How to get the compute result of glEvalCoord*?

I want to get the result of glEvalCoord*, such as the vertex coord (x, y, z).
How to do it?help

You can roll your own evaluator or use some sort of feedback mechanism to read OpenGL generated vertices back.

For example, see the section on feedback here:

Or if you’re up to the math, there are many demos and libraries online for curve and surface generation in a variety of flavors.