I was trying to use gl_FragData[n] to write multiple image outputs at once.

When I load the shader in the modules folder, I get one output. It does render the blue background of gl_FragData[0] though, which is not a bad fallback.

Is this something that makes sense as a feature enhancement request for this shader functionality in VUO? Does the ISF aspect a limitation on this, or no? There seemed to be no compiler error.

Should I expect this to work if I write a custom node and manually create the multiple image outputs, with each frag data index writing to a different out?

Support for simultaneously writing to multiple images from one fragment shader would require some backend changes in Vuo’s rendering code. If anyone’s interested in support for that, please create a feature request, so the community can vote on it to help us gauge interest and prioritize implementing it.