【原创】使用Unity在屏幕上画个框

来源：互联网发布：淘宝助理更新类目编辑：程序博客网时间：2024/06/06 03:35

【原创】使用Unity在屏幕上画个框
直接放在相机上！　　

Unity3D使用的图形引擎是DirectX，OpenGL和自带的APi（Wii），这里使用OpenGL的渲染方式

（使用过OpenGl的应该相对容易理解。另外：代码中使用Shader是因为矩形框中部的透明部分需要）　
using UnityEngine;
using System.Collections;

public class NewBehaviourScript : MonoBehaviour {

private Vector2 mMouseStart,mMouseEnd;
private boolmBDrawMouseRect;

private Material rectMat = null;//画线的材质不设定系统会用当前材质画线结果不可控

void Start()
{

  mBDrawMouseRect =false;

  rectMat = new Material("Shader\"Lines/Colored Blended\" {" +
                        "SubShader { Pass { " +
                        "    BlendSrcAlpha OneMinusSrcAlpha " +
                        "    ZWrite OffCull Off Fog { Mode Off } " +
                        "   BindChannels {" +
                        "     Bind \"vertex\", vertex Bind \"color\", color }"+
                        "} } }");//生成画线的材质
  rectMat.hideFlags =HideFlags.HideAndDontSave;
  rectMat.shader.hideFlags =HideFlags.HideAndDontSave;
} //Unity3D教程手册：www.unitymanual.com

void Update()
{
  if(Input.GetMouseButtonDown(0))
   //按下鼠标左键
  {
   Vector3mousePosition = Input.mousePosition;
   mMouseStart =new Vector2(mousePosition.x,mousePosition.y);
  }

  if(Input.GetMouseButton(0))
   //持续按下鼠标左键
  {
   mBDrawMouseRect= true;
   Vector3mousePosition = Input.mousePosition;
   mMouseEnd =new Vector2(mousePosition.x,mousePosition.y);
  }

  if(Input.GetMouseButtonUp(0))
  {
   mBDrawMouseRect= false;
  }
}
//Unity3D教程手册：www.unitymanual.com
void OnGUI()
{
  if(mBDrawMouseRect)
   Draw(mMouseStart,mMouseEnd);
}

//渲染2D框
void Draw(Vector2 start, Vector2end)
{
  rectMat.SetPass(0);

  GL.PushMatrix();//保存摄像机变换矩阵

  Color clr =Color.green;
  clr.a =0.1f;

  GL.LoadPixelMatrix();//设置用屏幕坐标绘图
  //透明框
  GL.Begin(GL.QUADS);
  GL.Color(clr);
  GL.Vertex3(start.x, start.y,0);
  GL.Vertex3(end.x, start.y,0);
  GL.Vertex3(end.x, end.y,0);
  GL.Vertex3(start.x, end.y,0);
  GL.End();

  //线
  //上
  GL.Begin(GL.LINES);
  GL.Color(Color.green);
  GL.Vertex3(start.x, start.y,0);
  GL.Vertex3(end.x, start.y,0);
  GL.End();

  //下
  GL.Begin(GL.LINES);
  GL.Color(Color.green);
  GL.Vertex3(start.x, end.y,0);
  GL.Vertex3(end.x, end.y,0);
  GL.End();

  //左
  GL.Begin(GL.LINES);
  GL.Color(Color.green);
  GL.Vertex3(start.x, start.y,0);
  GL.Vertex3(start.x, end.y,0);
  GL.End();

  //右
  GL.Begin(GL.LINES);
  GL.Color(Color.green);
  GL.Vertex3(end.x, start.y,0);
  GL.Vertex3(end.x, end.y,0);
  GL.End();

  GL.PopMatrix();//还原
}

}

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