getRayAtProjectedCoords(u, v) {
      // By default we use the builtin Raycaster functionality, but this can be overridden
      const ray = tempRaycaster.ray = new Ray()
      tempRaycaster.setFromCamera(tempVec2.set(u, v), this.threeObject)
      return ray
    }
Given a set of camera projection coordinates (u,v in the range [-1, 1]), return a `Ray`
representing that line of sight in worldspace.
@param {number} u
@param {number} v
@return Ray