textures and shapes

Hello,

This is probably very simple once you know how to do it, but I am having trouble jumping into GL in jitter. For my final output, all I want is a 1280x720 screen output divided into four segments horizontally: each segment would be 320x720, with different textures. These would be static, and not utilize the z axis. From what I have seen online so far, drawing the texture to jit.gl.gridshape seems to be the way to go.

However, I cannot seem to figure out how to manipulate the plane shape from the default square to a rectangle, nor can I figure out how to adjust the video dimensions over the shape once it is in place (keep the shape the same size, but zoom the video in and out, move it left and right, etc).

The conversion of pixel dimensions to the -1.-1. matrix are a bit arduous as well. In processing it was possible to set your origin point to the top left when working in GL. Is something like this possible in Jitter?

If anyone could post a simple patch explaining how to do these things, I would be forever grateful. Most of the examples I've found online so far involve flying doughnuts, which don't help me much.

Thanks!

Sara