Interface RenderTargetTexture

How many anisotropic samples the backend may take (§77's "anisotropy"; R-30b, 2026-08-21). An integer ≥ 1.

Optional, and absent means 1 — isotropic filtering, GL's own default and this contract's previous fixed behaviour.

Anisotropic filtering is an extension in WebGL 2 (EXT_texture_filter_anisotropic), so this is a request, not a guarantee: a backend clamps it to what the device reports and ignores it entirely where the extension is absent. That is §62's capability tiering rather than §85's refusal — a value the driver merely cannot honour is not an authoring mistake, and refusing it would make the same scene unrunnable on a conformant device. A non-integer or a value below 1 is an authoring mistake, and the concrete class refuses it.

The colour space the texels are in — §60a's texture metadata, read by the backend on the upload path (R-15, 2026-08-08).

Optional, and absent means "linear". §60a says colour textures default to sRGB-encoded; this tier defaults them to linear instead, and the deviation is deliberate and dated: flipping the default would change what every already-authored texture in the engine looks like — every pixel golden with it — for scenes that never asked for colour management. An author who has sRGB-encoded texels (a decoded PNG, an authored albedo map) says so with colorSpace: "srgb" and the backend decodes on sample; the §60a-conformant default is an owner decision, recorded with R-15.

Optional rather than required so that a test double, a procedurally generated atlas, and every texture written before this field existed keep satisfying the contract without a line of change. Read it as texture.colorSpace ?? "linear".

Whether the texture has been disposed (§83).

How the backend samples between texel centres (§77; R-30, 2026-08-13).

Optional, and absent means "linear" — the value this tier hard-coded before the field existed, so every texture written against an earlier build and every test double keeps issuing the identical texParameteri pair. Read it as texture.filter ?? "linear", exactly as MaterialTexture.colorSpace is read.

"nearest" is what a bitmap glyph atlas and pixel art want: a texel drawn at or above 1:1 stays a square instead of being blurred across its neighbours.

Height in texels.

Stable identity (§83's resource model). Backends key their upload caches on it and validate the entry with MaterialTexture.version, exactly as they do for BufferGeometry.

How the backend samples when the texture is minified (§77; R-30b, 2026-08-21).

Optional, and absent means "derived": without MaterialTexture.mipmaps it is MaterialTexture.filter, which is what this contract always meant; with them it is that filter's mip-chain-aware form ("linear" → "linear-mipmap-linear", i.e. trilinear). Read it as the concrete class resolves it, or as texture.minFilter ?? texture.filter ?? "linear" if the texture is known to carry no chain.

Whether the texture carries a full mip chain (§77's "mipmaps"; R-30b, 2026-08-21).

Optional, and absent means false — no chain, exactly the one level this contract described before the field existed, so every texture and test double written earlier uploads the identical call sequence.

true asks the backend to build the chain at upload time (WebGL 2's generateMipmap, which needs no power-of-two size). What the chain is for is minification: a 512² texture drawn across twenty pixels samples twenty of its half-million texels without one, which is the shimmer that appears when the camera moves.

Counter advanced by every mutation; the cache-invalidation key (§53, §77).

Width in texels.

How the backend addresses texture coordinates outside [0, 1] (§77; R-30, 2026-08-13).

Optional, and absent means "clamp-to-edge" — this tier's previous fixed choice, for MaterialTexture.filter's reason. Read it as texture.wrap ?? "clamp-to-edge".