效果

挖地形

通过绘制多边形获取边界点集合,把边界点分别计算生成多个ClippingPlane面 ,用ClippingPlaneCollection接口生成裁剪地形效果。最后分别将侧边和底部加上贴图效果

淹没分析

通过绘制多边形获取边界点集合,用extrudedHeight属性动态控制淹没高度,简单模拟淹没效果。熟悉webgl的可以通过修改shader的顶点和片段着色器创建淹没效果

坡度分析(地形)

通过绘制多段线获取线段点集合,用lerp获取点的线性插值结果,将返回的差值点高程绘制出来,实现坡度图

说明

挖地形插件

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import Cesium from '../namespace'

function TerrainClipPlan(t, i) {
this.viewer = t,
this.options = i || {},
this._positions = i.positions,
this._height = this.options.height || 0,
this.bottomImg = i.bottomImg,
this.wallImg = i.wallImg,
this.splitNum = Cesium.defaultValue(i.splitNum, 50),
this._positions && this._positions.length > 0 && this.updateData(this._positions)
}

Object.defineProperties(TerrainClipPlan.prototype, {
show: {
get: function () {
return this._show
},
set: function (e) {
this._show = e, this.viewer.scene.globe.clippingPlanes && (this.viewer.scene.globe.clippingPlanes.enabled = e), this._switchExcavate(e)
}
},

height: {
get: function () {
return this._height
},
set: function (e) {
this._height = e, this._updateExcavateDepth(e)
}
}
})


TerrainClipPlan.prototype.updateData = function (e) {
this.clear();
var t = [],
i = e.length,
a = new Cesium.Cartesian3,
n = Cesium.Cartesian3.subtract(e[0], e[1], a);
n = n.x > 0, this.excavateMinHeight = 9999;
for (var r = 0; r < i; ++r) {
var s = (r + 1) % i,
l = Cesium.Cartesian3.midpoint(e[r], e[s], new Cesium.Cartesian3),
u = Cesium.Cartographic.fromCartesian(e[r]),
c = this.viewer.scene.globe.getHeight(u) || u.height;
c < this.excavateMinHeight && (this.excavateMinHeight = c);
var d, h = Cesium.Cartesian3.normalize(l, new Cesium.Cartesian3);
d = n ? Cesium.Cartesian3.subtract(e[r], l, new Cesium.Cartesian3) : Cesium.Cartesian3.subtract(e[s], l, new Cesium.Cartesian3), d = Cesium.Cartesian3.normalize(d, d);
var f = Cesium.Cartesian3.cross(d, h, new Cesium.Cartesian3);
f = Cesium.Cartesian3.normalize(f, f);
var p = new Cesium.Plane(f, 0),
m = Cesium.Plane.getPointDistance(p, l);
t.push(new Cesium.ClippingPlane(f, m))
}
this.viewer.scene.globe.clippingPlanes = new Cesium.ClippingPlaneCollection({
planes: t,
edgeWidth: 1,
edgeColor: Cesium.Color.WHITE,
enabled: !0
}), this._prepareWell(e), this._createWell(this.wellData)
}

TerrainClipPlan.prototype.clear = function () {

this.viewer.scene.globe.clippingPlanes && (this.viewer.scene.globe.clippingPlanes.enabled = !1, this.viewer.scene.globe.clippingPlanes.removeAll(), this.viewer.scene.globe.clippingPlanes.isDestroyed() || this.viewer.scene.globe.clippingPlanes.destroy()), this.viewer.scene.globe.clippingPlanes = void 0, this.bottomSurface && this.viewer.scene.primitives.remove(this.bottomSurface), this.wellWall && this.viewer.scene.primitives.remove(this.wellWall), delete this.bottomSurface, delete this.wellWall, this.viewer.scene.render()
}

TerrainClipPlan.prototype._prepareWell = function (e) {
var t = this.splitNum,
i = e.length;
if (0 != i) {
for (var a = this.excavateMinHeight - this.height, n = [], r = [], s = [], l = 0; l < i; l++) {
var u = l == i - 1 ? 0 : l + 1,
c = Cesium.Cartographic.fromCartesian(e[l]),
d = Cesium.Cartographic.fromCartesian(e[u]),
h = [c.longitude, c.latitude],
f = [d.longitude, d.latitude];

0 == l && (
s.push(new Cesium.Cartographic(h[0], h[1])),
r.push(Cesium.Cartesian3.fromRadians(h[0], h[1], a)),
n.push(Cesium.Cartesian3.fromRadians(h[0], h[1], 0)));

for (var p = 1; p <= t; p++) {
var m = Cesium.Math.lerp(h[0], f[0], p / t),
g = Cesium.Math.lerp(h[1], f[1], p / t);
l == i - 1 && p == t || (
s.push(new Cesium.Cartographic(m, g)),
r.push(Cesium.Cartesian3.fromRadians(m, g, a)),
n.push(Cesium.Cartesian3.fromRadians(m, g, 0)))
}
}
this.wellData = {
lerp_pos: s,
bottom_pos: r,
no_height_top: n
}
}
}

TerrainClipPlan.prototype._createWell = function (e) {
if (Boolean(this.viewer.terrainProvider._layers)) {
var t = this;
this._createBottomSurface(e.bottom_pos);
var i = Cesium.sampleTerrainMostDetailed(this.viewer.terrainProvider, e.lerp_pos);
Cesium.when(i, function (i) {
for (var a = i.length, n = [], r = 0; r < a; r++) {
var s = Cesium.Cartesian3.fromRadians(i[r].longitude, i[r].latitude, i[r].height);
n.push(s)
}
t._createWellWall(e.bottom_pos, n)
})
} else {
this._createBottomSurface(e.bottom_pos);
this._createWellWall(e.bottom_pos, e.no_height_top)
}
}


TerrainClipPlan.prototype._getMinHeight = function (e) {
let minHeight = 5000000;
let minPoint = null;
for (let i = 0; i < e.length; i++) {
let height = e[i]['z'];
if (height < minHeight) {
minHeight = height;
minPoint = this._ellipsoidToLonLat(e[i]);
}
}
return minPoint.altitude;
}


TerrainClipPlan.prototype._ellipsoidToLonLat = function (c) {
let ellipsoid = this.viewer.scene.globe.ellipsoid;
let cartesian3 = new Cesium.Cartesian3(c.x, c.y, c.z);
let cartographic = ellipsoid.cartesianToCartographic(cartesian3);
let lat = Cesium.Math.toDegrees(cartographic.latitude);
let lng = Cesium.Math.toDegrees(cartographic.longitude);
let alt = cartographic.height;
return {
longitude: lng,
latitude: lat,
altitude: alt
}
}
TerrainClipPlan.prototype._createBottomSurface = function (e) {
if (e.length) {
let minHeight = this._getMinHeight(e);
let positions = [];
for (let i = 0; i < e.length; i++) {
let p = this._ellipsoidToLonLat(e[i]);
positions.push(p.longitude);
positions.push(p.latitude);
positions.push(minHeight);
}

let polygon = new Cesium.PolygonGeometry({
polygonHierarchy: new Cesium.PolygonHierarchy(
Cesium.Cartesian3.fromDegreesArrayHeights(positions)
),
perPositionHeight: true
});
let geometry = Cesium.PolygonGeometry.createGeometry(polygon);


var i = new Cesium.Material({
fabric: {
type: "Image",
uniforms: {
image: this.bottomImg
}
}
}),
a = new Cesium.MaterialAppearance({
translucent: !1,
flat: !0,
material: i
});
this.bottomSurface = new Cesium.Primitive({
geometryInstances: new Cesium.GeometryInstance({
geometry: geometry
}),
appearance: a,
asynchronous: !1
}), this.viewer.scene.primitives.add(this.bottomSurface)
}
}

TerrainClipPlan.prototype._createWellWall = function (e, t) {
let minHeight = this._getMinHeight(e);
let maxHeights = [];
let minHeights = [];
for (let i = 0; i < t.length; i++) {
maxHeights.push(this._ellipsoidToLonLat(t[i]).altitude);
minHeights.push(minHeight);
}
let wall = new Cesium.WallGeometry({
positions: t,
maximumHeights: maxHeights,
minimumHeights: minHeights,
});
let geometry = Cesium.WallGeometry.createGeometry(wall);
var a = new Cesium.Material({
fabric: {
type: "Image",
uniforms: {
image: this.wallImg
}
}
}),
n = new Cesium.MaterialAppearance({
translucent: !1,
flat: !0,
material: a
});
this.wellWall = new Cesium.Primitive({
geometryInstances: new Cesium.GeometryInstance({
geometry: geometry,
attributes: {
color: Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.GREY)
},
id: "PitWall"
}),
appearance: n,
asynchronous: !1
}), this.viewer.scene.primitives.add(this.wellWall)
}
TerrainClipPlan.prototype._switchExcavate = function (e) {
e ? (this.viewer.scene.globe.material = Cesium.Material.fromType("WaJue"), this.wellWall.show = !0, this.bottomSurface.show = !0) : (this.viewer.scene.globe.material = null, this.wellWall.show = !1, this.bottomSurface.show = !1)
}

TerrainClipPlan.prototype._updateExcavateDepth = function (e) {
this.bottomSurface && this.viewer.scene.primitives.remove(this.bottomSurface), this.wellWall && this.viewer.scene.primitives.remove(this.wellWall);
for (var t = this.wellData.lerp_pos, i = [], a = t.length, n = 0; n < a; n++) i.push(Cesium.Cartesian3.fromRadians(t[n].longitude, t[n].latitude, this.excavateMinHeight - e));
this.wellData.bottom_pos = i, this._createWell(this.wellData), this.viewer.scene.primitives.add(this.bottomSurface), this.viewer.scene.primitives.add(this.wellWall)
}

export default TerrainClipPlan

调用

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let terrainClipPlan = new TerrainClipPlan(this._viewer._delegate, {
height: this._height,
splitNum: this._splitNum,
wallImg: this._wallImg,
bottomImg: this._bottomImg
})

console.log(this._hierarchy.positions)
terrainClipPlan.updateData(this._hierarchy.positions)