A long time has passed since I programmed using OpenGL and posted to this forum (actually it was opengl.org then), so long that I had to open a new account. I’m sorry for this introduction, but I need to justify why newbie posts to the advanced coding section.
Well, I would like to use tessellation shaders for something I have already implemented in the vertex shader (VS), trying to compare the performances. The experiment will continue with the mesh shaders later.
The first question is: What is the most efficient way to invoke TCS without having to define a VBO with patch vertices?
Motivation: I actually do not need control vertices. It is common knowledge that TCS executes once for each vertex in the output patch. So, theoretically, I could use a dummy VBO with just one vertex for all patches. Furthermore, the vertex could have only one coordinate. Just to provoke a TCS execution. If it is so, could there be a way to avoid even that dummy VBO with a single floating-point value? VS can execute without attributes. Is it possible somehow for the TS?
The second question is performance-oriented: Is it better to use trivial TCS or set default tessellation levels from the application (and the number of patch vertices to 1) and remove TCS from the pipeline?
Thank you very much in advance!