1a40efbded
Turns out that with `-fassociative-math`, GCC turns `(1.0f - cos_NH2) + alpha2 * cos_NH2` into `cos_NH2 * (alpha2 - 1.0f) + 1.0f`. Not sure why since the operation count is the same, but if alpha2 is very small, `alpha2 - 1.0f` will be exactly -1.0f, which then causes issues. Luckily, having one_minus_cos_NH2 as its own variable appears to be enough to make GCC keep the original formulation. Just to be safe, I've also used one_minus_cos_NH2 in the other branch to hopefully reduce the chance of it being folded in again. Also turns a division into a reciprocal, which is in theory slightly faster. Pull Request: https://projects.blender.org/blender/blender/pulls/130469
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