Single Node Foot Pivot
Typically I have setup foot rolls with either dependency node graphs consisting of a variety of utility nodes, or using DagNodes to create a reverse cross shaped chain. Both systems work reliably and are a tried and tested approach.
However, whilst these are not particularly complex setup's, they do increase the node count in a rig, and therefore add to the cost of computation - and when trying to increase performance every little helps.
The StarPivot node was an experimentation with the Maya C++ API and attempting to boil down a four point foot pivot into a single dependency node. Rather than building a structure of DagNodes with mutliple utility nodes and connections, all the transformations are carried out within a compiled node.
The node itself takes in two animatable attributes to define a two dimensional direction. These are fed through the node logic which also takes in offsets (which can themselves be animated too!) to determine a final matrix transform.
Finally, there is a debugging option, which when enabled uses OpenGL (this was done prior to VP2) to draw the plane and the roll plane.
You can download/view the code for the star pivot by clicking the download link below. This code is the computation code for the node, so you'll still need to setup a cmake project or vs project to build it - and add the plugin registration block.