Unity GL画直线

public class DrawLineWindow : EditorWindow
{

    [MenuItem("Tools/测试")]
    public static void ShowWindow()
    {

        DrawLineWindow window = EditorWindow.GetWindow(typeof(DrawLineWindow)) as DrawLineWindow;
        window.Init();
    }

    private Material lineMaterial;

    Rect windowRect = new Rect(20, 20, 80, 100);
    int count = 2;
    List<Rect> rectList = new List<Rect>();

    void Init()
    {
        rectList.Clear();
        for (int i = 0; i < count; i++)
        {
            rectList.Add(new Rect(20, 20, 80, 100));
        }
    }


    void OnGUI()
    {
        if (!lineMaterial)
        {
            lineMaterial = new Material(Shader.Find("Mobile/VertexLit"));
        }


        BeginWindows();
        for(int i = 0; i < count; i++)
        {
            rectList[i] = GUI.Window(i, rectList[i], DrawWindow, "Start");
        }

        EndWindows();

        GL.PushMatrix(); //保存当前Matirx
        lineMaterial.SetPass(0); //刷新当前材质
        GL.LoadPixelMatrix();//设置pixelMatrix
        GL.Color(Color.yellow);
        GL.Begin(GL.LINES);
        GL.Vertex3(rectList[0].x, rectList[0].y, 0);
        GL.Vertex3(rectList[1].x, rectList[1].y, 0);
        GL.End();
        GL.PopMatrix();//读取之前的Matrix
    }

    void DrawWindow(int windowID)
    {
        GUILayout.Button("Start");
        GUI.DragWindow();
    }

}