Apply transform to "region" bounding volume type

CHANGES.md

@@ -9,6 +9,7 @@ Change Log
 #### Fixes :wrench:
 * Fixed bug causing billboards and labels to appear the wrong size when switching scene modes [#6745](https://github.com/AnalyticalGraphicsInc/cesium/issues/6745)
 * Fixed a bug that was preventing 3D Tilesets on the opposite side of the globe from being occluded [#6714](https://github.com/AnalyticalGraphicsInc/cesium/issues/6714)
+* Fixed a bug where 3D Tilesets using the `region` bounding volume don't get transformed when the tileset's `modelMatrix` changes. [6755](https://github.com/AnalyticalGraphicsInc/cesium/pull/6755)
 
 ### 1.47 - 2018-07-02
 

Source/Scene/Cesium3DTile.js

@@ -8,11 +8,14 @@ define([
         '../Core/defineProperties',
         '../Core/deprecationWarning',
         '../Core/destroyObject',
+        '../Core/Ellipsoid',
         '../Core/getMagic',
         '../Core/Intersect',
         '../Core/JulianDate',
+        '../Core/Math',
         '../Core/Matrix3',
         '../Core/Matrix4',
+        '../Core/OrientedBoundingBox',
         '../Core/Rectangle',
         '../Core/Request',
         '../Core/RequestScheduler',
@@ -41,11 +44,14 @@ define([
         defineProperties,
         deprecationWarning,
         destroyObject,
+        Ellipsoid,
         getMagic,
         Intersect,
         JulianDate,
+        CesiumMath,
         Matrix3,
         Matrix4,
+        OrientedBoundingBox,
         Rectangle,
         Request,
         RequestScheduler,
@@ -90,6 +96,9 @@ define([
         var parentTransform = defined(parent) ? parent.computedTransform : tileset.modelMatrix;
         var computedTransform = Matrix4.multiply(parentTransform, this.transform, new Matrix4());
 
+        var parentInitialTransform = defined(parent) ? parent._initialTransform : Matrix4.IDENTITY;
+        this._initialTransform = Matrix4.multiply(parentInitialTransform, this.transform, new Matrix4());
+
         /**
          * The final computed transform of this tile
          * @type {Matrix4}
@@ -882,6 +891,8 @@ define([
     var scratchHalfAxes = new Matrix3();
     var scratchCenter = new Cartesian3();
     var scratchRectangle = new Rectangle();
+    var scratchOrientedBoundingBox = new OrientedBoundingBox();
+    var scratchTransform = new Matrix4();
 
     function createBox(box, transform, result) {
         var center = Cartesian3.fromElements(box[0], box[1], box[2], scratchCenter);
@@ -899,13 +910,42 @@ define([
         return new TileOrientedBoundingBox(center, halfAxes);
     }
 
-    function createRegion(region, result) {
-        var rectangleRegion = Rectangle.unpack(region, 0, scratchRectangle);
+    function createBoxFromTransformedRegion(region, transform, initialTransform, result) {
+        var rectangle = Rectangle.unpack(region, 0, scratchRectangle);
+        var minimumHeight = region[4];
+        var maximumHeight = region[5];
+
+        var orientedBoundingBox = OrientedBoundingBox.fromRectangle(rectangle, minimumHeight, maximumHeight, Ellipsoid.WGS84, scratchOrientedBoundingBox);
+        var center = orientedBoundingBox.center;
+        var halfAxes = orientedBoundingBox.halfAxes;
+
+        // A region bounding volume is not transformed by the transform in the tileset JSON,
+        // but may be transformed by additional transforms applied in Cesium.
+        // This is why the transform is calculated as the difference between the initial transform and the current transform.
+        transform = Matrix4.multiplyTransformation(transform, Matrix4.inverseTransformation(initialTransform, scratchTransform), scratchTransform);
+        center = Matrix4.multiplyByPoint(transform, center, center);
+        var rotationScale = Matrix4.getRotation(transform, scratchMatrix);
+        halfAxes = Matrix3.multiply(rotationScale, halfAxes, halfAxes);
+
+        if (defined(result) && (result instanceof TileOrientedBoundingBox)) {
+            result.update(center, halfAxes);
+            return result;
+        }
+
+        return new TileOrientedBoundingBox(center, halfAxes);
+    }
+
+    function createRegion(region, transform, initialTransform, result) {
+        if (!Matrix4.equalsEpsilon(transform, initialTransform, CesiumMath.EPSILON8)) {
+            return createBoxFromTransformedRegion(region, transform, initialTransform, result);
+        }
 
         if (defined(result)) {
-            // Don't update regions when the transform changes
             return result;
         }
+
+        var rectangleRegion = Rectangle.unpack(region, 0, scratchRectangle);
+
         return new TileBoundingRegion({
             rectangle : rectangleRegion,
             minimumHeight : region[4],
@@ -949,16 +989,14 @@ define([
             return createBox(boundingVolumeHeader.box, transform, result);
         }
         if (defined(boundingVolumeHeader.region)) {
-            return createRegion(boundingVolumeHeader.region, result);
+            return createRegion(boundingVolumeHeader.region, transform, this._initialTransform, result);
         }
         if (defined(boundingVolumeHeader.sphere)) {
             return createSphere(boundingVolumeHeader.sphere, transform, result);
         }
         throw new RuntimeError('boundingVolume must contain a sphere, region, or box');
     };
 
-    var scratchTransform = new Matrix4();
-
     /**
      * Update the tile's transform. The transform is applied to the tile's bounding volumes.
      *
@@ -978,12 +1016,12 @@ define([
         // Update the bounding volumes
         var header = this._header;
         var content = this._header.content;
-        this._boundingVolume = this.createBoundingVolume(header.boundingVolume, computedTransform, this._boundingVolume);
+        this._boundingVolume = this.createBoundingVolume(header.boundingVolume, this.computedTransform, this._boundingVolume);
         if (defined(this._contentBoundingVolume)) {
-            this._contentBoundingVolume = this.createBoundingVolume(content.boundingVolume, computedTransform, this._contentBoundingVolume);
+            this._contentBoundingVolume = this.createBoundingVolume(content.boundingVolume, this.computedTransform, this._contentBoundingVolume);
         }
         if (defined(this._viewerRequestVolume)) {
-            this._viewerRequestVolume = this.createBoundingVolume(header.viewerRequestVolume, computedTransform, this._viewerRequestVolume);
+            this._viewerRequestVolume = this.createBoundingVolume(header.viewerRequestVolume, this.computedTransform, this._viewerRequestVolume);
         }
 
         // Destroy the debug bounding volumes. They will be generated fresh.

Specs/Scene/Batched3DModel3DTileContentSpec.js

@@ -202,9 +202,7 @@ defineSuite([
     });
 
     it('renders with a tile transform and region bounding volume', function() {
-        return Cesium3DTilesTester.loadTileset(scene, withTransformRegionUrl).then(function(tileset) {
-            Cesium3DTilesTester.expectRenderTileset(scene, tileset);
-        });
+        return expectRenderWithTransform(withTransformRegionUrl);
     });
 
     it('picks with batch table', function() {
@@ -392,6 +390,7 @@ defineSuite([
             var newHPR = new HeadingPitchRoll();
             var newTransform = Transforms.headingPitchRollToFixedFrame(newCenter, newHPR);
             tileset._root.transform = newTransform;
+            scene.camera.lookAt(newCenter, new HeadingPitchRange(0.0, 0.0, 15.0));
             scene.renderForSpecs();
 
             expectedModelTransform = Matrix4.multiply(tileset._root.computedTransform, rtcTransform, expectedModelTransform);