Map iterator error happens in World::Update() if prev wolrd/scene was not removed before loading new scene

[Dreikblack]

1. Checkout commit which was before removing prev game workaround fix:

https://github.com/Dreikblack/CppTutorialProject/commit/a9eb6a2ceb55d1aa03cd53029c0ee889bf939a8c

2. Save in game by F5.

3. Then just do load by F9 few times in row - usually on 3rd error happens

[Josh]

On 1/31/2025 at 9:23 AM, Dreikblack said:

Checkout commit which was before removing prev game workaround fix:

How do I check out a specifica commit on Github? I don't know how to do this.

[Dreikblack]

In git bash in project folder: git checkout a9eb6a2ceb55d1aa03cd53029c0ee889bf939a8c

UI needs to be reworked a bit due API changes.

[Dreikblack]

Updated master branch. Just checkout it.

Error may happen at random load. Had it once and 2nd load and two times at ~10th

[Josh]

Does this occur in the current build?

[Dreikblack]

15 hours ago, Josh said:

Does this occur in the current build?

Yes, same error after 5-6 loads

[Dreikblack]

To reproduce it you can checkout master branch and just comment or remove "game.reset();" line after comment "//to avoid random error in World::Update()" at 59 line

[Josh]

12 hours ago, Dreikblack said:

To reproduce it you can checkout master branch and just comment or remove "game.reset();" line after comment "//to avoid random error in World::Update()" at 59 line

What file is this in? I am up to date on the master branch, but cannot find any occurance of the text "to avoid random error" in the project.

[Dreikblack]

Sorry, i meant main.cpp (in https://github.com/Dreikblack/CppTutorialProject)

[Josh]

This is what the update loop looks like. It is crashing on the last line where the iterator is incremented. It says the iterator is the end iterator. I do not know how this is possible. The list "entitieswithnewcomponents" just means "entities that have a component with an Update method".

Do you know what component is in use that has an Update() method that causes this?

		//Update components
		{
			auto it = entitieswithnewcomponents.begin();
			while (it != entitieswithnewcomponents.end())
			{
				auto e = (*it).lock();
				if (e == NULL)
				{
					it = entitieswithnewcomponents.erase(it);
					continue;
				}
				e->failedcomponentcalls = 0;
				for (auto c : e->components)
				{
					if (c->GetEnabled()) c->Update(); 
				}
				if (e->failedcomponentcalls == e->components.size())
				{
					it = entitieswithnewcomponents.erase(it);
					continue;
				}
				++it;
			}
		}

 

[Dreikblack]

I don't know, i may try to find out next time later

[Josh]

It looks like TopDownCamera was the last component that executed, but I do not see anything suspicious in there.

Are you doing anything like loading a scene in a component?

[Dreikblack]

I don't think so, loading happens maybe in game and main files afaik

[Josh]

The code I had originally should handle changes to the STL set just fine. I replaced it with this code, and the error no longer occurs. I still don't understand why. This seems like incorrect behavior in STL.

//https://www.leadwerks.com/community/topic/67870-map-iterator-error-happens-in-worldupdate-if-prev-wolrdscene-was-not-removed-before-loading-new-scene/
auto it = entitieswithnewcomponents.begin();
std::vector<std::shared_ptr<Entity> > entities;
entities.reserve(entitieswithnewcomponents.size());

while (it != entitieswithnewcomponents.end())
{
	auto e = (*it).lock();
	if (e == NULL)
	{
		it = entitieswithnewcomponents.erase(it);
		continue;
	}
	entities.push_back(e);
	++it;
}

for (auto e : entities)
{
	e->failedcomponentcalls = 0;
	for (auto c : e->components)
	{
		if (c->GetEnabled()) c->Update();
	}
	if (e->failedcomponentcalls == e->components.size())
	{
		auto it = entitieswithnewcomponents.find(e);
		if (it != entitieswithnewcomponents.end()) entitieswithnewcomponents.erase(it);
	}
}

 

[Josh]

The update for this is available on Steam now.

[Josh]

BTW, the reason your project takes so long to compile is because every file is set to create a precompiled header. Only Leadwerks.cpp should have this set to Create. Every other file should be set to Use, or for SelectDevice.cpp, "Not using precompiled header".

[Dreikblack]

4 minutes ago, Josh said:

Every other file should be set to Use, or for SelectDevice.cpp, "Not using precompiled header".

How to do so?

[Josh]

CppTutorialProject-master.zip

[Dreikblack]

Found: