Interface LoadedMeshData

Vertex positions (vertexCount * ndim), flattened row-major

Triangle vertex indices (faceCount * 3), indexing into vertices.

Always Uint32Array here regardless of the store's dtype. Externally produced stores legitimately use int8..int64, and the writer's own INDEX encoder narrows to the smallest unsigned dtype that fits, so this is a widening the loader owns. Every value has been range-checked in [0, vertexCount) against the source-typed values, before coercion — each side of the cast hides its own wrap-around (spec §3.5 Stage 2).

Per-vertex normals (vertexCount * 3), or null when absent.

Only meaningful in the frame named by MeshMetadata.normal_dims.

Per-vertex colors (vertexCount * colorComponents), or null when absent

Channels per color entry: 3 (RGB) or 4 (RGBA, the alpha column being per-vertex opacity). Undefined when colors is null.

Per-vertex scalars for colormap lookup (vertexCount), or undefined

Per-vertex texture coordinates (vertexCount * 2), or undefined.

Deliberately NOT clamped to [0, 1]: values outside it are how a texture tiles under texture_wrap: 'repeat', so clamping would break the feature it looks like it protects. Non-finite values ARE refused, on both sides — a NaN UV pulls its whole triangle into an undefined sample.

The decoded texture, or undefined when the node has none

Number of vertices loaded

Number of triangles loaded

Dimensionality for interpreting vertices

Loader-owned scratch for the display-space projection, reused across epochs.

The Mesh counterpart of the Points accumulator's reusable target buffers (points-spatial-index-loader.ts hands positions3D to the projection rather than letting it allocate). Mesh's home for it is here because updateView returns this same object for the node's whole life and drops it on dispose, so the buffer inherits exactly the right lifetime with no separate cache to invalidate.

Without it, projectMeshTo3D allocated a fresh vertexCount * 3 buffer on every slice move — so the geometry's array-identity check never matched and every scrub copied and re-uploaded the whole vertex buffer and recomputed bounds, defeating the "only the index changes on a pure slice move" design (#1245).

displayDimsKey records which axis triple position currently holds, because once the buffer is reused its identity can no longer signal a change. Optional so a caller may still project without one (it then allocates, as before).