I like the overall architecture of the rendering classes @dcthomp They’re very simple, short and easy to use in other areas. Of particular interest to me are the vtkArrayRenderer and vtkDrawTexturedElements classes, and of course the vtkGLSLMod* classes. In hindsight, I should’ve added the GLSL mod classes in Rendering/OpenGL2.
I’m thinking about moving those classes from Rendering/CellGrid into Rendering/OpenGL2 because they use less memory and we need that for the GLES 3.0 polydata mapper. I see some ifdef…else…endif around glDrawElementsInstanced, did you want it to compile against GL 3.1? GLES 3.0 supports glDrawElementsInstanced.
Cc @sankhesh