fix gear examples (#1423)

Author: elalish

bindings/wasm/test/examples/gear-bearing.ts

@@ -66,7 +66,7 @@ ringNode.material = {
 const sunNode = new GLTFNode(shift);
 sunNode.manifold = sun;
 sunNode.rotation =
-    (t) => [0, 0, (np + 1) * 180 * m / ns + (t * 360) * (ns + np) * 2 / ns]
+    (t) => [0, 0, (np + 1) * 180 / ns + (t * 360) * (ns + np) * 2 / ns]
 sunNode.material = {
   baseColorFactor: [0.7, 0.7, 0.7]
 };

bindings/wasm/test/examples/involute-gear-library.ts

@@ -66,6 +66,10 @@ export function gear2D(teeth: number, {
   const backlashDeg = clearance / (pitchRadius * cos(pressureRad)) * 180 / PI;
   const halfThickDeg = 90 / teeth - backlashDeg / 2;
 
+  if (halfThickDeg <= 0) {
+    throw new Error('Clearance is too large for the circular pitch.');
+  }
+
   const pitchPoint =
       involute(baseRadius, involuteIntersectRad(baseRadius, pitchRadius));
   const pitchDeg = atan2(pitchPoint[1], pitchPoint[0]) * 180 / PI;