eight; y++) {
                        const maskColors = frontContext.getImageData(0, y, frontCanvas.width, 1).data;
                        if (notTransparentNum(maskColors) > 20) {
                            if (maskEdgeT == null) {
                                maskEdgeT = y;
                            }
                            maskEdgeB = y;
                        }
                    }

                    if (frontCanvasForDebug) {
                        frontContextForDebug.fillStyle = `rg