hello Charles,
you can render anything on a framebuffer, then using it as a texture to the polygon.
look at gem example: Gem/examples/12.multi_screen_projection/02.nfp-help.pd it's a bit more complex than what you want to do, but you'll may find it interesting.
cheers Cyrille
Le 27/03/2012 21:50, Charles Goyard a écrit :
Hi list,
this is very basic, in fact so basic no one ever asked it seems :)
I need to correct the trapezoidal/keystone deformation of a video. The beamer I use can't correct enough, so I need to do that with GEM. I heard of a keystone library but could not find it.
I tried various rotate/scale/translate without getting good enough results.
So I thought I could have a polygon with a texture mapped on it, and the stretch the corners. The problem I have is that my patch is as follows:
[pix_image test.png] | [pix_texture] | [circle 4]
(The circle is used to make a mask so the video boundaries are round.)
Adding a polygon after the circle does not seem to work.
Any advice welcome.