Function getSparseArray

packages/core/src/io/reader.ts:667–695

* Returns the contents of a sparse accessor, as a typed array. * @internal

(accessorDef: GLTF.IAccessor, context: ReaderContext)

 * @internal
 */
function getSparseArray(accessorDef: GLTF.IAccessor, context: ReaderContext): TypedArray {
	const TypedArray = ComponentTypeToTypedArray[accessorDef.componentType];
	const elementSize = Accessor.getElementSize(accessorDef.type);

	let array: TypedArray;
	if (accessorDef.bufferView !== undefined) {
		array = getAccessorArray(accessorDef, context);
	} else {
		array = new TypedArray(accessorDef.count * elementSize);
	}

	const sparseDef = accessorDef.sparse;
	if (!sparseDef) return array; // Zero-filled accessor.

	const count = sparseDef.count;
	const indicesDef = { ...accessorDef, ...sparseDef.indices, count, type: 'SCALAR' };
	const valuesDef = { ...accessorDef, ...sparseDef.values, count };
	const indices = getAccessorArray(indicesDef as GLTF.IAccessor, context);
	const values = getAccessorArray(valuesDef, context);

	// Override indices given in the sparse data.
	for (let i = 0; i < indicesDef.count; i++) {
		for (let j = 0; j < elementSize; j++) {
			array[indices[i] * elementSize + j] = values[i * elementSize + j];
		}
	}

	return array;
}