AMDX vertex shader tessellator

Discussion created by VilemOtte on Apr 19, 2009
Latest reply on Apr 25, 2009 by avk

Good day

I'm a programmer from one smaller company which now works on state of the art rendering engine, but I got stuck with one extension from AMD.

Triangle tessellation is very important for this project (and if we don't manage to get it through this extension, We will be forced to cancel support for AMD cards, or use software tessellation on them (which will lead to extreme slowdown).

The problem is - I've managed to tessellate the triangle, but I didn't manage to get texture coordinates, normals, tangents and bitangents for tessellated vertices (and that's huge problem).
My vertex texture fetch for texture coordinates and TBN along with vertices VTF are correct (i tested their generation and rendering from them - and it's correct), but tessellation using vertexFetchAMDX is returning corrupt result (always zero).

If anyone managed to complete tessellation using this extension, I'd very appreciate if he could give me some tips. I can even post some code, how I tried to do it - so those of you, who have experience with this, could look at it and direct me to right way (if there is).

I was forced to use GL_AMDX_vertex_shader_tessellator instead of GL_AMD_vertex_shader_tessellator, because there isn't any current gpu from AMD, that supports GL_AMD version (just those, that supports GL_AMDX - experimental version).

For information I'm debugging on ATI Radeon HD 2900XT gpu.