/// <summary>
            /// Exports all animation
            /// </summary>
            private void ExportAnimationClip(AnimationClip unityAnimClip, GameObject unityRoot, FbxScene fbxScene)
            {
                if (unityAnimClip == null)
                {
                    return;
                }

                // setup anim stack
                FbxAnimStack fbxAnimStack = FbxAnimStack.Create(fbxScene, unityAnimClip.name);

                fbxAnimStack.Description.Set("Animation Take: " + unityAnimClip.name);

                // add one mandatory animation layer
                FbxAnimLayer fbxAnimLayer = FbxAnimLayer.Create(fbxScene, "Animation Base Layer");

                fbxAnimStack.AddMember(fbxAnimLayer);

                // Set up the FPS so our frame-relative math later works out
                // Custom frame rate isn't really supported in FBX SDK (there's
                // a bug), so try hard to find the nearest time mode.
                FbxTime.EMode timeMode  = FbxTime.EMode.eCustom;
                double        precision = 1e-6;

                while (timeMode == FbxTime.EMode.eCustom && precision < 1000)
                {
                    timeMode   = FbxTime.ConvertFrameRateToTimeMode(unityAnimClip.frameRate, precision);
                    precision *= 10;
                }
                if (timeMode == FbxTime.EMode.eCustom)
                {
                    timeMode = FbxTime.EMode.eFrames30;
                }
                FbxTime.SetGlobalTimeMode(timeMode);

                // set time correctly
                var fbxStartTime = FbxTime.FromSecondDouble(0);
                var fbxStopTime  = FbxTime.FromSecondDouble(unityAnimClip.length);

                fbxAnimStack.SetLocalTimeSpan(new FbxTimeSpan(fbxStartTime, fbxStopTime));

                foreach (EditorCurveBinding unityCurveBinding in AnimationUtility.GetCurveBindings(unityAnimClip))
                {
                    Object unityObj = AnimationUtility.GetAnimatedObject(unityRoot, unityCurveBinding);
                    if (!unityObj)
                    {
                        continue;
                    }

                    AnimationCurve unityAnimCurve = AnimationUtility.GetEditorCurve(unityAnimClip, unityCurveBinding);
                    if (unityAnimCurve == null)
                    {
                        continue;
                    }

                    ExportAnimCurve(unityObj, unityAnimCurve, unityCurveBinding.propertyName, fbxAnimLayer);
                }
            }
            /// <summary>
            /// Export an AnimationClip as a single take
            /// </summary>
            protected void ExportAnimationClip(AnimationClip unityAnimClip, GameObject unityRoot, FbxScene fbxScene)
            {
                if (Verbose)
                {
                    Debug.Log(string.Format("exporting clip {1} for {0}", unityRoot.name, unityAnimClip.name));
                }

                // setup anim stack
                FbxAnimStack fbxAnimStack = FbxAnimStack.Create(fbxScene, unityAnimClip.name);

                fbxAnimStack.Description.Set("Animation Take: " + unityAnimClip.name);

                // add one mandatory animation layer
                FbxAnimLayer fbxAnimLayer = FbxAnimLayer.Create(fbxScene, "Animation Base Layer");

                fbxAnimStack.AddMember(fbxAnimLayer);

                // Set up the FPS so our frame-relative math later works out
                // Custom frame rate isn't really supported in FBX SDK (there's
                // a bug), so try hard to find the nearest time mode.
                FbxTime.EMode timeMode  = FbxTime.EMode.eCustom;
                double        precision = 1e-6;

                while (timeMode == FbxTime.EMode.eCustom && precision < 1000)
                {
                    timeMode   = FbxTime.ConvertFrameRateToTimeMode(unityAnimClip.frameRate, precision);
                    precision *= 10;
                }
                if (timeMode == FbxTime.EMode.eCustom)
                {
                    timeMode = FbxTime.EMode.eFrames30;
                }
                FbxTime.SetGlobalTimeMode(timeMode);

                // set time correctly
                var fbxStartTime = FbxTime.FromSecondDouble(0);
                var fbxStopTime  = FbxTime.FromSecondDouble(unityAnimClip.length);

                fbxAnimStack.SetLocalTimeSpan(new FbxTimeSpan(fbxStartTime, fbxStopTime));

                /* The major difficulty: Unity uses quaternions for rotation
                 * (which is how it should be) but FBX uses euler angles. So we
                 * need to gather up the list of transform curves per object. */
                var quaternions = new Dictionary <UnityEngine.GameObject, QuaternionCurve> ();

                foreach (EditorCurveBinding unityCurveBinding in AnimationUtility.GetCurveBindings(unityAnimClip))
                {
                    Object unityObj = AnimationUtility.GetAnimatedObject(unityRoot, unityCurveBinding);
                    if (!unityObj)
                    {
                        continue;
                    }

                    AnimationCurve unityAnimCurve = AnimationUtility.GetEditorCurve(unityAnimClip, unityCurveBinding);
                    if (unityAnimCurve == null)
                    {
                        continue;
                    }

                    int index = QuaternionCurve.GetQuaternionIndex(unityCurveBinding.propertyName);
                    if (index == -1)
                    {
                        if (Verbose)
                        {
                            Debug.Log(string.Format("export binding {1} for {0}", unityCurveBinding.propertyName, unityObj.ToString()));
                        }

                        /* Some normal property (e.g. translation), export right away */
                        ExportAnimCurve(unityObj, unityAnimCurve, unityCurveBinding.propertyName,
                                        fbxScene, fbxAnimLayer);
                    }
                    else
                    {
                        /* Rotation property; save it to convert quaternion -> euler later. */

                        var unityGo = GetGameObject(unityObj);
                        if (!unityGo)
                        {
                            continue;
                        }

                        QuaternionCurve quat;
                        if (!quaternions.TryGetValue(unityGo, out quat))
                        {
                            quat = new QuaternionCurve();
                            quaternions.Add(unityGo, quat);
                        }
                        quat.SetCurve(index, unityAnimCurve);
                    }
                }

                /* now export all the quaternion curves */
                foreach (var kvp in quaternions)
                {
                    var unityGo = kvp.Key;
                    var quat    = kvp.Value;

                    FbxNode fbxNode;
                    if (!MapUnityObjectToFbxNode.TryGetValue(unityGo, out fbxNode))
                    {
                        Debug.LogError(string.Format("no fbxnode found for '0'", unityGo.name));
                        continue;
                    }
                    quat.Animate(unityGo.transform, fbxNode, fbxAnimLayer, Verbose);
                }
            }