Blend Image With Feedback Node Bug

Steps causing the bug to occur

  1. Use Blend Image With Feedback node
  2. connect BIWF output to Blend Images
  3. also connect BIWF output to a blur or other filter, then connect filter output to Blend Images
  4. Blend Image With Feedback seems to get corrupted, but it is hard to pin down exactly what is happening. What I think seems to happen, is that Blend Image With Feedback seems to somehow start using the result one or two nodes down the line for feedback, not the actual input image.

Have you found a workaround?

To manually create feedback and blend nodes from scratch.

Other notes

  • Vuo version: 2.3.2
  • macOS version: macOS
  • How severely does this bug affect you? It’s annoying but I can work around it.

Both of these nodes also seem to perform very inefficiently. Quickly substituting out the shadertoy node with similar shader functions results in much better, non-buggy performance.

If you can reproduce, please send us a composition that shows this, and please let us know what you experience as “corrupted.”

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Yes, and this is another thing that may not be an issue in the most recent version.

I will go back to the composition I was encountering this with, add the parts back in that I think may have caused it, and try to capture video or have a clearer example.

The issue with providing the example immediately is that I had deleted those bits before saving a version, so I have to try to back into it. At the same time, I thought it would still be worth mentioning…sometimes a cause to glance across some code has something glare out, and it can still lead to a fix without a great example of the bug.

I remember that I was using blend with feedback on the results of a shadertoy node. I would feed output of feedback to the Blend Images node…while also sending output from feedback to various blurs, and then to the other input of Blend Images. I was basically wanting to composite the results of feedback unblurred and blurred, to create some kind of glow/halo effect.

While toggling through blend modes, every so often I would see the render screen kind of white out, as though too much brightness was taking place within the feedback loop itself, even though this composite node was past the feedback node in the chain.

And it wasn’t just brightness or inversion from the blend mode itself…the actual feedback loop would not recover rendering quality. It was obvious that somehow the loop itself was being affected by nodes after it.

However…may be irrelevant now. Just getting it jotted down here while I’m thinking of these particular details.  

We are closing this as “not a bug,” but should a community member reproduce it, please let us know here.