unity 生成缩略图 , 图片缩放

public static Texture2D Resize(Texture2D source, int newWidth, int newHeight)
{
    source.filterMode = FilterMode.Point;
    RenderTexture rt = RenderTexture.GetTemporary(newWidth, newHeight);
    rt.filterMode = FilterMode.Point;
    RenderTexture.active = rt;
    Graphics.Blit(source, rt);
    var nTex = new Texture2D(newWidth, newHeight);
    nTex.ReadPixels(new Rect(0, 0, newWidth, newHeight), 0, 0);
    nTex.Apply();
    RenderTexture.active = null;
    return nTex;
}