Ability to load z-up models

Source/Scene/Axis.js

@@ -0,0 +1,73 @@
+/*global define*/
+define([
+        '../Core/freezeObject',
+        '../Core/Math',
+        '../Core/Matrix3',
+        '../Core/Matrix4'
+], function(
+        freezeObject,
+        CesiumMath,
+        Matrix3,
+        Matrix4) {
+    'use strict';
+
+    /**
+     * An enum describing the x, y, and z axes and helper conversion functions.
+     *
+     * @exports Axis
+     * @private
+     */
+    var Axis = {
+        /**
+         * Denotes the x-axis.
+         *
+         * @type {Number}
+         * @constant
+         */
+        X : 0,
+
+        /**
+         * Denotes the y-axis.
+         *
+         * @type {Number}
+         * @constant
+         */
+        Y : 1,
+
+        /**
+         * Denotes the z-axis.
+         *
+         * @type {Number}
+         * @constant
+         */
+        Z : 2,
+
+        /**
+         * Matrix used to convert from y-up to z-up
+         *
+         * @type {Matrix4}
+         * @constant
+         */
+        Y_UP_TO_Z_UP : Matrix4.fromRotationTranslation(Matrix3.fromRotationX(CesiumMath.PI_OVER_TWO)),
+
+        /**
+         * Matrix used to convert from x-up to z-up
+         *
+         * @type {Matrix4}
+         * @constant
+         */
+        X_UP_TO_Z_UP : Matrix4.fromRotationTranslation(Matrix3.fromRotationY(CesiumMath.PI_OVER_TWO)),
+
+        /**
+         * Gets the axis by name
+         *
+         * @param {String} name The name of the axis.
+         * @returns {Number} The axis enum.
+         */
+        fromName : function(name) {
+            return Axis[name];
+        }
+    };
+
+    return freezeObject(Axis);
+});

Source/Scene/Model.js

@@ -52,6 +52,7 @@ define([
         '../ThirdParty/gltfDefaults',
         '../ThirdParty/Uri',
         '../ThirdParty/when',
+        './Axis',
         './BlendingState',
         './ColorBlendMode',
         './getAttributeOrUniformBySemantic',
@@ -118,6 +119,7 @@ define([
         gltfDefaults,
         Uri,
         when,
+        Axis,
         BlendingState,
         ColorBlendMode,
         getAttributeOrUniformBySemantic,
@@ -139,7 +141,6 @@ define([
         return {};
     }
 
-    var yUpToZUp = Matrix4.fromRotationTranslation(Matrix3.fromRotationX(CesiumMath.PI_OVER_TWO));
     var boundingSphereCartesian3Scratch = new Cartesian3();
 
     var ModelState = {
@@ -624,6 +625,15 @@ define([
         this._pickUniformMapLoaded = options.pickUniformMapLoaded;
         this._ignoreCommands = defaultValue(options.ignoreCommands, false);
 
+
+        /**
+         * By default models are y-up according to the glTF spec, however geo-referenced models will typically be z-up
+         *
+         * @private
+         * @readonly
+         */
+        this.upAxis = defaultValue(options.upAxis, Axis.Y);
+
         /**
          * @private
          * @readonly
@@ -1233,7 +1243,7 @@ define([
         };
     }
 
-    function computeBoundingSphere(gltf) {
+    function computeBoundingSphere(model, gltf) {
         var gltfNodes = gltf.nodes;
         var gltfMeshes = gltf.meshes;
         var rootNodes = gltf.scenes[gltf.scene].nodes;
@@ -1289,7 +1299,12 @@ define([
         }
 
         var boundingSphere = BoundingSphere.fromCornerPoints(min, max);
-        return BoundingSphere.transformWithoutScale(boundingSphere, yUpToZUp, boundingSphere);
+        if (model.upAxis === Axis.Y) {
+            BoundingSphere.transformWithoutScale(boundingSphere, Axis.Y_UP_TO_Z_UP, boundingSphere);
+        } else if (model.upAxis === Axis.X) {
+            BoundingSphere.transformWithoutScale(boundingSphere, Axis.X_UP_TO_Z_UP, boundingSphere);
+        }
+        return boundingSphere;
     }
 
     ///////////////////////////////////////////////////////////////////////////
@@ -4192,7 +4207,7 @@ define([
 
             this._state = ModelState.LOADING;
 
-            this._boundingSphere = computeBoundingSphere(this.gltf);
+            this._boundingSphere = computeBoundingSphere(this, this.gltf);
             this._initialRadius = this._boundingSphere.radius;
 
             checkSupportedExtensions(this);
@@ -4315,7 +4330,11 @@ define([
                 var scale = getScale(this, frameState);
                 var computedModelMatrix = this._computedModelMatrix;
                 Matrix4.multiplyByUniformScale(modelMatrix, scale, computedModelMatrix);
-                Matrix4.multiplyTransformation(computedModelMatrix, yUpToZUp, computedModelMatrix);
+                if (this.upAxis === Axis.Y) {
+                    Matrix4.multiplyTransformation(computedModelMatrix, Axis.Y_UP_TO_Z_UP, computedModelMatrix);
+                } else if (this.upAxis === Axis.X) {
+                    Matrix4.multiplyTransformation(computedModelMatrix, Axis.X_UP_TO_Z_UP, computedModelMatrix);
+                }
             }
 
             // Update modelMatrix throughout the graph as needed