How to get the vertex information of each Bezier patch from Control points???

I’ve known the control points, and by the code below I can surely draw a curve surface by Bezier patches, but here I do want to get each Bezier patches’ details such as each vertex information, normal, and the such. Can you tell me How to obtain these parameters in OpenGL? Thanks a lot!!!
My code :
glMap2f( GL_MAP2_VERTEX_3, 0.0, 1.0, 4, 4, 0.0, 1.0, 16, 4, @ControlPoints[0][0][0]);
glMapGrid2f(4, 0.0, 1.0, 4, 0.0, 1.0);
glEvalMesh2( FillMode, 0, 4, 0, 4);
How can I get each Bezier patch’s vertex information??? :confused: