Unity3D之如何创建正确的像素比在屏幕上

using UnityEngine;
using System.Collections;

public class SimpleSprite : MonoBehaviour {
	
	//标准摄像头的高度//
	public float standardCameraSize;
	
	//标准屏幕的高度//
	public float standardHeight;
	
	
	private float glTopixelRatio;
	
	
	
	//素材求//
	public Material spriteMaterial;
	
	//顶点数//
	private int verticesCount = 4;
	
	
	

	// Use this for initialization
	void Start () {
		//计算像素和世界单位的比值//
		glTopixelRatio = standardCameraSize * 2.0f / standardHeight;
		initSprite();
	}
	
	// Update is called once per frame
	void Update () {}
	
	//根据宽高生成对应的面//
	private void initSprite(){
		
		//获取图片的像素宽高//
		int pixelHeight = spriteMaterial.mainTexture.height;
		int pixelWidth = spriteMaterial.mainTexture.width;
		
		Debug.Log("pixeW:" + pixelWidth + ",pixeH:" + pixelHeight);
		
		//得到MeshFilter对象//
		MeshFilter meshFilter = gameObject.GetComponent<MeshFilter>();
		if(meshFilter == null){
			//为null时，自动添加//
			meshFilter = gameObject.AddComponent<MeshFilter>();
			MeshRenderer meshRenderer = gameObject.AddComponent<MeshRenderer>();
			meshRenderer.sharedMaterial = spriteMaterial;
		}
		//得到对应的网格对象//
		Mesh mesh = meshFilter.mesh;
		
		//三角形顶点的坐标数组//
		Vector3[] vertices = new Vector3[verticesCount];

		//得到三角形的数量//
		int trianglesCount = verticesCount - 2;

		//三角形顶点数组//
		int[] triangles   = new int[verticesCount *3];
		
		
		float glWidth = pixelWidth * glTopixelRatio;
		float glHeight = pixelHeight * glTopixelRatio;
		
		
		
		//以当前对象的中心坐标为标准//
		vertices[0] = new Vector3(0, 0, 0);
		vertices[1] = new Vector3(0, glHeight, 0);
		vertices[2] = new Vector3(glWidth, 0, 0);
		vertices[3] = new Vector3(glWidth, glHeight, 0);
		
		mesh.vertices = vertices;
		
		
		//绑定顶点顺序//
		triangles[0] = 0;
		triangles[1] = 1;
		triangles[2] = 2;
		triangles[3] = 1;
		triangles[4] = 3;
		triangles[5] = 2;		
		
		
		mesh.triangles = triangles;
		
		mesh.uv = new Vector2[]{new Vector2(0,0), new Vector2(0,1), new Vector2(1,0), new Vector2(1,1)};
		
		
	}	
	
}