imporve the wind layer #96

modules/wind/WindCanvas.js

   _drawPixelParticle(particle, min, max) {
     let pointPrev = [particle.x, particle.y]
     let pointNext = [particle.xt, particle.yt]
+    let dx = particle.xt - particle.x
+    let dy = particle.yt - particle.y
+    if (dx * dx + dy * dy > 20 * 20) {
+      return
+    }
     if (
       pointNext &&
       pointPrev &&

modules/wind/WindLayer.js

     let camera = this._viewer.camera
     let ellipsoid = Cesium.Ellipsoid.WGS84
     this._delegate.intersectsCoordinate = coordinate => {
-      let occluder = new Cesium.EllipsoidalOccluder(ellipsoid, camera.position)
-      let point = Cesium.Cartesian3.fromDegrees(coordinate[0], coordinate[1])
-      return occluder.isPointVisible(point)
+      if (scene.mode === Cesium.SceneMode.SCENE3D) {
+        let occluder = new Cesium.EllipsoidalOccluder(
+          ellipsoid,
+          camera.position
+        )
+        let point = Cesium.Cartesian3.fromDegrees(coordinate[0], coordinate[1])
+        return occluder.isPointVisible(point)
+      } else if (scene.mode === Cesium.SceneMode.SCENE2D) {
+        return !(coordinate[0] === -180 || coordinate[0] === 180)
+      }
+      return true
     }
 
     this._delegate.project = coordinate => {