The MatrixCHOP produces the screen-space coordinates of points based on a camera and an aspect ratio. The inputs:
The output:
In this image we render a white rectangle at an oblique angle. The MatrixCHOP takes the world-space positions of the rectangle's points, the camera's full view-projection-matrix, and then produces 4 new points. These 4 points are then depicted in a separate render of red squares. These squares land exactly on the corners in the first render, confirming that the MatrixCHOP outputs correct screen-space coordinates.
Build the dll yourself, or use a compiled DLL file. MatrixCHOP/MatrixCHOP/Plugins/MatrixCHOP.dll
has been compiled as a Custom Operator for TouchDesigner 2019.19160.