GunSystem/Assets/Standard Assets/Vehicles/Aircraft/Scripts/LandingGear.cs

using System;
using UnityEngine;

namespace UnityStandardAssets.Vehicles.Aeroplane
{
    public class LandingGear : MonoBehaviour
    {

        private enum GearState
        {
            Raised = -1,
            Lowered = 1
        }

        // The landing gear can be raised and lowered at differing altitudes.
        // The gear is only lowered when descending, and only raised when climbing.

        // this script detects the raise/lower condition and sets a parameter on
        // the animator to actually play the animation to raise or lower the gear.

        public float raiseAtAltitude = 40;
        public float lowerAtAltitude = 40;

        private GearState m_State = GearState.Lowered;
        private Animator m_Animator;
        private Rigidbody m_Rigidbody;
        private AeroplaneController m_Plane;

        // Use this for initialization
        private void Start()
        {
            m_Plane = GetComponent<AeroplaneController>();
            m_Animator = GetComponent<Animator>();
            m_Rigidbody = GetComponent<Rigidbody>();
        }


        // Update is called once per frame
        private void Update()
        {
            if (m_State == GearState.Lowered && m_Plane.Altitude > raiseAtAltitude && m_Rigidbody.velocity.y > 0)
            {
                m_State = GearState.Raised;
            }

            if (m_State == GearState.Raised && m_Plane.Altitude < lowerAtAltitude && m_Rigidbody.velocity.y < 0)
            {
                m_State = GearState.Lowered;
            }

            // set the parameter on the animator controller to trigger the appropriate animation
            m_Animator.SetInteger("GearState", (int) m_State);
        }
    }
}