feat: 增加官网渐变弧线案例

examples/line/arc/demo/meta.json

@@ -15,11 +15,15 @@
       "screenshot": "https://gw.alipayobjects.com/mdn/antv_site/afts/img/A*JjUcTZ8-PC8AAAAAAAAAAABkARQnAQ"
 
     },
+    {
+      "filename": "trip_arc_dark_linear.js",
+      "title": "3D 弧线（渐变）",
+      "screenshot": "https://gw.alipayobjects.com/mdn/rms_23a451/afts/img/A*RZEgSYZLeJIAAAAAAAAAAAAAARQnAQ"
+    },
     {
       "filename": "trip_arc.js",
       "title": "3D 弧线",
       "screenshot": "https://gw.alipayobjects.com/mdn/antv_site/afts/img/A*xvaaQo2c0gMAAAAAAAAAAABkARQnAQ"
-
     }
   ]
 }

examples/line/arc/demo/trip_arc_dark_linear.js

@@ -0,0 +1,38 @@
+import { Scene, LineLayer } from '@antv/l7';
+import { Mapbox } from '@antv/l7-maps';
+
+const scene = new Scene({
+  id: 'map',
+  map: new Mapbox({
+    pitch: 60,
+    style: 'dark',
+    center: [ 104.34278, 41.12554 ],
+    zoom: 2.94888,
+    rotation: 42.3999
+  })
+});
+scene.on('loaded', () => {
+  fetch('https://gw.alipayobjects.com/os/rmsportal/UEXQMifxtkQlYfChpPwT.txt')
+    .then(res => res.text())
+    .then(data => {
+      const layer = new LineLayer({})
+        .source(data, {
+          parser: {
+            type: 'csv',
+            x: 'lng1',
+            y: 'lat1',
+            x1: 'lng2',
+            y1: 'lat2'
+          }
+        })
+        .size(1)
+        .shape('arc3d')
+        .color('#FF7C6A')
+        .style({
+          opacity: 0.8,
+          sourceColor: '#f00',
+          targetColor: '#0f0',
+        });
+      scene.addLayer(layer);
+    });
+});