Detect glTF 2.0 and change forward to match Cesium's convention.

Apps/SampleData/models/DracoCompressed/CesiumMilkTruck.gltf

@@ -17,6 +17,24 @@
       "children": [
         3,
         1
+      ],
+      "matrix": [
+          0,
+          0,
+          1,
+          0,
+          0,
+          1,
+          0,
+          0,
+          -1,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          1
       ]
     },
     {

Apps/Sandcastle/gallery/Physically-Based Materials.html

@@ -53,7 +53,7 @@
 viewer.scene.globe.depthTestAgainstTerrain = true;
 
 var position = new Cesium.Cartesian3(-1371108.6511167218, -5508684.080096612, 2901825.449865087);
-var heading = Cesium.Math.toRadians(90);
+var heading = Cesium.Math.toRadians(180);
 var pitch = Cesium.Math.toRadians(2);
 var roll = Cesium.Math.toRadians(-6);
 var hpr = new Cesium.HeadingPitchRoll(heading, pitch, roll);

CHANGES.md

@@ -3,6 +3,9 @@ Change Log
 
 ### 1.47 - 2018-07-02
 
+##### Breaking Changes :mega:
+* glTF 2.0 models corrected to face +Z forwards per specification.  Internally Cesium uses +X as forward, so a new +Z to +X rotation was added for 2.0 models only.  [#6632](https://github.com/AnalyticalGraphicsInc/cesium/pull/6632)
+
 ##### Additions :tada:
 * `PostProcessStage` has a `selectedFeatures` property which is an array of primitives used for selectively applying a post-process stage. In the fragment shader, use the function `bool czm_selected(vec2 textureCoordinates` to determine whether or not the stage should be applied at that fragment.
    * The black-and-white and silhouette stages have per-feature support.
@@ -27,6 +30,7 @@ Change Log
 * Removed `Scene.copyGlobeDepth`. Globe depth will now be copied by default when supported. [#6393](https://github.com/AnalyticalGraphicsInc/cesium/pull/6393)
 * The default `classificationType` for `GroundPrimitive`, `CorridorGraphics`, `EllipseGraphics`, `PolygonGraphics` and `RectangleGraphics` is now `ClassificationType.TERRAIN`.  If you wish the geometry to color both terrain and 3D tiles, pass in the option `classificationType: Cesium.ClassificationType.BOTH`.
 * Removed support for the `options` argument for `Credit` [#6373](https://github.com/AnalyticalGraphicsInc/cesium/issues/6373).  Pass in an html string instead.
+* glTF 2.0 models corrected to face +Z forwards per specification.  Internally Cesium uses +X as forward, so a new +Z to +X rotation was added for 2.0 models only.  [#6632](https://github.com/AnalyticalGraphicsInc/cesium/pull/6632)
 
 ##### Deprecated :hourglass_flowing_sand:
 * The `Scene.fxaa` property has been deprecated and will be removed in Cesium 1.47. Use `Scene.postProcessStages.fxaa.enabled`.

Source/Scene/Batched3DModel3DTileContent.js

@@ -12,6 +12,7 @@ define([
         '../Core/RequestType',
         '../Core/RuntimeError',
         '../Renderer/Pass',
+        './Axis',
         './Cesium3DTileBatchTable',
         './Cesium3DTileFeature',
         './Cesium3DTileFeatureTable',
@@ -32,6 +33,7 @@ define([
         RequestType,
         RuntimeError,
         Pass,
+        Axis,
         Cesium3DTileBatchTable,
         Cesium3DTileFeature,
         Cesium3DTileFeatureTable,
@@ -356,6 +358,7 @@ define([
                 requestType : RequestType.TILES3D,
                 modelMatrix : tile.computedTransform,
                 upAxis : tileset._gltfUpAxis,
+                forwardAxis : Axis.X,
                 shadows: tileset.shadows,
                 debugWireframe: tileset.debugWireframe,
                 incrementallyLoadTextures : false,
@@ -376,6 +379,7 @@ define([
                 requestType : RequestType.TILES3D,
                 modelMatrix : tile.computedTransform,
                 upAxis : tileset._gltfUpAxis,
+                forwardAxis : Axis.X,
                 debugWireframe : tileset.debugWireframe,
                 vertexShaderLoaded : getVertexShaderCallback(content),
                 classificationShaderLoaded : getClassificationFragmentShaderCallback(content),

Source/Scene/Model.js

@@ -577,6 +577,7 @@ define([
         this._ignoreCommands = defaultValue(options.ignoreCommands, false);
         this._requestType = options.requestType;
         this._upAxis = defaultValue(options.upAxis, Axis.Y);
+        this._forwardAxis = defaultValue(options.forwardAxis, Axis.Z);
 
         /**
          * @private
@@ -970,6 +971,25 @@ define([
             }
         },
 
+        /**
+         * Gets the model's forward axis.
+         * By default, glTF 2.0 models are z-forward according to the glTF spec, however older
+         * glTF (1.0, 0.8) models used x-forward.  Note that only Axis.X and Axis.Z are supported.
+         *
+         * @memberof Model.prototype
+         *
+         * @type {Number}
+         * @default Axis.Z
+         * @readonly
+         *
+         * @private
+         */
+        forwardAxis : {
+            get : function() {
+                return this._forwardAxis;
+            }
+        },
+
         /**
          * Gets the model's triangle count.
          *
@@ -1367,6 +1387,10 @@ define([
         } else if (model._upAxis === Axis.X) {
             BoundingSphere.transformWithoutScale(boundingSphere, Axis.X_UP_TO_Z_UP, boundingSphere);
         }
+        if (model._forwardAxis === Axis.Z) {
+            // glTF 2.0 has a Z-forward convention that must be adapted here to X-forward.
+            BoundingSphere.transformWithoutScale(boundingSphere, Axis.Z_UP_TO_X_UP, boundingSphere);
+        }
         return boundingSphere;
     }
 
@@ -4225,6 +4249,10 @@ define([
                     };
                     frameState.brdfLutGenerator.update(frameState);
                     updateVersion(this.gltf);
+                    if (defined(this.gltf.asset) && defined(this.gltf.asset.extras) &&
+                        this.gltf.asset.extras.gltf_pipeline_upgrade_10to20) {
+                            this._forwardAxis = Axis.X;
+                    }
                     ModelUtility.checkSupportedExtensions(this.extensionsRequired);
                     addPipelineExtras(this.gltf);
                     addDefaults(this.gltf);
@@ -4358,6 +4386,10 @@ define([
                 } else if (this._upAxis === Axis.X) {
                     Matrix4.multiplyTransformation(computedModelMatrix, Axis.X_UP_TO_Z_UP, computedModelMatrix);
                 }
+                if (this._forwardAxis === Axis.Z) {
+                    // glTF 2.0 has a Z-forward convention that must be adapted here to X-forward.
+                    Matrix4.multiplyTransformation(computedModelMatrix, Axis.Z_UP_TO_X_UP, computedModelMatrix);
+                }
             }
 
             // Update modelMatrix throughout the graph as needed

Source/ThirdParty/GltfPipeline/updateVersion.js

@@ -883,8 +883,12 @@ define([
         if (!defined(gltf.asset)) {
             gltf.asset = {};
         }
+        if (!defined(gltf.asset.extras)) {
+            gltf.asset.extras = {};
+        }
         var asset = gltf.asset;
         asset.version = '2.0';
+        asset.extras.gltf_pipeline_upgrade_10to20 = true;
         // material.instanceTechnique properties should be directly on the material. instanceTechnique is a gltf 0.8 property but is seen in some 1.0 models.
         updateInstanceTechniques(gltf);
         // animation.samplers now refers directly to accessors and animation.parameters should be removed

Specs/Data/Models/DracoCompression/CesiumMan/CesiumMan.gltf

@@ -18,13 +18,13 @@
         1
       ],
       "matrix": [
-        1,
         0,
         0,
+        1,
         0,
+        1,
         0,
         0,
-        -1,
         0,
         0,
         1,

Specs/Data/Models/DracoCompression/CesiumMilkTruck/CesiumMilkTruck.gltf

@@ -17,6 +17,24 @@
       "children": [
         3,
         1
+      ],
+      "matrix": [
+          0,
+          0,
+          1,
+          0,
+          0,
+          1,
+          0,
+          0,
+          -1,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          1
       ]
     },
     {

Specs/Scene/ModelSpec.js

@@ -396,7 +396,7 @@ defineSuite([
         model.show = false;
     });
 
-    it('Renders x-up model', function() {
+    it('renders x-up model', function() {
         return Resource.fetchJson(boxEcefUrl).then(function(gltf) {
             // Model data is z-up. Edit the transform to be z-up to x-up.
             gltf.nodes.node_transform.matrix = Matrix4.pack(Axis.Z_UP_TO_X_UP, new Array(16));
@@ -412,7 +412,7 @@ defineSuite([
         });
     });
 
-    it('Renders y-up model', function() {
+    it('renders y-up model', function() {
         return Resource.fetchJson(boxEcefUrl).then(function(gltf) {
             // Model data is z-up. Edit the transform to be z-up to y-up.
             gltf.nodes.node_transform.matrix = Matrix4.pack(Axis.Z_UP_TO_Y_UP, new Array(16));
@@ -428,7 +428,7 @@ defineSuite([
         });
     });
 
-    it('Renders z-up model', function() {
+    it('renders z-up model', function() {
         return Resource.fetchJson(boxEcefUrl).then(function(gltf) {
             // Model data is z-up. Edit the transform to be the identity.
             gltf.nodes.node_transform.matrix = Matrix4.pack(Matrix4.IDENTITY, new Array(16));
@@ -444,6 +444,50 @@ defineSuite([
         });
     });
 
+    it('renders x-forward model', function() {
+        return Resource.fetchJson(boxEcefUrl).then(function(gltf) {
+            return loadModelJson(gltf, {
+                forwardAxis : Axis.X
+            }).then(function(m) {
+                verifyRender(m);
+                expect(m.forwardAxis).toBe(Axis.X);
+                primitives.remove(m);
+            });
+        });
+    });
+
+    it('renders z-forward model', function() {
+        return Resource.fetchJson(boxPbrUrl).then(function(gltf) {
+            return loadModelJson(gltf, {
+                forwardAxis : Axis.Z
+            }).then(function(m) {
+                verifyRender(m);
+                expect(m.forwardAxis).toBe(Axis.Z);
+                primitives.remove(m);
+            });
+        });
+    });
+
+    it('detects glTF 1.0 models as x-forward', function() {
+        return Resource.fetchJson(boxEcefUrl).then(function(gltf) {
+            return loadModelJson(gltf).then(function(m) {
+                verifyRender(m);
+                expect(m.forwardAxis).toBe(Axis.X);
+                primitives.remove(m);
+            });
+        });
+    });
+
+    it('detects glTF 2.0 models as z-forward', function() {
+        return Resource.fetchJson(boxPbrUrl).then(function(gltf) {
+            return loadModelJson(gltf).then(function(m) {
+                verifyRender(m);
+                expect(m.forwardAxis).toBe(Axis.Z);
+                primitives.remove(m);
+            });
+        });
+    });
+
     it('resolves readyPromise', function() {
         return texturedBoxModel.readyPromise.then(function(model) {
             verifyRender(model);
@@ -2229,6 +2273,7 @@ defineSuite([
 
     function checkVertexColors(model) {
         model.zoomTo();
+        scene.camera.rotateRight(CesiumMath.PI_OVER_TWO);
         scene.camera.moveUp(0.1);
         // Red
         scene.camera.moveLeft(0.5);
@@ -2453,7 +2498,8 @@ defineSuite([
 
     it('loads a glTF with KHR_draco_mesh_compression extension with integer attributes', function() {
         return loadModel(dracoCompressedModelWithAnimationUrl, {
-            dequantizeInShader : false
+            dequantizeInShader : false,
+            forwardAxis : Axis.X
         }).then(function(m) {
             verifyRender(m);
             primitives.remove(m);
@@ -2501,7 +2547,8 @@ defineSuite([
 
     it('loads a draco compressed glTF and dequantizes in the shader, skipping generic attributes', function() {
         return loadModel(dracoCompressedModelWithAnimationUrl, {
-            dequantizeInShader : true
+            dequantizeInShader : true,
+            forwardAxis : Axis.X
         }).then(function(m) {
             verifyRender(m);