Cluster LOD: visible seams between separate meshes on some avatars (no seam with legacy LOD) #798

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opened 2026-10-16 12:50:31 +00:00 by sky_line · 0 comments

sky_line commented

2026-10-16 12:50:31 +00:00

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Owner-confirmed. With cluster LOD on (RenderVKClusterLOD), some avatars (not all) show a visible seam where two separate meshes meet, e.g. a leg mesh against the torso/rump, or a tail base. The seam is a jagged, regular saw-tooth crack along the mesh boundary, with the environment and reflections visible through it. With regular (legacy) LOD the same avatar has no seam.

Not the previous cause: the earlier seam lines (fixed in ffb3556fd2, "Cluster LOD weld: capacity follows demand; overflow skips whole avatars") came from weld capacity overflow. The live log now shows the weld scratch at 16.7 / 29.0 MB with no overflow.

Leading hypothesis (being investigated): the cluster DAG simplifies each mesh on its own. Vertices on a boundary that the rigged weld joins to another mesh of the same avatar are not locked through the DAG levels, so a simplified cut moves or drops them and the two sides no longer meet. Legacy welds the full-detail vertices, so it stays seamless. The even teeth fit independently simplified boundaries. It only hits avatars made of separate meshes that weld at a seam.

Other candidates:

Weld pairs reference source vertices that don't exist in the selected cut.
Adjacent meshes are selected at different DAG levels; there's no cross-mesh crack guarantee.
Welded partners are transformed differently: character-space arena (6a14337296) or held-pose reuse (b384c2379e).

Repro: an avatar with a separate leg/tail/body mesh joined at a seam. Cluster LOD on, then off: the seam appears and disappears.

**Owner-confirmed.** With cluster LOD on (`RenderVKClusterLOD`), some avatars (not all) show a visible seam where two separate meshes meet, e.g. a leg mesh against the torso/rump, or a tail base. The seam is a jagged, regular saw-tooth crack along the mesh boundary, with the environment and reflections visible through it. With regular (legacy) LOD the same avatar has **no** seam. **Not the previous cause:** the earlier seam lines (fixed in ffb3556fd2, "Cluster LOD weld: capacity follows demand; overflow skips whole avatars") came from weld capacity overflow. The live log now shows the weld scratch at 16.7 / 29.0 MB with no overflow. **Leading hypothesis (being investigated):** the cluster DAG simplifies each mesh on its own. Vertices on a boundary that the rigged weld joins to *another* mesh of the same avatar are not locked through the DAG levels, so a simplified cut moves or drops them and the two sides no longer meet. Legacy welds the full-detail vertices, so it stays seamless. The even teeth fit independently simplified boundaries. It only hits avatars made of separate meshes that weld at a seam. **Other candidates:** - Weld pairs reference source vertices that don't exist in the selected cut. - Adjacent meshes are selected at different DAG levels; there's no cross-mesh crack guarantee. - Welded partners are transformed differently: character-space arena (6a14337296) or held-pose reuse (b384c2379e). **Repro:** an avatar with a separate leg/tail/body mesh joined at a seam. Cluster LOD on, then off: the seam appears and disappears.

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2026-10-16 12:50:31 +00:00

sky_line added this to the Slipstream project

2026-10-16 12:50:32 +00:00

sky_line referenced this issue from a commit

2026-10-16 17:53:48 +00:00

Cluster LOD weld seams: re-skin a held row whole for a stale kept slot; seam diagnostics

sky_line closed this issue