Function createInstanceNodes

packages/functions/src/uninstance.ts:94–141

(batchNode: Node)

 * ```
 */
export function createInstanceNodes(batchNode: Node): Node[] {
	const batch = batchNode.getExtension<InstancedMesh>('EXT_mesh_gpu_instancing');
	if (!batch) return [];

	const semantics = batch.listSemantics();
	if (semantics.length === 0) return [];

	const document = Document.fromGraph(batchNode.getGraph())!;
	const instanceCount = batch.listAttributes()[0].getCount();
	const instanceCountDigits = String(instanceCount).length;
	const mesh = batchNode.getMesh();
	const batchName = batchNode.getName();

	const instanceNodes = [];

	// For each instance construct a Node, assign attributes, and push to list.
	for (let i = 0; i < instanceCount; i++) {
		const instanceNode = document.createNode().setMesh(mesh);

		// MyNode_001, MyNode_002, ...
		if (batchName) {
			const paddedIndex = String(i).padStart(instanceCountDigits, '0');
			instanceNode.setName(`${batchName}_${paddedIndex}`);
		}

		// TRS attributes are applied to node transform; all other attributes are extras.
		for (const semantic of semantics) {
			const attribute = batch.getAttribute(semantic)!;
			switch (semantic) {
				case 'TRANSLATION':
					instanceNode.setTranslation(attribute.getElement(i, [0, 0, 0]));
					break;
				case 'ROTATION':
					instanceNode.setRotation(attribute.getElement(i, [0, 0, 0, 1]));
					break;
				case 'SCALE':
					instanceNode.setScale(attribute.getElement(i, [1, 1, 1]));
					break;
				default:
					_setInstanceExtras(instanceNode, semantic, attribute, i);
			}
		}

		instanceNodes.push(instanceNode);
	}

	return instanceNodes;
}

function _setInstanceExtras(node: Node, semantic: string, attribute: Accessor, index: number): void {
	const value = attribute.getType() === 'SCALAR' ? attribute.getScalar(index) : attribute.getElement(index, []);