A tutorial on Pivot Painter, an HDA that stores model pivot and rotation information in the model’s vertex data and additional UV channels.
SideFX has shared a guide to Pivot Painter in Houdini 16. For those you unfamiliar with the thing, it is a Houdini Digital Asset (HDA) by Paul Ambrosiussen that stores model pivot and rotation information in the model’s vertex data and additional UV channels. That information can then be referenced inside of Unreal’s shader system to create interactive effects.
METHOD 1: PER OBJECT BASIS
Method 1 allows users to animate any non-hierarchical sub-meshes of a mesh to be aimated using its pivot location and rotation. Using this data, you could generate interesting looking motion on things like grass, bushes, hair, abstract vfx and much more. Simply plug in your geometry and pivots into the tool and you are ready for export to an engine such as Unreal Engine.
The examples shown in the video mainly use Method 1, which is the most frequently used functionality of the tool. You would only really use Method two when desiring multi-layered motion.
METHOD 2: HIERARCHICAL BASIS
This functionality of the tool is used to store child parent relationships like the relation between a branch and leaf for instance, as well as the model pivot and rotation information in the meshes. It is important to note that this mode has two ways of processing pivot information: 1. Generate Pivots: When selecting this option, the tool will figure out what the optimal position is for the pivots on every single sub-object. This allows the user to import non-procedural assets, and make them pivot painter compatible. 2. Custom Pivots: Should the user have generated the object to be processed by the tool, and have access to the original pivot points, this option should be used. This allows the user to have fine control over the pivot positions used in the vertex shader.
Make sure to check out the full written guide here.