动态更换地形纹理图

更改terrain地形中的纹理贴图，代码如下：

public class TerrainTextureAssigner : MonoBehaviour
{
	public Texture2D[] TerrainTextures;//更换的纹理贴图
    public Texture2D[] PingChangTerrainTextures;//原纹理图
	private SplatPrototype[] oriPrototypes;
	private SplatPrototype[] newPrototypes;
	public Material mat;//地形的材质球
	private TerrainData terraindata;
	public Terrain terrain;
	private bool isIR = false;
	
	public void CreateTerrain(){
		newPrototypes = new SplatPrototype [TerrainTextures.Length];
		for (int i=0; i<TerrainTextures.Length; i++) {
			newPrototypes [i] = new SplatPrototype ();
			//newPrototypes [i] = oriPrototypes [i];
			newPrototypes [i].texture = TerrainTextures [i];    //Sets the texture
			newPrototypes [i].texture.filterMode = FilterMode.Point;
			newPrototypes [i].normalMap = oriPrototypes[i].normalMap;
			newPrototypes [i].tileSize = oriPrototypes[i].tileSize;    //Sets the size of the texture            

        }
	}

	void Start()
	{