KAPLAY v4000 Alpha 22

lajbel, 10/9/2025, from sponges factory

Hey! lajbel here to introduce you the 4000.0.0-alpha.22 and this new blog format, where we gonna talk about the specific releases in the KAPLAY repository.

To install it, you can use:

npm install kaplay@4000.0.0-alpha.22

There’s a new super cool thing called Advanced TypeScript features, a new API that will let you use TypeScript in a more powerful way, getting autocomplete in places where before it has been impossible, until now:

In the other side, we got constraints, a way to restrict the movement of game objects.

A lot of more was added, like improvements in Animation API, new AI methods and new ways to transform objects (with skew). Thanks to all contributors helping with KAPLAY. I’ll leave you with the full changelog.

[4000.0.0-alpha.22] - 2025-10-9

Added

Added KAPLAYOpt.types, kaplayTypes() and Opt to config specific TypeScript Advanced Features (TAF) - @lajbel

kaplay({
    types: kaplayTypes<
        // Opt<> is optional but recommended to get autocomplete
        Opt<{
            scenes: {}; // define scenes and arguments
            strictScenes: true; // you can only use defined scenes
        }>
    >(),
});

Added TypesOpt.scenes to type scenes and parameters - @lajbel

const k = kaplay({
    types: kaplayTypes<
        Opt<{
            scenes: {
                game: [gamemode: "normal" | "hard"];
                gameOver: [score: number, highScore: number];
            };
        }>
    >(),
});

// If you trigger autocomplete it shows "game" or "gameOver"
k.scene("game", (gamemode) => {
    // gamemode is now type "normal" | "hard"

    // @ts-expect-error Argument of type 'string' is not assignable
    // to parameter of type 'number'.
    k.go("gameOver", "10", 10); //
});

The methods that support this are:

Added TypesOpt.strictScenes to make usable scenes just the ones defined - @lajbel

const k = kaplay({
    types: kaplayTypes<
        Opt<{
            scenes: {
                game: [gamemode: "normal" | "hard"];
                gameOver: [score: number, highScore: number];
            };
            strictScenes: true;
        }>
    >(),
});

// @ts-expect-error Argument of type '"hi"' is not assignable to
// parameter of type '"game" | "gameOver"'.
k.scene("hi", () => {});

Added named animations - @mflerackers

By giving a name to an animation, you can define more than one animation
```
const anim = obj.animation.get("idle");
anim.animate("pos", [0, 5, 0], { relative: true });
```
Added screenshotToBlob() to get a screenshot as a Blob - @dragoncoder047
Added getButtons() to get the input binding buttons definition - @lajbel
Added RuleSystem, DecisionTree and StateMachine for enemy AI - @mflerackers
Added constraint components for distance, translation, rotation, scale and transform constraints - @mflerackers
Added inverse kinematics constraint components using FABRIK and CCD, the latter one can use bone constraints to constrain the angle - @mflerackers
Added skew to Mat23, transformation stack, RenderProps, GameObjRaw as well as a component - @mflerackers
Added texture uniforms, in order to access more than one texture at a time in shaders - @mflerackers

Fixed

Now error screen should be instantly shown - @lajbel

Changed

Now, you can use color(c) with a hexadecimal literal number (ex: 0x00ff00) - @lajbel
```
// blue frog
add([
    sprite("bean"),
    color(0x0000ff),
]);
```
(!) KAPLAYCtx doesn’t use generics anymore. Now, KAPLAYCtxT uses them - @lajbel
Now, kaplay will return KAPLAYCtx or KAPLAYCtxT depending if it’s using Advanced TypeScript Features or not - @lajbel
loadShader() now also checks for link errors as well as compile errors and reports them rather than just silently trying to use a borked shader - @dragoncoder047
The debug record() function now records with sound enabled like it should - @dragoncoder047
Now KAPLAYOpt.spriteAtlasPadding is set to 2 by default - @lajbel
Transformation and drawing is split now, so the transform can be modified before drawing - @mflerackers