Hello,
Well, then what do you mean by writing shaders “properly in VTK”? I mean, if you program compiles and you get your shader working, you got it “properly in VTK”. VTK simply forwards whatever you wrote to OpenGL via a mapper object and that’s that… You don’t have access to VTK data from inside the shader context, if that’s what you’re looking for. Maybe you can pass information of your original data set via some mechanism (alpha channel?), but I’m speculating. Sorry if I’m missing something.