GaussianPayload

Codec-agnostic envelope for a parsed Gaussian-splat payload — what every GaussianLoader implementation returns regardless of the wire format it consumes (Niantic SPZ, SuperSplat .splat, Cesium's draft EXT_3DTILES_gaussian_splat glTF wrapper, or any future codec).

All arrays are flat tile-local. Sizes are bounded by splatCount:

• centers: splatCount * 3 Float32 (vec3 splat positions)

• scales: splatCount * 3 Float32 (vec3 anisotropic scales; one std-dev per axis)

• rotations: splatCount * 4 Float32 (quaternion w, x, y, z per splat)

• opacities: splatCount Float32 (one alpha per splat, typically in 0, 1)

• rgba: splatCount * 4 UInt8 — direct RGBA colors. Mutually exclusive with sphericalHarmonics; codecs supply exactly one of the two color paths. Null when sphericalHarmonics is the colour source.

• sphericalHarmonics: splatCount * 3 * (sphericalHarmonicsBands + 1)^2 Float32 — SH coefficients for view-dependent color, packed in interleaved RGB-per-coefficient layout. Null when rgba is the colour source.

• sphericalHarmonicsBands: SH band count. 0 = degree-0 only (DC term), 1 = degree-1 (4 coefficients per channel), 2 = degree-2 (9), 3 = degree-3 (16). Renderers that don't implement higher bands can stop at their supported level.

• rtcCenter: Optional tile-local origin offset; renderer applies before tile-to-world (parallel to b3dm / i3dm / pnts RTC_CENTER semantics).

Codec-supplied. Construction is via the codec-side loader; the engine does not validate field consistency beyond what's needed to enqueue a GPU upload.