First post, by Dege
I move all TruForm or general N-patch related posts to this topic.
RaVeN-05 wrote on 2021-07-25, 10:33:
P.S. Have big hopes that ATI TruForm coming to wrapper
TBH, I don't know. Once a while ago I evaluated if it could be implemented but it turned out to be very problematic.
ATI TruFrom is 'N-patch', subdividing/curving triangles based on the vertex normal vectors.
There also were RT-patches (rect-triangle patches) supported in DX8/9 and those were based on different concepts than "just enable it and it just works" N-Patches, needing additional vertex data to the geometry.
I say it because the tesselator on modern hw is the generalized form of 'RT-patches' so ATI TruForm is not compatible with it. It subdivides the triangles along a different pattern and also, culling can't be controlled on per-triangle basis.
Geometry shaders (which are slow) could help here and a modern hw may be able to render the old DX8 truform-geometry with a decent performance but from an engineer's point of view, the implementation would be very inefficient.