PostFX Library

Hello! It would be great to have a short video on the [PostFX library](https://github.com/cansik/processing-postfx). It's very easy to use and set up and I would love it if you could show how to port a shader from something like [the Wagner effect composer for ThreeJs](https://github.com/spite/Wagner/) into a Processing compatible post FX shader.

Review the PostFX library and the Wagner effect composer linked in the issue, then determine whether a shader port can be demonstrated in Processing. Done means producing a short video that covers setup, usage, and the requested porting example.

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