TruForm™ Resources N-Patches are a higher-order surface primitive developed by ATI for DirectX® 8. N-Patches are Bezier triangles whose control meshes are derived from the position and normal data associated with a given triangle. TruForm™ FAQ

Tools N-Patch Plug-in for 3D Studio Max R3 - This 3D Studio MAX Plug-In gives the artist the ability to create a viewport for previewing objects using N-Patch tesselation rules. Updated 5/11/01 . ATI N-Patch Exporter and Viewer - This zip file contains a 3D Studio MAX 3.1 exporter and stand-alone N-Patch viewer written in GLUT. Provided is sample code for exporting a model from 3D Studio MAX 3.1 while preserving creases defined by MAX's smoothing groups. The source code for the viewer is also included which gives example source code for tessellating N-Patches in software for prototyping purposes.

Presentations I3D 2001, Curved PN Triangles by Alex Vlachos and Jörg Peters Alex Vlachos, Jörg Peters, Chas Boyd and Jason L. Mitchell, "Curved PN Triangles", ACM Symposium on Interactive 3D Graphics, 2001.