diff --git a/.github/workflows/ccpp.yml b/.github/workflows/ccpp.yml
index 61e804b2e..15f7643ce 100644
--- a/.github/workflows/ccpp.yml
+++ b/.github/workflows/ccpp.yml
@@ -7,8 +7,7 @@ on:
     branches: [ master ]
 
 jobs:
-  build-ubuntu:
-
+  linux:
     runs-on: ubuntu-latest
     
     steps:
@@ -19,4 +18,29 @@ jobs:
       run: cmake --build .
     - name: test
       run: cd bin && ./unit
-      
+  
+  mac:
+    runs-on: macos-latest
+    
+    steps:
+    - uses: actions/checkout@v1
+    - name: configure
+      run: cmake CMakeLists.txt
+    - name: build
+      run: cmake --build .
+    - name: test
+      run: cd bin && ./unit
+
+  windows:
+    runs-on: windows-latest
+    
+    steps:
+    - uses: actions/checkout@v1
+    - name: configure
+      run: cmake CMakeLists.txt
+    - name: build
+      run: cmake --build . --config Release
+    - name: test
+      run: | 
+        cd bin\Release
+        .\unit
diff --git a/code/Common/Assimp.cpp b/code/Common/Assimp.cpp
index 66588f0bc..7dae2633c 100644
--- a/code/Common/Assimp.cpp
+++ b/code/Common/Assimp.cpp
@@ -693,3 +693,598 @@ ASSIMP_API C_STRUCT const aiImporterDesc* aiGetImporterDesc( const char *extensi
 }
 
 // ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiVector2AreEqual(
+    const C_STRUCT aiVector2D* a,
+    const C_STRUCT aiVector2D* b) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return *a == *b;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiVector2AreEqualEpsilon(
+    const C_STRUCT aiVector2D* a,
+    const C_STRUCT aiVector2D* b,
+    const float epsilon) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return a->Equal(*b, epsilon);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector2Add(
+    C_STRUCT aiVector2D* dst,
+    const C_STRUCT aiVector2D* src) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != src);
+    *dst = *dst + *src;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector2Subtract(
+    C_STRUCT aiVector2D* dst,
+    const C_STRUCT aiVector2D* src) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != src);
+    *dst = *dst - *src;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector2Scale(
+    C_STRUCT aiVector2D* dst,
+    const float s) {
+    ai_assert(NULL != dst);
+    *dst *= s;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector2SymMul(
+    C_STRUCT aiVector2D* dst,
+    const C_STRUCT aiVector2D* other) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != other);
+    *dst = dst->SymMul(*other);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector2DivideByScalar(
+    C_STRUCT aiVector2D* dst,
+    const float s) {
+    ai_assert(NULL != dst);
+    *dst /= s;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector2DivideByVector(
+    C_STRUCT aiVector2D* dst,
+    C_STRUCT aiVector2D* v) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != v);
+    *dst = *dst / *v;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API float aiVector2Length(
+    const C_STRUCT aiVector2D* v) {
+    ai_assert(NULL != v);
+    return v->Length();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API float aiVector2SquareLength(
+    const C_STRUCT aiVector2D* v) {
+    ai_assert(NULL != v);
+    return v->SquareLength();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector2Negate(
+    C_STRUCT aiVector2D* dst) {
+    ai_assert(NULL != dst);
+    *dst = -(*dst);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API float aiVector2DotProduct(
+    const C_STRUCT aiVector2D* a,
+    const C_STRUCT aiVector2D* b) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return (*a) * (*b);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector2Normalize(
+    C_STRUCT aiVector2D* v) {
+    ai_assert(NULL != v);
+    v->Normalize();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiVector3AreEqual(
+    const C_STRUCT aiVector3D* a,
+    const C_STRUCT aiVector3D* b) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return *a == *b;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiVector3AreEqualEpsilon(
+    const C_STRUCT aiVector3D* a,
+    const C_STRUCT aiVector3D* b,
+    const float epsilon) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return a->Equal(*b, epsilon);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiVector3LessThan(
+    const C_STRUCT aiVector3D* a,
+    const C_STRUCT aiVector3D* b) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return *a < *b;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector3Add(
+    C_STRUCT aiVector3D* dst,
+    const C_STRUCT aiVector3D* src) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != src);
+    *dst = *dst + *src;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector3Subtract(
+    C_STRUCT aiVector3D* dst,
+    const C_STRUCT aiVector3D* src) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != src);
+    *dst = *dst - *src;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector3Scale(
+    C_STRUCT aiVector3D* dst,
+    const float s) {
+    ai_assert(NULL != dst);
+    *dst *= s;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector3SymMul(
+    C_STRUCT aiVector3D* dst,
+    const C_STRUCT aiVector3D* other) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != other);
+    *dst = dst->SymMul(*other);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector3DivideByScalar(
+    C_STRUCT aiVector3D* dst, const float s) {
+    ai_assert(NULL != dst);
+    *dst /= s;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector3DivideByVector(
+    C_STRUCT aiVector3D* dst,
+    C_STRUCT aiVector3D* v) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != v);
+    *dst = *dst / *v;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API float aiVector3Length(
+    const C_STRUCT aiVector3D* v) {
+    ai_assert(NULL != v);
+    return v->Length();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API float aiVector3SquareLength(
+    const C_STRUCT aiVector3D* v) {
+    ai_assert(NULL != v);
+    return v->SquareLength();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector3Negate(
+    C_STRUCT aiVector3D* dst) {
+    ai_assert(NULL != dst);
+    *dst = -(*dst);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API float aiVector3DotProduct(
+    const C_STRUCT aiVector3D* a,
+    const C_STRUCT aiVector3D* b) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return (*a) * (*b);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector3CrossProduct(
+    C_STRUCT aiVector3D* dst,
+    const C_STRUCT aiVector3D* a,
+    const C_STRUCT aiVector3D* b) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    *dst = *a ^ *b;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector3Normalize(
+    C_STRUCT aiVector3D* v) {
+    ai_assert(NULL != v);
+    v->Normalize();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector3NormalizeSafe(
+    C_STRUCT aiVector3D* v) {
+    ai_assert(NULL != v);
+    v->NormalizeSafe();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiVector3RotateByQuaternion(
+    C_STRUCT aiVector3D* v,
+    const C_STRUCT aiQuaternion* q) {
+    ai_assert(NULL != v);
+    ai_assert(NULL != q);
+    *v = q->Rotate(*v);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix3FromMatrix4(
+    C_STRUCT aiMatrix3x3* dst,
+    const C_STRUCT aiMatrix4x4* mat) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != mat);
+    *dst = aiMatrix3x3(*mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix3FromQuaternion(
+    C_STRUCT aiMatrix3x3* mat,
+    const C_STRUCT aiQuaternion* q) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != q);
+    *mat = q->GetMatrix();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiMatrix3AreEqual(
+    const C_STRUCT aiMatrix3x3* a,
+    const C_STRUCT aiMatrix3x3* b) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return *a == *b;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiMatrix3AreEqualEpsilon(
+    const C_STRUCT aiMatrix3x3* a,
+    const C_STRUCT aiMatrix3x3* b,
+    const float epsilon) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return a->Equal(*b, epsilon);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix3Inverse(C_STRUCT aiMatrix3x3* mat) {
+    ai_assert(NULL != mat);
+    mat->Inverse();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API float aiMatrix3Determinant(const C_STRUCT aiMatrix3x3* mat) {
+    ai_assert(NULL != mat);
+    return mat->Determinant();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix3RotationZ(
+    C_STRUCT aiMatrix3x3* mat,
+    const float angle) {
+    ai_assert(NULL != mat);
+    aiMatrix3x3::RotationZ(angle, *mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix3FromRotationAroundAxis(
+    C_STRUCT aiMatrix3x3* mat,
+    const C_STRUCT aiVector3D* axis,
+    const float angle) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != axis);
+    aiMatrix3x3::Rotation(angle, *axis, *mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix3Translation(
+    C_STRUCT aiMatrix3x3* mat,
+    const C_STRUCT aiVector2D* translation) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != translation);
+    aiMatrix3x3::Translation(*translation, *mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix3FromTo(
+    C_STRUCT aiMatrix3x3* mat,
+    const C_STRUCT aiVector3D* from,
+    const C_STRUCT aiVector3D* to) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != from);
+    ai_assert(NULL != to);
+    aiMatrix3x3::FromToMatrix(*from, *to, *mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4FromMatrix3(
+    C_STRUCT aiMatrix4x4* dst,
+    const C_STRUCT aiMatrix3x3* mat) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != mat);
+    *dst = aiMatrix4x4(*mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4FromScalingQuaternionPosition(
+    C_STRUCT aiMatrix4x4* mat,
+    const C_STRUCT aiVector3D* scaling,
+    const C_STRUCT aiQuaternion* rotation,
+    const C_STRUCT aiVector3D* position) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != scaling);
+    ai_assert(NULL != rotation);
+    ai_assert(NULL != position);
+    *mat = aiMatrix4x4(*scaling, *rotation, *position);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4Add(
+    C_STRUCT aiMatrix4x4* dst,
+    const C_STRUCT aiMatrix4x4* src) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != src);
+    *dst = *dst + *src;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiMatrix4AreEqual(
+    const C_STRUCT aiMatrix4x4* a,
+    const C_STRUCT aiMatrix4x4* b) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return *a == *b;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiMatrix4AreEqualEpsilon(
+    const C_STRUCT aiMatrix4x4* a,
+    const C_STRUCT aiMatrix4x4* b,
+    const float epsilon) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return a->Equal(*b, epsilon);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4Inverse(C_STRUCT aiMatrix4x4* mat) {
+    ai_assert(NULL != mat);
+    mat->Inverse();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API float aiMatrix4Determinant(const C_STRUCT aiMatrix4x4* mat) {
+    ai_assert(NULL != mat);
+    return mat->Determinant();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiMatrix4IsIdentity(const C_STRUCT aiMatrix4x4* mat) {
+    ai_assert(NULL != mat);
+    return mat->IsIdentity();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4DecomposeIntoScalingEulerAnglesPosition(
+    const C_STRUCT aiMatrix4x4* mat,
+    C_STRUCT aiVector3D* scaling,
+    C_STRUCT aiVector3D* rotation,
+    C_STRUCT aiVector3D* position) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != scaling);
+    ai_assert(NULL != rotation);
+    ai_assert(NULL != position);
+    mat->Decompose(*scaling, *rotation, *position);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4DecomposeIntoScalingAxisAnglePosition(
+    const C_STRUCT aiMatrix4x4* mat,
+    C_STRUCT aiVector3D* scaling,
+    C_STRUCT aiVector3D* axis,
+    float* angle,
+    C_STRUCT aiVector3D* position) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != scaling);
+    ai_assert(NULL != axis);
+    ai_assert(NULL != angle);
+    ai_assert(NULL != position);
+    mat->Decompose(*scaling, *axis, *angle, *position);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4DecomposeNoScaling(
+    const C_STRUCT aiMatrix4x4* mat,
+    C_STRUCT aiQuaternion* rotation,
+    C_STRUCT aiVector3D* position) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != rotation);
+    ai_assert(NULL != position);
+    mat->DecomposeNoScaling(*rotation, *position);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4FromEulerAngles(
+    C_STRUCT aiMatrix4x4* mat,
+    float x, float y, float z) {
+    ai_assert(NULL != mat);
+    mat->FromEulerAnglesXYZ(x, y, z);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4RotationX(
+    C_STRUCT aiMatrix4x4* mat,
+    const float angle) {
+    ai_assert(NULL != mat);
+    aiMatrix4x4::RotationX(angle, *mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4RotationY(
+    C_STRUCT aiMatrix4x4* mat,
+    const float angle) {
+    ai_assert(NULL != mat);
+    aiMatrix4x4::RotationY(angle, *mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4RotationZ(
+    C_STRUCT aiMatrix4x4* mat,
+    const float angle) {
+    ai_assert(NULL != mat);
+    aiMatrix4x4::RotationZ(angle, *mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4FromRotationAroundAxis(
+    C_STRUCT aiMatrix4x4* mat,
+    const C_STRUCT aiVector3D* axis,
+    const float angle) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != axis);
+    aiMatrix4x4::Rotation(angle, *axis, *mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4Translation(
+    C_STRUCT aiMatrix4x4* mat,
+    const C_STRUCT aiVector3D* translation) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != translation);
+    aiMatrix4x4::Translation(*translation, *mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4Scaling(
+    C_STRUCT aiMatrix4x4* mat,
+    const C_STRUCT aiVector3D* scaling) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != scaling);
+    aiMatrix4x4::Scaling(*scaling, *mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiMatrix4FromTo(
+    C_STRUCT aiMatrix4x4* mat,
+    const C_STRUCT aiVector3D* from,
+    const C_STRUCT aiVector3D* to) {
+    ai_assert(NULL != mat);
+    ai_assert(NULL != from);
+    ai_assert(NULL != to);
+    aiMatrix4x4::FromToMatrix(*from, *to, *mat);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiQuaternionFromEulerAngles(
+    C_STRUCT aiQuaternion* q,
+    float x, float y, float z) {
+    ai_assert(NULL != q);
+    *q = aiQuaternion(x, y, z);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiQuaternionFromAxisAngle(
+    C_STRUCT aiQuaternion* q,
+    const C_STRUCT aiVector3D* axis,
+    const float angle) {
+    ai_assert(NULL != q);
+    ai_assert(NULL != axis);
+    *q = aiQuaternion(*axis, angle);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiQuaternionFromNormalizedQuaternion(
+    C_STRUCT aiQuaternion* q,
+    const C_STRUCT aiVector3D* normalized) {
+    ai_assert(NULL != q);
+    ai_assert(NULL != normalized);
+    *q = aiQuaternion(*normalized);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiQuaternionAreEqual(
+    const C_STRUCT aiQuaternion* a,
+    const C_STRUCT aiQuaternion* b) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return *a == *b;
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API int aiQuaternionAreEqualEpsilon(
+    const C_STRUCT aiQuaternion* a,
+    const C_STRUCT aiQuaternion* b,
+    const float epsilon) {
+    ai_assert(NULL != a);
+    ai_assert(NULL != b);
+    return a->Equal(*b, epsilon);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiQuaternionNormalize(
+    C_STRUCT aiQuaternion* q) {
+    ai_assert(NULL != q);
+    q->Normalize();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiQuaternionConjugate(
+    C_STRUCT aiQuaternion* q) {
+    ai_assert(NULL != q);
+    q->Conjugate();
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiQuaternionMultiply(
+    C_STRUCT aiQuaternion* dst,
+    const C_STRUCT aiQuaternion* q) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != q);
+    *dst = (*dst) * (*q);
+}
+
+// ------------------------------------------------------------------------------------------------
+ASSIMP_API void aiQuaternionInterpolate(
+    C_STRUCT aiQuaternion* dst,
+    const C_STRUCT aiQuaternion* start,
+    const C_STRUCT aiQuaternion* end,
+    const float factor) {
+    ai_assert(NULL != dst);
+    ai_assert(NULL != start);
+    ai_assert(NULL != end);
+    aiQuaternion::Interpolate(*dst, *start, *end, factor);
+}
diff --git a/code/FBX/FBXConverter.cpp b/code/FBX/FBXConverter.cpp
index e7ef8fa61..880b5de76 100644
--- a/code/FBX/FBXConverter.cpp
+++ b/code/FBX/FBXConverter.cpp
@@ -655,7 +655,8 @@ bool FBXConverter::NeedsComplexTransformationChain(const Model &model) {
     for (size_t i = 0; i < TransformationComp_MAXIMUM; ++i) {
         const TransformationComp comp = static_cast<TransformationComp>(i);
 
-        if (comp == TransformationComp_Rotation || comp == TransformationComp_Scaling || comp == TransformationComp_Translation) {
+        if (comp == TransformationComp_Rotation || comp == TransformationComp_Scaling || comp == TransformationComp_Translation ||
+            comp == TransformationComp_PreRotation || comp == TransformationComp_PostRotation) {
             continue;
         }
 
@@ -2739,15 +2740,12 @@ void FBXConverter::GenerateNodeAnimations(std::vector<aiNodeAnim *> &node_anims,
     // be invoked _later_ (animations come first). If this node has only rotation,
     // scaling and translation _and_ there are no animated other components either,
     // we can use a single node and also a single node animation channel.
-    if (!has_complex && !NeedsComplexTransformationChain(target)) {
-
-        aiNodeAnim *const nd = GenerateSimpleNodeAnim(fixed_name, target, chain,
+    if( !has_complex && !NeedsComplexTransformationChain(target)) {
+        aiNodeAnim* const nd = GenerateSimpleNodeAnim(fixed_name, target, chain,
                 node_property_map.end(),
-                layer_map,
                 start, stop,
                 max_time,
-                min_time,
-                true // input is TRS order, assimp is SRT
+                min_time
         );
 
         ai_assert(nd);
@@ -3021,133 +3019,121 @@ aiNodeAnim *FBXConverter::GenerateTranslationNodeAnim(const std::string &name,
     return na.release();
 }
 
-aiNodeAnim *FBXConverter::GenerateSimpleNodeAnim(const std::string &name,
-        const Model &target,
+aiNodeAnim* FBXConverter::GenerateSimpleNodeAnim(const std::string& name,
+        const Model& target,
         NodeMap::const_iterator chain[TransformationComp_MAXIMUM],
-        NodeMap::const_iterator iter_end,
-        const LayerMap &layer_map,
+        NodeMap::const_iterator iterEnd,
         int64_t start, int64_t stop,
-        double &max_time,
-        double &min_time,
-        bool reverse_order)
-
+        double& maxTime,
+        double& minTime)
 {
     std::unique_ptr<aiNodeAnim> na(new aiNodeAnim());
     na->mNodeName.Set(name);
 
     const PropertyTable &props = target.Props();
 
-    // need to convert from TRS order to SRT?
-    if (reverse_order) {
+    // collect unique times and keyframe lists
+    KeyFrameListList keyframeLists[TransformationComp_MAXIMUM];
+    KeyTimeList keytimes;
 
-        aiVector3D def_scale = PropertyGet(props, "Lcl Scaling", aiVector3D(1.f, 1.f, 1.f));
-        aiVector3D def_translate = PropertyGet(props, "Lcl Translation", aiVector3D(0.f, 0.f, 0.f));
-        aiVector3D def_rot = PropertyGet(props, "Lcl Rotation", aiVector3D(0.f, 0.f, 0.f));
+    for (size_t i = 0; i < TransformationComp_MAXIMUM; ++i) {
+        if (chain[i] == iterEnd)
+            continue;
 
-        KeyFrameListList scaling;
-        KeyFrameListList translation;
-        KeyFrameListList rotation;
+        keyframeLists[i] = GetKeyframeList((*chain[i]).second, start, stop);
 
-        if (chain[TransformationComp_Scaling] != iter_end) {
-            scaling = GetKeyframeList((*chain[TransformationComp_Scaling]).second, start, stop);
+        for (KeyFrameListList::const_iterator it = keyframeLists[i].begin(); it != keyframeLists[i].end(); ++it) {
+            const KeyTimeList& times = *std::get<0>(*it);
+            keytimes.insert(keytimes.end(), times.begin(), times.end());
         }
 
-        if (chain[TransformationComp_Translation] != iter_end) {
-            translation = GetKeyframeList((*chain[TransformationComp_Translation]).second, start, stop);
-        }
+        // remove duplicates
+        std::sort(keytimes.begin(), keytimes.end());
 
-        if (chain[TransformationComp_Rotation] != iter_end) {
-            rotation = GetKeyframeList((*chain[TransformationComp_Rotation]).second, start, stop);
-        }
+        auto last = std::unique(keytimes.begin(), keytimes.end());
+        keytimes.erase(last, keytimes.end());
+    }
 
-        KeyFrameListList joined;
-        joined.insert(joined.end(), scaling.begin(), scaling.end());
-        joined.insert(joined.end(), translation.begin(), translation.end());
-        joined.insert(joined.end(), rotation.begin(), rotation.end());
+    const Model::RotOrder rotOrder = target.RotationOrder();
+    const size_t keyCount = keytimes.size();
 
-        const KeyTimeList &times = GetKeyTimeList(joined);
+    aiVector3D defTranslate = PropertyGet(props, "Lcl Translation", aiVector3D(0.f, 0.f, 0.f));
+    aiVector3D defRotation = PropertyGet(props, "Lcl Rotation", aiVector3D(0.f, 0.f, 0.f));
+    aiVector3D defScale = PropertyGet(props, "Lcl Scaling", aiVector3D(1.f, 1.f, 1.f));
+    aiQuaternion defQuat = EulerToQuaternion(defRotation, rotOrder);
 
-        aiQuatKey *out_quat = new aiQuatKey[times.size()];
-        aiVectorKey *out_scale = new aiVectorKey[times.size()];
-        aiVectorKey *out_translation = new aiVectorKey[times.size()];
+    aiVectorKey* outTranslations = new aiVectorKey[keyCount];
+    aiQuatKey* outRotations = new aiQuatKey[keyCount];
+    aiVectorKey* outScales = new aiVectorKey[keyCount];
 
-        if (times.size()) {
-            ConvertTransformOrder_TRStoSRT(out_quat, out_scale, out_translation,
-                    scaling,
-                    translation,
-                    rotation,
-                    times,
-                    max_time,
-                    min_time,
-                    target.RotationOrder(),
-                    def_scale,
-                    def_translate,
-                    def_rot);
-        }
-
-        // XXX remove duplicates / redundant keys which this operation did
-        // likely produce if not all three channels were equally dense.
-
-        na->mNumScalingKeys = static_cast<unsigned int>(times.size());
-        na->mNumRotationKeys = na->mNumScalingKeys;
-        na->mNumPositionKeys = na->mNumScalingKeys;
-
-        na->mScalingKeys = out_scale;
-        na->mRotationKeys = out_quat;
-        na->mPositionKeys = out_translation;
+    if (keyframeLists[TransformationComp_Translation].size() > 0) {
+        InterpolateKeys(outTranslations, keytimes, keyframeLists[TransformationComp_Translation], defTranslate, maxTime, minTime);
     } else {
-
-        // if a particular transformation is not given, grab it from
-        // the corresponding node to meet the semantics of aiNodeAnim,
-        // which requires all of rotation, scaling and translation
-        // to be set.
-        if (chain[TransformationComp_Scaling] != iter_end) {
-            ConvertScaleKeys(na.get(), (*chain[TransformationComp_Scaling]).second,
-                    layer_map,
-                    start, stop,
-                    max_time,
-                    min_time);
-        } else {
-            na->mScalingKeys = new aiVectorKey[1];
-            na->mNumScalingKeys = 1;
-
-            na->mScalingKeys[0].mTime = 0.;
-            na->mScalingKeys[0].mValue = PropertyGet(props, "Lcl Scaling",
-                    aiVector3D(1.f, 1.f, 1.f));
-        }
-
-        if (chain[TransformationComp_Rotation] != iter_end) {
-            ConvertRotationKeys(na.get(), (*chain[TransformationComp_Rotation]).second,
-                    layer_map,
-                    start, stop,
-                    max_time,
-                    min_time,
-                    target.RotationOrder());
-        } else {
-            na->mRotationKeys = new aiQuatKey[1];
-            na->mNumRotationKeys = 1;
-
-            na->mRotationKeys[0].mTime = 0.;
-            na->mRotationKeys[0].mValue = EulerToQuaternion(
-                    PropertyGet(props, "Lcl Rotation", aiVector3D(0.f, 0.f, 0.f)),
-                    target.RotationOrder());
-        }
-
-        if (chain[TransformationComp_Translation] != iter_end) {
-            ConvertTranslationKeys(na.get(), (*chain[TransformationComp_Translation]).second,
-                    layer_map,
-                    start, stop,
-                    max_time,
-                    min_time);
-        } else {
-            na->mPositionKeys = new aiVectorKey[1];
-            na->mNumPositionKeys = 1;
-
-            na->mPositionKeys[0].mTime = 0.;
-            na->mPositionKeys[0].mValue = PropertyGet(props, "Lcl Translation",
-                    aiVector3D(0.f, 0.f, 0.f));
+        for (size_t i = 0; i < keyCount; ++i) {
+            outTranslations[i].mTime = CONVERT_FBX_TIME(keytimes[i]) * anim_fps;
+            outTranslations[i].mValue = defTranslate;
         }
     }
+
+    if (keyframeLists[TransformationComp_Rotation].size() > 0) {
+        InterpolateKeys(outRotations, keytimes, keyframeLists[TransformationComp_Rotation], defRotation, maxTime, minTime, rotOrder);
+    } else {
+        for (size_t i = 0; i < keyCount; ++i) {
+            outRotations[i].mTime = CONVERT_FBX_TIME(keytimes[i]) * anim_fps;
+            outRotations[i].mValue = defQuat;
+        }
+    }
+
+    if (keyframeLists[TransformationComp_Scaling].size() > 0) {
+        InterpolateKeys(outScales, keytimes, keyframeLists[TransformationComp_Scaling], defScale, maxTime, minTime);
+    } else {
+        for (size_t i = 0; i < keyCount; ++i) {
+            outScales[i].mTime = CONVERT_FBX_TIME(keytimes[i]) * anim_fps;
+            outScales[i].mValue = defScale;
+        }
+    }
+
+    bool ok = false;
+    const float zero_epsilon = 1e-6f;
+
+    const aiVector3D& preRotation = PropertyGet<aiVector3D>(props, "PreRotation", ok);
+    if (ok && preRotation.SquareLength() > zero_epsilon) {
+        const aiQuaternion preQuat = EulerToQuaternion(preRotation, Model::RotOrder_EulerXYZ);
+        for (size_t i = 0; i < keyCount; ++i) {
+            outRotations[i].mValue = preQuat * outRotations[i].mValue;
+        }
+    }
+
+    const aiVector3D& postRotation = PropertyGet<aiVector3D>(props, "PostRotation", ok);
+    if (ok && postRotation.SquareLength() > zero_epsilon) {
+        const aiQuaternion postQuat = EulerToQuaternion(postRotation, Model::RotOrder_EulerXYZ);
+        for (size_t i = 0; i < keyCount; ++i) {
+            outRotations[i].mValue = outRotations[i].mValue * postQuat;
+        }
+    }
+
+    // convert TRS to SRT
+    for (size_t i = 0; i < keyCount; ++i) {
+        aiQuaternion& r = outRotations[i].mValue;
+        aiVector3D& s = outScales[i].mValue;
+        aiVector3D& t = outTranslations[i].mValue;
+
+        aiMatrix4x4 mat, temp;
+        aiMatrix4x4::Translation(t, mat);
+        mat *= aiMatrix4x4(r.GetMatrix());
+        mat *= aiMatrix4x4::Scaling(s, temp);
+
+        mat.Decompose(s, r, t);
+    }
+
+    na->mNumScalingKeys = static_cast<unsigned int>(keyCount);
+    na->mNumRotationKeys = na->mNumScalingKeys;
+    na->mNumPositionKeys = na->mNumScalingKeys;
+
+    na->mScalingKeys = outScales;
+    na->mRotationKeys = outRotations;
+    na->mPositionKeys = outTranslations;
+
     return na.release();
 }
 
@@ -3328,10 +3314,7 @@ void FBXConverter::InterpolateKeys(aiQuatKey *valOut, const KeyTimeList &keys, c
         // take shortest path by checking the inner product
         // http://www.3dkingdoms.com/weekly/weekly.php?a=36
         if (quat.x * lastq.x + quat.y * lastq.y + quat.z * lastq.z + quat.w * lastq.w < 0) {
-            quat.x = -quat.x;
-            quat.y = -quat.y;
-            quat.z = -quat.z;
-            quat.w = -quat.w;
+            quat.Conjugate();
         }
         lastq = quat;
 
@@ -3339,60 +3322,6 @@ void FBXConverter::InterpolateKeys(aiQuatKey *valOut, const KeyTimeList &keys, c
     }
 }
 
-void FBXConverter::ConvertTransformOrder_TRStoSRT(aiQuatKey *out_quat, aiVectorKey *out_scale,
-        aiVectorKey *out_translation,
-        const KeyFrameListList &scaling,
-        const KeyFrameListList &translation,
-        const KeyFrameListList &rotation,
-        const KeyTimeList &times,
-        double &maxTime,
-        double &minTime,
-        Model::RotOrder order,
-        const aiVector3D &def_scale,
-        const aiVector3D &def_translate,
-        const aiVector3D &def_rotation) {
-    if (rotation.size()) {
-        InterpolateKeys(out_quat, times, rotation, def_rotation, maxTime, minTime, order);
-    } else {
-        for (size_t i = 0; i < times.size(); ++i) {
-            out_quat[i].mTime = CONVERT_FBX_TIME(times[i]) * anim_fps;
-            out_quat[i].mValue = EulerToQuaternion(def_rotation, order);
-        }
-    }
-
-    if (scaling.size()) {
-        InterpolateKeys(out_scale, times, scaling, def_scale, maxTime, minTime);
-    } else {
-        for (size_t i = 0; i < times.size(); ++i) {
-            out_scale[i].mTime = CONVERT_FBX_TIME(times[i]) * anim_fps;
-            out_scale[i].mValue = def_scale;
-        }
-    }
-
-    if (translation.size()) {
-        InterpolateKeys(out_translation, times, translation, def_translate, maxTime, minTime);
-    } else {
-        for (size_t i = 0; i < times.size(); ++i) {
-            out_translation[i].mTime = CONVERT_FBX_TIME(times[i]) * anim_fps;
-            out_translation[i].mValue = def_translate;
-        }
-    }
-
-    const size_t count = times.size();
-    for (size_t i = 0; i < count; ++i) {
-        aiQuaternion &r = out_quat[i].mValue;
-        aiVector3D &s = out_scale[i].mValue;
-        aiVector3D &t = out_translation[i].mValue;
-
-        aiMatrix4x4 mat, temp;
-        aiMatrix4x4::Translation(t, mat);
-        mat *= aiMatrix4x4(r.GetMatrix());
-        mat *= aiMatrix4x4::Scaling(s, temp);
-
-        mat.Decompose(s, r, t);
-    }
-}
-
 aiQuaternion FBXConverter::EulerToQuaternion(const aiVector3D &rot, Model::RotOrder order) {
     aiMatrix4x4 m;
     GetRotationMatrix(order, rot, m);
diff --git a/code/FBX/FBXConverter.h b/code/FBX/FBXConverter.h
index c3830b894..d4f75820f 100644
--- a/code/FBX/FBXConverter.h
+++ b/code/FBX/FBXConverter.h
@@ -349,12 +349,10 @@ private:
     aiNodeAnim* GenerateSimpleNodeAnim(const std::string& name,
         const Model& target,
         NodeMap::const_iterator chain[TransformationComp_MAXIMUM],
-        NodeMap::const_iterator iter_end,
-        const LayerMap& layer_map,
+        NodeMap::const_iterator iterEnd,
         int64_t start, int64_t stop,
-        double& max_time,
-        double& min_time,
-        bool reverse_order = false);
+        double& maxTime,
+        double& minTime);
 
     // key (time), value, mapto (component index)
     typedef std::tuple<std::shared_ptr<KeyTimeList>, std::shared_ptr<KeyValueList>, unsigned int > KeyFrameList;
@@ -379,20 +377,6 @@ private:
         double& minTime,
         Model::RotOrder order);
 
-    // ------------------------------------------------------------------------------------------------
-    void ConvertTransformOrder_TRStoSRT(aiQuatKey* out_quat, aiVectorKey* out_scale,
-        aiVectorKey* out_translation,
-        const KeyFrameListList& scaling,
-        const KeyFrameListList& translation,
-        const KeyFrameListList& rotation,
-        const KeyTimeList& times,
-        double& maxTime,
-        double& minTime,
-        Model::RotOrder order,
-        const aiVector3D& def_scale,
-        const aiVector3D& def_translate,
-        const aiVector3D& def_rotation);
-
     // ------------------------------------------------------------------------------------------------
     // euler xyz -> quat
     aiQuaternion EulerToQuaternion(const aiVector3D& rot, Model::RotOrder order);
diff --git a/include/assimp/cimport.h b/include/assimp/cimport.h
index dab60584b..a6ab93051 100644
--- a/include/assimp/cimport.h
+++ b/include/assimp/cimport.h
@@ -562,6 +562,675 @@ ASSIMP_API size_t aiGetImportFormatCount(void);
  * @return A description of that specific import format. NULL if pIndex is out of range.
  */
 ASSIMP_API const C_STRUCT aiImporterDesc* aiGetImportFormatDescription( size_t pIndex);
+
+// --------------------------------------------------------------------------------
+/** Check if 2D vectors are equal.
+ *  @param a First vector to compare
+ *  @param b Second vector to compare
+ *  @return 1 if the vectors are equal
+ *  @return 0 if the vectors are not equal
+ */
+ASSIMP_API int aiVector2AreEqual(
+    const C_STRUCT aiVector2D* a,
+    const C_STRUCT aiVector2D* b);
+
+// --------------------------------------------------------------------------------
+/** Check if 2D vectors are equal using epsilon.
+ *  @param a First vector to compare
+ *  @param b Second vector to compare
+ *  @param epsilon Epsilon
+ *  @return 1 if the vectors are equal
+ *  @return 0 if the vectors are not equal
+ */
+ASSIMP_API int aiVector2AreEqualEpsilon(
+    const C_STRUCT aiVector2D* a,
+    const C_STRUCT aiVector2D* b,
+    const float epsilon);
+
+// --------------------------------------------------------------------------------
+/** Add 2D vectors.
+ *  @param dst First addend, receives result.
+ *  @param src Vector to be added to 'dst'.
+ */
+ASSIMP_API void aiVector2Add(
+    C_STRUCT aiVector2D* dst,
+    const C_STRUCT aiVector2D* src);
+
+// --------------------------------------------------------------------------------
+/** Subtract 2D vectors.
+ *  @param dst Minuend, receives result.
+ *  @param src Vector to be subtracted from 'dst'.
+ */
+ASSIMP_API void aiVector2Subtract(
+    C_STRUCT aiVector2D* dst,
+    const C_STRUCT aiVector2D* src);
+
+// --------------------------------------------------------------------------------
+/** Multiply a 2D vector by a scalar.
+ *  @param dst Vector to be scaled by \p s
+ *  @param s Scale factor
+ */
+ASSIMP_API void aiVector2Scale(
+    C_STRUCT aiVector2D* dst,
+    const float s);
+
+// --------------------------------------------------------------------------------
+/** Multiply each component of a 2D vector with
+ *  the components of another vector.
+ *  @param dst First vector, receives result
+ *  @param other Second vector
+ */
+ASSIMP_API void aiVector2SymMul(
+    C_STRUCT aiVector2D* dst,
+    const C_STRUCT aiVector2D* other);
+
+// --------------------------------------------------------------------------------
+/** Divide a 2D vector by a scalar.
+ *  @param dst Vector to be divided by \p s
+ *  @param s Scalar divisor
+ */
+ASSIMP_API void aiVector2DivideByScalar(
+    C_STRUCT aiVector2D* dst,
+    const float s);
+
+// --------------------------------------------------------------------------------
+/** Divide each component of a 2D vector by
+ *  the components of another vector.
+ *  @param dst Vector as the dividend
+ *  @param v Vector as the divisor
+ */
+ASSIMP_API void aiVector2DivideByVector(
+    C_STRUCT aiVector2D* dst,
+    C_STRUCT aiVector2D* v);
+
+// --------------------------------------------------------------------------------
+/** Get the length of a 2D vector.
+ *  @return v Vector to evaluate
+ */
+ASSIMP_API float aiVector2Length(
+    const C_STRUCT aiVector2D* v);
+
+// --------------------------------------------------------------------------------
+/** Get the squared length of a 2D vector.
+ *  @return v Vector to evaluate
+ */
+ASSIMP_API float aiVector2SquareLength(
+    const C_STRUCT aiVector2D* v);
+
+// --------------------------------------------------------------------------------
+/** Negate a 2D vector.
+ *  @param dst Vector to be negated
+ */
+ASSIMP_API void aiVector2Negate(
+    C_STRUCT aiVector2D* dst);
+
+// --------------------------------------------------------------------------------
+/** Get the dot product of 2D vectors.
+ *  @param a First vector
+ *  @param b Second vector
+ *  @return The dot product of vectors
+ */
+ASSIMP_API float aiVector2DotProduct(
+    const C_STRUCT aiVector2D* a,
+    const C_STRUCT aiVector2D* b);
+
+// --------------------------------------------------------------------------------
+/** Normalize a 2D vector.
+ *  @param v Vector to normalize
+ */
+ASSIMP_API void aiVector2Normalize(
+    C_STRUCT aiVector2D* v);
+
+// --------------------------------------------------------------------------------
+/** Check if 3D vectors are equal.
+ *  @param a First vector to compare
+ *  @param b Second vector to compare
+ *  @return 1 if the vectors are equal
+ *  @return 0 if the vectors are not equal
+ */
+ASSIMP_API int aiVector3AreEqual(
+    const C_STRUCT aiVector3D* a,
+    const C_STRUCT aiVector3D* b);
+
+// --------------------------------------------------------------------------------
+/** Check if 3D vectors are equal using epsilon.
+ *  @param a First vector to compare
+ *  @param b Second vector to compare
+ *  @param epsilon Epsilon
+ *  @return 1 if the vectors are equal
+ *  @return 0 if the vectors are not equal
+ */
+ASSIMP_API int aiVector3AreEqualEpsilon(
+    const C_STRUCT aiVector3D* a,
+    const C_STRUCT aiVector3D* b,
+    const float epsilon);
+
+// --------------------------------------------------------------------------------
+/** Check if vector \p a is less than vector \p b.
+ *  @param a First vector to compare
+ *  @param b Second vector to compare
+ *  @param epsilon Epsilon
+ *  @return 1 if \p a is less than \p b
+ *  @return 0 if \p a is equal or greater than \p b
+ */
+ASSIMP_API int aiVector3LessThan(
+    const C_STRUCT aiVector3D* a,
+    const C_STRUCT aiVector3D* b);
+
+// --------------------------------------------------------------------------------
+/** Add 3D vectors.
+ *  @param dst First addend, receives result.
+ *  @param src Vector to be added to 'dst'.
+ */
+ASSIMP_API void aiVector3Add(
+    C_STRUCT aiVector3D* dst,
+    const C_STRUCT aiVector3D* src);
+
+// --------------------------------------------------------------------------------
+/** Subtract 3D vectors.
+ *  @param dst Minuend, receives result.
+ *  @param src Vector to be subtracted from 'dst'.
+ */
+ASSIMP_API void aiVector3Subtract(
+    C_STRUCT aiVector3D* dst,
+    const C_STRUCT aiVector3D* src);
+
+// --------------------------------------------------------------------------------
+/** Multiply a 3D vector by a scalar.
+ *  @param dst Vector to be scaled by \p s
+ *  @param s Scale factor
+ */
+ASSIMP_API void aiVector3Scale(
+    C_STRUCT aiVector3D* dst,
+    const float s);
+
+// --------------------------------------------------------------------------------
+/** Multiply each component of a 3D vector with
+ *  the components of another vector.
+ *  @param dst First vector, receives result
+ *  @param other Second vector
+ */
+ASSIMP_API void aiVector3SymMul(
+    C_STRUCT aiVector3D* dst,
+    const C_STRUCT aiVector3D* other);
+
+// --------------------------------------------------------------------------------
+/** Divide a 3D vector by a scalar.
+ *  @param dst Vector to be divided by \p s
+ *  @param s Scalar divisor
+ */
+ASSIMP_API void aiVector3DivideByScalar(
+    C_STRUCT aiVector3D* dst,
+    const float s);
+
+// --------------------------------------------------------------------------------
+/** Divide each component of a 3D vector by
+ *  the components of another vector.
+ *  @param dst Vector as the dividend
+ *  @param v Vector as the divisor
+ */
+ASSIMP_API void aiVector3DivideByVector(
+    C_STRUCT aiVector3D* dst,
+    C_STRUCT aiVector3D* v);
+
+// --------------------------------------------------------------------------------
+/** Get the length of a 3D vector.
+ *  @return v Vector to evaluate
+ */
+ASSIMP_API float aiVector3Length(
+    const C_STRUCT aiVector3D* v);
+
+// --------------------------------------------------------------------------------
+/** Get the squared length of a 3D vector.
+ *  @return v Vector to evaluate
+ */
+ASSIMP_API float aiVector3SquareLength(
+    const C_STRUCT aiVector3D* v);
+
+// --------------------------------------------------------------------------------
+/** Negate a 3D vector.
+ *  @param dst Vector to be negated
+ */
+ASSIMP_API void aiVector3Negate(
+    C_STRUCT aiVector3D* dst);
+
+// --------------------------------------------------------------------------------
+/** Get the dot product of 3D vectors.
+ *  @param a First vector
+ *  @param b Second vector
+ *  @return The dot product of vectors
+ */
+ASSIMP_API float aiVector3DotProduct(
+    const C_STRUCT aiVector3D* a,
+    const C_STRUCT aiVector3D* b);
+
+// --------------------------------------------------------------------------------
+/** Get cross product of 3D vectors.
+ *  @param dst Vector to receive the result.
+ *  @param a First vector
+ *  @param b Second vector
+ *  @return The dot product of vectors
+ */
+ASSIMP_API void aiVector3CrossProduct(
+    C_STRUCT aiVector3D* dst,
+    const C_STRUCT aiVector3D* a,
+    const C_STRUCT aiVector3D* b);
+
+// --------------------------------------------------------------------------------
+/** Normalize a 3D vector.
+ *  @param v Vector to normalize
+ */
+ASSIMP_API void aiVector3Normalize(
+    C_STRUCT aiVector3D* v);
+
+// --------------------------------------------------------------------------------
+/** Check for division by zero and normalize a 3D vector.
+ *  @param v Vector to normalize
+ */
+ASSIMP_API void aiVector3NormalizeSafe(
+    C_STRUCT aiVector3D* v);
+
+// --------------------------------------------------------------------------------
+/** Rotate a 3D vector by a quaternion.
+ *  @param v The vector to rotate by \p q
+ *  @param q Quaternion to use to rotate \p v
+ */
+ASSIMP_API void aiVector3RotateByQuaternion(
+    C_STRUCT aiVector3D* v,
+    const C_STRUCT aiQuaternion* q);
+
+// --------------------------------------------------------------------------------
+/** Construct a 3x3 matrix from a 4x4 matrix.
+ *  @param dst Receives the output matrix
+ *  @param mat The 4x4 matrix to use
+ */
+ASSIMP_API void aiMatrix3FromMatrix4(
+    C_STRUCT aiMatrix3x3* dst,
+    const C_STRUCT aiMatrix4x4* mat);
+
+// --------------------------------------------------------------------------------
+/** Construct a 3x3 matrix from a quaternion.
+ *  @param mat Receives the output matrix
+ *  @param q The quaternion matrix to use
+ */
+ASSIMP_API void aiMatrix3FromQuaternion(
+    C_STRUCT aiMatrix3x3* mat,
+    const C_STRUCT aiQuaternion* q);
+
+// --------------------------------------------------------------------------------
+/** Check if 3x3 matrices are equal.
+ *  @param a First matrix to compare
+ *  @param b Second matrix to compare
+ *  @return 1 if the matrices are equal
+ *  @return 0 if the matrices are not equal
+ */
+ASSIMP_API int aiMatrix3AreEqual(
+    const C_STRUCT aiMatrix3x3* a,
+    const C_STRUCT aiMatrix3x3* b);
+
+// --------------------------------------------------------------------------------
+/** Check if 3x3 matrices are equal.
+ *  @param a First matrix to compare
+ *  @param b Second matrix to compare
+ *  @param epsilon Epsilon
+ *  @return 1 if the matrices are equal
+ *  @return 0 if the matrices are not equal
+ */
+ASSIMP_API int aiMatrix3AreEqualEpsilon(
+    const C_STRUCT aiMatrix3x3* a,
+    const C_STRUCT aiMatrix3x3* b,
+    const float epsilon);
+
+// --------------------------------------------------------------------------------
+/** Invert a 3x3 matrix.
+ *  @param mat Matrix to invert
+ */
+ASSIMP_API void aiMatrix3Inverse(
+    C_STRUCT aiMatrix3x3* mat);
+
+// --------------------------------------------------------------------------------
+/** Get the determinant of a 3x3 matrix.
+ *  @param mat Matrix to get the determinant from
+ */
+ASSIMP_API float aiMatrix3Determinant(
+    const C_STRUCT aiMatrix3x3* mat);
+
+// --------------------------------------------------------------------------------
+/** Get a 3x3 rotation matrix around the Z axis.
+ *  @param mat Receives the output matrix 
+ *  @param angle Rotation angle, in radians
+ */
+ASSIMP_API void aiMatrix3RotationZ(
+    C_STRUCT aiMatrix3x3* mat,
+    const float angle);
+
+// --------------------------------------------------------------------------------
+/** Returns a 3x3 rotation matrix for a rotation around an arbitrary axis.
+ *  @param mat Receives the output matrix 
+ *  @param axis Rotation axis, should be a normalized vector
+ *  @param angle Rotation angle, in radians
+ */
+ASSIMP_API void aiMatrix3FromRotationAroundAxis(
+    C_STRUCT aiMatrix3x3* mat,
+    const C_STRUCT aiVector3D* axis,
+    const float angle);
+
+// --------------------------------------------------------------------------------
+/** Get a 3x3 translation matrix.
+ *  @param mat Receives the output matrix 
+ *  @param translation The translation vector
+ */
+ASSIMP_API void aiMatrix3Translation(
+    C_STRUCT aiMatrix3x3* mat,
+    const C_STRUCT aiVector2D* translation);
+
+// --------------------------------------------------------------------------------
+/** Create a 3x3 matrix that rotates one vector to another vector.
+ *  @param mat Receives the output matrix 
+ *  @param from Vector to rotate from
+ *  @param to Vector to rotate to
+ */
+ASSIMP_API void aiMatrix3FromTo(
+    C_STRUCT aiMatrix3x3* mat,
+    const C_STRUCT aiVector3D* from,
+    const C_STRUCT aiVector3D* to);
+
+// --------------------------------------------------------------------------------
+/** Construct a 4x4 matrix from a 3x3 matrix.
+ *  @param dst Receives the output matrix
+ *  @param mat The 3x3 matrix to use
+ */
+ASSIMP_API void aiMatrix4FromMatrix3(
+    C_STRUCT aiMatrix4x4* dst,
+    const C_STRUCT aiMatrix3x3* mat);
+
+// --------------------------------------------------------------------------------
+/** Construct a 4x4 matrix from scaling, rotation and position.
+ *  @param mat Receives the output matrix.
+ *  @param scaling The scaling for the x,y,z axes
+ *  @param rotation The rotation as a hamilton quaternion
+ *  @param position The position for the x,y,z axes
+ */
+ASSIMP_API void aiMatrix4FromScalingQuaternionPosition(
+    C_STRUCT aiMatrix4x4* mat,
+    const C_STRUCT aiVector3D* scaling,
+    const C_STRUCT aiQuaternion* rotation,
+    const C_STRUCT aiVector3D* position);
+
+// --------------------------------------------------------------------------------
+/** Add 4x4 matrices.
+ *  @param dst First addend, receives result.
+ *  @param src Matrix to be added to 'dst'.
+ */
+ASSIMP_API void aiMatrix4Add(
+    C_STRUCT aiMatrix4x4* dst,
+    const C_STRUCT aiMatrix4x4* src);
+
+// --------------------------------------------------------------------------------
+/** Check if 4x4 matrices are equal.
+ *  @param a First matrix to compare
+ *  @param b Second matrix to compare
+ *  @return 1 if the matrices are equal
+ *  @return 0 if the matrices are not equal
+ */
+ASSIMP_API int aiMatrix4AreEqual(
+    const C_STRUCT aiMatrix4x4* a,
+    const C_STRUCT aiMatrix4x4* b);
+
+// --------------------------------------------------------------------------------
+/** Check if 4x4 matrices are equal.
+ *  @param a First matrix to compare
+ *  @param b Second matrix to compare
+ *  @param epsilon Epsilon
+ *  @return 1 if the matrices are equal
+ *  @return 0 if the matrices are not equal
+ */
+ASSIMP_API int aiMatrix4AreEqualEpsilon(
+    const C_STRUCT aiMatrix4x4* a,
+    const C_STRUCT aiMatrix4x4* b,
+    const float epsilon);
+
+// --------------------------------------------------------------------------------
+/** Invert a 4x4 matrix.
+ *  @param result Matrix to invert
+ */
+ASSIMP_API void aiMatrix4Inverse(
+    C_STRUCT aiMatrix4x4* mat);
+
+// --------------------------------------------------------------------------------
+/** Get the determinant of a 4x4 matrix.
+ *  @param mat Matrix to get the determinant from
+ *  @return The determinant of the matrix
+ */
+ASSIMP_API float aiMatrix4Determinant(
+    const C_STRUCT aiMatrix4x4* mat);
+
+// --------------------------------------------------------------------------------
+/** Returns true of the matrix is the identity matrix.
+ *  @param mat Matrix to get the determinant from
+ *  @return 1 if \p mat is an identity matrix.
+ *  @return 0 if \p mat is not an identity matrix.
+ */
+ASSIMP_API int aiMatrix4IsIdentity(
+    const C_STRUCT aiMatrix4x4* mat);
+
+// --------------------------------------------------------------------------------
+/** Decompose a transformation matrix into its scaling,
+ *  rotational as euler angles, and translational components.
+ *
+ * @param mat Matrix to decompose
+ * @param scaling Receives the output scaling for the x,y,z axes
+ * @param rotation Receives the output rotation as a Euler angles
+ * @param position Receives the output position for the x,y,z axes
+ */
+ASSIMP_API void aiMatrix4DecomposeIntoScalingEulerAnglesPosition(
+    const C_STRUCT aiMatrix4x4* mat,
+    C_STRUCT aiVector3D* scaling,
+    C_STRUCT aiVector3D* rotation,
+    C_STRUCT aiVector3D* position);
+
+// --------------------------------------------------------------------------------
+/** Decompose a transformation matrix into its scaling,
+ *  rotational split into an axis and rotational angle,
+ *  and it's translational components.
+ *
+ * @param mat Matrix to decompose
+ * @param rotation Receives the rotational component
+ * @param axis Receives the output rotation axis
+ * @param angle Receives the output rotation angle
+ * @param position Receives the output position for the x,y,z axes.
+ */
+ASSIMP_API void aiMatrix4DecomposeIntoScalingAxisAnglePosition(
+    const C_STRUCT aiMatrix4x4* mat,
+    C_STRUCT aiVector3D* scaling,
+    C_STRUCT aiVector3D* axis,
+    float* angle,
+    C_STRUCT aiVector3D* position);
+
+// --------------------------------------------------------------------------------
+/** Decompose a transformation matrix into its rotational and
+ *  translational components.
+ *
+ * @param mat Matrix to decompose
+ * @param rotation Receives the rotational component
+ * @param position Receives the translational component.
+ */
+ASSIMP_API void aiMatrix4DecomposeNoScaling(
+    const C_STRUCT aiMatrix4x4* mat,
+    C_STRUCT aiQuaternion* rotation,
+    C_STRUCT aiVector3D* position);
+
+// --------------------------------------------------------------------------------
+/** Creates a 4x4 matrix from a set of euler angles.
+ *  @param mat Receives the output matrix 
+ *  @param x Rotation angle for the x-axis, in radians
+ *  @param y Rotation angle for the y-axis, in radians
+ *  @param z Rotation angle for the z-axis, in radians
+ */
+ASSIMP_API void aiMatrix4FromEulerAngles(
+    C_STRUCT aiMatrix4x4* mat,
+    float x, float y, float z);
+
+// --------------------------------------------------------------------------------
+/** Get a 4x4 rotation matrix around the X axis.
+ *  @param mat Receives the output matrix
+ *  @param angle Rotation angle, in radians
+ */
+ASSIMP_API void aiMatrix4RotationX(
+    C_STRUCT aiMatrix4x4* mat,
+    const float angle);
+
+// --------------------------------------------------------------------------------
+/** Get a 4x4 rotation matrix around the Y axis.
+ *  @param mat Receives the output matrix
+ *  @param angle Rotation angle, in radians
+ */
+ASSIMP_API void aiMatrix4RotationY(
+    C_STRUCT aiMatrix4x4* mat,
+    const float angle);
+
+// --------------------------------------------------------------------------------
+/** Get a 4x4 rotation matrix around the Z axis.
+ *  @param mat Receives the output matrix
+ *  @param angle Rotation angle, in radians
+ */
+ASSIMP_API void aiMatrix4RotationZ(
+    C_STRUCT aiMatrix4x4* mat,
+    const float angle);
+
+// --------------------------------------------------------------------------------
+/** Returns a 4x4 rotation matrix for a rotation around an arbitrary axis.
+ *  @param mat Receives the output matrix
+ *  @param axis Rotation axis, should be a normalized vector
+ *  @param angle Rotation angle, in radians
+ */
+ASSIMP_API void aiMatrix4FromRotationAroundAxis(
+    C_STRUCT aiMatrix4x4* mat,
+    const C_STRUCT aiVector3D* axis,
+    const float angle);
+
+// --------------------------------------------------------------------------------
+/** Get a 4x4 translation matrix.
+ *  @param mat Receives the output matrix
+ *  @param translation The translation vector
+ */
+ASSIMP_API void aiMatrix4Translation(
+    C_STRUCT aiMatrix4x4* mat,
+    const C_STRUCT aiVector3D* translation);
+
+// --------------------------------------------------------------------------------
+/** Get a 4x4 scaling matrix.
+ *  @param mat Receives the output matrix
+ *  @param scaling The scaling vector
+ */
+ASSIMP_API void aiMatrix4Scaling(
+    C_STRUCT aiMatrix4x4* mat,
+    const C_STRUCT aiVector3D* scaling);
+
+// --------------------------------------------------------------------------------
+/** Create a 4x4 matrix that rotates one vector to another vector.
+ *  @param mat Receives the output matrix
+ *  @param from Vector to rotate from
+ *  @param to Vector to rotate to
+ */
+ASSIMP_API void aiMatrix4FromTo(
+    C_STRUCT aiMatrix4x4* mat,
+    const C_STRUCT aiVector3D* from,
+    const C_STRUCT aiVector3D* to);
+
+// --------------------------------------------------------------------------------
+/** Create a Quaternion from euler angles.
+ *  @param q Receives the output quaternion 
+ *  @param x Rotation angle for the x-axis, in radians
+ *  @param y Rotation angle for the y-axis, in radians
+ *  @param z Rotation angle for the z-axis, in radians
+ */
+ASSIMP_API void aiQuaternionFromEulerAngles(
+    C_STRUCT aiQuaternion* q,
+    float x, float y, float z);
+
+// --------------------------------------------------------------------------------
+/** Create a Quaternion from an axis angle pair.
+ *  @param q Receives the output quaternion
+ *  @param axis The orientation axis
+ *  @param angle The rotation angle, in radians
+ */
+ASSIMP_API void aiQuaternionFromAxisAngle(
+    C_STRUCT aiQuaternion* q,
+    const C_STRUCT aiVector3D* axis,
+    const float angle);
+
+// --------------------------------------------------------------------------------
+/** Create a Quaternion from a normalized quaternion stored
+ *  in a 3D vector.
+ *  @param q Receives the output quaternion
+ *  @param normalized The vector that stores the quaternion
+ */
+ASSIMP_API void aiQuaternionFromNormalizedQuaternion(
+    C_STRUCT aiQuaternion* q,
+    const C_STRUCT aiVector3D* normalized);
+
+// --------------------------------------------------------------------------------
+/** Check if quaternions are equal.
+ *  @param a First quaternion to compare
+ *  @param b Second quaternion to compare
+ *  @return 1 if the quaternions are equal
+ *  @return 0 if the quaternions are not equal
+ */
+ASSIMP_API int aiQuaternionAreEqual(
+    const C_STRUCT aiQuaternion* a,
+    const C_STRUCT aiQuaternion* b);
+
+// --------------------------------------------------------------------------------
+/** Check if quaternions are equal using epsilon.
+ *  @param a First quaternion to compare
+ *  @param b Second quaternion to compare
+ *  @param epsilon Epsilon
+ *  @return 1 if the quaternions are equal
+ *  @return 0 if the quaternions are not equal
+ */
+ASSIMP_API int aiQuaternionAreEqualEpsilon(
+    const C_STRUCT aiQuaternion* a,
+    const C_STRUCT aiQuaternion* b,
+    const float epsilon);
+
+// --------------------------------------------------------------------------------
+/** Normalize a quaternion.
+ *  @param q Quaternion to normalize
+ */
+ASSIMP_API void aiQuaternionNormalize(
+    C_STRUCT aiQuaternion* q);
+
+// --------------------------------------------------------------------------------
+/** Compute quaternion conjugate.
+ *  @param q Quaternion to compute conjugate,
+ *           receives the output quaternion
+ */
+ASSIMP_API void aiQuaternionConjugate(
+    C_STRUCT aiQuaternion* q);
+
+// --------------------------------------------------------------------------------
+/** Multiply quaternions.
+ *  @param dst First quaternion, receives the output quaternion
+ *  @param q Second quaternion
+ */
+ASSIMP_API void aiQuaternionMultiply(
+    C_STRUCT aiQuaternion* dst,
+    const C_STRUCT aiQuaternion* q);
+
+// --------------------------------------------------------------------------------
+/** Performs a spherical interpolation between two quaternions.
+ * @param dst Receives the quaternion resulting from the interpolation.
+ * @param start Quaternion when factor == 0
+ * @param end Quaternion when factor == 1
+ * @param factor Interpolation factor between 0 and 1
+ */
+ASSIMP_API void aiQuaternionInterpolate(
+    C_STRUCT aiQuaternion* dst,
+    const C_STRUCT aiQuaternion* start,
+    const C_STRUCT aiQuaternion* end,
+    const float factor);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/assimp/quaternion.h b/include/assimp/quaternion.h
index fd9abfd21..9a14bd413 100644
--- a/include/assimp/quaternion.h
+++ b/include/assimp/quaternion.h
@@ -99,7 +99,7 @@ public:
     aiQuaterniont& Conjugate ();
 
     /** Rotate a point by this quaternion */
-    aiVector3t<TReal> Rotate (const aiVector3t<TReal>& in);
+    aiVector3t<TReal> Rotate (const aiVector3t<TReal>& in) const;
 
     /** Multiply two quaternions */
     aiQuaterniont operator* (const aiQuaterniont& two) const;
diff --git a/include/assimp/quaternion.inl b/include/assimp/quaternion.inl
index e8bdb9aeb..32549db3b 100644
--- a/include/assimp/quaternion.inl
+++ b/include/assimp/quaternion.inl
@@ -277,7 +277,7 @@ inline aiQuaterniont<TReal>& aiQuaterniont<TReal>::Conjugate ()
 
 // ---------------------------------------------------------------------------
 template<typename TReal>
-inline aiVector3t<TReal> aiQuaterniont<TReal>::Rotate (const aiVector3t<TReal>& v)
+inline aiVector3t<TReal> aiQuaterniont<TReal>::Rotate (const aiVector3t<TReal>& v) const
 {
     aiQuaterniont q2(0.f,v.x,v.y,v.z), q = *this, qinv = q;
     qinv.Conjugate();