Interface MeshMetadata

Node type identifier

Total vertex count. Capped at MAX_MESH_VERTICES (spec §3.5, §6.5).

Total triangle count

Vertex position dimensionality

Whether a per-vertex normals array is present

Which three dimension indices the 3-component stored normals describe. Present iff has_normals.

This is never implicit. For a (t, x, y, z) mesh the "first three dimensions" are (t, x, y) — meaningless as a normal frame — which is the bug this attr exists to prevent. It is also the authored winding frame: sorted(normal_dims) is the axis triple whose column order the stored face winding is front-facing in (spec §3.2, §5.4).

Whether a per-vertex colors array is present

Whether per-vertex scalar values for colormap lookup are present

Whether a per-vertex uvs array is present.

Paired with has_texture: the writer refuses either alone, because each is inert without the other (UVs index into nothing; a texture with no mapping samples one arbitrary texel across every triangle).

Whether a texture array is present

How texture is stored. Present iff has_texture.

Declared texture width in pixels. Present iff has_texture.

These three dimension attrs are load-bearing, not descriptive. For an encoded texture they are the only thing that bounds the decode before any bytes are fetched — a 200 KB JPEG can declare 30000x30000 and expand to 3.6 GB — so the preflight charges the decoded surface from these numbers and Stage 2 re-checks the decoded bitmap against them. See data/mesh/preflight.ts.

Declared texture height in pixels. Present iff has_texture.

Channels per texel: 1, 3 or 4. Present iff has_texture.

Colour space of the texture's values. Present iff has_texture.

[min, max] of an HDR texture's RGB values, stamped only when the raw payload carried a value above 1.0.

The texture peer of color_data_range, computed over RGB only (alpha excluded) so the viewer's window derivation reads one shape whatever the source.

Sampling filter; viewer-defaulted to 'linear' when absent.

Wrap mode; viewer-defaulted when absent to repeat-in-u / clamp-in-v, which is what an equirectangular basemap needs — tiling across the dateline seam without bleeding the north pole into the south.

How to obtain surface normals; always stamped by the writer

Whether both faces of the surface are drawn (THREE.DoubleSide) rather than only the front (THREE.FrontSide).

Note the viewer may render double-sided even when this is false: when projected winding cannot be decided against the authored frame, no index post-pass can restore it, so the epoch falls back to DoubleSide with a one-time notice (spec §5.4, §7).

Spatial ordering method. Always 'none' in v1 — the loader is whole-node, so there is no chunk index to skip. Stamped unconditionally so a reader never has to distinguish "no ordering" from "attr missing".

Named colormap or 'custom' (paired with a colormap_lut zarr array)

[min, max] for normalising scalars before LUT lookup

Min/max of the color data, computed at encoding time

Whether per-vertex string labels exist (CSR-encoded, for hover tooltips)

Whether per-vertex image labels exist (CSR-encoded, for hover thumbnails)

Whether per-vertex stable string keys exist (CSR-encoded, for element actions)

4x4 transform matrix (column-major for THREE.js)

Opacity multiplier

Absorption coefficient (volumetric blending; mesh refuses that mode, §6.3)

Gamma correction

Intensity (linear color multiplier / gain)

Offset (additive brightness shift / black level subtraction)

Offset-key shade floor in [0, 1] — what a face-away fragment keeps (§6.2). 1.0 removes the diffuse gradient; set specular = 0.0 as well for a fully emissive look.

Optional and viewer-defaulted: the writer never stamps it, so it is present only when an author passed it through add_mesh(**attrs). Authoring support and the material read landed together so accepted values affect the rendered mesh.

Wrapped-diffuse exponent (§6.2). Clamped positive — pow(0, 0) is undefined GLSL.

Additive specular strength in [0, 1] (§6.2).

Specular highlight exponent (> 0) (§6.2).

opaque-mode alpha cutout threshold in [0, 1] (§6.2).

Which material family renders this mesh (docs/guides/specs/MESH_PHYSICAL_MATERIALS_SPEC.md §3.1).

Absent or 'luxar': the house shader (§6.2). 'physical': three's own physically based material, lit by the scene environment the viewer builds lazily on the first such mesh. Written only when authored, so every pre-existing store reads as the house shader.

Physical: microfacet roughness in [0, 1]; three's default 1.

Physical: metalness in [0, 1]; three's default 0.

Physical: clearcoat layer strength in [0, 1]; three's default 0.

Physical: clearcoat roughness in [0, 1]; three's default 0.

Physical: thin-film iridescence strength in [0, 1]; three's default 0.

Physical: sheen strength in [0, 1]; three's default 0.

Physical: sheen tint as #rrggbb. Viewer-defaulted to WHITE rather than three's black, because a black sheen is a no-op and sheen alone would then render nothing.

Physical (glass, spec §3.4): share of light transmitted in [0, 1]; three's default 0. Above zero the mesh composites as translucent and refracts the background and other meshes — NOT points, lines or splats, which three's transmission pass never sees, unless refract_data opts it in.

Physical: index of refraction in [1, 2.333]; three's default 1.5.

Physical: refraction volume thickness in scene units, >= 0; three's default 0.

Physical: #rrggbb tint reached after attenuation_distance through the volume (Beer–Lambert); three's default white = no tint.

Physical: attenuation length in scene units, > 0; absent = Infinity (none).

Physical: chromatic dispersion strength, >= 0; three's default 0.

Physical (glass, spec §3.4 Phase 3): draw this glass AFTER the emissive data so it refracts the points, lines and splats behind it. Absent = false (Phase 2 glass-first). Authoring refuses it without transmission > 0. Data in front of the glass stays crisp: the refraction split partitions every data fragment by depth against the glass's front surface (materials/_shared/glass-partition.ts).

Half-width, IN CELLS, of the nD membership slab a CONTINUOUS hidden dimension is culled against (§5.2.1): a vertex is inside when it is within slab_tolerance cells of the slice. Strictly positive; defaults to one cell.

The only authored control mesh has over its nD approximation, and the only per-node input to computeTolerance('mesh', …). Mesh culls whole triangles against the slab — a triangle draws only when all three of its vertices are inside — so on a continuous hidden axis it shows "the surface near this slice" as a thick slab, never a planar cut (§5.3). This says how far from the slice — the slab spans twice that.

Mesh is the only geometry type whose continuous arm is tunable, and the reason is that it has nothing to measure: the other three derive their tolerance from a per-element extent (radii / widths / the truncated sigma) that a mesh vertex does not have, so the slab thickness is invented rather than read off the data.

No effect on a DISCRETE hidden dimension (time, channel — the dominant real case), which takes the half-cell membership rule instead.

Whether this node is exposed as a layer in the Layers panel

Dimension names to extend visibility across — a mesh with extend_to_all is visible regardless of slice position in those dimensions.