I don’t think the scenarios where uniform steps of angle is vanishingly small. There are plenty of cases where it matters to animators, on character rigs, on cameras
The amount that it matters depends on the angle between keys. Suggesting it rarely matters means you’re claiming nobody ever animates large angles, which I can confidently say I’ve seen plenty of counter-examples in game development.
I also wouldn’t be so sure that lerp+normalize is that much faster on today’s GPUs. Normalize takes a sqrt and reciprocal or divide, while slerp takes a few sin evaluations and a recip or divide. These special functions these days execute in a separate pipeline from linear (FMA) type instructions, and can be had for “free” as long as you can mix enough independent linear math in between the special functions. It used to be that sin() was very slow, but these days you can often mix a couple calls in without affecting your perf at all.
The amount that it matters depends on the angle between keys. Suggesting it rarely matters means you’re claiming nobody ever animates large angles, which I can confidently say I’ve seen plenty of counter-examples in game development.
I also wouldn’t be so sure that lerp+normalize is that much faster on today’s GPUs. Normalize takes a sqrt and reciprocal or divide, while slerp takes a few sin evaluations and a recip or divide. These special functions these days execute in a separate pipeline from linear (FMA) type instructions, and can be had for “free” as long as you can mix enough independent linear math in between the special functions. It used to be that sin() was very slow, but these days you can often mix a couple calls in without affecting your perf at all.