First Application

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This tutorial assumes the initial project setup has already been completed.

For this tutorial we will be using the JVM target for our testing. Ensure there is a jvmMain module already created.

The application

The first thing when creating a new LittleKt application is to create a LittleKtApp. This app, once started, will create a context in which we can pass on in to our listeners to make use of. Each target may take slightly different parameters when creating a new LittleKtApp but fortunately there is a method that we can make use of to make it easy.

// Under jvmMain/kotlin/my/game

fun main(args: Array<String>) {
    val app = createLittleKtApp {
        width = 960
        height = 540
        vSync = true
        title = "My First LittleKt App"

Pretty easy, right? We can start the app by using the start method which expects a lambda that returns a ContextListener. But before that we need to actually create a ContextListener.

ContextListener allows use to “listen” in on the Context and access all the goodies it offers. Creating a ContextListener is as easy as extending the class under commonMain.

class MyGame(context: Context) : ContextListener(context) {

    override suspend fun Context.start() {
        // this is where we can use the context to add render calls, dispose, calls, etc. All the logic should go here.
        val texture = resourceVfs["texture.png"].readTexture() // reads a texture on the main thread from the resources
        onRender { dt -> // this adds a render updater that is called on every frame
            // render logic can go here

Now we can go back and start the app by calling the start method. The lambda passes in a Context reference which we can use to pass into our ContextListener.

app.start { MyGame(it) }

Now if we run the application, we should see a window pop up with the title of “My First LittleKt App”.