From c3c1d5ae286c864200994d1b18fee44d871d463f Mon Sep 17 00:00:00 2001
From: Bram Verhulst <Brammieverhulst@gmail.com>
Date: Wed, 12 Aug 2026 01:18:47 +0200
Subject: [PATCH] feat: add "Add component" button

---
 .../destrum/Serialization/ComponentFactory.h  | 17 +++++
 .../Serialization/EngineComponentList.h       | 27 +++++++
 .../src/Serialization/ComponentRegistry.cpp   | 61 ++--------------
 destrum/src/Util/ImGuiUtils.cpp               | 71 ++++++++++++++++++-
 tests/destrum_tests.cpp                       | 29 ++++++++
 5 files changed, 146 insertions(+), 59 deletions(-)
 create mode 100644 destrum/include/destrum/Serialization/EngineComponentList.h

diff --git a/destrum/include/destrum/Serialization/ComponentFactory.h b/destrum/include/destrum/Serialization/ComponentFactory.h
index 0d86f86..9a31fd1 100644
--- a/destrum/include/destrum/Serialization/ComponentFactory.h
+++ b/destrum/include/destrum/Serialization/ComponentFactory.h
@@ -5,6 +5,7 @@
 #include <memory>
 #include <string>
 #include <unordered_map>
+#include <vector>
 
 #include <destrum/ObjectModel/Component.h>
 #include <destrum/ObjectModel/GameObject.h>
@@ -17,6 +18,13 @@ public:
         Registry()[typeName] = std::move(createFn);
     }
 
+    template <typename TComponent>
+    static void Register(const char* typeName) {
+        Register(std::string{typeName}, [](GameObject& owner) -> Component* {
+            return owner.AddComponent<TComponent>();
+        });
+    }
+
     static Component* Create(const std::string& typeName, GameObject& owner) {
         const auto it = Registry().find(typeName);
 
@@ -31,6 +39,15 @@ public:
         return Registry().contains(typeName);
     }
 
+    [[nodiscard]] static std::vector<std::string> GetRegisteredTypeNames() {
+        std::vector<std::string> typeNames;
+        typeNames.reserve(Registry().size());
+        for (const auto& [typeName, _] : Registry()) {
+            typeNames.push_back(typeName);
+        }
+        return typeNames;
+    }
+
 private:
     static std::unordered_map<std::string, CreateFn>& Registry() {
         static std::unordered_map<std::string, CreateFn> registry;
diff --git a/destrum/include/destrum/Serialization/EngineComponentList.h b/destrum/include/destrum/Serialization/EngineComponentList.h
new file mode 100644
index 0000000..88eca6e
--- /dev/null
+++ b/destrum/include/destrum/Serialization/EngineComponentList.h
@@ -0,0 +1,27 @@
+#ifndef DESTRUM_ENGINECOMPONENTLIST_H
+#define DESTRUM_ENGINECOMPONENTLIST_H
+
+// Keep the component manifest in one place. Consumers define X before
+// expanding one of these lists to generate registration or other metadata.
+#include <destrum/Components/Animator.h>
+#include <destrum/Components/MeshRendererComponent.h>
+#include <destrum/Components/OrbitAndSpin.h>
+#include <destrum/Components/Rotator.h>
+#include <destrum/Components/Spinner.h>
+#include <destrum/Components/Physics/BoxCollider.h>
+#include <destrum/Components/Physics/CapsuleCollider.h>
+#include <destrum/Components/Physics/Rigidbody.h>
+#include <destrum/Components/Physics/SphereCollider.h>
+
+#define DESTRUM_ENGINE_COMPONENTS(X) \
+    X(MeshRendererComponent) \
+    X(Rotator) \
+    X(Spinner) \
+    X(OrbitAndSpin) \
+    X(Animator) \
+    X(Rigidbody) \
+    X(BoxCollider) \
+    X(SphereCollider) \
+    X(CapsuleCollider)
+
+#endif // DESTRUM_ENGINECOMPONENTLIST_H
diff --git a/destrum/src/Serialization/ComponentRegistry.cpp b/destrum/src/Serialization/ComponentRegistry.cpp
index 7eb5feb..428d4e3 100644
--- a/destrum/src/Serialization/ComponentRegistry.cpp
+++ b/destrum/src/Serialization/ComponentRegistry.cpp
@@ -1,18 +1,6 @@
-// destrum/Serialization/ComponentRegistry.cpp
-
 #include <destrum/Serialization/ComponentRegistry.h>
 #include <destrum/Serialization/ComponentFactory.h>
-
-#include <destrum/Components/MeshRendererComponent.h>
-#include <destrum/Components/Rotator.h>
-#include <destrum/Components/Spinner.h>
-#include <destrum/Components/OrbitAndSpin.h>
-#include <destrum/Components/Animator.h>
-
-#include <destrum/Components/Physics/Rigidbody.h>
-#include <destrum/Components/Physics/BoxCollider.h>
-#include <destrum/Components/Physics/CapsuleCollider.h>
-#include <destrum/Components/Physics/SphereCollider.h>
+#include <destrum/Serialization/EngineComponentList.h>
 
 void RegisterEngineComponents()
 {
@@ -23,47 +11,8 @@ void RegisterEngineComponents()
 
     registered = true;
 
-    ComponentFactory::Register("MeshRendererComponent", [](GameObject& owner) {
-        return owner.AddComponent<MeshRendererComponent>();
-    });
-    // Keep the old serialized spelling readable while writing the canonical
-    // component name returned by MeshRendererComponent.
-    ComponentFactory::Register("MeshRenderer", [](GameObject& owner) {
-        return owner.AddComponent<MeshRendererComponent>();
-    });
-
-    ComponentFactory::Register("Rotator", [](GameObject& owner) {
-        return owner.AddComponent<Rotator>();
-    });
-
-    ComponentFactory::Register("Spinner", [](GameObject& owner) {
-        return owner.AddComponent<Spinner>();
-    });
-
-    ComponentFactory::Register("OrbitAndSpin", [](GameObject& owner) {
-        return owner.AddComponent<OrbitAndSpin>();
-    });
-
-    ComponentFactory::Register("Animator", [](GameObject& owner) {
-        return owner.AddComponent<Animator>();
-    });
-
-    ComponentFactory::Register("Rigidbody", [](GameObject& owner) {
-        return owner.AddComponent<Rigidbody>();
-    });
-    ComponentFactory::Register("RigidBody", [](GameObject& owner) {
-        return owner.AddComponent<Rigidbody>();
-    });
-
-    ComponentFactory::Register("BoxCollider", [](GameObject& owner) {
-        return owner.AddComponent<BoxCollider>();
-    });
-
-    ComponentFactory::Register("SphereCollider", [](GameObject& owner) {
-        return owner.AddComponent<SphereCollider>();
-    });
-
-    ComponentFactory::Register("CapsuleCollider", [](GameObject& owner) {
-        return owner.AddComponent<CapsuleCollider>();
-    });
+#define DESTRUM_REGISTER_COMPONENT(ComponentType) \
+    ComponentFactory::Register<ComponentType>(#ComponentType);
+    DESTRUM_ENGINE_COMPONENTS(DESTRUM_REGISTER_COMPONENT)
+#undef DESTRUM_REGISTER_COMPONENT
 }
diff --git a/destrum/src/Util/ImGuiUtils.cpp b/destrum/src/Util/ImGuiUtils.cpp
index d405004..854ce18 100644
--- a/destrum/src/Util/ImGuiUtils.cpp
+++ b/destrum/src/Util/ImGuiUtils.cpp
@@ -2,6 +2,7 @@
 
 #include <algorithm>
 #include <cfloat>
+#include <exception>
 #include <string>
 #include <unordered_set>
 #include <vector>
@@ -14,6 +15,8 @@
 #include <destrum/ObjectModel/Component.h>
 #include <destrum/ObjectModel/GameObject.h>
 #include <destrum/ObjectModel/Transform.h>
+#include <destrum/Serialization/ComponentFactory.h>
+#include <destrum/Serialization/ComponentRegistry.h>
 
 namespace {
     [[nodiscard]] bool IsInspectableObject(const GameObject* object) {
@@ -121,6 +124,8 @@ namespace ImGuiUtils {
         const std::vector<std::shared_ptr<GameObject>>& objectsSource,
         const std::vector<std::shared_ptr<GameObject>>& pendingAdditions,
         ObjectId& selectedObjectId) {
+        RegisterEngineComponents();
+
         std::vector<GameObject*> objects;
         objects.reserve(objectsSource.size() + pendingAdditions.size());
 
@@ -268,9 +273,69 @@ namespace ImGuiUtils {
                         worldPosition.z);
                 }
 
-                if (ImGui::CollapsingHeader(
-                        "Components",
-                        ImGuiTreeNodeFlags_DefaultOpen)) {
+                const bool componentsOpen = ImGui::CollapsingHeader(
+                    "Components",
+                    ImGuiTreeNodeFlags_DefaultOpen);
+
+                if (componentsOpen) {
+                    if (ImGui::Button("+ Add Component")) {
+                        ImGui::OpenPopup("AddComponentPopup");
+                    }
+
+                    std::string addComponentError;
+                    if (ImGui::BeginPopup("AddComponentPopup")) {
+                        std::vector<std::string> componentTypes =
+                            ComponentFactory::GetRegisteredTypeNames();
+                        std::sort(componentTypes.begin(), componentTypes.end());
+
+                        bool hasAvailableComponent = false;
+                        for (const std::string& componentType : componentTypes) {
+                            const bool alreadyAdded = std::any_of(
+                                selectedObject->GetComponents().begin(),
+                                selectedObject->GetComponents().end(),
+                                [&componentType](const auto& component) {
+                                    return component != nullptr &&
+                                           !component->IsBeingDestroyed() &&
+                                           component->GetTypeName() == componentType;
+                                });
+
+                            if (alreadyAdded) {
+                                const std::string label =
+                                    componentType + " (already added)";
+                                ImGui::BeginDisabled();
+                                ImGui::MenuItem(label.c_str());
+                                ImGui::EndDisabled();
+                                continue;
+                            }
+
+                            hasAvailableComponent = true;
+                            if (ImGui::MenuItem(componentType.c_str())) {
+                                try {
+                                    if (ComponentFactory::Create(
+                                            componentType,
+                                            *selectedObject) == nullptr) {
+                                        addComponentError =
+                                            "Component type is not registered: " +
+                                            componentType;
+                                    } else {
+                                        ImGui::CloseCurrentPopup();
+                                    }
+                                } catch (const std::exception& exception) {
+                                    addComponentError = exception.what();
+                                }
+                            }
+                        }
+
+                        if (!hasAvailableComponent) {
+                            ImGui::TextDisabled("All components are already added.");
+                        }
+                        if (!addComponentError.empty()) {
+                            ImGui::TextWrapped("Failed to add component: %s",
+                                               addComponentError.c_str());
+                        }
+                        ImGui::EndPopup();
+                    }
+
                     bool hasComponents = false;
                     for (const auto& component : selectedObject->GetComponents()) {
                         if (component == nullptr || component->IsBeingDestroyed()) {
diff --git a/tests/destrum_tests.cpp b/tests/destrum_tests.cpp
index 6253001..25eb481 100644
--- a/tests/destrum_tests.cpp
+++ b/tests/destrum_tests.cpp
@@ -13,6 +13,8 @@
 #include <destrum/ObjectModel/GameObject.h>
 #include <destrum/Scene/Scene.h>
 #include <destrum/Scene/SceneManager.h>
+#include <destrum/Serialization/ComponentFactory.h>
+#include <destrum/Serialization/ComponentRegistry.h>
 #include <destrum/Serialization/SceneSerializer.h>
 #include <destrum/Physics/SimplePhysicsWorld.h>
 #include <destrum/Physics/JoltPhysicsWorld.h>
@@ -161,6 +163,32 @@ namespace {
         SceneManager::GetInstance().Destroy();
     }
 
+    void testEngineComponentRegistration()
+    {
+        RegisterEngineComponents();
+
+        const char* canonicalNames[] = {
+            "MeshRendererComponent",
+            "Rotator",
+            "Spinner",
+            "OrbitAndSpin",
+            "Animator",
+            "Rigidbody",
+            "BoxCollider",
+            "SphereCollider",
+            "CapsuleCollider"
+        };
+        for (const char* name : canonicalNames) {
+            check(ComponentFactory::IsRegistered(name),
+                  "all canonical engine component names must be registered");
+        }
+
+        check(!ComponentFactory::IsRegistered("MeshRenderer"),
+              "MeshRenderer legacy alias must not be registered");
+        check(!ComponentFactory::IsRegistered("RigidBody"),
+              "RigidBody legacy alias must not be registered");
+    }
+
     void testAssetPathValidation()
     {
         const auto root = std::filesystem::temp_directory_path() / "destrum_asset_test";
@@ -440,6 +468,7 @@ int main()
     testEventMutation();
     testEventRemoval();
     testComponentRemoval();
+    testEngineComponentRegistration();
     testAssetPathValidation();
     testLegacySceneLoad();
     testSceneLoadRollback();