Degenerate triangle show up on some devices

[rreusser]

In version 1.0.0, iOS 15 Safari shows some overlapping pixels where caps meet segments. I'm not sure what's causing this, unless maybe triangle strips require knowledge that it's a triangle strip in order to avoid? I thought as long as the tris met floating-point-correctly that the GPU had some magic way to get this right.

At any rate it's not a blocker and there are bigger self-intersection issues with transparent lines anyway, but it'd be nice to understand.

[rreusser]

Ah, the existence of these on the no-caps test suggests it's a result of degenerate triangles still resulting in a couple rasterized pixels. I think they should be degenerate to within floating point accuracy, so maybe this is just the way it works. https://rreusser.github.io/regl-gpu-lines/docs/tests.html#miter/insert-caps/none

Only seems to happen for endpoint caps. Full opacity or depth testing are not subject to the problem. Backface culling cuts it in half.