ResourceManager doesn't implement Reference Counting.

[Kaminate]

According to 04_resource_management.adoc,

When designing a resource management system, you’ll need to address several challenges:
3. Reference Counting - Track how many objects are using a resource to know when it can be safely unloaded.

This seems to be implemented as int ResourceManager::ResourceData::refCount, but it's never modified in 04_resource_management.adoc, and doesn't exist in resource_manager.h.

[gpx1000]

While in general, we shouldn't expect the tutorial text to exactly match the example code for the game engine (done that way on purpose) as the tutorial text is more of a survey of popular implementations and provides a chance to research and implement etc with the code provided as a starting point, along with copious code snippets of differing techniques for explanation for each concept; I think you might have found an unintentional gap in what was intended. Thanks for the report.

I'll try to address it.