y intersections in this sample.
          let targetRay = new Ray(targetRayPose.transform);
          let cursorDistance = 2.0;
          let cursorPos = vec3.fromValues(
              targetRay.origin.x,
              targetRay.origin.y,
              targetRay.origin.z
              );
          vec3.add(cursorPos, cursorPos, [
              targetRay.direction.x * cursorDistance,
              targetRay.direction.y * cursorDistance,
              targetRay.direction.z * cursorDistance,
              ]);
