unity3d 学习笔记_____Native2d 刚体、碰撞器、关节的使用

Mass	Mass of the rigidbody.
Linear Drag	Drag coefficient affecting positional movement.
Angular Drag	Drag coefficient affecting rotational movement.
Gravity Scale	Degree to which the object is affected by gravity.
Fixed Angle	Can the rigidbody rotate when forces are applied?
Is Kinematic	Is the rigidbody moved by forces and collisions?
Interpolate	How the object's movement is interpolated between physics updates (useful when motion tends to be jerky).
None	No movement smoothing is applied.
Interpolate	Movement is smoothed based on the object's positions in previous frames.
Extrapolate	Movement is smoothed based on an estimate of its position in the next frame.
Sleeping Mode	How the object "sleeps" to save processor time when it is at rest.
Never Sleep	Sleeping is disabled.
Start Awake	Object is initially awake.
Start Asleep	Object is initially asleep but can be woken by collisions.
Collision Detection	How collisions with other objects are detected.
Discrete	A collision is registered only if the object's collider is in contact with another during a physics update.
Continuous	A collision is registered if the object's collider appears to have contacted another between updates.

碰撞器Collider 分为两种:

（1）刚体碰撞

（2） 触发碰撞、会穿透其他刚体

对应Collider组件中的is Trigger,两种都会产生碰撞事件

	void OnCollisionEnter2D(Collision2D cod)
	{
		print (cod.gameObject.name);
		if(cod.rigidbody)
		cod.rigidbody.AddForce(new Vector2(0,500f));
	}

	void OnTriggerEnter2D(Collider2D other)
	{
		Destroy(other.gameObject);
	}

两个方法都属于MonoBehaviour的Message 回调方法，注意区分它们的参数类型是不同的

另外还有 OnTriggerExit2D、OnTriggerStay2D、 OnCollisionExit2D、OnCollisionStay2D 

关节的使用：

SpringJoint和DistantanceJoint有点类似多了弹性参数和频率设置（在unity中暂时没看出效果）

hingeJoint 可以理解为一个围绕Z轴旋转的关节，可以设置响应moto、以及角度的限制

sliderJoint 滑动关节类似hingeJoint 以一个角度值设置Moto进行滑动,可以对距离(translation)进行限制

下面是一个用HingeJoint做的一个demo:

两只小鸟同时添加HingeJoint 连接到盒子，后面的小鸟加下以下脚本控制方向键盘即可前后运动

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(HingeJoint2D))]
public class MotoControl : MonoBehaviour {

	public float MotoSpeed = 0;
	private JointMotor2D motor;
	HingeJoint2D hj;

	// Use this for initialization
	void Start () {
		hj = GetComponent<HingeJoint2D>();
		motor = hj.motor;
		hj.useMotor = true;
		motor = hj.motor;
		motor.motorSpeed = MotoSpeed;
		motor.maxMotorTorque = 10000;
	}
	
	// Update is called once per frame
	void Update () {
		motor.motorSpeed = Input.GetAxis("Horizontal") * MotoSpeed;
		hj.motor = motor;
	}
}

做Demo时遇到的问题：

（1）刚开始用hj.motor.motorSpeed一直报错，后来分两步写终于没问题

motor = hj.motor;
motor.motorSpeed = MotoSpeed;

（2）错是没了，可是小车还是不走，最后知道还需要把motor对象重新赋给HingeJoint

motor.motorSpeed = Input.GetAxis("Horizontal") * MotoSpeed;
hj.motor = motor;

其他一些常用的属性：

breakForce、breakTorque分别设定多大力、多大扭矩能给丫的拆了

connectedBody 连接的另外一个刚体的引用 （Joint2D中不存在）

hj.connectedBody = null;连接到一个空对象上

要想断开关节直接去掉关节组件 destroy(hj);

断开将发送 OnJointBreak Message.