如何绘制优步折线？

Question

优步应用程序有一条弯曲的折线,甚至还包括一个阴影.阴影可能只是一个黑色,透明折线连接两个点.这很容易.但第二条折线有曲线,如何实现呢？这是Bezier曲线,还是像setGeodesic(true)这样的内置函数？

我查看了谷歌地图示例,我看到了有关圆形折线的部分.这可以适应创建半圆吗？来自demo的代码片段.

PolylineOptions options = new PolylineOptions();
int radius = 5; //What is that?
int numPoints = 100;
double phase = 2 * Math.PI / numPoints;
for (int i = 0; i <= numPoints; i++) {
    options.add(new LatLng(SYDNEY.latitude + radius * Math.sin(i * phase),
            SYDNEY.longitude + radius * Math.cos(i * phase)));
}
int color = Color.RED;
mMap.addPolyline(options
        .color(color)
        .width(2));

Answer 1

通过以下贝塞尔曲线计算,我能够实现这一目标

    double cLat = ((start.latitude + end.latitude) / 2);
    double cLon = ((start.longitude + end.longitude) / 2);

    //add skew and arcHeight to move the midPoint
    if(Math.abs(start.longitude - end.longitude) < 0.0001){
        cLon -= 0.0195;
    } else {
        cLat += 0.0195;
    }

    double tDelta = 1.0/50;
    for (double t = 0;  t <= 1.0; t+=tDelta) {
        double oneMinusT = (1.0-t);
        double t2 = Math.pow(t, 2);
        double lon = oneMinusT * oneMinusT * start.longitude
                + 2 * oneMinusT * t * cLon
                + t2 * end.longitude;
        double lat = oneMinusT * oneMinusT * start.latitude
                + 2 * oneMinusT * t * cLat
                + t2 * end.latitude;
        alLatLng.add(new LatLng(lat, lon));
    }

    // draw polyline
    PolylineOptions line = new PolylineOptions();
    line.width(POLYGON_STROKE_WIDTH_PX);
    line.color(Color.RED);
    line.addAll(alLatLng);
    map.addPolyline(line);