For where there's no vertex JIT. It skins the same way as the steps:
the skin matrix is 0 + bone * weight, kept as the columns that
Vec3ByMatrix43() and Norm3ByMatrix43() multiply and add unfused in the
same order (by lane on ARM64, like those), and only rebuilt when the
weight changes. 2.2 ns a vertex in God of War against the JIT's 1.95
and the steps' 12-18.
Without the vertex JIT, God of War's instructions drop by 6.8% per 10
emulated seconds.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
For where there's no vertex JIT (iOS), as they're a few percent slower
than the JIT's but four to eleven times faster than the steps. The
formats carry most of the vertices of ATV Offroad Fury: Blazin' Trails,
Wipeout Pure and Killzone: Liberation, and a lot of Gods Eater Burst's.
They convert like the steps (PrescaleUV moves to the header for that),
and the vertex decoder test now also compares each format's decoder
without the JIT against the steps.
Without the vertex JIT, 10 emulated seconds on an M1, instructions:
ATV -9.9%, Wipeout -6.0%, Killzone -5.4%, Gods Eater -2.2%.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
They were only used for UV from texture coordinates. With the texture
matrix or environment map, UV isn't prescaled, which is the same as a
scale of 1 and no offset, so NoPrescale versions pass that. God of War
draws 5 million of its vertices per 10 seconds this way, which without
the vertex JIT took 9.6 ns each through the steps and now 2.4.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
