The code contains a system of interfaces for coding games, defined in software/internal/game/game.go. This interface is:

type Game interface {
	Update(dt float64, input platform.InputSystem, log platform.LogSystem) Game
	Draw(platform.Screen)
}

In addition to this, each game should implement a function that returns a new Game object, for instantiation.

Functions

Update function

The update function takes dt, the delta time since the last frame, a reference to the input system (which has methods such as input.WasKeyJustPressed), and a logging system, which contains a single function (log.Log) to log information to either the browser console or to serial, depending on whether the wasm or device version is running.

At the end of the function, you must return a Game object. This normally is just a reference to the current game; the only times that this is not the case is in the Menu game where other games can be launched, and when a game is being exited, in which nil can be returned in order to exit the game and return to the menu

Draw function

The draw function is pretty simple. It gives a reference to the Screen object (with functions such as Pixel and DrawRect), which can be drawn to. At the end of this function, you must call Screen.Present(). Also it should be noted that the buffer is not reset in between frames, so if you don’t want to be drawing on top of the previous frame, you should call screen.Fill to set the entire buffer to a certain colour.

There are also some helpers functions in the helpers module for drawing images and text, which you can pass the screen object to. These functions work by just calling Pixel() a bunch of times to draw to the screen.

Images

to include an image in the program, you’ll need to process it before you can use it with DrawSprite. First, draw your image in whatever program you use, like krita or ms paint. Then, put your image into /helpers, rename it to image.png, and run the python script. The python script will give you a .bin file that you can put into your code with //go:embed. For example, in the flappy bird game, there’s a system. I also made a website at /software/web/convert that does the same thing, with a nice ui. This is fully vibe coded in like 30 seconds, but works ok for what it needs to. It’s just a simple tool, i didn’t want to devote any actual coding time to.

//go:embed bird.bin
var rawBirdData string

var BirdSprite = helpers.Image{
	Data: rawBirdData,
	W:    12,
	H:    12,
}

This means that the data of the sprite never clogs up our ram, and is streamed straight from the flash ROM to the screen buffer!

Template

You can find a simple template game in software/game/template/template.go, which provides a minimal implementation of all these methods to build off.