Run on your computer¶

The desktop build uses SDL2 to open a window, read the keyboard or a gamepad, and play sound. It's the fastest way to work: rebuilds take seconds, and you can use your normal debugger.

The window shows the console's 128×128 screen at 2× scale. Resize it and the picture scales to fit.

Build¶

With the template's preset:

cmake --preset linux
cmake --build out/build/linux
./out/build/linux/game.elf

Or with plain CMake, from your game's folder:

mkdir build
cd build
cmake .. -D32BLIT_DIR=../../32blit-sdk
make
./game.elf

On Windows with Visual Studio, open the game's folder and let Visual Studio's CMake support configure it; see Visual Studio.

Controls¶

Console	Keyboard
D-pad	`Up` `Down` `Left` `Right` or `W` `A` `S` `D`
A	`Z` or `U`
B	`X` or `I`
X	`C` or `O`
Y	`V` or `P`
MENU	`2` or `Esc`
HOME	`1`

A game controller works too: its d-pad and face buttons map to the same buttons, Start is MENU, Back is HOME, and the left stick sets joystick.

The desktop build has no system menu or home screen, so HOME is just a button your game can read. Closing the window counts as quitting: on_quit is called, so your game can save.

Command line options¶

Option	Effect
`--fullscreen`	start full screen
`--position x,y`	place the window
`--size w,h`	set the window size
`--launch_path <file>`	pretend the game was opened with a file, as `get_launch_path()` returns
`--listen` / `--connect <addr>`	link two copies for multiplayer
`--info`	print the game's metadata and exit
`--credits`	print the 32blit contributors and exit

The title bar shows [SLOW] when update() can't keep up with 100 updates a second, and [FROZEN] if it stops returning.

Differences from the console¶

The desktop build runs the same engine code, but it is not an emulator:

Speed. Your computer is many times faster than the RP2350. A game that runs smoothly on the desktop can still drop frames on the console, so test on hardware regularly. See Performance and memory.
Memory. The desktop has no 448 KB limit. Allocations that work here can fail on the console.
Pixel format. The desktop screen is 24-bit RGB; the console's is 16-bit RGB565, so subtle gradients band slightly more on the console.
Files and saves. Files are read from the folder the game runs in. Saves go to SDL's per-user folder for the game's author and title, for example ~/.local/share/<author>/<title>/ on Linux, rather than the console's USB drive.
System calls. The battery, USB, settings and system info calls report "not available". Your game should cope with that, which it needs to do on older firmware anyway.

Build for the web¶

The same code builds to WebAssembly with Emscripten, which is handy for putting a playable demo online. See Web (Emscripten).