Opengl: Quadratic interplation between vertex and fragment shader

Question

Is it possible to implement iterpolation that is of a higher order than linear when passing data from vertex to fragment shaders? Ideally I would like some form of quadratic interpolation, but that would require access to vertices beyond the corners of the face being interpolated across.

Answer 1

The short answer is: no.

I do not think that there is a native support for interpolation other than linear if it comes to attributes passed from vertices to the fragment shader.

However you could incorporate a trick to have non linear interpolation by using geometry shader an inserting interpolated vertices in-between. Or, if you want so have some kind of distribution of values along the interpolated line, you can use a predefined 1D texture that will contain the interpolation curve you need to use in the fragment shader.