Add test case for mode=POINTS input to weld()

packages/functions/src/weld.ts

@@ -110,7 +110,7 @@ export function weld(_options: WeldOptions = WELD_DEFAULTS): Transform {
 			for (const prim of mesh.listPrimitives()) {
 				weldPrimitive(doc, prim, options);
 
-				if (prim.getIndices()?.getCount() === 0) prim.dispose();
+				if (isPrimEmpty(prim)) prim.dispose();
 			}
 
 			if (mesh.listPrimitives().length === 0) mesh.dispose();
@@ -430,3 +430,13 @@ function expandWeldOptions(_options: WeldOptions): Required<WeldOptions> {
 
 	return options;
 }
+
+/**
+ * For purposes of welding, we consider a primitive to be 'empty' or degenerate
+ * if (1) it has an index, and (2) that index is empty. In some cases
+ * (mode=POINTS) the index may be missing — this is outside the scope of welding.
+ */
+function isPrimEmpty(prim: Primitive): boolean {
+	const indices = prim.getIndices();
+	return !!indices && indices.getCount() === 0;
+}

packages/functions/test/weld.test.ts

@@ -215,11 +215,25 @@ test('modes', async (t) => {
 		t.deepEqual(
 			Array.from(primDef.indices),
 			Array.from(prim.getIndices().getArray()),
-			`${(i + 1).toString().padStart(2, '0')}: indices ${Array.from(primDef.indices)}`
+			`${(i + 1).toString().padStart(2, '0')}: indices ${Array.from(primDef.indices)}`,
 		);
 	}
 });
 
+test('points', async (t) => {
+	const doc = new Document().setLogger(logger);
+	const positionArray = new Float32Array([0, 0, 0, 0, 0, 1, 0, 0, -1, 0, 0, 0, 0, 0, 1, 0, 0, -1]);
+	const position = doc.createAccessor().setType('VEC3').setArray(positionArray);
+	const prim = doc.createPrimitive().setAttribute('POSITION', position).setMode(Primitive.Mode.POINTS);
+	doc.createMesh().addPrimitive(prim);
+
+	// points can't be welded, but also shouldn't throw an error.
+	await doc.transform(weld({ tolerance: 0.001 }));
+
+	t.false(prim.isDisposed(), 'prim not disposed');
+	t.is(prim.getAttribute('POSITION').getArray().length, positionArray.length, 'prim vertices');
+});
+
 test('targets', async (t) => {
 	const document = new Document().setLogger(logger);
 	// prettier-ignore
@@ -265,7 +279,7 @@ test('targets', async (t) => {
 	t.deepEqual(
 		prim.listTargets()[0].getAttribute('POSITION').getArray(),
 		positionTargetArray.slice(9, 27),
-		'target positions'
+		'target positions',
 	);
 	t.is(document.getRoot().listAccessors().length, 3, 'accessor count');
 });
@@ -297,6 +311,6 @@ test('degenerate', async (t) => {
 			0, 0, 1,
 			0, 0, -1
 		],
-		'vertices on prim'
+		'vertices on prim',
 	);
 });