
                    for (let x = 0; x < frontCanvas.width; x++) {
                        const maskColors = frontContext.getImageData(x, 0, 1, frontCanvas.height).data;
                        if (notTransparentNum(maskColors) > 20) {
                            if (maskEdgeL == null) {
                                maskEdgeL = x;
                            }
                            maskEdgeR = x;
                        }
                    }

                    for (let y = 0; y < frontCanvas.h