After a first messy attempt to bring  shadertoy compatibility to Processing (see at the bottom of this topic), here is a more refined one. It should allow to paste shader code back and forth from shadertoy to your shader file. The sketch example already takes care of loading the shader and passing the appropriate uniforms. 

Look at the comments in the code for more information.

https://github.com/SableRaf/Processing-Experiments/tree/master/2013/Shaders/ShadertoyToProcessing

It is a work in progress that will work for most shaders but doesn't include the iChannel.., iChannelTime and iDate uniforms of shadertoy yet. Please contribute back if you implement those features for your project.

Raphaël