Unity3D研究院之IOS运行时合并PVRTC贴图（九十九）

using System;
using UnityEngine;
using UnityEngine.UI;

public class PVRTCombine : MonoBehaviour {

    public Texture2D texture256;
    public Texture2D texture128;


	void Start () 
    {
        GetComponent<RawImage>().texture = Combine(texture256, texture128);;
	}
  
    Texture2D Combine(Texture2D tex,Texture2D tex1)
    {
        int length = 512;
        byte[] data = null;
        var blcokBytes = 0;
        switch (tex.format)
        {
            case TextureFormat.PVRTC_RGB2:
            case TextureFormat.PVRTC_RGBA2:
                blcokBytes = 4;
                data = new byte[length / 4 * length];
                break;
            case TextureFormat.PVRTC_RGB4:
            case TextureFormat.PVRTC_RGBA4:
                blcokBytes = 8;
                data = new byte[length / 2 * length];
                break;
            default:
                Debug.Log("Not supported.");
                return null;
        }

        //填充左下角 256
        CombineBlocks(tex.GetRawTextureData(), data, tex.width, 4, blcokBytes, 0);
        //填充左上角 256 
        CombineBlocks(tex.GetRawTextureData(), data, tex.width, 4, blcokBytes, BlcokOffset(tex.width,blcokBytes));
        //填充右下角 256 
        CombineBlocks(tex.GetRawTextureData(), data, tex.width, 4, blcokBytes, 2 * BlcokOffset(tex.width,blcokBytes));

        //填充右上角区域
        //左下角 128
        CombineBlocks(tex1.GetRawTextureData(), data, tex1.width, 4, blcokBytes, 3 * BlcokOffset(tex.width,blcokBytes));
        //左上角 128
        CombineBlocks(tex1.GetRawTextureData(), data, tex1.width, 4, blcokBytes, 3 * BlcokOffset(tex.width,blcokBytes) + BlcokOffset(tex1.width,blcokBytes));
        //右下角 128
        CombineBlocks(tex1.GetRawTextureData(), data, tex1.width, 4, blcokBytes, 3 * BlcokOffset(tex.width,blcokBytes) + 2 * BlcokOffset(tex1.width, blcokBytes));
        //右上角 128
        CombineBlocks(tex1.GetRawTextureData(), data, tex1.width, 4, blcokBytes, 3 * BlcokOffset(tex.width,blcokBytes) + 3 * BlcokOffset(tex1.width, blcokBytes));


        var combinedTex = new Texture2D(length, length, tex.format, false);

        combinedTex.LoadRawTextureData(data);
        combinedTex.Apply(false,true);

        return combinedTex;
    }

    int BlcokOffset(int length, int blcokBytes)
    {
        return length / (16 / blcokBytes) * length;
    }

    void CombineBlocks(byte[] src, byte[] dst, int length, int block, int bytes, int blockOffest)
    {
        int cell = length / block;
        for (int i = 0; i < cell; i++)
        {
            for (int j = 0; j < cell; j++)
            {
                int srcindex = ((i * cell) + j) * bytes;
                int dstindex = srcindex + blockOffest;
                Buffer.BlockCopy(src, srcindex, dst, dstindex, bytes);
            }
        }
    }

}