unity3d：物体寻路贴合地面，y轴与地面normal方向平行（坦克爬斜坡问题）

坦克在爬斜坡时，保持坦克是贴合地面前进

寻路挂在父物体上，控制姿态脚本挂在坦克子物体上

RaycastHit hit;
 
int Rmask = LayerMask.GetMask ("Terrain");
 
Vector3 Point_dir = transform.TransformDirection(Vector3.down);
 
if (Physics.Raycast(transform.position, Point_dir, out hit, 50.0f,Rmask)) {
 
Quaternion NextRot=Quaternion.LookRotation(Vector3.Cross(hit.normal,Vector3.Cross(transform.forward,hit.normal)),hit.normal);
 
 
transform.MoveRotation(Quaternion.Lerp(transform.rotation,NextRot,0.1f));
 
}