I'm trying to create a flame mask where a vertical row of flames are masking one side of the screen. I need my generated media on the left which would be where the flame effect gif is, cutting off half the screen so that the video on the right would be visible underneath. I think I've got half way... I've managed to work out the cutting off half the screen part at the right angle, but I can't see where to define the shape... I hope that's clear...