Got ray/triangle intersection working 😇
Still no acceleration structure, so still slow...
Though came up with an in/out-testing approach for tetrahedral-triangles that's ~30% faster
(doing it in tangent-space instead of world-space):
y > 0 && y < x*SQRT3 && y < (1 - x)*SQRT3
Donno it it's a common thing I've re-invented or not, but works very nicely 😎