So I'm working on my first hobby game where I have to implement a proper asset loading system, in my previous projects I have had no problem fitting everything in memory at once. In this, I have estimated that VRAM will most likely be a limiting factor that makes that approach impossible. Though fitting it all in system RAM should not be an issue.
Now, I do not need every art asset loaded at once of course, and determining and limiting what needs to be loaded and what does not is not really what I wonder here. Instead I'm unsure on how to go about designing a proper asset loading system.
While I try to eliminate loading screens, beyond an initial, altogether by being smart about what is loaded and what is not the game still nicely needs to handle the sudden need for an unloaded art asset. Perhaps an object that requires it is suddenly spawned by an in-game event. The way I would like to handle this from the users perspective is to simply pause the game until it is loaded and pop up a "Loading" text on the screen.
I have two possible implementations in mind for this:
1. Finish executing the current frame, render the game state with the "Loading" text and do not do another update until the asset(s) are done loading asynchoniously. This does pose the limitation that any assets cannot be used in the frame they are requested as they may not have loaded yet, which can be an issue as the heaviest of them are both used for graphical and gameplay data.
2. Have the game-loop execute in a seperate thread, and pause that thread whenever an unloaded asset is used. The seperate rendering thread needs to handle this correctly (note that I already have a seperate rendering thread). This should pose few issues, but feels overly complicated for such a task.
So how do games usually do this?
Finally, I'm wondering if it is a good idea to have each State (ie startup menu, game running and the like) provide a seperate "loading state" that they enter when they want to show the user that they are loading something? It feels like it should not be their concern, but each state may need to show different loading screens and at least one of the different "loading screens" will need graphical information for the current game state.