Building Custom Operators

Registration

Registering a custom operator.

Parameters

Defining parameters for operators.

• Basics
• Parameter Types
• Switchers
• Multi-Parms
• Ramps
• Menus
• Disabling and Hiding Parameters
• Obsolete Parameters

Cooking

The cooking mechanism.

Local Variables

Defining local variables for operators.

Dependencies

How dependencies work in Houdini.

• Name Dependencies
• Data Dependencies

Help

How to create help for your custom operator.

Icon

How to create an icon for your custom operator.

Writing an OBJ

• Object Transform Model
  Dealing with object space transformations.
• Implementing a New Operator
  Creating a new OBJ operator
• Hiding Inherited Parameters
  Hiding the parameters inherited from the base geometry class.
• Using Creation Scripts
  Using creation scripts and default geometry.

Writing a SOP

• Creating Geometry
  Creating a SOP that creates geometry.
• Changing Geometry
  SOPs that transform their input
• Local Variables in SOPs
  Enabling $CR style local variables for incoming attributes.
• Adding Guide Geometry to SOPs
  Adding guide geometry to SOPs
• Manipulating Attributes inside SOPs
  Manipulating attributes inside SOPs.
• Abusing SOP Cook Mechanism
  Handling blind data to your own data structures, along with rendering thereof.
• The Many Ways To Create A SOP
  A comparison of the different methods of building SOPs.

Writing a DOP

• Auto DOP Nodes
  Creating DOP nodes for creating and manipulating custom data and forces.
• Defining Custom Simulation Geometry
  Creating an alternative geometry representation for use with a custom solver.
• Writing Solvers for DOPs
  Writing a custom solver.
• Building DOP Microsolvers from GAS_SubSolver
  Using the GAS_SubSolver to make a microsolver that manipulates SIM_ScalarField, SIM_VectorField, and SIM_MatrixField.
• Storing and Manipulating Physical Fields
  Using the SIM_*Field classes.

Writing a LOP

• USD Stage Management in LOPs
  How layer and stage ownership works in the LOP context.
• Maximizing LOP Performance
  Ensuring your LOP node runs as fast as possible.
• Primitive Patterns
  Creating a custom primitive pattern auto-collection.

Writing a COP

• Creating a generator COP
  An example of a generator creating random white noise.
• Creating a filter COP
  An example of a 3x3 kernel filter enhancing individual image edges.
• Creating a pixel filter COP
  An example of a simple pixel filter which adds & multiplies constants with the input image.
• Creating a full image filter COP
  An example of a filter which operates on the entire image at once, without tiling.
• Creating a multi-input COP
  An example of a 2 input COP which does a transition between the input sequences.

Writing a CHOP

Writing a VOP

• Creating a Switch VOP
  Shows how to created a basic custom Switch VOP.

Writing a ROP

• Creating Custom ROP Nodes
  Creating a custom ROP operator.
• SOHO Output Drivers
  Scripted Output of Houdini Objects

Writing a TOP

• Creating Custom TOP Nodes
  Creating a custom PDG node definition.