Drawing thousands of dynamic z-ordered sprites with SFML

Moony-SpriteBatch allows C++ developers that use SFML to draw many more sprites without worrying about performance limitations. This is significant because applications using SFML begin to slow down when drawing a couple thousand sprites. You can use Moony-SpriteBatch for drawing very large tilemaps, making a bullet hell game or a particle simulator. Moony-SpriteBatch also supports dynamic sprites and z-ordering. This library works directly with Moony-TexturePacker by rendering sprites that use the same texture and can even load .mtpf files produced by the TexturePacker.

The library is header only so there really isn't anything to build if you want to just jump straight in and use it. You only need to include TextureAtlas.h, SpriteBatch.h and Log.h if you want to use it for logging info. If you are going to be loading zlib compressed texture pack files then define USE_ZLIB in your source somewhere and link zlib to your application.

I provided an Example.cpp that showcases what Moony-SpriteBatch can do. To build the example program on Windows with Visual Studio open a Developer Command Prompt and enter this:

Change your directory to the source directory

cd C:/path/to/source

Compile and link the source code

cl /I C:/path/to/SFML/include C:/path/to/SFML/lib/sfml-system.lib C:/path/to/SFML/lib/sfml-window.lib C:/path/to/SFML/lib/sfml-graphics.lib Example.cpp

The code should compile and produce Example.exe.

If you want to build with zlib feature do this:

cl /D USE_ZLIB /I C:/path/to/SFML/include /I C:/path/to/zlib/include C:/path/to/SFML/lib/sfml-system.lib C:/path/to/SFML/lib/sfml-window.lib C:/path/to/SFML/lib/sfml-graphics.lib C:/path/to/zlib/lib/zlib.lib Example.cpp

You can also change out the names with debug versions of the libraries if you'd like. Remember that you must put sfml-system-2.dll, sfml-window-2.dll, sfml-graphics-2.dll and zlib.dll with the executable in order for it to run. If you want to link statically it's essentially the same thing but using the /MT flag, though I haven't tried it..

If you are using GCC or MinGW open a Command Prompt or Terminal and enter this:

Change your directory to the source directory

cd C:/path/to/source

Compile and link the source code

g++ Example.cpp -I C:/path/to/SFML/include -L C:/path/to/SFML/lib -lsfml-graphics -lsfml-window -lsfml-system -s -O2 -o Example.exe

And if you want to build with zlib:

g++ Example.cpp -D USE_ZLIB -I C:/path/to/SFML/include -I C:/path/to/zlib/include -L C:/path/to/SFML/lib -lsfml-graphics -lsfml-window -lsfml-system -L C:/path/to/zlib/lib -lzlib -s -O2 -o Example.exe

Note! I don't know if this needs saying but use your own directories. C:/path/to/SFML is not a real directory, just an example. Just in case..

The library is designed to be a drop in solution if you are using SFML. Grab the header files and put them where your project can see them and that's it. Now you have to include TextureAtlas.h to load .mtpf files. Loading the files work very similarly to loading resources in other SFML classes.

moony::TextureAtlas texture_atlas;
...
if(!texture_atlas.loadFromFile("path/to/texture/texture.mtpf");

Now that the moony::TextureAtlas object has deserialized our texture.mtpf file we need to create a moony::SpriteBatch object so that we can actually draw our sprites later on. Don't forget to include SpriteBatch.h!

...
moony::SpriteBatch sprite_batch;

Okay let's make our moony::Sprite object and set its texture and layer.

...
moony::Sprite player1;
player1.m_subtexture = texture_atlas.findSubTexture("mario.png");
player1.m_layer = 1;

As you can see getting your textures out of the moony::TextureAtlas object is super simple. The findSubTexture(); function returns a moony::Texture object that has a pointer to the underlying sf::Texture and the sf::IntRect which defines the bounds of the texture we requested. The reason I designed the system like this is so that you can use the textures with moony::Sprite or sf::Sprite by using the setTexture() and setTextureRect() functions.

Now on to the drawing. To draw your moony::Sprite objects you just need to pass it to moony::SpriteBatch in your render loop.

window.clear();

sprite_batch.clear();
sprite_batch.draw(player1);
...
sprite_batch.order();

window.draw(sprite_batch);

The moony::SpriteBatch has an API very similar to SFML's own sf::RenderTarget class. The sprite batch holds all the vertices of every sprite you have drawn and needs to be cleared or you will push extra vertices onto it's list. I do plan on coding a fool-proof way of doing this so you can't memory leak even if you tried but if you just remember to call moony::SpriteBatch::clear() before drawing your sprites you should be fine. The order function just arranges the sprites in order according to layer and texture. Finally, the sprite batch object is itself a sf::Drawable and can be drawn just like a sf::Sprite.

Can moony::SpriteBatch draw sf::Sprite objects? No.

Create a switch so that after every call to order() you are required to call clear() so that you don't overdraw and cause the internal array to grow without bounds.