Dear Axel,
I recently found a minor index bug in dump_image.cpp, more specifically, 29Aug2024 version, line 890. I attached a screenshot here.
In the highlighted line, I believe the index should be j, not i. Indeed, this line of code will cause rendering error if there are several kinds of body particles. After replacing “body[i]” with “body[j]”, the rendering works correctly. I can provide a simple test input file to reproduce this bug if you are interested. I was wondering if it worths to open a issue on github to report and fix it. I never did this before and I think this is a good process to learn.