 i_colors[0];
		for (var i = 0; i < points.length; ++i) {
			context.beginPath();
			const x = x2s(points[i][0]);
			const y = y2s(points[i][1]);
			context.arc(x, y, 4, 0, 2*Math.PI);
			context.fill();
			context.closePath();
		}


		// the grid
		function sharp(x) {return Math.floor(x) + 0.5;}
		context.font = "14px Arial";
		context.fillStyle = "#444444";
		context.textAlign = "center";
		context.textBaseline = "middle";
		context.strokeStyle = "#000000";
		context.lineWidth = 1;
		context.beginPath();
