Splatter (splatter.app) — hosted Gaussian-splat viewer, status notes

A hosted, content-addressed Gaussian-splat viewer/host by Jakub Červený. Its splatter-three library's actual source lives in splatter-app/splatter-three, a private repo — nothing beyond its published, intentionally-public consumer demo bundle is reverse-engineered or reproduced here. Tested against a real 103M-splat scene hosted on splatter.app.

Status: not a candidate source format (yet)

Unlike every other format in format-comparison.md, Splatter isn't a file format at all — it's a hosted rendering service. Content is addressed by an opaque splatId resolved against splatter.app's own backend; there is no published, standalone wire format a converter could point at (.splat/.ply/.sog/.spz/etc. are not it — whatever bytes actually stream over the wire are a private implementation detail of the closed splatter-three package). That makes it a dead end for → 3D Tiles conversion today: there's nothing to parse. It's tracked here (rather than in candidate-source-formats-roadmap-not-yet-supported.md) as a rendering-technique reference instead — see Related tilers for how its progressive-loading/hit-testing ideas compare to this repo's own SOG/GeoSplats octree LOD.

This could change if splatter.app ever publishes the wire format or open-sources splatter-three — until then, re-open this doc rather than starting a new investigation from scratch.

Observable public API surface

From splatter-app/three-demo's main.js — the only public source — the following API surface is observable:

• new Splatter(renderer, { splatId }) — content addressed by an opaque ID, loaded/streamed independent of the Three.js scene graph; renderer.render(scene, camera) and splatter.render(camera, controls.target) are called separately per frame (the splat cloud is not a normal scene-graph object — it's composited in its own render pass, alongside whatever three.js drew).
• Progressive loading via 'update' (redraw on each streamed chunk) and 'loaded'(totalLoaded, numDisplayed) events — their own demo hides a loading spinner once numDisplayed > 1e6, well before totalLoaded finishes, i.e. partial-scene display while still streaming (conceptually close to this repo's own SOG octree LOD and MapTiler GeoSplats' progressive octant LODs, though the wire format itself isn't public).
• splatter.setTransform(matrix) positions the splat cloud independent of the rest of the scene.
• splatter.addUniform(type, name) + splatter.setShaderEffect(glsl) — a small GLSL-injection point operating on per-splat position/scale (their demo uses it for a radial reveal-on-load animation) without needing to fork the splat renderer itself.
• splatter.hitTest(camera, [x, y], { alphaThreshold }) — screen-space picking weighted by actual rendered alpha, not just geometry — used for a recenter-on-double-click interaction.
• Requires an explicit WebGL2 context (canvas.getContext('webgl2', options)), passed into new THREE.WebGLRenderer({ canvas, context }).

Why this boundary

splatter-three's actual source is a private GitHub repo. Only its published, intentionally-public consumer demo (three-demo) was read — the production bundle served from splatter.app itself was deliberately not fetched or decompiled. This mirrors the same boundary this repo holds for closed services elsewhere (e.g. Google Photorealistic 3D Tiles' ToS forbidding re-serving/caching, tracked in the roadmap doc's Tier 3).