[PD] Keystone correction

Cyrille Henry ch at chnry.net
Tue Mar 27 22:58:53 CEST 2012


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.
>



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