Cesium在线绘制PolyLine折线
使用Cesium.CallbackProperty可以实时更改Geometry.position等参数，从而达到绘制的效果。
1.封装PolyLine对象
var PolyLinePrimitive = (function(){
function _(positions){
this.options = {
polyline : {
show : true,
positions : [],
material : Cesium.Color.CORNFLOWERBLUE,
width : 5
}
};
this.positions = positions;
this._init();
}
_.prototype._init = function(){
var _self = this;
var _update = function(){
return _self.positions;
};
//实时更新polyline.positions
this.options.polyline.positions = new Cesium.CallbackProperty(_update,false);
viewer.entities.add(this.options);
};
return _;
})();
2.初始化
var handler = new Cesium.ScreenSpaceEventHandler(scene.canvas); var positions = []; var poly = undefined;var handler = new Cesium.ScreenSpaceEventHandler(scene.canvas); var positions = []; var poly = undefined;
3.鼠标监听事件
handler.setInputAction(function(movement){
var cartesian = scene.camera.pickEllipsoid(movement.position,scene.globe.ellipsoid);
if(positions.length == 0) {
positions.push(cartesian.clone());
}
positions.push(cartesian);
},Cesium.ScreenSpaceEventType.LEFT_CLICK);
handler.setInputAction(function(movement){
var cartesian = scene.camera.pickEllipsoid(movement.endPosition,scene.globe.ellipsoid);
if(positions.length >= 2){
if (!Cesium.defined(poly)) {
poly = new PolyLinePrimitive(positions);
}else{
positions.pop();
cartesian.y += (1 + Math.random());
positions.push(cartesian);
}
}
},Cesium.ScreenSpaceEventType.MOUSE_MOVE);
handler.setInputAction(function(movement){
handler.destroy();
},Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK);
handler.setInputAction(function(movement){ var cartesian = scene.camera.pickEllipsoid(movement.position,scene.globe.ellipsoid); if(positions.length == 0) { positions.push(cartesian.clone()); } positions.push(cartesian); },Cesium.ScreenSpaceEventType.LEFT_CLICK); handler.setInputAction(function(movement){ var cartesian = scene.camera.pickEllipsoid(movement.endPosition,scene.globe.ellipsoid); if(positions.length >= 2){ if (!Cesium.defined(poly)) { poly = new PolyLinePrimitive(positions); }else{ positions.pop(); cartesian.y += (1 + Math.random()); positions.push(cartesian); } } },Cesium.ScreenSpaceEventType.MOUSE_MOVE); handler.setInputAction(function(movement){ handler.destroy(); },Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK);
