Skin weights: 16 B -> 10 B per rigged vertex (8-bit joints + 3x16-bit weights, 4th implied) #582

New issue

Closed

opened 2026-10-09 01:49:14 +00:00 by sky_line · 1 comment

sky_line commented

2026-10-09 01:49:14 +00:00

Owner

Rigged vertex weights are stored as 4 floats (16 B; LL encoding: integer part = joint index, fractional part = weight). In a heavy region the w share of geom is about 422 MB.

Format

4 × u8 joint index.
3 × u16 unorm weight; the 4th is 1 minus the sum.
10 B per vertex.

This is lossless against the SL asset format (8-bit joint, 16-bit weight). Joint counts per skin are at most about 110. Identical source weights quantize identically, so seams between meshes are unaffected.

Scope

Every consumer of the weight stream:
- CPU mirror (MirrorWeight)
- VK packer
- clean_preskin.comp
- decimator (#561)
- shadow-caster LOD matching
- pick skinning
- rigged BLAS inputs
- system-avatar raw slots
Weight normalisation must match the current float path.

Done when

w in the mesh: / geom #573 log lines drops to about 62.5%.
Rigged avatars deform identically, including fingers, faces and body/head seams.

Rigged vertex weights are stored as 4 floats (16 B; LL encoding: integer part = joint index, fractional part = weight). In a heavy region the `w` share of `geom` is about 422 MB. ## Format - 4 × u8 joint index. - 3 × u16 unorm weight; the 4th is 1 minus the sum. - 10 B per vertex. This is lossless against the SL asset format (8-bit joint, 16-bit weight). Joint counts per skin are at most about 110. Identical source weights quantize identically, so seams between meshes are unaffected. ## Scope - Every consumer of the weight stream: - CPU mirror (`MirrorWeight`) - VK packer - `clean_preskin.comp` - decimator (#561) - shadow-caster LOD matching - pick skinning - rigged BLAS inputs - system-avatar raw slots - Weight normalisation must match the current float path. ## Done when - `w` in the `mesh:` / `geom #573` log lines drops to about 62.5%. - Rigged avatars deform identically, including fingers, faces and body/head seams.

sky_line added the

labels

2026-10-09 01:49:14 +00:00

sky_line added this to the Slipstream project

2026-10-09 01:49:14 +00:00

sky_line added

status