[转]unity3d 鼠标2D控制

/*

* 用到了unity3d非常好的协同机制实现这一点，OnMouseDown事件表示鼠标已作了射线判断得到了对象。

* 拖拽时保持z轴不变，因为屏幕是xy二维的，空间是三维的。

* */

IEnumerator OnMouseDown ()

{




var camera = Camera.mainCamera;

if (camera) {

//转换对象到当前屏幕位置

Vector3 screenPosition = camera.WorldToScreenPoint (transform.position);


//鼠标屏幕坐标

Vector3 mScreenPosition=new Vector3 (Input.mousePosition.x, Input.mousePosition.y, screenPosition.z);

//获得鼠标和对象之间的偏移量,拖拽时相机应该保持不动

Vector3 offset = transform.position - camera.ScreenToWorldPoint( mScreenPosition);

print ("drag starting:"+transform.name);



//若鼠标左键一直按着则循环继续

while (Input.GetMouseButton (0)) {


//鼠标屏幕上新位置

mScreenPosition = new Vector3 (Input.mousePosition.x, Input.mousePosition.y, screenPosition.z);



// 对象新坐标

transform.position=offset + camera.ScreenToWorldPoint (mScreenPosition);




//协同，等待下一帧继续

yield return new WaitForEndOfFrame ();

}



print ("drag compeleted");


}

}















/// <summary>

/// 跟随鼠标旋转物体，并判断手势滑动离开时的旋转方向顺时针还是逆时针，可作些模拟拖拽完成时减速度效果

/// </summary>

/// <returns>

/// A <see cref="IEnumerator"/>

/// </returns>

IEnumerator OnMouseDown ()

{


Camera camera = Camera.mainCamera;


if (camera) {

//一般指旋转物体的中心点或鼠标围绕某个旋转的中心

Vector3 relativePoint = camera.WorldToScreenPoint (transform.position);


//鼠标操作时只用x,y轴,计算时必须忽略z轴

relativePoint.z = 0;


//鼠标按下时的方向向量，作为拖拽起始参考向量

Vector3 relativeDirection = Input.mousePosition - relativePoint;



//手势滑动时旋转方向，1：顺时针，-1：逆时针

int flingDir = 1;


//最后倒数第二个方向的角度，用于比较最后旋转方向

float last2Angle =0;



print ("rotation starting:" + transform.name);


//对象原始角度

Vector3 originAngles = transform.eulerAngles;


Quaternion originRotation=transform.rotation;


//旋转总角度

float sumAngle = 0;


while (Input.GetMouseButton (0)) {


#region 当前旋转角度


Vector3 currentDirection = Input.mousePosition - relativePoint;

//0-180正角度，不适合拖拽旋转

//float currentAngle = Vector3.Angle (relativeDirection, currentDirection);

//有正负角度，可做鼠标跟随旋转角度

float currentSignAngle = SignAngle (relativeDirection, currentDirection);



#endregion


//离上次角度偏移量

float offsetAngle = currentSignAngle - last2Angle;


#region 判断方向


flingDir = currentSignAngle - last2Angle >= 0 ? 1 : -1;


#endregion


#region 总计正方向旋转角度


if (offsetAngle > 0) {

sumAngle += offsetAngle;

}


#endregion


last2Angle = currentSignAngle;

//print(offsetAngle+","+sumAngle);

print ("angle:" + currentSignAngle + ",fling:" + flingDir + ",sum:" + sumAngle);


//设置新的角度


transform.eulerAngles=originAngles+ originRotation*direction*currentSignAngle;


yield return new WaitForEndOfFrame ();


}


print ("rotation compeleted");



}


}



/// <summary>

/// Math.atan2(y2-y1,x2-x1)

/// </summary>

/// <param name="vector1">

/// A <see cref="Vector2"/>

/// </param>

/// <param name="vector2">

/// A <see cref="Vector2"/>

/// </param>

/// <returns>

/// A <see cref="System.Single"/>

/// </returns>

float SignAngle (Vector2 start, Vector2 end)

{

float num1 =  (end.x * start.y)-(start.x * end.y);

float num2 = (start.x * end.x) + (start.y * end.y);

return (Mathf.Atan2 (num1, num2) * Mathf.Rad2Deg);

}