ke(context);
            if (polygon.filled) {
                polygon.fill(context);
            }
        });
    }

    function drawCentroid(polygon) {
        context.beginPath();
        context.save();
        context.strokeStyle = CENTROID_STROKE_STYLE;
        context.fillStyle = CENTROID_FILL_STYLE;
        context.shadowColor = CENTROID_SHADOW_COLOR;
        context.arc(polygon.x, polygon.y, CENTROID_RADIUS, 0, Math.PI*2, false);
        context.stroke();
        context.fill();
        context.r