网上提供了地表测距方法,这里供上【空间】测距的方法:
两者区别是前者只是两点间的水平距离,仅考虑到【经纬度】,后者还考虑到了【高度】。
/******************************************* */
//测量空间直线距离
/******************************************* */
var measureLineSpace = function (viewer,handler) {
handler = new Cesium.ScreenSpaceEventHandler(viewer.scene._imageryLayerCollection);
var positions = [];
var poly = null;
var tooltip = document.getElementById("toolTip");
var distance = 0;
var cartesian = null;
var floatingPoint;
tooltip.style.display = "block";
handler.setInputAction(function (movement) {
tooltip.style.left = movement.endPosition.x + 3 + "px";
tooltip.style.top = movement.endPosition.y - 25 + "px";
tooltip.innerHTML = '<p>单击开始,右击结束</p>';
///////=================================
cartesian = viewer.scene.pickPosition(movement.endPosition);
/////==================================
//cartesian = viewer.scene.camera.pickEllipsoid(movement.endPosition, viewer.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);
}
distance = getSpaceDistance(positions);
// console.log("distance: " + distance);
// tooltip.innerHTML='<p>'+distance+'米</p>';
}
}, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
handler.setInputAction(function (movement) {
tooltip.style.display = "none";
// cartesian = viewer.scene.camera.pickEllipsoid(movement.position, viewer.scene.globe.ellipsoid);
cartesian = viewer.scene.pickPosition(movement.position);
if (positions.length == 0) {
positions.push(cartesian.clone());
}
positions.push(cartesian);
//在三维场景中添加Label
// var cartographic = Cesium.Cartographic.fromCartesian(cartesian);
var textDisance = distance + "米";
// console.log(textDisance + ",lng:" + cartographic.longitude/Math.PI*180.0);
floatingPoint = viewer.entities.add({
name: '空间直线距离',
// position: Cesium.Cartesian3.fromDegrees(cartographic.longitude / Math.PI * 180, cartographic.latitude / Math.PI * 180,cartographic.height),
position:positions[positions.length - 1],
point: {
pixelSize: 5,
color: Cesium.Color.RED,
outlineColor: Cesium.Color.WHITE,
outlineWidth: 2,
heightReference:Cesium.HeightReference.NONE
},
label: {
text: textDisance,
font: '18px sans-serif',
fillColor: Cesium.Color.GOLD,
style: Cesium.LabelStyle.FILL_AND_OUTLINE,
outlineWidth: 2,
verticalOrigin: Cesium.VerticalOrigin.BOTTOM,
pixelOffset: new Cesium.Cartesian2(20, -20),
heightReference:Cesium.HeightReference.NONE
}
});
}, Cesium.ScreenSpaceEventType.LEFT_CLICK);
handler.setInputAction(function (movement) {
handler.destroy();//关闭事件句柄
positions.pop();//最后一个点无效
viewer_g.entities.remove(floatingPoint);
tooltip.style.display = "none";
}, Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK);
var PolyLinePrimitive = (function () {
function _(positions) {
this.options = {
name: '直线',
polyline: {
show: true,
positions: [],
material: Cesium.Color.CHARTREUSE ,
width: 2
}
};
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 _;
})();
};
//空间两点距离计算函数
function getSpaceDistance(positions) {
var distance = 0;
for (var i = 0; i < positions.length - 1; i++) {
var point1cartographic = Cesium.Cartographic.fromCartesian(positions[i]);
var point2cartographic = Cesium.Cartographic.fromCartesian(positions[i+1]);
/**根据经纬度计算出距离**/
var geodesic = new Cesium.EllipsoidGeodesic();
geodesic.setEndPoints(point1cartographic, point2cartographic);
var s = geodesic.surfaceDistance;
//console.log(Math.sqrt(Math.pow(distance, 2) + Math.pow(endheight, 2)));
//返回两点之间的距离
s = Math.sqrt(Math.pow(s, 2) + Math.pow(point2cartographic.height - point1cartographic.height, 2));
distance = distance + s;
}
return distance.toFixed(2);
}