This sample demonstrates render-to-vertex-array using FBO, PBO, and VBO. A VBO is allocated with storage and indices for an N x N mesh. Then content is drawn into an N x N texture attached to an FBO. The pixel data is copied from the FBO into the VBO, by binding a PBO to the VBO id and calling glReadPixels. Now the pixel RGBA colors can be used as vertex XYZW data.