Ok because someone asked in the shoutbox, and I am a glutton for learning new math I decided to give the polar coordinates shader a shot. I am mostly done, with almost everything working (I need to rotate the whole thing 90 CCW, to mirror photoshops implementation). I will attach the .fx file to the end of the post.
In general it was a lot easier than I thought (the first implementation was a nightmare (and I complained for a while in irc to tonfilm today, I forgot to K.I.S.S). I am having some issues with the coordinates only showing half of the image and mirroring it to the other half. I think it has something to do with gettting the atan2 wrong (wrong signs for the x and the y). Its late now so I will sleep on it, to see if I can figure it out.
here 'tis though! Once I get the bugs worked out I will upload a help file.
thank you very much for this shader! it helped me tremendously when working on an ffgl polar coordinate plugin (available soon at https://www.assembla.com/wiki/show/ffgl/ ) here is my version, ported back to hlsl in order to work with vvvv. the modifications are slight:
photoshop magic numbers added
conversion from polar to cartesian added
interpolation parameter added, for animation purposes