Add clamped vector polylines

Source/Core/decodeVectorPolylinePositions.js

@@ -0,0 +1,51 @@
+import AttributeCompression from "./AttributeCompression.js";
+import Cartesian3 from "./Cartesian3.js";
+import Cartographic from "./Cartographic.js";
+import CesiumMath from "./Math.js";
+
+var maxShort = 32767;
+
+var scratchBVCartographic = new Cartographic();
+var scratchEncodedPosition = new Cartesian3();
+
+function decodeVectorPolylinePositions(
+  positions,
+  rectangle,
+  minimumHeight,
+  maximumHeight,
+  ellipsoid
+) {
+  var positionsLength = positions.length / 3;
+  var uBuffer = positions.subarray(0, positionsLength);
+  var vBuffer = positions.subarray(positionsLength, 2 * positionsLength);
+  var heightBuffer = positions.subarray(
+    2 * positionsLength,
+    3 * positionsLength
+  );
+  AttributeCompression.zigZagDeltaDecode(uBuffer, vBuffer, heightBuffer);
+
+  var decoded = new Float64Array(positions.length);
+  for (var i = 0; i < positionsLength; ++i) {
+    var u = uBuffer[i];
+    var v = vBuffer[i];
+    var h = heightBuffer[i];
+
+    var lon = CesiumMath.lerp(rectangle.west, rectangle.east, u / maxShort);
+    var lat = CesiumMath.lerp(rectangle.south, rectangle.north, v / maxShort);
+    var alt = CesiumMath.lerp(minimumHeight, maximumHeight, h / maxShort);
+
+    var cartographic = Cartographic.fromRadians(
+      lon,
+      lat,
+      alt,
+      scratchBVCartographic
+    );
+    var decodedPosition = ellipsoid.cartographicToCartesian(
+      cartographic,
+      scratchEncodedPosition
+    );
+    Cartesian3.pack(decodedPosition, decoded, i * 3);
+  }
+  return decoded;
+}
+export default decodeVectorPolylinePositions;

Source/Scene/Cesium3DTileset.js

@@ -898,6 +898,13 @@ function Cesium3DTileset(options) {
    */
   this.debugShowUrl = defaultValue(options.debugShowUrl, false);
 
+  /**
+   * Function for examining vector lines as they are being streamed.
+   *
+   * @private
+   */
+  this.examineVectorLinesFunction = undefined;
+
   var that = this;
   var resource;
   when(options.url)
@@ -1654,6 +1661,20 @@ Object.defineProperties(Cesium3DTileset.prototype, {
       Cartesian2.clone(value, this._imageBasedLightingFactor);
     },
   },
+
+  /**
+   * Minimum and maximum heights that vector tiles clamped to surfaces will clamp to.
+   *
+   * @memberof Cesium3DTileset.prototype
+   *
+   * @type {Cartesian2}
+   * @default undefined
+   */
+  minimumMaximumVectorHeights: {
+    get: function () {
+      return this._minimumMaximumVectorHeights;
+    },
+  },
 });
 
 /**