From 7054d9f1622817b3ba21b73d710a7212a9dacc31 Mon Sep 17 00:00:00 2001
From: Adam Kewley <contact@adamkewley.com>
Date: Fri, 17 Nov 2023 11:57:27 +0100
Subject: [PATCH] Clean up headers in OpenSimCreator/ModelGraph (#802)

---
 src/OpenSimCreator/CMakeLists.txt             |  4 +-
 src/OpenSimCreator/ModelGraph/BodyEl.cpp      | 25 +++++++++++
 src/OpenSimCreator/ModelGraph/BodyEl.hpp      | 27 ++----------
 .../CommittableModelGraphActions.cpp          |  1 +
 src/OpenSimCreator/ModelGraph/EdgeEl.cpp      | 21 ++++++++++
 src/OpenSimCreator/ModelGraph/EdgeEl.hpp      | 22 +++-------
 src/OpenSimCreator/ModelGraph/GroundEl.cpp    | 38 +++++++++++++++++
 src/OpenSimCreator/ModelGraph/GroundEl.hpp    | 32 +++------------
 .../ModelGraph/ISceneElLookup.hpp             |  3 +-
 src/OpenSimCreator/ModelGraph/JointEl.cpp     | 38 +++++++++++++++++
 src/OpenSimCreator/ModelGraph/JointEl.hpp     | 41 ++++---------------
 src/OpenSimCreator/ModelGraph/MeshEl.cpp      | 39 ++++++++++++++++++
 src/OpenSimCreator/ModelGraph/MeshEl.hpp      | 39 +++---------------
 src/OpenSimCreator/ModelGraph/ModelGraph.cpp  | 11 +++++
 src/OpenSimCreator/ModelGraph/ModelGraph.hpp  |  6 +--
 .../ModelGraph/ModelGraphHelpers.cpp          |  4 +-
 .../ModelGraph/ModelGraphHelpers.hpp          |  4 +-
 src/OpenSimCreator/ModelGraph/StationEl.cpp   | 36 ++++++++++++++++
 src/OpenSimCreator/ModelGraph/StationEl.hpp   | 35 ++--------------
 19 files changed, 251 insertions(+), 175 deletions(-)
 create mode 100644 src/OpenSimCreator/ModelGraph/GroundEl.cpp
 create mode 100644 src/OpenSimCreator/ModelGraph/ModelGraph.cpp

diff --git a/src/OpenSimCreator/CMakeLists.txt b/src/OpenSimCreator/CMakeLists.txt
index 844feeee8..9a08e457a 100644
--- a/src/OpenSimCreator/CMakeLists.txt
+++ b/src/OpenSimCreator/CMakeLists.txt
@@ -64,6 +64,7 @@ add_library(OpenSimCreator STATIC
     ModelGraph/CrossrefDirection.hpp
     ModelGraph/EdgeEl.cpp
     ModelGraph/EdgeEl.hpp
+    ModelGraph/GroundEl.cpp
     ModelGraph/GroundEl.hpp
     ModelGraph/ISceneElLookup.hpp
     ModelGraph/JointEl.cpp
@@ -71,6 +72,7 @@ add_library(OpenSimCreator STATIC
     ModelGraph/MeshEl.cpp
     ModelGraph/MeshEl.hpp
     ModelGraph/ModelCreationFlags.hpp
+    ModelGraph/ModelGraph.cpp
     ModelGraph/ModelGraph.hpp
     ModelGraph/ModelGraphHelpers.cpp
     ModelGraph/ModelGraphHelpers.hpp
@@ -271,7 +273,7 @@ add_library(OpenSimCreator STATIC
     Utils/TPS3D.hpp
     Utils/UndoableModelActions.cpp
     Utils/UndoableModelActions.hpp
- "UI/Tabs/MeshImporter/ImportStationsFromCSVPopup.cpp")
+)
 
 # OpenSimCreatorConfig.hpp
 #
diff --git a/src/OpenSimCreator/ModelGraph/BodyEl.cpp b/src/OpenSimCreator/ModelGraph/BodyEl.cpp
index 544aade6f..f250a0075 100644
--- a/src/OpenSimCreator/ModelGraph/BodyEl.cpp
+++ b/src/OpenSimCreator/ModelGraph/BodyEl.cpp
@@ -1,10 +1,14 @@
 #include "BodyEl.hpp"
 
+#include <OpenSimCreator/ModelGraph/ModelGraphStrings.hpp>
+#include <OpenSimCreator/ModelGraph/SceneElClass.hpp>
 #include <OpenSimCreator/Utils/OpenSimHelpers.hpp>
 
+#include <IconsFontAwesome5.h>
 #include <oscar/Maths/Transform.hpp>
 #include <oscar/Utils/UID.hpp>
 
+#include <iostream>
 #include <string>
 #include <string_view>
 
@@ -23,3 +27,24 @@ void osc::BodyEl::implSetLabel(std::string_view sv)
 {
     m_Name = SanitizeToOpenSimComponentName(sv);
 }
+
+osc::SceneElClass osc::BodyEl::CreateClass()
+{
+    return
+    {
+        ModelGraphStrings::c_BodyLabel,
+        ModelGraphStrings::c_BodyLabelPluralized,
+        ModelGraphStrings::c_BodyLabelOptionallyPluralized,
+        ICON_FA_CIRCLE,
+        ModelGraphStrings::c_BodyDescription,
+    };
+}
+
+std::ostream& osc::BodyEl::implWriteToStream(std::ostream& o) const
+{
+    return o << "BodyEl(ID = " << m_ID
+        << ", Name = " << m_Name
+        << ", m_Transform = " << m_Xform
+        << ", Mass = " << Mass
+        << ')';
+}
diff --git a/src/OpenSimCreator/ModelGraph/BodyEl.hpp b/src/OpenSimCreator/ModelGraph/BodyEl.hpp
index 761c4a699..8574b2e56 100644
--- a/src/OpenSimCreator/ModelGraph/BodyEl.hpp
+++ b/src/OpenSimCreator/ModelGraph/BodyEl.hpp
@@ -1,19 +1,17 @@
 #pragma once
 
-#include <OpenSimCreator/ModelGraph/ModelGraphIDs.hpp>
-#include <OpenSimCreator/ModelGraph/ModelGraphStrings.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElClass.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElCRTP.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElFlags.hpp>
 
-#include <IconsFontAwesome5.h>
 #include <oscar/Maths/AABB.hpp>
 #include <oscar/Maths/Transform.hpp>
 #include <oscar/Utils/CStringView.hpp>
 #include <oscar/Utils/UID.hpp>
 
-#include <iostream>
+#include <iosfwd>
 #include <string>
+#include <string_view>
 
 namespace osc
 {
@@ -44,17 +42,7 @@ namespace osc
         }
     private:
         friend class SceneElCRTP<BodyEl>;
-        static SceneElClass CreateClass()
-        {
-            return
-            {
-                ModelGraphStrings::c_BodyLabel,
-                ModelGraphStrings::c_BodyLabelPluralized,
-                ModelGraphStrings::c_BodyLabelOptionallyPluralized,
-                ICON_FA_CIRCLE,
-                ModelGraphStrings::c_BodyDescription,
-            };
-        }
+        static SceneElClass CreateClass();
 
         SceneElFlags implGetFlags() const final
         {
@@ -71,14 +59,7 @@ namespace osc
             return m_ID;
         }
 
-        std::ostream& implWriteToStream(std::ostream& o) const final
-        {
-            return o << "BodyEl(ID = " << m_ID
-                << ", Name = " << m_Name
-                << ", m_Transform = " << m_Xform
-                << ", Mass = " << Mass
-                << ')';
-        }
+        std::ostream& implWriteToStream(std::ostream&) const final;
 
         CStringView implGetLabel() const final
         {
diff --git a/src/OpenSimCreator/ModelGraph/CommittableModelGraphActions.cpp b/src/OpenSimCreator/ModelGraph/CommittableModelGraphActions.cpp
index db7c04f14..c91bce6e5 100644
--- a/src/OpenSimCreator/ModelGraph/CommittableModelGraphActions.cpp
+++ b/src/OpenSimCreator/ModelGraph/CommittableModelGraphActions.cpp
@@ -4,6 +4,7 @@
 #include <OpenSimCreator/ModelGraph/JointEl.hpp>
 #include <OpenSimCreator/ModelGraph/MeshEl.hpp>
 #include <OpenSimCreator/ModelGraph/ModelGraph.hpp>
+#include <OpenSimCreator/ModelGraph/ModelGraphIDs.hpp>
 #include <OpenSimCreator/ModelGraph/ModelGraphHelpers.hpp>
 #include <OpenSimCreator/ModelGraph/SceneEl.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElHelpers.hpp>
diff --git a/src/OpenSimCreator/ModelGraph/EdgeEl.cpp b/src/OpenSimCreator/ModelGraph/EdgeEl.cpp
index 769991acd..79f44b80b 100644
--- a/src/OpenSimCreator/ModelGraph/EdgeEl.cpp
+++ b/src/OpenSimCreator/ModelGraph/EdgeEl.cpp
@@ -2,12 +2,28 @@
 
 #include <OpenSimCreator/ModelGraph/ISceneElLookup.hpp>
 #include <OpenSimCreator/ModelGraph/SceneEl.hpp>
+#include <OpenSimCreator/ModelGraph/SceneElClass.hpp>
 
+#include <IconsFontAwesome5.h>
 #include <oscar/Maths/AABB.hpp>
 #include <oscar/Maths/MathHelpers.hpp>
 #include <oscar/Maths/Transform.hpp>
 #include <oscar/Maths/Vec3.hpp>
 
+#include <iostream>
+
+osc::SceneElClass osc::EdgeEl::CreateClass()
+{
+    return SceneElClass
+    {
+        "Edge",
+        "Edges",
+        "Edge(s)",
+        ICON_FA_ARROWS_ALT,
+        "An edge between the centers of two other scene elements",
+    };
+}
+
 osc::Transform osc::EdgeEl::implGetXform(ISceneElLookup const& lookup) const
 {
     SceneEl const* first = lookup.find(m_FirstAttachmentID);
@@ -23,6 +39,11 @@ osc::Transform osc::EdgeEl::implGetXform(ISceneElLookup const& lookup) const
     }
 }
 
+std::ostream& osc::EdgeEl::implWriteToStream(std::ostream& out) const
+{
+    return out << "Edge(id = " << m_ID << ", lhs = " << m_FirstAttachmentID << ", rhs = " << m_SecondAttachmentID << ')';
+}
+
 osc::AABB osc::EdgeEl::implCalcBounds(ISceneElLookup const& lookup) const
 {
     SceneEl const* first = lookup.find(m_FirstAttachmentID);
diff --git a/src/OpenSimCreator/ModelGraph/EdgeEl.hpp b/src/OpenSimCreator/ModelGraph/EdgeEl.hpp
index 8c42772b2..775acb0bc 100644
--- a/src/OpenSimCreator/ModelGraph/EdgeEl.hpp
+++ b/src/OpenSimCreator/ModelGraph/EdgeEl.hpp
@@ -1,16 +1,17 @@
 #pragma once
 
 #include <OpenSimCreator/ModelGraph/CrossrefDescriptor.hpp>
+#include <OpenSimCreator/ModelGraph/SceneElClass.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElCRTP.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElFlags.hpp>
 
-#include <IconsFontAwesome5.h>
 #include <oscar/Maths/AABB.hpp>
 #include <oscar/Maths/Transform.hpp>
 #include <oscar/Utils/CStringView.hpp>
 #include <oscar/Utils/UID.hpp>
 
-#include <iostream>
+#include <iosfwd>
+#include <stdexcept>
 #include <string_view>
 #include <vector>
 
@@ -40,17 +41,7 @@ namespace osc
         }
     private:
         friend class SceneElCRTP<EdgeEl>;
-        static SceneElClass CreateClass()
-        {
-            return SceneElClass
-            {
-                "Edge",
-                "Edges",
-                "Edge(s)",
-                ICON_FA_ARROWS_ALT,
-                "An edge between the centers of two other scene elements",
-            };
-        }
+        static SceneElClass CreateClass();
 
         std::vector<CrossrefDescriptor> implGetCrossReferences() const final
         {
@@ -89,10 +80,7 @@ namespace osc
             return m_ID;
         }
 
-        std::ostream& implWriteToStream(std::ostream& out) const final
-        {
-            return out << "Edge(id = " << m_ID << ", lhs = " << m_FirstAttachmentID << ", rhs = " << m_SecondAttachmentID << ')';
-        }
+        std::ostream& implWriteToStream(std::ostream&) const final;
 
         CStringView implGetLabel() const
         {
diff --git a/src/OpenSimCreator/ModelGraph/GroundEl.cpp b/src/OpenSimCreator/ModelGraph/GroundEl.cpp
new file mode 100644
index 000000000..9beeb9aa0
--- /dev/null
+++ b/src/OpenSimCreator/ModelGraph/GroundEl.cpp
@@ -0,0 +1,38 @@
+#include "GroundEl.hpp"
+
+#include <OpenSimCreator/ModelGraph/ModelGraphStrings.hpp>
+#include <OpenSimCreator/ModelGraph/ModelGraphIDs.hpp>
+#include <OpenSimCreator/ModelGraph/SceneElClass.hpp>
+
+#include <IconsFontAwesome5.h>
+#include <oscar/Utils/CStringView.hpp>
+#include <oscar/Utils/UID.hpp>
+
+#include <iostream>
+
+osc::SceneElClass osc::GroundEl::CreateClass()
+{
+    return
+    {
+        ModelGraphStrings::c_GroundLabel,
+        ModelGraphStrings::c_GroundLabelPluralized,
+        ModelGraphStrings::c_GroundLabelOptionallyPluralized,
+        ICON_FA_DOT_CIRCLE,
+        ModelGraphStrings::c_GroundDescription,
+    };
+}
+
+osc::UID osc::GroundEl::implGetID() const
+{
+    return ModelGraphIDs::Ground();
+}
+
+std::ostream& osc::GroundEl::implWriteToStream(std::ostream& o) const
+{
+    return o << ModelGraphStrings::c_GroundLabel << "()";
+}
+
+osc::CStringView osc::GroundEl::implGetLabel() const
+{
+    return ModelGraphStrings::c_GroundLabel;
+}
diff --git a/src/OpenSimCreator/ModelGraph/GroundEl.hpp b/src/OpenSimCreator/ModelGraph/GroundEl.hpp
index e6f404069..80c1aff62 100644
--- a/src/OpenSimCreator/ModelGraph/GroundEl.hpp
+++ b/src/OpenSimCreator/ModelGraph/GroundEl.hpp
@@ -2,16 +2,13 @@
 
 #include <OpenSimCreator/ModelGraph/SceneElCRTP.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElFlags.hpp>
-#include <OpenSimCreator/ModelGraph/ModelGraphIDs.hpp>
-#include <OpenSimCreator/ModelGraph/ModelGraphStrings.hpp>
 
-#include <IconsFontAwesome5.h>
 #include <oscar/Maths/AABB.hpp>
 #include <oscar/Maths/Transform.hpp>
 #include <oscar/Utils/CStringView.hpp>
 #include <oscar/Utils/UID.hpp>
 
-#include <iostream>
+#include <iosfwd>
 
 namespace osc
 {
@@ -19,37 +16,18 @@ namespace osc
     class GroundEl final : public SceneElCRTP<GroundEl> {
     private:
         friend class SceneElCRTP<GroundEl>;
-        static SceneElClass CreateClass()
-        {
-            return
-            {
-                ModelGraphStrings::c_GroundLabel,
-                ModelGraphStrings::c_GroundLabelPluralized,
-                ModelGraphStrings::c_GroundLabelOptionallyPluralized,
-                ICON_FA_DOT_CIRCLE,
-                ModelGraphStrings::c_GroundDescription,
-            };
-        }
+        static SceneElClass CreateClass();
 
         SceneElFlags implGetFlags() const final
         {
             return SceneElFlags::None;
         }
 
-        UID implGetID() const final
-        {
-            return ModelGraphIDs::Ground();
-        }
+        UID implGetID() const final;
 
-        std::ostream& implWriteToStream(std::ostream& o) const final
-        {
-            return o << ModelGraphStrings::c_GroundLabel << "()";
-        }
+        std::ostream& implWriteToStream(std::ostream&) const final;
 
-        CStringView implGetLabel() const final
-        {
-            return ModelGraphStrings::c_GroundLabel;
-        }
+        CStringView implGetLabel() const final;
 
         Transform implGetXform(ISceneElLookup const&) const final
         {
diff --git a/src/OpenSimCreator/ModelGraph/ISceneElLookup.hpp b/src/OpenSimCreator/ModelGraph/ISceneElLookup.hpp
index 069d2a97f..015ab9c79 100644
--- a/src/OpenSimCreator/ModelGraph/ISceneElLookup.hpp
+++ b/src/OpenSimCreator/ModelGraph/ISceneElLookup.hpp
@@ -2,11 +2,12 @@
 
 #include <oscar/Utils/UID.hpp>
 
+namespace osc { class SceneEl; }
+
 namespace osc
 {
     // virtual interface to something that can be used to lookup scene elements in
     // some larger document
-    class SceneEl;
     class ISceneElLookup {
     protected:
         ISceneElLookup() = default;
diff --git a/src/OpenSimCreator/ModelGraph/JointEl.cpp b/src/OpenSimCreator/ModelGraph/JointEl.cpp
index d193a59f6..5c6f65c08 100644
--- a/src/OpenSimCreator/ModelGraph/JointEl.cpp
+++ b/src/OpenSimCreator/ModelGraph/JointEl.cpp
@@ -1,16 +1,22 @@
 #include "JointEl.hpp"
 
+#include <OpenSimCreator/ModelGraph/CrossrefDescriptor.hpp>
+#include <OpenSimCreator/ModelGraph/CrossrefDirection.hpp>
+#include <OpenSimCreator/ModelGraph/ModelGraphStrings.hpp>
 #include <OpenSimCreator/Registry/ComponentRegistry.hpp>
 #include <OpenSimCreator/Registry/StaticComponentRegistries.hpp>
 #include <OpenSimCreator/Utils/OpenSimHelpers.hpp>
 
+#include <IconsFontAwesome5.h>
 #include <oscar/Maths/Transform.hpp>
 #include <oscar/Utils/CStringView.hpp>
 #include <oscar/Utils/SpanHelpers.hpp>
 #include <oscar/Utils/UID.hpp>
 
 #include <cstddef>
+#include <iostream>
 #include <string>
+#include <vector>
 
 osc::JointEl::JointEl(
     UID id,
@@ -29,11 +35,43 @@ osc::JointEl::JointEl(
 {
 }
 
+osc::SceneElClass osc::JointEl::CreateClass()
+{
+    return
+    {
+        ModelGraphStrings::c_JointLabel,
+        ModelGraphStrings::c_JointLabelPluralized,
+        ModelGraphStrings::c_JointLabelOptionallyPluralized,
+        ICON_FA_LINK,
+        ModelGraphStrings::c_JointDescription,
+    };
+}
+
+std::vector<osc::CrossrefDescriptor> osc::JointEl::implGetCrossReferences() const
+{
+    return
+    {
+        {m_Parent, ModelGraphStrings::c_JointParentCrossrefName, CrossrefDirection::ToParent},
+        {m_Child,  ModelGraphStrings::c_JointChildCrossrefName,  CrossrefDirection::ToChild },
+    };
+}
+
 osc::CStringView osc::JointEl::getSpecificTypeName() const
 {
     return osc::At(osc::GetComponentRegistry<OpenSim::Joint>(), m_JointTypeIndex).name();
 }
 
+std::ostream& osc::JointEl::implWriteToStream(std::ostream& o) const
+{
+    return o << "JointEl(ID = " << m_ID
+        << ", JointTypeIndex = " << m_JointTypeIndex
+        << ", UserAssignedName = " << m_UserAssignedName
+        << ", Parent = " << m_Parent
+        << ", Child = " << m_Child
+        << ", m_Transform = " << m_Xform
+        << ')';
+}
+
 void osc::JointEl::implSetLabel(std::string_view sv)
 {
     m_UserAssignedName = osc::SanitizeToOpenSimComponentName(sv);
diff --git a/src/OpenSimCreator/ModelGraph/JointEl.hpp b/src/OpenSimCreator/ModelGraph/JointEl.hpp
index aa1904eb9..2b8d427b5 100644
--- a/src/OpenSimCreator/ModelGraph/JointEl.hpp
+++ b/src/OpenSimCreator/ModelGraph/JointEl.hpp
@@ -3,17 +3,15 @@
 #include <OpenSimCreator/ModelGraph/CrossrefDescriptor.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElCRTP.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElFlags.hpp>
-#include <OpenSimCreator/ModelGraph/ModelGraphIDs.hpp>
-#include <OpenSimCreator/ModelGraph/ModelGraphStrings.hpp>
 
-#include <IconsFontAwesome5.h>
 #include <oscar/Maths/AABB.hpp>
 #include <oscar/Maths/Transform.hpp>
 #include <oscar/Utils/CStringView.hpp>
 #include <oscar/Utils/UID.hpp>
 
 #include <cstddef>
-#include <iostream>
+#include <iosfwd>
+#include <stdexcept>
 #include <string>
 #include <string_view>
 #include <vector>
@@ -31,7 +29,8 @@ namespace osc
             std::string const& userAssignedName,  // can be empty
             UID parent,
             UID child,
-            Transform const& xform);
+            Transform const& xform
+        );
 
         CStringView getSpecificTypeName() const;
 
@@ -67,26 +66,9 @@ namespace osc
 
     private:
         friend class SceneElCRTP<JointEl>;
-        static SceneElClass CreateClass()
-        {
-            return
-            {
-                ModelGraphStrings::c_JointLabel,
-                ModelGraphStrings::c_JointLabelPluralized,
-                ModelGraphStrings::c_JointLabelOptionallyPluralized,
-                ICON_FA_LINK,
-                ModelGraphStrings::c_JointDescription,
-            };
-        }
+        static SceneElClass CreateClass();
 
-        std::vector<CrossrefDescriptor> implGetCrossReferences() const final
-        {
-            return
-            {
-                {m_Parent, ModelGraphStrings::c_JointParentCrossrefName, CrossrefDirection::ToParent},
-                {m_Child,  ModelGraphStrings::c_JointChildCrossrefName,  CrossrefDirection::ToChild },
-            };
-        }
+        std::vector<CrossrefDescriptor> implGetCrossReferences() const final;
 
         void implSetCrossReferenceConnecteeID(int i, UID id) final
         {
@@ -117,16 +99,7 @@ namespace osc
             return m_ID;
         }
 
-        std::ostream& implWriteToStream(std::ostream& o) const final
-        {
-            return o << "JointEl(ID = " << m_ID
-                << ", JointTypeIndex = " << m_JointTypeIndex
-                << ", UserAssignedName = " << m_UserAssignedName
-                << ", Parent = " << m_Parent
-                << ", Child = " << m_Child
-                << ", m_Transform = " << m_Xform
-                << ')';
-        }
+        std::ostream& implWriteToStream(std::ostream&) const final;
 
         CStringView implGetLabel() const final
         {
diff --git a/src/OpenSimCreator/ModelGraph/MeshEl.cpp b/src/OpenSimCreator/ModelGraph/MeshEl.cpp
index a41dc11a1..6e49f2bb1 100644
--- a/src/OpenSimCreator/ModelGraph/MeshEl.cpp
+++ b/src/OpenSimCreator/ModelGraph/MeshEl.cpp
@@ -1,14 +1,21 @@
 #include "MeshEl.hpp"
 
+#include <OpenSimCreator/ModelGraph/CrossrefDescriptor.hpp>
+#include <OpenSimCreator/ModelGraph/CrossrefDirection.hpp>
+#include <OpenSimCreator/ModelGraph/SceneElClass.hpp>
+#include <OpenSimCreator/ModelGraph/ModelGraphStrings.hpp>
 #include <OpenSimCreator/Utils/OpenSimHelpers.hpp>
 
+#include <IconsFontAwesome5.h>
 #include <oscar/Maths/AABB.hpp>
 #include <oscar/Maths/MathHelpers.hpp>
 #include <oscar/Utils/FilesystemHelpers.hpp>
 #include <oscar/Utils/UID.hpp>
 
 #include <filesystem>
+#include <iostream>
 #include <utility>
+#include <vector>
 
 osc::MeshEl::MeshEl(
     UID id,
@@ -29,6 +36,38 @@ osc::AABB osc::MeshEl::calcBounds() const
     return TransformAABB(m_MeshData.getBounds(), m_Transform);
 }
 
+osc::SceneElClass osc::MeshEl::CreateClass()
+{
+    return
+    {
+        ModelGraphStrings::c_MeshLabel,
+        ModelGraphStrings::c_MeshLabelPluralized,
+        ModelGraphStrings::c_MeshLabelOptionallyPluralized,
+        ICON_FA_CUBE,
+        ModelGraphStrings::c_MeshDescription,
+    };
+}
+
+std::vector<osc::CrossrefDescriptor> osc::MeshEl::implGetCrossReferences() const
+{
+    return
+    {
+        {m_Attachment, ModelGraphStrings::c_MeshAttachmentCrossrefName, CrossrefDirection::ToParent},
+    };
+}
+
+std::ostream& osc::MeshEl::implWriteToStream(std::ostream& o) const
+{
+    return o << "MeshEl("
+        << "ID = " << m_ID
+        << ", Attachment = " << m_Attachment
+        << ", m_Transform = " << m_Transform
+        << ", MeshData = " << &m_MeshData
+        << ", Path = " << m_Path
+        << ", Name = " << m_Name
+        << ')';
+}
+
 void osc::MeshEl::implSetLabel(std::string_view sv)
 {
     m_Name = SanitizeToOpenSimComponentName(sv);
diff --git a/src/OpenSimCreator/ModelGraph/MeshEl.hpp b/src/OpenSimCreator/ModelGraph/MeshEl.hpp
index f03fe335e..3244a6aaf 100644
--- a/src/OpenSimCreator/ModelGraph/MeshEl.hpp
+++ b/src/OpenSimCreator/ModelGraph/MeshEl.hpp
@@ -1,22 +1,19 @@
 #pragma once
 
 #include <OpenSimCreator/ModelGraph/CrossrefDescriptor.hpp>
-#include <OpenSimCreator/ModelGraph/ModelGraphIDs.hpp>
-#include <OpenSimCreator/ModelGraph/ModelGraphStrings.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElClass.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElCRTP.hpp>
 
-#include <IconsFontAwesome5.h>
 #include <oscar/Graphics/Mesh.hpp>
 #include <oscar/Maths/AABB.hpp>
 #include <oscar/Maths/Transform.hpp>
 #include <oscar/Utils/UID.hpp>
 
 #include <filesystem>
-#include <iostream>
+#include <iosfwd>
 #include <stdexcept>
 #include <string>
-#include <utility>
+#include <string_view>
 #include <vector>
 
 namespace osc
@@ -74,25 +71,9 @@ namespace osc
 
     private:
         friend class SceneElCRTP<MeshEl>;
-        static SceneElClass CreateClass()
-        {
-            return
-            {
-                ModelGraphStrings::c_MeshLabel,
-                ModelGraphStrings::c_MeshLabelPluralized,
-                ModelGraphStrings::c_MeshLabelOptionallyPluralized,
-                ICON_FA_CUBE,
-                ModelGraphStrings::c_MeshDescription,
-            };
-        }
+        static SceneElClass CreateClass();
 
-        std::vector<CrossrefDescriptor> implGetCrossReferences() const final
-        {
-            return
-            {
-                {m_Attachment, ModelGraphStrings::c_MeshAttachmentCrossrefName, CrossrefDirection::ToParent},
-            };
-        }
+        std::vector<CrossrefDescriptor> implGetCrossReferences() const final;
 
         void implSetCrossReferenceConnecteeID(int i, UID id) final
         {
@@ -120,17 +101,7 @@ namespace osc
             return m_ID;
         }
 
-        std::ostream& implWriteToStream(std::ostream& o) const final
-        {
-            return o << "MeshEl("
-                << "ID = " << m_ID
-                << ", Attachment = " << m_Attachment
-                << ", m_Transform = " << m_Transform
-                << ", MeshData = " << &m_MeshData
-                << ", Path = " << m_Path
-                << ", Name = " << m_Name
-                << ')';
-        }
+        std::ostream& implWriteToStream(std::ostream&) const final;
 
         CStringView implGetLabel() const final
         {
diff --git a/src/OpenSimCreator/ModelGraph/ModelGraph.cpp b/src/OpenSimCreator/ModelGraph/ModelGraph.cpp
new file mode 100644
index 000000000..2a057eee4
--- /dev/null
+++ b/src/OpenSimCreator/ModelGraph/ModelGraph.cpp
@@ -0,0 +1,11 @@
+#include "ModelGraph.hpp"
+
+#include <OpenSimCreator/ModelGraph/GroundEl.hpp>
+#include <OpenSimCreator/ModelGraph/ModelGraphIDs.hpp>
+
+#include <oscar/Utils/ClonePtr.hpp>
+
+osc::ModelGraph::ModelGraph() :
+    m_Els{{ModelGraphIDs::Ground(), ClonePtr<SceneEl>{GroundEl{}}}}
+{
+}
diff --git a/src/OpenSimCreator/ModelGraph/ModelGraph.hpp b/src/OpenSimCreator/ModelGraph/ModelGraph.hpp
index a7e9497a1..84845b3c1 100644
--- a/src/OpenSimCreator/ModelGraph/ModelGraph.hpp
+++ b/src/OpenSimCreator/ModelGraph/ModelGraph.hpp
@@ -1,8 +1,6 @@
 #pragma once
 
-#include <OpenSimCreator/ModelGraph/GroundEl.hpp>
 #include <OpenSimCreator/ModelGraph/ISceneElLookup.hpp>
-#include <OpenSimCreator/ModelGraph/ModelGraphIDs.hpp>
 #include <OpenSimCreator/ModelGraph/SceneEl.hpp>
 
 #include <oscar/Utils/ClonePtr.hpp>
@@ -136,7 +134,7 @@ namespace osc
 
     public:
 
-        ModelGraph() = default;
+        ModelGraph();
 
         template<DerivedFrom<SceneEl> T = SceneEl>
         T* tryUpdElByID(UID id)
@@ -379,7 +377,7 @@ namespace osc
 
         // insert a senteniel ground element into the model graph (it should always
         // be there)
-        SceneElMap m_Els = {{ModelGraphIDs::Ground(), ClonePtr<SceneEl>{GroundEl{}}}};
+        SceneElMap m_Els;
         std::unordered_set<UID> m_SelectedEls;
         std::vector<ClonePtr<SceneEl>> m_DeletedEls;
     };
diff --git a/src/OpenSimCreator/ModelGraph/ModelGraphHelpers.cpp b/src/OpenSimCreator/ModelGraph/ModelGraphHelpers.cpp
index 4d9c66415..af0553698 100644
--- a/src/OpenSimCreator/ModelGraph/ModelGraphHelpers.cpp
+++ b/src/OpenSimCreator/ModelGraph/ModelGraphHelpers.cpp
@@ -304,8 +304,10 @@ void osc::PointAxisTowards(
 osc::SceneDecorationFlags osc::computeFlags(
     ModelGraph const& mg,
     UID id,
-    UID hoverID)
+    std::optional<UID> maybeHoverID)
 {
+    UID const hoverID = maybeHoverID ? *maybeHoverID : ModelGraphIDs::Empty();
+
     if (id == ModelGraphIDs::Empty())
     {
         return SceneDecorationFlags::None;
diff --git a/src/OpenSimCreator/ModelGraph/ModelGraphHelpers.hpp b/src/OpenSimCreator/ModelGraph/ModelGraphHelpers.hpp
index 57cf5e217..53f94102b 100644
--- a/src/OpenSimCreator/ModelGraph/ModelGraphHelpers.hpp
+++ b/src/OpenSimCreator/ModelGraph/ModelGraphHelpers.hpp
@@ -1,7 +1,6 @@
 #pragma once
 
 #include <OpenSimCreator/ModelGraph/ModelGraph.hpp>
-#include <OpenSimCreator/ModelGraph/ModelGraphIDs.hpp>
 #include <OpenSimCreator/ModelGraph/SceneEl.hpp>
 
 #include <oscar/Maths/Transform.hpp>
@@ -12,6 +11,7 @@
 #include <oscar/Utils/UID.hpp>
 
 #include <string>
+#include <optional>
 #include <unordered_set>
 #include <vector>
 
@@ -109,6 +109,6 @@ namespace osc
     SceneDecorationFlags computeFlags(
         ModelGraph const&,
         UID id,
-        UID hoverID = ModelGraphIDs::Empty()
+        std::optional<UID> maybeHoverID = std::nullopt
     );
 }
diff --git a/src/OpenSimCreator/ModelGraph/StationEl.cpp b/src/OpenSimCreator/ModelGraph/StationEl.cpp
index 79a9d8104..6a3c52e3e 100644
--- a/src/OpenSimCreator/ModelGraph/StationEl.cpp
+++ b/src/OpenSimCreator/ModelGraph/StationEl.cpp
@@ -1,12 +1,18 @@
 #include "StationEl.hpp"
 
+#include <OpenSimCreator/ModelGraph/CrossrefDescriptor.hpp>
+#include <OpenSimCreator/ModelGraph/CrossrefDirection.hpp>
+#include <OpenSimCreator/ModelGraph/ModelGraphStrings.hpp>
 #include <OpenSimCreator/Utils/OpenSimHelpers.hpp>
 
+#include <IconsFontAwesome5.h>
 #include <oscar/Maths/Vec3.hpp>
 #include <oscar/Utils/UID.hpp>
 
+#include <iostream>
 #include <string>
 #include <string_view>
+#include <vector>
 
 osc::StationEl::StationEl(
     UID id,
@@ -32,6 +38,36 @@ osc::StationEl::StationEl(
 {
 }
 
+osc::SceneElClass osc::StationEl::CreateClass()
+{
+    return
+    {
+        ModelGraphStrings::c_StationLabel,
+        ModelGraphStrings::c_StationLabelPluralized,
+        ModelGraphStrings::c_StationLabelOptionallyPluralized,
+        ICON_FA_MAP_PIN,
+        ModelGraphStrings::c_StationDescription,
+    };
+}
+
+std::vector<osc::CrossrefDescriptor> osc::StationEl::implGetCrossReferences() const
+{
+    return
+    {
+        {m_Attachment, ModelGraphStrings::c_StationParentCrossrefName, CrossrefDirection::ToParent},
+    };
+}
+
+std::ostream& osc::StationEl::implWriteToStream(std::ostream& o) const
+{
+    return o << "StationEl("
+        << "ID = " << m_ID
+        << ", Attachment = " << m_Attachment
+        << ", Position = " << m_Position
+        << ", Name = " << m_Name
+        << ')';
+}
+
 void osc::StationEl::implSetLabel(std::string_view sv)
 {
     m_Name = SanitizeToOpenSimComponentName(sv);
diff --git a/src/OpenSimCreator/ModelGraph/StationEl.hpp b/src/OpenSimCreator/ModelGraph/StationEl.hpp
index a4361658c..737ff2bdc 100644
--- a/src/OpenSimCreator/ModelGraph/StationEl.hpp
+++ b/src/OpenSimCreator/ModelGraph/StationEl.hpp
@@ -3,16 +3,13 @@
 #include <OpenSimCreator/ModelGraph/CrossrefDescriptor.hpp>
 #include <OpenSimCreator/ModelGraph/CrossrefDirection.hpp>
 #include <OpenSimCreator/ModelGraph/SceneElCRTP.hpp>
-#include <OpenSimCreator/ModelGraph/ModelGraphIDs.hpp>
-#include <OpenSimCreator/ModelGraph/ModelGraphStrings.hpp>
 
-#include <IconsFontAwesome5.h>
 #include <oscar/Maths/AABB.hpp>
 #include <oscar/Maths/Transform.hpp>
 #include <oscar/Maths/Vec3.hpp>
 #include <oscar/Utils/UID.hpp>
 
-#include <iostream>
+#include <iosfwd>
 #include <stdexcept>
 #include <string>
 #include <string_view>
@@ -48,25 +45,9 @@ namespace osc
 
     private:
         friend class SceneElCRTP<StationEl>;
-        static SceneElClass CreateClass()
-        {
-            return
-            {
-                ModelGraphStrings::c_StationLabel,
-                ModelGraphStrings::c_StationLabelPluralized,
-                ModelGraphStrings::c_StationLabelOptionallyPluralized,
-                ICON_FA_MAP_PIN,
-                ModelGraphStrings::c_StationDescription,
-            };
-        }
+        static SceneElClass CreateClass();
 
-        std::vector<CrossrefDescriptor> implGetCrossReferences() const final
-        {
-            return
-            {
-                {m_Attachment, ModelGraphStrings::c_StationParentCrossrefName, CrossrefDirection::ToParent},
-            };
-        }
+        std::vector<CrossrefDescriptor> implGetCrossReferences() const final;
 
         void implSetCrossReferenceConnecteeID(int i, UID id) final
         {
@@ -91,15 +72,7 @@ namespace osc
             return m_ID;
         }
 
-        std::ostream& implWriteToStream(std::ostream& o) const final
-        {
-            return o << "StationEl("
-                << "ID = " << m_ID
-                << ", Attachment = " << m_Attachment
-                << ", Position = " << m_Position
-                << ", Name = " << m_Name
-                << ')';
-        }
+        std::ostream& implWriteToStream(std::ostream&) const final;
 
         CStringView implGetLabel() const final
         {