求一个点到任意两个点所在直线距离的代码公式

using UnityEngine;
using System.Collections;

public class test : MonoBehaviour {

private Vector2 A = new Vector2(0,1);
private Vector2 B = new Vector2(1,0);
private Vector2 C = new Vector2(0,0);

void Start () {
float length = Mathf.Abs((B.y-A.y)*C.x + (A.x-B.x)*C.y+(B.x-A.x)*A.y+(A.y-B.y)*A.x)/Mathf.Sqrt((B.y-A.y)*(B.y-A.y)+(A.x-B.x)*(A.x-B.x));
Log.E("{0}",length);
}

// Update is called once per frame
void Update () {

}
}