Ray Low Level API

The Low Level API (Engine.*) is designed for versatile 2D game creation.

Every API function takes one parameter. The parameter must be a dictionary, and arguments must be stored as key-and-value pairs.

Skelton

// Do not define variables outside functions because it's a syntax error.

// Called when the window is created.
func setup() {
    // Return the window configuration.
    return {
        width: 1280,
        height: 720,
        title: "My First Game"
    };
}

// Called once when the game starts.
func start() {
    // Global variables should be defined here.
    posX = 0;
    posY = 0;

    // Create a white 100x100 texture.
    tex = Engine.createColorTexture({
        width: 100,
        height: 100,
        r: 255, g: 255, b: 255, a: 255
    });
}

// Called every frame before rendering.
func update() {
    posX = Engine.mousePosX;
    posY = Engine.mousePosY;
}

// Called every frame to render graphics.
func render() {
    Engine.draw({ texture: tex, x: posX, y: posY });
}

Debug

print()

This API prints a string or dumps an object. Only takes a non-dictionary argument.

func dumpEnemies() {
    if (Engine.isGamepadXPressed) {
        print("[Current emenies]");
        print(enemies);
    }
}

Time

Absolute Time

func update() {
    // Get the seconds since the last call.
    var curTime = Engine.millisec;
    var dt = (curTime - lastTime) * 0.001;
    lastTime = curTime;

    updateCharacters(dt);
}

Engine.getDate()

Returns a date dictionary.

func frame() {
    var date = Engine.getDate({});

    var year  = date.year;
    var month = date.month;
    var day   = date.day;
    var hour  = date.hour;
    var min   = date.minute;
    var sec   = date.second;
}

Input

These are variables, not functions.

func update() {
    if (Engine.isMouseLeftPressed) {
        player.x = player.x + 100;
    }
}

Rendering

Engine.createColorTexture()

This API creates a texture with the specified color, and returns a texture.

func createBlockTexture() {
    blockTex = Engine.createColorTexture({
                   width:  16,
                   height: 16,
                   r:      255,
                   g:      255,
                   b:      255,
                   a:      255
               });
}

Engine.loadTexture()

This API loads a texture from assets, and returns a texture.

func loadPlayerTexture() {
   playerTex = Engine.loadTexture({
                   file: "player.png"
               });

   var width = playerTex.width;
   var height = playerTex.height;
}

Engine.destroyTexture()

This API destroys a texture.

func destroyPlayerTexture() {
    Engine.loadTexture({
        texture: playerTex
    });
}

Engine.renderTexture()

This API renders a texture to the screen.

func renderPlayer() {
    Engine.renderTexture({
        dstLeft:   playerPos.x,
        dstTop:    playerPos.y,
        dstWidth:  playerTex.width,
	dstHeight: playerTex.height,
        texture:   playerTex,
        srcLeft:   0,
        srcTop:    0,
        srcWidth:  playerTex.width,
        srcHeight: playerTex.height,
        alpha:     255
    });
}

Engine.draw()

This API renders a texture to the screen (a simpler version of Engine.renderTexture().)

func renderPlayer() {
    Engine.draw({
        texture: playerTex,
        x:       playerPos.x,
        y:       playerPos.y
    });
}

Engine.renderTexture3D()

This API renders a texture to the screen.

func renderPlayer() {
    Engine.renderTexture({
        dstLeft:   playerPos.x,
        dstTop:    playerPos.y,
        dstWidth:  playerTex.width,
	dstHeight: playerTex.height,
        texture:   playerTex,
        srcLeft:   0,
        srcTop:    0,
        srcWidth:  playerTex.width,
        srcHeight: playerTex.height,
        alpha:     255
    });
}

Engine.loadFont()

This API loads an asset font file to a specified font slot.

func loadNotoSansFont() {
    Engine.loadFont({ slot: 0, file: "NotoSans.ttf" });
}

Engine.createTextTexture()

This API creates a texture and draws a text on it.

func createScoreTexture() {
    scoreTex = Engine.createTextTexture({
                   slot: 0,
                   text: "Score: " + score,
                   size: 32,
                   r:    255,
                   g:    255,
                   b:    255,
                   a:    255
               });
}

Sound

Engine.playSound()

This API starts playing a sound asset file on a specified sound track.

func playJumpSound() {
    Engine.playSound({ stream: 0, file: "jump.ogg" });
}

Engine.playSoundLoop()

This API starts playing a sound asset file on a specified sound track.

func playBGM() {
    Engine.playSoundLoop({ stream: 0, file: "jump.ogg" });
}

Engine.stopSound()

This API stops a sound playback on a specified sound track.

func playJumpSound() {
    Engine.stopSound({ stream: 0 });
}

Engine.setSoundVolume()

This API sets a sound volume on a specified sound track.

func playJumpSound() {
    Engine.setSoundVolume({
        stream: 0,
        volume: 1.0
    });
}

Save Data

Engine.writeSaveData()

This API writes a save data value that corresponds to a key string. If the save data value is too large, this API will fail.

Engine.readSaveData()

This API reads save data value that corresponds to a key string. The return value will be an object that represents a save data value. This API will fail when the specified key is not available.

Engine.checkSaveData()

This API checks whether the save data exists for a key string or not. The return value is a boolean.