GL_ARB_copy_buffer http://www.opengl.org/registry/specs/ARB/copy_buffer.txt GL_ARB_copy_buffer GL_COPY_READ_BUFFER 0x8F36 GL_COPY_WRITE_BUFFER 0x8F37 void glCopyBufferSubData (GLenum readtarget, GLenum writetarget, GLintptr readoffset, GLintptr writeoffset, GLsizeiptr size)