expression. With instancepoint() you can vary some attributes of your instances such as object and material parameters per instance point.

There are many ways to apply dynamics to points. In this entry, part 1 of 2, we will look at how to use CHOPs to add dynamics to points by settling them back from where they started nice and gracefully.

One way to paint particles without the sorting issue is to first scatter points on a surface, and then paint into a primitive attribute on the surface to add those points by weight. What we are left with is a weight map, a whole bunch of points, and a Delete SOP with a weighted expression that uses random probability to add or remove points. Either way it appears to the user that they are painting points.

Houdini9 is now public and it has been a fantastic two years in development. What this means for existing Houdini users is a tremendous amount of change. Today I will give you some tips and pointers to help you with your transition to Houdini9.