public void Filter_Left(ref Texture2D source)
    {


        // If we haven't initialized our history buffer, do so.
        // Match the size/format of whatever render target
        // we were passed as a source.
        if (_historyPages == null)
        {
            _historyPages = new Texture2D[HISTORY_CAPACITY];
            for (int i = 0; i < HISTORY_CAPACITY; i++)
            {
                _historyPages[i] = new Texture2D(width, height);
                filterMaterialAssetLeft.SetTexture(_historyIDs[i], _historyPages[i]);

            }
        }
        filterMaterialAssetLeft.SetFloat(_dataDeltaID, dataDelta);
        filterMaterialAssetLeft.SetFloat("_blurRadius", _blurRadius);
        filterMaterialAssetLeft.SetFloat("_StandardDeviation", _StandardDeviation);
        Graphics.Blit(source, destination_left, filterMaterialAssetLeft);


        // Our source becomes the newest sample in our history.
        // (Or, if it's supposed to be your destination, use that instead).
        // The oldest history page takes its place as a new writable source texture.
        var newPage = source;
        source = _historyPages[_oldestPage];
        _historyPages[_oldestPage] = newPage;
        filterMaterialAssetLeft.SetTexture(_historyIDs[_oldestPage], newPage);

        _oldestPage = (_oldestPage + 1) % HISTORY_CAPACITY;


    }