Odd stripey artifact in my pulgin's output

Question

Hey everybody,
I've been experiencing an unpleasant bug in many of my plugins where I get an unpleasant stripey artifact in the output.
This happens in my plugins which involove several PF_ITERATE steps and some fast blurring. What it looks like is for certain rows of the image, an operation or two is skipped and not applied to those pixels.
It tends to happen when we're changing the value of a parameter with a slider or some such control and After Effects is rushing to complete the operations and something gets dropped at some point. These artifacts tend to go away when I turn the effect off and back on again but I'm not confident that it won't keep cropping up. Has anyone seen this type of behavior? Anyone hava an explanation/solution?
Any help is appreciated!
P.S. I'll try and post some screenshots later...

Answer 1

Hey everybody, I fixed my own problem!!
Here's what happened:
I was screwing up my PF_Err flag.
I had multiple calls to PF_ITERATE and each one was like:
err = PF_ITERATE(0, height, input_worldP, &input_worldP->extent_hint,
                                     &si, myFunction1, output_worldP);
err = PF_ITERATE(0, height, input_worldP, &input_worldP->extent_hint,
                                     &si, myFunction2, output_worldP);
err = PF_ITERATE(0, height, input_worldP, &input_worldP->extent_hint,
                                     &si, myFunction3, output_worldP);
so each call overwrote err, thereby blocking any previous errors from getting through.
I rewrote it like:
ERR(PF_ITERATE(0, height, input_worldP, &input_worldP->extent_hint,
                                     &si, myFunction1, output_worldP));
ERR(PF_ITERATE(0, height, input_worldP, &input_worldP->extent_hint,
                                     &si, myFunction2, output_worldP));
ERR(PF_ITERATE(0, height, input_worldP, &input_worldP->extent_hint,
                                     &si, myFunction3, output_worldP));
and everything was better.
Here's what I think was happening under the hood:
The stripes would show up when one changed parameter values quickly, like moving a slider fast back and forth. This would interrupt the rendering which would result in a error that if properly caught would tell AE to not display this frame, it didn't get finished properly. Well I was screwing up that error reporting so AE was displaying interrupted frames which looked like crap.
This was clearly a rookie mistake which I made by blindly copying code form an example without properly understading how it should work. Alas....
                    ERR(PF_ITERATE(0, height, input_worldP, &input_worldP->extent_hint,
                                     &si, generateSkinIsolationMatteDemo8, output_worldP));