Cesium专栏-terrain地形、3dtiles模型、gltf模型 高度采样

在Cesium中，对于terrain地形、3dtiles模型、gltf模型的高度采样是一个很基本的功能，基于此，可以做一些深度应用，而Cesium已经帮我们提供了相应的API，在这里，我帮大家总结一下，如果遇到了，可以当做帮助文档随时浏览。

terrain地形 高度采样（API: Cesium.sampleTerrainMostDetailed）

通过两点决定一条直线，求取这条直线在地表高度

var start = Cesium.Cartesian3.fromDegrees(114, 30);
var end = Cesium.Cartesian3.fromDegrees(115, 30);

var positions = [Cesium.Cartographic.fromCartesian(start)];
// 插值100个点（自定义）
var count = 100;
for (var i = 1; i < count; i++) {
    var cart = Cesium.Cartesian3.lerp(start, end, i / count, new Cesium.Cartesian3());
    positions.push(Cesium.Cartographic.fromCartesian(cart));
}
positions.push(Cesium.Cartographic.fromCartesian(end));

var promise = Cesium.sampleTerrainMostDetailed(terrainProvider, positions);
Cesium.when(promise, function (updatedPositions) {
    // 每个点的高度        
    var height = [];
    for (var i = 0; i < updatedPositions.length; i++) {
       height.push(updatedPositions[i].height);
    }
}

3dtiles模型 高度采样（API: Scene.clampToHeightMostDetailed）

var start = new Cesium.Cartesian3(1216467.760147752, -4736154.3567799, 4081478.9167016773);
var end = new Cesium.Cartesian3(1216183.8039071201, -4736456.592237458, 4081200.6372076278);
// 插值100个点
var count = 100;
var positions = [];
for (var i = 0; i <= count; i++) {
    positions.push(Cesium.Cartesian3.lerp(start , end , i / count, new Cesium.Cartesian3()));
}
scene.clampToHeightMostDetailed(positions).then(function (clampedCartesians) {
    // 每个点的高度
    var height = [];
    for (var i = 0; i < count; ++i) {
        height.push(Cesium.Cartographic.fromCartesian(clampedCartesians[i]).height);
    }
}

gltf模型 高度采样（API: Scene.sampleHeightMostDetailed）

var start = new Cesium.Cartesian3(-2505765.4115135744, -3847571.788472332, 4412115.866010899);
var end  = new Cesium.Cartesian3(-2505753.7330809264, -3847579.139677606, 4412116.086420342);
// 插值1000个点
var count = 1000;
var positions = [];
for (var i = 0; i <= count; i++) {
    var cart = Cesium.Cartesian3.lerp(start , end  , i / count, new Cesium.Cartesian3());
    positions.push(Cesium.Cartographic.fromCartesian(cart));
}
scene.sampleHeightMostDetailed(positions).then(function (clampedCartesians) {
    // 每个点的高度
    var height = [];
    for (var i = 0; i < count; ++i) {
        height.push(clampedCartesians[i].height);
    }
}