Blackstone
07-05-2010, 02:29 PM
Hello folks,
Is there anybody tried to access the subdivision parametric UV in mr shader before ?
I wrote a tiny mr shader to show the miState::bary[4] as color and found that the minimal primitive in mr is absolute the triangle, not the quad as I thought before.
I used RenderMan for a long time and I know that the Catmul-Clark subdivision control mesh will be subdivided to massive grids, and there is a independent parametric region in each grid, the grid will be also a quad in most situations if we use high quality control mesh.
So I would like to know is there any possible to access the subdivision parametric UV (not the ST for texturing) in shader and how to ? And I also want to know which facet of control mesh the current shading point belongs to, I thought the per-face data maybe useful but I did not found any example.
Thanks !
Is there anybody tried to access the subdivision parametric UV in mr shader before ?
I wrote a tiny mr shader to show the miState::bary[4] as color and found that the minimal primitive in mr is absolute the triangle, not the quad as I thought before.
I used RenderMan for a long time and I know that the Catmul-Clark subdivision control mesh will be subdivided to massive grids, and there is a independent parametric region in each grid, the grid will be also a quad in most situations if we use high quality control mesh.
So I would like to know is there any possible to access the subdivision parametric UV (not the ST for texturing) in shader and how to ? And I also want to know which facet of control mesh the current shading point belongs to, I thought the per-face data maybe useful but I did not found any example.
Thanks !