gridshape and slab processing

Hi

Im working on a patch at the moment where I would like to process a jit.gl.gridshape object with slab.gauss6x. I've really hit a brickwall with this, and even though I can use the slab processing on an isight input with no problem (from the tutorials) I can't seem to join the dots to get the same effect with the gridshape. The patch below is where I am so far, from the various searches I've done on the forum would I be right in thinking that I need to capture the gridshape as a texture? The idea of the patch is to generate a shape on a midi note but I'd like some more processing over the output visually. Any help or pointers would be greatly appreciated