Function smoothSpline

libs/echarts/echarts.simple.js:15907–15948

(points, isLoop)

 * @return {Array}
 */
var smoothSpline = function (points, isLoop) {
    var len$$1 = points.length;
    var ret = [];

    var distance$$1 = 0;
    for (var i = 1; i < len$$1; i++) {
        distance$$1 += distance(points[i - 1], points[i]);
    }

    var segs = distance$$1 / 2;
    segs = segs < len$$1 ? len$$1 : segs;
    for (var i = 0; i < segs; i++) {
        var pos = i / (segs - 1) * (isLoop ? len$$1 : len$$1 - 1);
        var idx = Math.floor(pos);

        var w = pos - idx;

        var p0;
        var p1 = points[idx % len$$1];
        var p2;
        var p3;
        if (!isLoop) {
            p0 = points[idx === 0 ? idx : idx - 1];
            p2 = points[idx > len$$1 - 2 ? len$$1 - 1 : idx + 1];
            p3 = points[idx > len$$1 - 3 ? len$$1 - 1 : idx + 2];
        }
        else {
            p0 = points[(idx - 1 + len$$1) % len$$1];
            p2 = points[(idx + 1) % len$$1];
            p3 = points[(idx + 2) % len$$1];
        }

        var w2 = w * w;
        var w3 = w * w2;

        ret.push([
            interpolate(p0[0], p1[0], p2[0], p3[0], w, w2, w3),
            interpolate(p0[1], p1[1], p2[1], p3[1], w, w2, w3)
        ]);
    }
    return ret;
};

/**
 * 贝塞尔平滑曲线