The GLB Format

GLB (binary glTF) can store 3D Gaussian Splat data using the Khronos KHR_gaussian_splatting extension. This makes splats first-class citizens of the glTF ecosystem: they travel through standard glTF pipelines and can live alongside regular meshes, materials and animations in a single file.

You can create these files with SplatTransform and load them directly with the PlayCanvas Engine.

How Splats Are Stored

The extension stores each splat scene as a glTF mesh primitive with POINTS topology. Splat properties are supplied as vertex attributes:

Attribute	Type	Contents
POSITION	VEC3	Splat center positions
KHR_gaussian_splatting:ROTATION	VEC4	Rotation quaternion (xyzw)
KHR_gaussian_splatting:SCALE	VEC3	Per-axis size in linear space
KHR_gaussian_splatting:OPACITY	SCALAR	Opacity with sigmoid already applied
KHR_gaussian_splatting:SH_DEGREE_{d}_COEF_{n}	VEC3	Spherical harmonics coefficients (RGB per coefficient)
COLOR_0	VEC4	Optional fallback color for viewers without splat support

Some differences from the PLY format worth knowing about:

• Activated values: scale is stored in linear space (PLY stores log-space) and opacity is post-sigmoid (PLY stores pre-sigmoid values).
• Coordinate system: splat data uses the standard glTF coordinate system (+Y up), so unlike PLY files, no flip rotation is needed when placing the loaded splat in a scene.
• Fallback rendering: viewers that don't understand the extension can still render the COLOR_0 point cloud.

Creating GLB Files

Convert any supported splat format using SplatTransform:

splat-transform scene.ply scene.glb

Loading in PlayCanvas

Splat GLB files load as container assets (like any other glTF content), not as gsplat assets:

const asset = new pc.Asset('scene', 'container', { url: 'scene.glb' });
app.assets.add(asset);
app.assets.load(asset);

asset.ready(() => {
    // creates an entity hierarchy with gsplat components
    const entity = asset.resource.instantiateRenderEntity();
    app.root.addChild(entity);
});

The container exposes the loaded splats as subordinate gsplat assets via asset.resource.gsplats, mirroring how renders and materials are exposed. Make sure your application registers the GSplatComponentSystem.

Engine Support Notes

• Only the ellipse kernel (standard 3D Gaussian Splatting) is supported. Other kernels render as ellipse with a warning in debug builds.
• The sortingMethod and projection properties are ignored — sorting is controlled by the engine's global gsplat settings.
• The KHR_gaussian_splatting_compression_spz_2 compression extension (still a draft) is not supported.

When to Use GLB

GLB stores splat data uncompressed, so files are comparable in size to PLY. Use it when you need splats in standards-based glTF pipelines or combined with mesh content in a single asset.

tip

For web delivery, SOG remains the recommended format — it offers 15-20× compression and faster loading.