Question about attribute indexes

[CarterFendley]

Thank you for the great videos + code!

I am following along here. After watching your second tutorial, I was getting the results shown below.

Comparing the diff between my code at the time and yours, I could not see any meaningful difference. Eventually I stumbled into the get_attrib_location(...) function and gave that a try. In this commit I was able to use this function to patch the issue and get the result shown at the end of the second video (very exciting!).

When printing out the attribute values, I found that they were reversed from the ones I expected (aColor: 0, aPosition: 1). This happens even though I list my attributes in the same order you have them in the shader.

My question is: Why might this happen? Do different GPUs order the indexes differently?

The docs for enable_vertex_attrib_array(...) does note "Some vertex attribute indices may have predefined purposes, depending on the platform and/or the GPU." Could this be related.

Cheers 🍻