OpenGL question

[voidstar@tin.it]

Hi,
does anybody knows if and how can I do a thing like
this in OpenGL?

  unsigned char* pA000 = vga_getgraphmem();
  pA000[pos] = color;

With svgalib i can do this, but in OpenGL? Is there
a way to access the screen like an array (not only 320x200,
but also 640x480, etc.)

Thanks in advance,
	voidstar