Javascript chart.js？特别是雷达图和负数

我是JavaScript新手，使用Chart.js中的雷达图，但每次我在图表的数据上加负数，我总是得到一个变形的图像

代码如下：

var radarChartData = {
        labels: [
                  "Soccer",
                  "Basketball",
                  "Swimming",
                  "Volleyball",
                  "Computer games",
                  "Tennis",  
                ],
        datasets: [
            {
                label: "My First dataset",
                fillColor: "rgba(220,220,220,0.2)",
                strokeColor: "rgba(220,220,220,1)",
                pointColor: "rgba(220,220,220,1)",
                pointStrokeColor: "#fff",
                pointHighlightFill: "#fff",
                pointHighlightStroke: "rgba(220,220,220,1)",
                data: [-3,7,6,6,4,6]
            },

        ]
    };


    window.onload = function(){
        window.myRadar = new Chart(document.getElementById("canvas").getContext("2d")).Radar(radarChartData,                          
        { 
            responsive: true
        });
    }

---

1/要将实值更改为整数，可以使用：

var intvalue = Math.floor( floatvalue );
var intvalue = Math.ceil( floatvalue ); 
var intvalue = Math.round( floatvalue );

2/对于变形图像： 尝试

Math.abs（val）