refresh hierarchy after spawning model

Author: ProtectedVariable

ICEBERG/include/Viewport.h

@@ -13,6 +13,10 @@ class Viewport : public Controller {
 
     void setSelectedEntity(ICE::Entity e);
 
+    // True once after a model has been dropped into the viewport (the flag is cleared by the read),
+    // signalling that the scene gained entities and the hierarchy needs rebuilding.
+    bool entitySpawned();
+
    private:
     std::shared_ptr<ICE::ICEEngine> m_engine;
     bool m_done = false;
@@ -23,6 +27,7 @@ class Viewport : public Controller {
     const double scroll_speed = 0.5;
     ImGuizmo::OPERATION m_guizmo_mode = ImGuizmo::TRANSLATE;
     ICE::Entity m_selected_entity = 0;
+    bool m_entity_spawned = false;
     std::function<void()> m_entity_transformed_callback = [] {
     };
     std::function<void(ICE::Entity e)> m_entity_picked_callback = [](ICE::Entity) {

ICEBERG/src/Editor.cpp

@@ -59,6 +59,11 @@ bool Editor::update() {
     }
     m_audio_mixer.render();
     m_viewport->update();
+    // A model dropped into the viewport spawns entities behind the Hierarchy's back: rebuild its
+    // cached tree before it renders, so the new nodes show up on the same frame.
+    if (m_viewport->entitySpawned()) {
+        m_hierarchy->rebuildTree();
+    }
     m_hierarchy->update();
     m_inspector->update();
     m_assets->update();

ICEBERG/src/Viewport.cpp

@@ -100,6 +100,9 @@ Viewport::Viewport(const std::shared_ptr<ICE::ICEEngine> &engine, const std::fun
         if (uid == NO_ASSET_ID)
             return;
         ICE::Entity e = m_engine->getProject()->getCurrentScene()->spawnTree(uid, m_engine->getAssetBank());
+        // The spawn adds a whole node tree to the scene; the Hierarchy caches its view and has no
+        // other way to learn about it.
+        m_entity_spawned = true;
         m_entity_picked_callback(e);
     });
 }
@@ -161,3 +164,9 @@ bool Viewport::update() {
 void Viewport::setSelectedEntity(ICE::Entity e) {
     m_selected_entity = e;
 }
+
+bool Viewport::entitySpawned() {
+    bool spawned = m_entity_spawned;
+    m_entity_spawned = false;
+    return spawned;
+}