I can not find a technique for isolating, analysing and
processing part af a matrix, which would be NOT
rectangular. The idea is to make a sort of stained
glass, which would change it's shape. I'd like to
control this changes, let's say they should not be
It seems to be rather heavy task for CPU, but I hardly
imagine this effect in Open GL.
In fact there are 2 tasks:
1st - draw this stained glass shape.
2nd - process picture or movie "under"it - to apply
color and transparency variations according to areas on
Would anybody advise?