diff --git a/CMakeLists.txt b/CMakeLists.txt
index a337356be..c1a92ea61 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -966,6 +966,7 @@ target_sources(polyvr PRIVATE src/core/math/patch.cpp)
 target_sources(polyvr PRIVATE src/core/math/path.cpp)
 target_sources(polyvr PRIVATE src/core/math/partitioning/graph.cpp)
 target_sources(polyvr PRIVATE src/core/math/datarow.cpp)
+target_sources(polyvr PRIVATE src/core/math/PID.cpp)
 target_sources(polyvr PRIVATE src/core/navigation/VRNavigator.cpp)
 endif()
 
diff --git a/src/core/objects/geometry/VRPhysics.cpp b/src/core/objects/geometry/VRPhysics.cpp
index 3562aab65..3947ac466 100644
--- a/src/core/objects/geometry/VRPhysics.cpp
+++ b/src/core/objects/geometry/VRPhysics.cpp
@@ -1431,7 +1431,7 @@ void VRPhysics::updateConstraint(VRPhysics* p) {
         double a = c->getMin(i);
         double b = c->getMax(i);
         //if (a <= b) {
-            double pi = M_PI;
+            const double pi = 3.14159265358979323846;
             if (i == 3) { a = min( max(-pi, a), pi ); b = min( max(-pi, b), pi ); } // clamp to -pi/pi
             if (i == 4) { a = min( max(-pi*0.5, a), pi*0.5 ); b = min( max(-pi*0.5, b), pi*0.5 ); } // clamp to -0.5pi/0.5pi
             if (i == 5) { a = min( max(-pi, a), pi ); b = min( max(-pi, b), pi ); } // clamp to -pi/pi
diff --git a/src/core/objects/material/VRMaterial.cpp b/src/core/objects/material/VRMaterial.cpp
index 650019eaf..81644565e 100644
--- a/src/core/objects/material/VRMaterial.cpp
+++ b/src/core/objects/material/VRMaterial.cpp
@@ -231,7 +231,7 @@ struct VRMatData {
 }
 
 map<string, VRMaterialWeakPtr> VRMaterial::materials;
-map<Material*, VRMaterialWeakPtr> VRMaterial::materialsByPtr;
+map<size_t, VRMaterialWeakPtr> VRMaterial::materialsById;
 map<size_t, size_t> VRMaterial::fieldContainerMap;
 
 VRMaterial::VRMaterial(string name) : VRObject(name) {}
@@ -245,7 +245,7 @@ VRMaterialPtr VRMaterial::create(string name, bool reg) {
     p->init();
     Material* mat = p->getMaterial()->mat.get();
     if (reg) materials[p->getName()] = p;
-    if (reg) materialsByPtr[mat] = p;
+    if (reg) materialsById[mat->getId()] = p;
 #ifdef OSG_OGL_ES2
     p->updateOGL2Shader(); // TODO: find a better place!
 #endif
@@ -516,12 +516,12 @@ void VRMaterial::testFix() {
 
 void VRMaterial::clearAll() {
     materials.clear();
-    materialsByPtr.clear();
+    materialsById.clear();
 }
 
 vector<VRMaterialPtr> VRMaterial::getAll() {
     vector<VRMaterialPtr> res;
-    for (auto wm : materialsByPtr) if (auto m = wm.second.lock()) res.push_back(m);
+    for (auto wm : materialsById) if (auto m = wm.second.lock()) res.push_back(m);
     return res;
 }
 
@@ -600,21 +600,21 @@ void VRMaterial::prependPasses(VRMaterialPtr mat) {
 }
 
 VRMaterialPtr VRMaterial::get(MaterialMTRecPtr mat) {
-    Material* key = mat.get();
+    size_t key = mat->getId();
     VRMaterialPtr m;
-    if (materialsByPtr.count(key) == 0) {
+    if (materialsById.count(key) == 0) {
         m = VRMaterial::create("mat");
         m->setMaterial(mat);
-        materialsByPtr[key] = m;
+        materialsById[key] = m;
         return m;
-    } else if (materialsByPtr[key].lock() == 0) {
+    } else if (materialsById[key].lock() == 0) {
         m = VRMaterial::create("mat");
         m->setMaterial(mat);
-        materialsByPtr[key] = m;
+        materialsById[key] = m;
         return m;
     }
 
-    return materialsByPtr[key].lock();
+    return materialsById[key].lock();
 }
 
 VRMaterialPtr VRMaterial::get(string s) {
diff --git a/src/core/objects/material/VRMaterial.h b/src/core/objects/material/VRMaterial.h
index f847150a4..9bda8db90 100644
--- a/src/core/objects/material/VRMaterial.h
+++ b/src/core/objects/material/VRMaterial.h
@@ -32,7 +32,7 @@ Color3f toColor3f(Color4f c);
 class VRMaterial : public VRObject {
     public:
         static map<string, VRMaterialWeakPtr> materials;
-        static map<Material*, VRMaterialWeakPtr> materialsByPtr;
+        static map<size_t, VRMaterialWeakPtr> materialsById;
         static map<size_t, size_t> fieldContainerMap;
 
         void setup();