Don't mark entities with a ComponentState::NoChange component as modi…

…fied (#1391)

Signed-off-by: Ashton Larkin <[email protected]>

src/EntityComponentManager.cc

@@ -1912,6 +1912,10 @@ void EntityComponentManager::SetChanged(
     auto oneTimeIter = this->dataPtr->oneTimeChangedComponents.find(_type);
     if (oneTimeIter != this->dataPtr->oneTimeChangedComponents.end())
       oneTimeIter->second.erase(_entity);
+
+    // the component state is flagged as no change, so don't mark the
+    // corresponding entity as one with a modified component
+    return;
   }
 
   this->dataPtr->AddModifiedComponent(_entity);

src/EntityComponentManager_TEST.cc

@@ -2238,6 +2238,17 @@ TEST_P(EntityComponentManagerFixture,
   EXPECT_EQ(ComponentState::NoChange,
       manager.ComponentState(e2, c2->TypeId()));
 
+  // Marking a component that isn't changed as unchanged again shouldn't effect
+  // the ecm's changed state
+  manager.RunClearNewlyCreatedEntities();
+  EXPECT_EQ(0, manager.ChangedState().entities_size());
+  manager.SetChanged(e1, c1->TypeId(), ComponentState::NoChange);
+  EXPECT_EQ(ComponentState::NoChange,
+      manager.ComponentState(e1, c1->TypeId()));
+  EXPECT_FALSE(manager.HasOneTimeComponentChanges());
+  EXPECT_EQ(0u, manager.ComponentTypesWithPeriodicChanges().size());
+  EXPECT_EQ(0, manager.ChangedState().entities_size());
+
   // Mark as changed
   manager.SetChanged(e1, c1->TypeId(), ComponentState::PeriodicChange);