quantizePrimitive()

[samevision]

Is it possible to quantize single objects?

The idea is to use different settings for each object.

Best

[donmccurdy]

Yes and no. When quantizing primitives, their vertex data is translated and scaled to a 3D quantization grid. The inverse of that translation and scale must be applied to objects referencing the primitive (nodes, skins, volumetric materials). As a result, all of a particular mesh's primitives must share the same transform.

You can find the internal code responsible for quantizing a primitive here:

glTF-Transform/packages/functions/src/quantize.ts

Lines 202 to 215 in 964fa3d

	function quantizePrimitive(
	document: Document,
	prim: Primitive | PrimitiveTarget,
	nodeTransform: VectorTransform<vec3>,
	options: Required<QuantizeOptions>,
	): void {
	const isTarget = prim instanceof PrimitiveTarget;
	const logger = document.getLogger();
	for (const semantic of prim.listSemantics()) {
	if (!isTarget && !options.pattern.test(semantic)) continue;
	if (isTarget && !options.patternTargets.test(semantic)) continue;
	const srcAttribute = prim.getAttribute(semantic)!;

It's not exposed as a public API because computing the transform for the mesh, and applying that to all references to the mesh, is not trivial and would need to be done by the caller.

If a quantizeNode(node, settings) function would work just as well for you, that might be easier to create and expose in the API.