How to load textures at other times than startup in XNA using vb.net?

Question

I've encountered a problem with my game project lately. When I load more than a certain number of textures (around 1000) at startup I recieve an error regarding memory, because I have to use 32-bit in XNA. I am self-taught and so have only basic knowledge of the "correct" ways to program a game. The project itself is getting very big and although I try to compress images together etc, I will have to use more than 1000 textures throughout the project.

My question is this: How can I load textures at other points of time than at startup in XNA, using vb.net? (I'm not using classes at all that I'm aware of, so I hope to stay away from that if possible)

Answer 1

First things first: You are free to call the ContentManager at any point in your game cycle (you're not restricted to the use the LoadContent() method created in the main class).

This doesn't solve your memory problem though, so on to part two:

If you run into memory issues because you have too much content loaded at the same time, you should only load the content that you actually need at that point in your game.

To free memory from loaded content, you can use Content.Unload() to release all content that the ContentManager holds. Note: Texture2D.Dispose() does not free up memory for Textures that are loaded via the ContentManager- as the ContentManager is in control of the lifetime of its content! (Sidenote: one should call Dispose() on content that is unmanaged -created without the ContentManager- though!)

A Content.Unload() releases all the content it contains so one might separate "generic" game content from "level specific" game content. Luckily you are able to create your own instance of the ContentManager so you can control what content is kept and what content is unloaded, like so:

C#:

ContentManager levelContentManager = new ContentManager( Game.Services, Content.RootDirectory );

or VB.Net

levelContentManager As New ContentManager(Content.ServiceProvider, Content.RootDirectory)

Now use:

levelContentManager.Unload()

when your level is completed and the level specific content is no longer used.

See also:

• MSDN: ContentManager Constructor
• MSDN: ContentManager Unload

An example application would be in a game like Street Fighter (only used as example, Street Fighter wasn't build in XNA). The "Generic ContentManager" holds generic data: the titlescreen, the "Get Ready, Fight!" letters and healthbars. The other "level ContentManager" only loads the sprite info of the selected chars and level.

When the characters and level object are created, have those objects load their content via the "level ContentManager". When the fight is over and the game goes back to the title screen: the "level ContentManager" unloads to free up the resources.

When the players start a new fight, the "level ContentManager" is used again to load the now selected characters and level data and the cycle repeats.

This way, the memory only holds the content it is actually using.

Answer 2

So the answer seems a lot easier than I expected, if I'm doing it right at the moment(?).

I simply Load the content needed for all "Worlds" in the beginning of the game (in the Protected Overrides Sub LoadContent()) and then Dispose() and Load.Content() depending on what World is loaded later (in any Sub I choose):

TextureName = Content.Load(Of Texture2D)("")
TextureName.Dispose()

If there isn't any problem I'm not yet aware of, this seem to do the trick and does not leave me with the memory error in the start.