It does filter the trend with simple moving averages of 21 and 55 periods, but it doesn't filter for retracements in the trend (you should consider only the order blocks that are coming from engulfings after a retracement)
- Rectangles are now based on the candle's body instead of the candle's range;
- Rectangles representing order blocks are now transparent, so the price action that occurs through them is now more visible;
- Color of the rectangle now tells if the trend is generally up or down, filtering the appropriate orderblocks (bullish OBs are blue, bearish are red);
The criteria by which the trend is defined is the sma(21) and sma(55) reciprocal position: if sma21 > sma55 the script considers the actual condition an uptrend. Viceversa it does consider a downtrend situations in which sma55 > sma21. These periods where chosen because I am a fan of Fibonacci numbers and I usually use these two simple moving averages to get an idea of the short-mid term trend direction, however you can set your own periods: just change the numbers in line 10 and 16 of the code.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.