cument.getElementById("scale").value);
			if(e.deltaY < 0)
				document.getElementById("scale").value = scale / 2;
			else
				document.getElementById("scale").value = scale * 2;
			draw_canvas();
		}
	}, false);

	draw_canvas();
}

function draw_arrow(context, x1, y1, x2, y2, color) {
	const d = Math.sqrt(Math.pow(x2-x1, 2) + Math.pow(y2-y1, 2));
	context.beginPath();
	context.moveTo(x1, y1);
	context.lineTo(x2, y2);
	context.moveTo(x2 - (y2 - y1) * 4.3 / d - (x2 - x1) * 16.7 / d, y2 - (y2 - y1) * 16.7 / d