Snake

// main.cpp:
#include <QGuiApplication>
#include <QQmlApplicationEngine>

int main(int argc, char *argv[]) {
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

// main.qml:
import QtQuick 2.9
import QtQuick.Window 2.2
import "logic.js" as Logic

Window {
    property bool stop: true
    property bool first: true
    property bool loose: false

    property string text: "Press Space"
    property int score: 0
    property int w: 400
    property int h: 400
    property int interval: 100

    id: mainWindow
    visible: true
    width: w
    height: h
    color: "transparent"
    minimumWidth: w
    maximumWidth: w
    minimumHeight: h
    maximumHeight: h
    title: qsTr("Snake")

    Text {
        text: mainWindow.text
        font.family: "Helvetica"
        font.pointSize: 24
        color: "red"
        x: mainWindow.w/2 - width/2
        y: mainWindow.h/2 - height/2 - 16
    }

    Text {
        text: "punkty " + mainWindow.score
        color: "red"
    }

    Item {
        focus: true
        Keys.onPressed: {
            if      (event.key === Qt.Key_Up)    Logic.turnUp()
            else if (event.key === Qt.Key_Down)  Logic.turnDown()
            else if (event.key === Qt.Key_Left)  Logic.turnLeft()
            else if (event.key === Qt.Key_Right) Logic.turnRight()
            else if (event.key === Qt.Key_Space) {
                if (first) {
                    first = false
                    stop = false
                    text = ""
                }
                else if (loose) {
                    text = ""
                    loose = false
                    stop = false
                    Logic.clear()
                    mainWindow.interval = 100
                }
            }
        }
    }

    Timer {
        id: timer
        interval: mainWindow.interval
        running: true
        repeat: true
        onTriggered: {
            if (!mainWindow.stop) {
                if (!Logic.update()) {
                    mainWindow.loose = true
                    mainWindow.stop = true
                    mainWindow.text = "Game Over!"
                }
                else {
                    score = Logic.score
                    if (score > 10) mainWindow.interval = 90
                    else if (score > 40) mainWindow.interval = 80
                    else if (score > 80) mainWindow.interval = 70
                    else if (score > 120) mainWindow.interval = 60
                }
            }
        }
    }

    Component.onCompleted: {
        Logic.start()
    }
}

// Segment.qml:
import QtQuick 2.0

Rectangle {
    id: root
    width: 20
    height: 20

    x: 0
    y: 0

    border.width: 2
    border.color: "#111111"
    //color: "#ff1111"
    color: "#172208"

    function ded() {
        root.destroy()
    }
}

// logic.js:
.import QtQuick 2.0 as Quick

var snake = new Array
var food = null
var component = Qt.createComponent("Segment.qml")

var vx = 0
var vy = -1

var score = 0

function start() {
    snake.push(createSegment(mainWindow.width/2, mainWindow.height/2, "#ff1111"))
    createFood()
}

function createSegment(x, y, color) {
    var dynamicObject = component.createObject(mainWindow)
    if (dynamicObject === null) {
        console.log(component.errorString())
        return false
    }

    dynamicObject.x = x
    dynamicObject.y = y
    dynamicObject.color = color
    //dynamicObject.opacity = 1
    return dynamicObject
}

function forward() {
    for (var i = snake.length-1; i > 0; i--) {
        snake[i].x = snake[i-1].x
        snake[i].y = snake[i-1].y
    }

    snake[0].x += 20*vx
    snake[0].y += 20*vy
}

function eat() {
    food.color = "#ff1111"
    food.x = snake[snake.length-1].x
    food.y = snake[snake.length-1].y
    snake.push(food)
}


function turnUp() {
    if (vy === 1 && snake.length > 1) return
    else {
        vx = 0
        vy = -1
    }
}

function turnDown() {
    if (vy === -1 && snake.length > 1) return
    else {
        vx = 0
        vy = 1
    }
}

function turnRight() {
    if (vx === -1 && snake.length > 1) return
    else {
        vx = 1
        vy = 0
    }
}

function turnLeft() {
    if (vx === 1 && snake.length > 1) return
    else {
        vx = -1
        vy = 0
    }
}

function createFood() {
    var repeat = true
    var x
    var y

    while (repeat) {
        repeat = false
        x = parseInt(Math.random()*mainWindow.w/20)*20
        y = parseInt(Math.random()*mainWindow.h/20)*20
        for (var i = 0; i < snake.length; i++) {
            if (x === snake[i].x && y === snake[i].y) repeat = true
        }
    }

    food = createSegment(x, y, "#11ff11")
}

function update() {
    forward()
    if (collision()) return false
    if (food.x === snake[0].x && food.y === snake[0].y) {
        eat()
        score++
        createFood()
    }

    return true
}

function collision() {
    for (var i = 1; i < snake.length; i++) {
        if (snake[0].x === snake[i].x && snake[0].y === snake[i].y) return true
    }

    if (snake[0].x < 0 || snake[0].x > mainWindow.w - 20 || snake[0].y < 0 || snake[0].y > mainWindow.h - 20) {
        return true
    }

    return false
}

function clear() {
    for (var i = snake.length-1; i > 0; i--) {
        snake[i].ded()
        snake.pop()
    }
    snake[0].x = mainWindow.width/2
    snake[0].y = mainWindow.height/2
    vx = 0
    vy = -1
    score = 0
}