WIP

entitysystem/systems/HierarchySystem.cpp

@@ -0,0 +1,27 @@
+#include "stdafx.h"
+#include "HierarchySystem.h"
+
+#include "entitysystem/ECWorld.h"
+#include "entitysystem/components/BasicComponents.h"
+
+void HierarchySystem::Update(ECWorld& world, float dt)
+{
+    world.Each<ECSComponent::Parent, ECSComponent::Transform>(
+        entt::exclude<ECSComponent::Disabled>,
+        [&](entt::entity, ECSComponent::Parent& parent, ECSComponent::Transform& childTransform)
+        {
+            if (parent.value == entt::null || !world.IsAlive(parent.value))
+                return;
+
+            const auto* parentTransform = world.GetComponent<ECSComponent::Transform>(parent.value);
+            if (!parentTransform)
+                return;
+
+            // Rotate local offset by parent rotation then add parent world position.
+            glm::dvec3 rotatedOffset = glm::dvec3(parentTransform->Rotation * glm::vec3(parent.localOffset));
+            childTransform.Position = parentTransform->Position + rotatedOffset;
+
+            // Compose rotations: child world = parent world * child local.
+            childTransform.Rotation = parentTransform->Rotation * parent.localRotation;
+        });
+}