code: function getProjection () {
      let projection = current
      let speed = currentSpeed
      for (let i = 0; i < 600; i++) {
        const targetSpeed = speed * (1 - springK)
        speed = linearlyApproach(speed, targetSpeed, acceleration)
        projection += speed
      }
      return projection
    }
docs: Based on current animation state, simulate the projected rotation angle if we allow the spinning to stop without intervention.