Offer me a good QML exercise

[J.Hilk]

@tomy you mean Pong ? :-)

Go for it, always fun to recreate classic games in a fraction of the time the original took.

[tomy]

@J.Hilk
Pong is much cooler but how to play such a two-player game on a smartphone? We need joysticks. So I go for the one-player version of the game.

[J.Hilk]

@tomy ok,
but fyi, Most, if not all, smartphones have a multi touch screen, So it should be possible to play with 2 players.

alternatively, this could also be a good option for you to get into networking, to play on 2 phones via bluetooth or wlan. ;-)

[tomy]

@J.Hilk

alternatively, this could also be a good option for you to get into networking, to play on 2 phones via bluetooth or wlan. ;-)

I guess we have two parts, the first is designing the stuff and the last part is networking (via wlan).
I think it's too advanced for me, but I like it and go for that.

[tomy]

@J.Hilk

I started by a project named PingPong! I've reached that point up to now:

main.qml:

import QtQuick 2.8
import QtQuick.Window 2.2

Window {
    visible: true
    width: 800
    height: 600
    title: qsTr("The Ping Pong game")

    Rectangle {
        id: root
        width: 700; height: 500
        border.width: 10
        border.color: "black"
        color: "royalblue"
        property int duration: 1000

   Racket {
       x: 630; y: 100
       color: "red"
   }

   Racket {
       x: 50; y: 100
       color: "black"
   }

   Ball {
       id: ball
       x: root.width/2 - 50
       y: root.height/2
   }

   Rectangle {
       x: root.width/2
       y: 10
       width: 10
       height: root.height - 20
       color: "white"
    }
       
  }

}

Ball.qml:

import QtQuick 2.8

Rectangle {
    width: 20; height: 20
    x: 250; y: 250
    color: "white"
    radius: width/2
}

Racket.qml:

import QtQuick 2.8

Rectangle {
    id: root
    width: 15; height: 50
    x: 400; y: 100
    color: "red"

    MouseArea {
        anchors.fill: parent
        drag.target: root
        drag.axis: Drag.YAxis
        drag.minimumY: 10
        drag.maximumY: 440
    }
}

I have this up to now:

The rackets work good with the mouse button but will they work as well with touching on smartphones?

Now what I need is animating the ball using Easing.Linear. The ball also should start animating when the program starts and recognizes the rackets and the top and down part of the table to reflect.
what should I read for these please?

[J.Hilk]

@tomy
Hiho,

Internaly Qt does not differ between mouse clicks and touch events, so if it works fine with the mouse, than it should work fine on the phone display.

I don't think there is much to read upon for you, you should be able to do that "collision" with what you know.

E.g
You monitor the x-position of your ball. If it hits the x-position of one of the rackets, check if the y-positions of ball and racket overlap.
If yes : Stop old animation of ball and start new one if not, let animation finish and change score counter.

[tomy]

@J.Hilk

For this point I changed the main.qml to this:

import QtQuick 2.8
import QtQuick.Window 2.2

Window {
    visible: true
    width: 800
    height: 600
    title: qsTr("The Ping Pong game")

    Rectangle {
        id: root
        width: 700; height: 500
        border.width: 10
        border.color: "black"
        color: "royalblue"
        property int duration: 1000
        property real xPos: root.width
        property real yPos: Math.random()

   Racket {
       id: redRacket
       x: 630; y: 100
       color: "red"
   }

   Racket {
       id: blackRacket
       x: 50; y: 100
       color: "black"
   }

   Ball {
       id: ball
       x: root.width/2 - 50
       y: root.height/2
   }

   Column {
       spacing: 3
       x: root.width/2
       y: 10

         Repeater {
           model: 21
             delegate:  Rectangle {
                      width: 5
                      height: 20
                      color: "white"
                }
             }
     }

   ParallelAnimation {
            id: anim1
               NumberAnimation
               {
                   target: ball
                   properties: "x"
                   to: root.xPos
                   duration: root.duration
                   easing.type: Easing.Linear
               }
               NumberAnimation
               {
                   target: ball
                   properties: "y"
                   to: root.yPos
                   duration: root.duration
                   easing.type: Easing.Linear
               }
          }
   function nextPos()
   {
     if(ball.x == redRacket.x && ball.y == redRacket.y)
     {
         ParallelAnimation {
            id: anim2
               NumberAnimation
               {
                   target: ball
                   properties: "x"
                   to: -root.xPos
                   duration: root.duration
                   easing.type: Easing.Linear
               }
               NumberAnimation
               {
                   target: ball
                   properties: "y"
                   to: root.yPos
                   duration: root.duration
                   easing.type: Easing.Linear
               }
          }
      }
   }
   
    MouseArea {
        anchors.fill: ball
        onClicked:
        { anim1.restart(); anim2.restart() }
    }
  }
}

The net is better and also I tried to make the ball animate on two opposite directions. But I get these errors:

qrc:/main.qml:76 Expected token ,'
qrc:/main.qml:78 Expected token `}'

By the way, the Math.random() function seems not to work!

[J.Hilk]

@tomy
first of let me tell you, as a person with slight ocd-issues, the fact that your indenting is off, is driving me nuts x)

Anyway:

you define a function nextPos() and insinde the function-body you try to define a ParallelAnimation item and NumberAnimation items. That can't work.

only calculate assign values&properties in functions! Not new items.
In C++ you would, kind of, get way with it, but defenitly not in QML :-)

[tomy]

@J.Hilk
Sorry, I don't know if there is an option that offer automatic indenting on Qt Creator. Do you mean the code looks ugly? :-)

Anyway,
The functions Math.random() and nextPos() and if-condition are fixed:

import QtQuick 2.8
import QtQuick.Window 2.2

Window {
    visible: true
    width: 800
    height: 600
    title: qsTr("The Ping Pong game")

    Rectangle {
        id: root
        width: 700; height: 500
        border.width: 10
        border.color: "black"
        color: "royalblue"
        property int duration: 1000
        property real xPos: root.width
        property real yPos: Math.random() * root.height

   Racket {
       id: redRacket
       x: 630; y: 100
       color: "red"
   }

   Racket {
       id: blackRacket
       x: 50; y: 100
       color: "black"
   }

   Ball {
       id: ball
       x: root.width/2 - 50
       y: root.height/2
   }

   Column {
       spacing: 3
       x: root.width/2
       y: 10
          Repeater {
            model: 21
             delegate: Rectangle {
                      width: 5
                      height: 20
                      color: "white"
                   }
             }
       }

   ParallelAnimation {
      id: anim1
          NumberAnimation {
                   target: ball
                   properties: "x"
                   to: root.xPos
                   duration: root.duration
                   easing.type: Easing.Linear
               }
          NumberAnimation {
                   target: ball
                   properties: "y"
                   to: root.yPos
                   duration: root.duration
                   easing.type: Easing.Linear
               }
          }

   ParallelAnimation {
      id: anim2
         NumberAnimation {
             target: ball
             properties: "x"
             to: -root.xPos
             duration: root.duration
             easing.type: Easing.Linear
         }
         NumberAnimation {
             target: ball
             properties: "y"
             to: root.yPos
             duration: root.duration
             easing.type: Easing.Linear
         }
    }

   function nextPos() {

     if(ball.x >= redRacket.x && ball.x <= redRacket.x + redRacket.height)
     {
       anim1.stop();
       anim2.start();
     }
   }

    MouseArea {
        anchors.fill: ball
        onClicked: { anim1.start(); root.nextPos(); }
    }
  }
}

The x position of the ball is for when it hasn't been animated yet so it won't work in the condition. I need something like:

if (hit(ball,redRacket))

The second is that in:

anim1.stop();
anim2.start();

anim2.start() doesn't let anim1.start() work!

[J.Hilk]

@tomy Hiho

So, I took a look at your code. I'm not quite sure why it's not working like you want it to.
My guess would be, its quite difficult to click upon the ball when its in the window when its in the Racket.

So I simpliefied the situation a bit

I added 2 Properties and a timer to help:
The timer was needed in my testing, otherwise it would change animation an

property bool toTheRight: true
property bool delay: false

Timer{
        id: delayTimer
        interval: 500; running:  false; repeat: false
        onTriggered: delay = false
}
onToTheRightChanged: {
        delay = true
        delayTimer.start()
}

nextPos() was slighly changed, it currently only checks if the ball is past a line:

function nextPos() {
        if(!delay){
            if(ball.x + ball.width >= redRacket.x || ball.x <= blackRacket.x + blackRacket.width){
                toRight = !toRight
                console.log("Ball hits a racket")
                if(anim1.running)
                    anim1.stop()
                else
                    anim1.start()

                if(anim2.running)
                    anim2.stop()
                else
                    anim2.start()
            }
       }
}

The Ball item calls nextPos():

Ball {
       id: ball
       x: root.width/2 - 50
       y: root.height/2
       onXChanged: nextPos()
}
...
MouseArea {
        anchors.fill: ball
        onClicked: { anim1.start(); /*root.nextPos();*/}
    }

This works fine for me, its results in the ball pinging from one wall to the other.
Next step would be to add the player input conditions.

hope this helps.

[tomy]

@J.Hilk
Thank you.
Timer was very useful. I wrote this:

import QtQuick 2.8
import QtQuick.Window 2.2

Window {
    visible: true
    width: 800
    height: 600
    title: qsTr("The Ping Pong game")

    Rectangle {
        id: table
        width: 700; height: 500
        border.width: 10
        border.color: "black"
        color: "royalblue"

   Racket {
       id: redRacket
       x: 630; y: 100
       color: "red"
   }

   Racket {
       id: blackRacket
       x: 50; y: 100
       color: "black"
   }

   Ball {
       id: ball
       x: table.width/2 - 50
       y: table.height/2
       property double ran: Math.random() + 0.5
       property double xincrement: ran
       property double yincrement: ran
   }

   Column {
       spacing: 3
       x: table.width/2
       y: 10
          Repeater {
            model: 21
             delegate: Rectangle {
                      width: 5
                      height: 20
                      color: "white"
                   }
             }
       }

   Timer {
     interval: 5; repeat: true; running: true

        onTriggered: {
            ball.x = ball.x + (ball.xincrement * 2.0);
            ball.y = ball.y + (ball.yincrement * 2.0);

            if((ball.x + ball.width  >= redRacket.x)  &&
              ((ball.y + ball.height >= redRacket.y)  &&
               (ball.y + ball.height <= redRacket.y + redRacket.height)))
                   ball.xincrement *= (-1);

            if((ball.x - ball.width  <= blackRacket.x)  &&
              ((ball.y + ball.height >= blackRacket.y)  &&
               (ball.y + ball.height <= blackRacket.y + blackRacket.height)))
                   ball.xincrement *= (-1);

             if(ball.y <= 0 || ball.y + ball.height >= table.height)
                  ball.yincrement *= (-1);
           }
        }
    }
 }

It works fine but the players can't shoot the ball towards a target they want! The rackets are this way only for defending. I need to alter the code so that when the racket has speed upward or downward hitting the ball, the ball goes and gets acceleration on that direction. The real game has that feature.
How can I do that, please?

After that I'll go for other missing parts for the game.

[J.Hilk]

@tomy
well, first you'll need to somehow monitor if the racket moved up or down as its last movement.

I don't see how in the code examples you posted how you manage the "Racket-Movement" .

but it doesn't matter much, it can be a property of the Racket Item

#untested Stuff
e.g:

Rectangle {
       id: redRacket
       x: 630; y: 100
       color: "red"

       property int oldY: 100
       
       property bool upMovement: false

      onYChanged:{
          upMovement = y -oldY < 0  ? true : false
          oldY = y
      }

       width: 50
       height: 100
   }

and when the Ball hits the racket you decrease the duration, and depending on the up or down movement you change the angle

function onCollisionWithRacket(){
    root.duration = root.duration -10
    if(redRacket.upMovement){
        //Angle to the Top
    }else{
        //Angle to the bottom
    }
}

[tomy]

@J.Hilk
Thanks.
I tried to make the work done and here is the code.
I don't use the prior versions of the code (above) but this one.

Ball.qml and Racket.qml are as before but main.qml is completely as below.

As you see I haven't used a function and I don't know if it's needed or not.
If possible please run that code to see its function. I don't think it's flawless.
The code also to me is very messy. If it can make the work done using little changes, what to do for removing the problems from that please?

import QtQuick 2.8
import QtQuick.Window 2.2

Window {
    visible: true
    width: 800
    height: 600
    title: qsTr("The PingPong Game")

    Rectangle {
        id: table
        width: 700; height: 500
        border.width: 10
        border.color: "black"
        color: "royalblue"

   Racket {
       id: redRacket
       x: 630; y: 100
       color: "red"
       property int  rOldy: y
       property bool rYmovement: false
       onYChanged: {
           rYmovement = y - rOldy < 0 ? true : false
           rOldy = y
       }
   }

   Racket {
       id: blackRacket
       x: 50; y: 100
       color: "black"
       property int  bOldy: y
       property bool bYmovement: false
       onYChanged: {
           bYmovement = y - bOldy < 0 ? true : false
           bOldy = y
       }
   }

   Ball {
       id: ball
       x: table.width/2 - 50
       y: table.height/2
       property double ran: Math.random() + 0.5
       property double xincrement: ran
       property double yincrement: ran
   }

   Column {
       spacing: 3
       x: table.width/2
       y: 10
          Repeater {
            model: 21
             delegate: Rectangle {
                      width: 5
                      height: 20
                      color: "white"
                   }
             }
       }

   Timer {
     interval: 15; repeat: true; running: true

        onTriggered: {
            ball.x = ball.x + (ball.xincrement * 2.0);
            ball.y = ball.y + (ball.yincrement * 2.0);

            if((ball.x + ball.width  >= redRacket.x)  &&
              ((ball.y + ball.height >= redRacket.y)  &&
               (ball.y + ball.height <= redRacket.y + redRacket.height)))
                if(redRacket.rYmovement) {
                     ball.yincrement *= -1
                     ball.xincrement *= -1
                    redRacket.rYmovement = false
                   }
                 else ball.xincrement *= -1

            if((ball.x - ball.width  <= blackRacket.x)  &&
              ((ball.y + ball.height >= blackRacket.y)  &&
               (ball.y + ball.height <= blackRacket.y + blackRacket.height)))
                if(blackRacket.bYmovement) {
                     ball.yincrement *= -1
                     ball.xincrement *= -1
                    blackRacket.bYmovement = false
                   }
                 else ball.xincrement *= -1

             if(ball.y <= 0 || ball.y + ball.height >= table.height)
                  ball.yincrement *= -1
           }
       }
    }
 }

[J.Hilk]

@tomy

to make it a bit cleaner, if you for example moved some stuff to the Ball and Racket qml-files

//Racket
import QtQuick 2.8

Rectangle {
    id: root
    width: 15; height: 50
    x: 400; y: 100
    color: "red"

    property int oldY: y
    property bool yMovement: false
    onYChanged: {
        yMovement = y - oldY < 0 ? true : false
        oldY = y
    }

    MouseArea {
        anchors.fill: parent
        drag.target: root
        drag.axis: Drag.YAxis
        drag.minimumY: 10
        drag.maximumY: 440
    }
}

//Ball.qml
import QtQuick 2.8

Rectangle {
    width: 20; height: 20
    x: 250; y: 250
    color: "white"
    radius: width/2

    property double ran: Math.random() + 0.5
    property double xincrement: ran
    property double yincrement: ran
}

Besides that I don't see what the problem is, theres at least 1 bug I run into whilst playing, x) but thats part of coding.

If you thinks the animation is a but stuttery thats to be expected, you replaced a propertyanimation with a Timer and x/y changes.

I believe, PropertyAnimation does some internal stuff to make the animation as smooth as possible, a change each refresh frame e.g. Where as with a timer aproeach you are fixed to 5 ms updates and in that you only increase the distance the ball is moved. That gonna look like jumps eventually ;-)

[tomy]

@J.Hilk

I replaced the PropertyAnimation with Timer because I didn't know how to achieve what I have now without Timer but with PropertyAnimation.
The Timer works fine with smoothness but in this example I'd changed the interval from 2 to 15 to slow the movement of the ball for better testing.

The game has defects even in this point unfortunately. And it's the feature of targeting.
The if(redRacket.rYmovement) conditions code don't work as expected. I should think over them so that they work as needed.
But a question here, does the y coordinate change relate to the "last" movement of the racket before the ball hits it?

[J.Hilk]

@tomy

I changed the timer stuff a bit, to make it more readable, what happens

   Timer {
     interval: 15; repeat: true; running: true

     function hitsRightRacket(){
         if(ball.x +ball.width >= redRacket.x  && ball.x < redRacket.x + redRacket.width){
             if(ball.y >= redRacket.y && ball.y <= redRacket.y+redRacket.height)
                 return true
         }
         return false
     }

     function hitsLeftRacket(){
         if(ball.x +ball.width >= blackRacket.x  && ball.x < blackRacket.x + blackRacket.width){
             if(ball.y >= blackRacket.y && ball.y <= blackRacket.y+blackRacket.height)
                 return true
         }
         return false
     }

     function hitsRightWall(){
         if(ball.x +ball.width >= table.width)
             return true
         else
             return false
     }

     function hitsLeftWall(){
         if(ball.x <= 0)
             return true
         else
             return false
     }

     function hitsUpperOrLowerWall(){
         if(ball.y <= 0 || ball.y + ball.height >= table.height)
              return true
         return false
     }

     property bool lastHitLeft: false
     property bool lastHitRight: false

        onTriggered: {
            if(hitsRightWall()){
                console.log("Point Left Side")
                running = false
            }else if(hitsLeftWall()){
                console.log("Point Right Side")
                running = false
            }else if(hitsLeftRacket() && !lastHitLeft){
                console.log("Hits Black Racket",blackRacket.yMovement)
                lastHitLeft = true
                lastHitRight = false
                if(blackRacket.yMovement){
                    ball.yincrement *= -1
                    ball.xincrement *= -1
                 }else
                    ball.xincrement *= -1
            }else if(hitsRightRacket() && !lastHitRight){
                console.log("Hits Red Racket",redRacket.yMovement)
                lastHitLeft = false
                lastHitRight = true
                if(redRacket.yMovement) {
                     ball.yincrement *= -1
                     ball.xincrement *= -1
                   }
                 else ball.xincrement *= -1
            }else if(hitsUpperOrLowerWall())
                ball.yincrement *= -1

            //Move Ball
            ball.x = ball.x + (ball.xincrement * 2.0);
            ball.y = ball.y + (ball.yincrement * 2.0);
           }
       }

This showed me that you'll need a better case handleing for ball movement and racket movement,

• ball moves towards y = 0 and Racket moves towards y = 0
• ball moves towards y = 0 and Racket moves towards y = table height
• ball moves towards y = table and Racket moves towards y = 0
• ball moves towards y = table Racket moves towards y = table height

currently you're only checking in what direction the racket moved,

[tomy]

@J.Hilk
Hi,
Thank you for your assistance.

If we divide the task into part I and II, the first part I think is almost done! Please take a look at the code below and if possible please run the program on your system. It works fine for me.

In part I, I need two extra components I think: one, a series of buttons for starting, resuming and finishing the game when it's not over yet. And second, some sound for goals and when a player wins the game.
If we can complete part I, I assume part II will be about networking! :)

Ball.qml:

import QtQuick 2.9

Rectangle {
    width: 12; height: 12
    x: 250; y: 250
    color: "white"
    radius: width/2
    property double ran: Math.random() + 0.5
    property double xincrement: ran
    property double yincrement: ran
}

Counter.qml:

import QtQuick 2.9

Rectangle {
    width: 40; height: 50
    color: "lightskyblue"
    property int count: 0

    Text {
        id: text
        anchors.centerIn: parent
        text: count.toString()
        color: "gray"
        font.bold: true
        font.pixelSize: 30
    }
}

Light.qml:

import QtQuick 2.9

Rectangle {
    width: 50; height: 50
    border.width: 5
    border.color: "silver"
    radius: width/2
    property bool start: false
}

Racket.qml:

import QtQuick 2.9

Rectangle {
    id: root
    width: 12; height: 40
    property int oldY: y
    property bool yUwards: false
    property bool yDwards: false

       onYChanged: {
           if(y > oldY)
               yDwards = true
           else if (y < oldY)
               yUwards = true
           oldY = y
       }

    MouseArea {
        anchors.fill: parent
        drag.target: root
        drag.axis: Drag.YAxis
        drag.minimumY: table.y - 20
        drag.maximumY: table.y + table.height - 60
    }
}

WinBox.qml:

import QtQuick 2.9

Text {
     width: 50; height: 50
     text: "WINNER"
     color: "royalblue"
     font.bold: true
     font.pixelSize: 40
     visible: false
}

main.qml:

import QtQuick 2.9
import QtQuick.Window 2.2

Window {
    visible: true
    width: 820
    height: 620
    title: qsTr("The PingPong Game")
    color: "gray"

    Rectangle {
        x: 10; y: 10
        width: 800; height: 500
        color: "white"
    }

    Rectangle {
        id: table
        x: 20; y: 20
        width: 780; height: 480
        color: "royalblue"
        property int count: 1
        property bool turn: false
        property bool lightState: false

        Racket {
            id: redRacket
            x: table.width - 30; y: 100
            color: "red"
        }

        Racket {
            id: blackRacket
            x: table.x; y: 100
            color: "black"
        }

        Ball {
            id: ball
            x: table.width/2
            y: table.height/2
        }

        Column {
            spacing: 3
            x: table.width/2
            Repeater {
                model: 21
                delegate: Rectangle {
                    width: 5
                    height: 20
                    color: "white"
                }
            }
        }

        Counter {
            id: rightCounter
            x: table.width / 2 + 90
            y: 50
        }

        Counter {
            id: leftCounter
            x: table.width / 4 + 70
            y: 50
        }

        Light {
            id: rightLight
            x: table.width/2 + 80
            y: table.height + 20
            color: "silver"
        }

        Light {
            id: leftLight
            x: table.width/2 - 120
            y: table.height + 20
            color: "lime"
        }

        WinBox {
            id: rightWin
            x: table.width/2 + 160
            y: table.height + 40
        }

        WinBox {
            id: leftWin
            x: table.width/2 - 350
            y: table.height + 40
        }

        Timer {
            interval: 40; repeat: true; running: true

            onTriggered: {
                redRacket.yUwards = false
                redRacket.yDwards = false
                blackRacket.yUwards = false
                blackRacket.yDwards = false
            }
        }

        Timer {
            id: out_timer
            interval: 1; repeat: false; running: false

            function lightChange() {
                if (table.lightState) {
                    rightLight.color = "silver"
                    leftLight.color= "lime"
                  }

                else {
                    rightLight.color = "lime"
                    leftLight.color= "silver"
                  }
                table.lightState = !table.lightState
            }

            onTriggered: {
                ball.xincrement = Math.random() + 0.5
                ball.yincrement = Math.random() + 0.5

                if( table.count % 5 == 0) {
                    table.turn = !table.turn
                    lightChange()
                }


                 if(table.turn)
                    ball.xincrement *= -1

                ball.x = table.width/2
                ball.y = table.height/2

                if (ball.yincrement > 1.1)
                    ball.yincrement *= -1

                in_timer.restart()
                table.count++
            }
        }

        Timer {
            id: in_timer
            interval: duration; repeat: true; running: true
            property int duration: 2

            function hitsRightWall() {
                if (ball.x + ball.width >= table.width)
                    return true
                else return false
            }

            function hitsLeftWall() {
                if(ball.x <= 0) return true
                else return false
            }

            property bool lastHitLeft: false
            property bool lastHitRight: false

            onTriggered: {

                if(hitsRightWall()) {
                    in_timer.stop()
                    leftCounter.count++
                    out_timer.interval = 2000
                    out_timer.running = true
                }

                else if(hitsLeftWall()) {
                    in_timer.stop()
                    rightCounter.count++
                    out_timer.interval = 2000
                    out_timer.running = true
                }

                ball.x = ball.x + (ball.xincrement * 2.0);
                ball.y = ball.y + (ball.yincrement * 2.0);

                if ((ball.x + ball.width >= redRacket.x  &&
                     ball.x < redRacket.x + redRacket.width / 3) &&
                        (ball.y + ball.height >= redRacket.y - 10 &&
                         ball.y <= redRacket.y + redRacket.height))
                {
                    if(redRacket.yUwards) {
                        if(ball.yincrement == 0)
                            ball.yincrement = -ball.ran
                        else if(ball.yincrement > 0)
                            ball.yincrement *= -1
                        interval = duration/2
                    }
                    else if (redRacket.yDwards) {
                        if(ball.yincrement == 0)
                            ball.yincrement = ball.ran
                        else if(ball.yincrement < 0)
                            ball.yincrement *= -1
                        interval = duration/2
                    }
                    else {
                        ball.yincrement = 0
                        interval = duration
                    }

                    ball.xincrement *= -1
                }

                if ((ball.x + ball.width >= blackRacket.x &&
                     ball.x < blackRacket.x + blackRacket.width)  &&
                        (ball.y + ball.height >= blackRacket.y &&
                         ball.y <= blackRacket.y + blackRacket.height))
                {
                    if(blackRacket.yUwards) {
                        if(ball.yincrement == 0)
                            ball.yincrement = -ball.ran
                        else if(ball.yincrement > 0)
                            ball.yincrement *= -1
                        interval = duration/2
                    }
                    else if (blackRacket.yDwards) {
                        if(ball.yincrement == 0)
                            ball.yincrement = ball.ran
                        else if(ball.yincrement < 0)
                            ball.yincrement *= -1
                        interval = duration/2
                    }
                    else {
                        ball.yincrement = 0
                        interval = duration
                    }

                    ball.xincrement *= -1
                }

                if(ball.x <= 0 || ball.x + ball.width >= table.width)
                    ball.xincrement *= (-1);

                if(ball.y <= 0 || ball.y + ball.height >= table.height)
                    ball.yincrement *= -1

                if(rightCounter.count + leftCounter.count == 21) {
                       in_timer.stop()
                    if(rightCounter.count > leftCounter.count)
                        rightWin.visible = true
                    else if (rightCounter.count < leftCounter.count)
                        leftWin.visible = true
                    else {
                        rightWin.visible = true
                        leftWin.visible = true
                    }
                }
            }            
        }
    }
}

[J.Hilk]

Looks great! You're defenitly on the right track.

However I have a bug to report. I managed to catch the ball in the racket. That's the reasdon why I introtuced the 2 properties lastHitLeft and lastHitRight in my previous post. You still have them in your code, but they are not used.

[tomy]

@J.Hilk
Hi, thanks.

Well, I laid those factors and ran the code. Unfortunately it made the issue more prominent! The ball passes through the ball obliquely.

So I think I must return back to the version without them and the issue is subtle! It happens when a racket tries to hit the ball from the top/down moving downwards/upwards and the ball gets stuck in the upper/lower edge of the racket. I think I should work on this.

Previously I was thinking of making the racket thinner to prevent this bug. But I try to find a more logical way.

[tomy]

Hi,

For a while I was trying to use contains(point p), mapFromItem(...) or mapToItem(...). But unfortunately, no success! So I got back to the prior method, which was using the X and Y coordinates as follows.

Please run it on your system. It works fine for me. The bug is also solved.
But there's another bug!

• Moving the racket when playing the game on the Desktop kit (Windows) doesn't affect the speed of ball's movement but when run on an Android device, moving the racket affects the speed of ball's movement as though their movements have been tied together.

I also tried to manipulate the MouseArea in the Racket.qml to cope with that, but no change in the result! :(

Please check it and express your idea how to solve that issue.

QML files Ball, Counter, Light and Winbox are as before.

Racket.qml:

import QtQuick 2.9

Rectangle {
    id: root
    width: 15; height: 65
    property int oldY: y
    property bool yUwards: false
    property bool yDwards: false

    onYChanged: {
        if(y > oldY)  yDwards = true
        else if (y < oldY)  yUwards = true
        oldY = y
    }

    MouseArea {
        anchors.fill: parent
        anchors.margins: -root.height
        drag.target: root
        focus: true
        hoverEnabled: true
        pressAndHoldInterval: 0
        drag.axis: Drag.YAxis
        drag.minimumY: table.y
        drag.maximumY: table.height - root.height - 10
    }
}

main.qml:

import QtQuick 2.9
import QtQuick.Window 2.2
import QtQuick.Controls 2.1

Window {
    id: window
    visibility: Window.Maximized
    title: qsTr("The PingPong Game - A QML Game")
    color: "gray"
    
    Rectangle {
        id: table
        width: window.width / 1.15; height: window.height / 1.15
        x: window.x + 100; y: 10;
        border.width: 10
        border.color: "white"
        color: "royalblue"
        property int count: 1
        property bool turn: false
        property bool lightState: false
        property double step: 3.0
        property int duration: 4
        
        Racket {
            id: blackRacket
            anchors.left: table.left
            anchors.leftMargin: width * 2
            y: height
            color: "black"
        }
        Racket {
            id: redRacket
            anchors.right: table.right
            anchors.rightMargin: width * 2
            y: height
            color: "red"
        }
        
        
        Ball {
            id: ball
            x: table.width/2
            y: table.height/2
        }
        
        Column {
            spacing: 3
            anchors.centerIn: table
            anchors.top: table.top
            Repeater {
                model: table.height/(blackRacket.height / 2 + 3)
                delegate: Rectangle {
                    width: 5
                    height: blackRacket.height / 2
                    color: "white"
                }
            }
        }
        
        Counter {
            id: leftCounter
            x: table.width / 2 - height - 100
            y: 50
        }
        Counter {
            id: rightCounter
            x: table.width / 2 + 100
            y: 50
        }
        
        
        Light {
            id: leftLight
            x: table.width/2 - 280
            y: table.height + 10
            color: "lime"
        }
        Light {
            id: rightLight
            x: table.width/2 + 220
            y: table.height + 10
            color: "silver"
        }
        
        WinBox {
            id: rightWin
            x: table.width/2 + 380
            y: table.height + 10
        }
        WinBox {
            id: leftWin
            x: table.x + 40
            y: table.height + 10
        }
        
        Button {
            x: table.width/2 - 45
            y: table.height + 10
            
            contentItem: Text {
                id: st_tx
                horizontalAlignment: Text.AlignHCenter
                verticalAlignment: Text.AlignVCenter
                text: qsTr("START")
                font.bold: true
                font.pixelSize: 20
                color: "green"
            }
            background: Rectangle {
                implicitHeight: 60
                implicitWidth: 100
                color: "lightGrey"
                border.width: 8
                border.color: "lightBlue"
                radius: 20
            }
            onClicked: table.startGame()
        }
        Button {
            x: table.width/2 - 150
            y: table.height + 10
            
            contentItem: Text {
                id: pu_tx
                horizontalAlignment: Text.AlignHCenter
                verticalAlignment: Text.AlignVCenter
                text: qsTr("PAUSE")
                font.bold: true
                font.pixelSize: 20
                color: "green"
            }
            background: Rectangle {
                id: pu_rec
                implicitHeight: 60
                implicitWidth: 100
                color: "lightGrey"
                border.width: 8
                border.color: "lightBlue"
                radius: 20
            }
            onClicked: table.pauseGame()
        }
        Button {
            x: table.width/2 + 60
            y: table.height + 10
            
            contentItem: Text {
                id: sp_tx
                horizontalAlignment: Text.AlignHCenter
                verticalAlignment: Text.AlignVCenter
                text: qsTr("STOP")
                font.bold: true
                font.pixelSize: 20
                color: "green"
            }
            background: Rectangle {
                implicitHeight: 60
                implicitWidth: 100
                color: "lightGrey"
                border.width: 8
                border.color: "lightBlue"
                radius: 20
                
            }
            onClicked: table.stopGame()
        }
        
        Text {
            x: window.x; y: table.height + 50
            color: "white"
            text: "Ver: 1.1"
            font.family: "Helvetica"
            font.pointSize: 15
        }
        Text {
            x: table.width - 200; y: table.height + 50
            color: "white"
            text: " Programmed By S.R. Abbasi (Tomy)"
            font.family: "Helvetica"
            font.pointSize: 10
        }
        
        function startGame() {
            st_tx.text = qsTr("START")
            if (leftWin.visible)
                leftWin.visible = false
            if (rightWin.visible)
                rightWin.visible = false
            in_timer.restart()
        }
        function pauseGame() {
            st_tx.text = qsTr("RESUME")
            in_timer.running = false
        }
        function stopGame() {
            st_tx.text = qsTr("START")
            in_timer.running = false
            rightCounter.count = 0
            leftCounter.count = 0
            ball.x = table.width/2
            ball.y = table.height/2
            table.count = 1
            table.turn = false
            rightLight.color = "silver"
            leftLight.color = "lime"
            
            if(ball.xincrement < 0 )
                ball.xincrement *= -1
        }
        
        Timer {
            interval: 40; repeat: true; running: true
            
            onTriggered: {
                redRacket.yUwards = false
                redRacket.yDwards = false
                blackRacket.yUwards = false
                blackRacket.yDwards = false
            }
        }
        Timer {
            id: out_timer
            interval: 1; repeat: false; running: false
            
            function lightChange() {
                if (table.lightState) {
                    rightLight.color = "silver"
                    leftLight.color= "lime"
                }
                else {
                    rightLight.color = "lime"
                    leftLight.color= "silver"
                }
                table.lightState = !table.lightState
            }
            
            onTriggered: {
                ball.xincrement = Math.random() + 0.5
                ball.yincrement = Math.random() + 0.5
                
                if (table.count % 5 == 0) {
                    table.turn = !table.turn
                    lightChange()
                }
                
                if (table.turn)
                    ball.xincrement *= -1
                
                ball.x = table.width/2
                ball.y = table.height/2
                
                if (ball.yincrement > 1.1)
                    ball.yincrement *= -1
                
                in_timer.restart()
                table.count++
            }
        }
        Timer {
            id: right_return_timer
            interval: 1; repeat: true; running: false
            onTriggered: {
                ball.x = ball.x + (ball.xincrement * table.step)
                ball.y = ball.y + (ball.yincrement * table.step)
                if(ball.x + ball.width < redRacket.x) {
                    running = false
                    in_timer.running = true
                }
            }
        }
        Timer {
            id: left_return_timer
            interval: 1; repeat: true; running: false
            onTriggered: {
                ball.x = ball.x + (ball.xincrement * table.step)
                ball.y = ball.y + (ball.yincrement * table.step)
                if(ball.x > blackRacket.x + blackRacket.width) {
                    running = false
                    in_timer.running = true
                }
            }
        }
        Timer {
            id: in_timer
            interval: table.duration; repeat: true; running: false
            
            
            function hitsRightRacket() {
                if ((ball.x + ball.width >= redRacket.x &&
                     ball.x <= redRacket.x + redRacket.width) &&
                        (ball.y + ball.height >= redRacket.y &&
                         ball.y <= redRacket.y + redRacket.height))
                    return true
                return false
            }
            function hitsLeftRacket() {
                if ((ball.x + ball.width >= blackRacket.x &&
                     ball.x < blackRacket.x + blackRacket.width)  &&
                        (ball.y + ball.height >= blackRacket.y &&
                         ball.y <= blackRacket.y + blackRacket.height))
                    return true
                return false
            }
            function hitsUpperOrLowerWall(){
                if (ball.y <= 0 || ball.y + ball.height >= table.height)
                    return true
                return false
            }
            function hitsRightWall() {
                if (ball.x + ball.width >= table.width)
                    return true
                else return false
            }
            function hitsLeftWall() {
                if (ball.x <= 0) return true
                else return false
            }
            
            onTriggered: {
                if (hitsRightWall()) {
                    in_timer.stop()
                    leftCounter.count++
                    out_timer.interval = 2000
                    out_timer.running = true
                }
                else if (hitsLeftWall()) {
                    in_timer.stop()
                    rightCounter.count++
                    out_timer.interval = 2000
                    out_timer.running = true
                }
                else if (hitsRightRacket()) {
                    if (redRacket.yUwards) {
                        if (ball.yincrement == 0)
                            ball.yincrement = -ball.ran
                        else if (ball.yincrement > 0)
                            ball.yincrement *= -1
                        interval = (table.duration/4)
                    }
                    else if (redRacket.yDwards) {
                        if (ball.yincrement == 0)
                            ball.yincrement = ball.ran
                        else if (ball.yincrement < 0)
                            ball.yincrement *= -1
                        interval = (table.duration/4)
                    }
                    else {
                        ball.yincrement = 0
                        interval = (table.duration/2)
                    }
                    ball.xincrement *= -1
                    running = false
                    right_return_timer.running = true
                }
                else if (hitsLeftRacket()) {
                    if(blackRacket.yUwards) {
                        if (ball.yincrement == 0)
                            ball.yincrement = -ball.ran
                        else if (ball.yincrement > 0)
                            ball.yincrement *= -1
                        interval = (table.duration/4)
                    }
                    else if (blackRacket.yDwards) {
                        if (ball.yincrement == 0)
                            ball.yincrement = ball.ran
                        else if (ball.yincrement < 0)
                            ball.yincrement *= -1
                        interval = (table.duration/4)
                    }
                    else {
                        ball.yincrement = 0
                        interval = (table.duration/2)
                    }
                    ball.xincrement *= -1
                    running = false
                    left_return_timer.running = true
                }
                else if (hitsUpperOrLowerWall())
                    ball.yincrement *= -1
                
                // Move Ball
                ball.x = ball.x + (ball.xincrement * table.step);
                ball.y = ball.y + (ball.yincrement * table.step);
                
                if(rightCounter.count + leftCounter.count == 21) {
                    in_timer.stop()
                    if (rightCounter.count > leftCounter.count)
                        rightWin.visible = true
                    else
                        leftWin.visible = true
                }
            }
        }
    }
}