KineFX Ball for Houdini: Animation Rig and Geometry (HDALC)

Article / 13 May 2023

I made the rig for practice in animation and as example for how to make a squash and stretch constraint using KineFX in Houdini.

It consists of 3 nodes:
1. KineFX Ball Geometry (optional) node contains set of 6 pre-cached geometry presets for different types of balls: Tennis, Golf, Soccer, Volleyball, Basketball and Toy.
You can replace this node with any geometry that should be placed on the ground and be 1 unit in height.
Or don't use anything at all because next node contains a simple test sphere inside.

2. KineFX Ball Rig contains a skeleton rig for a ball, controllers, and a shape library for them. You can change the appearance of those shapes by diving inside the node and adjusting the Attach controls node's parameters.
3. KineFX Ball Animation gives you access to the Rig Pose state for animating in the viewport and a set of parameters for precise control. The node also contains logic for calculating squash and stretch deformations of the rig and "Joint Deform" to output final deformed(animated) geometry.

How to install:
1. Download these HDA files from the github repo:
2. Install them through Houdini: File - Import - Houdini Digital Asset or copy them to the Houdini preferences folder (Documents/Houdini 19.5 on Windows) - otls.
3. In SOP context in Houdini, press TAB and type: KineFX Ball

How to animate a ball?
- The rig made and inspired to be used along with the tutorials for Maya:
FREE Ball Animation Rig for Maya
Simple Ball Bounce Animation Tutorial
Ball Bouncing Along Animation Tutorial in Maya - PART 2
But how to do the same in Houdini?
If you don't familiar with Houdini's animation editor, watch the series:
Houdini Animation Editor 101 - Part I 
Houdini Animation Editor 101 - Part II
How do I reset the animation?
In the KineFX Ball Animation node right, right-click on any parameter or parameters tab (Ball Animation tab, for example) - Delete Channels, Revert to default.