画线

using UnityEngine;
using System.Collections;

public class DragIt : MonoBehaviour {

public Material mat;
public Color color = Color.red;
public Vector3 pos1;
public Vector3 pos2;
public bool isReady = false;

void Start()
{
mat.color = color;
}

void Update()
{
if (Input.GetMouseButtonDown(0))
{
pos1 = Input.mousePosition;
}
if (Input.GetMouseButtonUp(0))
{
pos2 = Input.mousePosition;
isReady = true;
}
}

void OnPostRender()
{
if (isReady)
{
GL.PushMatrix();
mat.SetPass(0);
GL.LoadOrtho();
GL.Begin(GL.LINES);
GL.Color(color);
GL.Vertex3(pos1.x / Screen.width, pos1.y / Screen.height, pos1.z);
GL.Vertex3(pos2.x / Screen.width, pos2.y / Screen.height, pos2.z);
GL.End();
GL.PopMatrix();
}
}
}