Tennis-Game-using-JS/index.html at master · soumitri2001/Tennis-Game-using-JS · GitHub

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<html>
    <canvas id="gameCanvas" width="800"
            height="600"></canvas>

<script type="text/javascript">

    var canvas;
    var canvasContext;
    var ballX=50,ballY=50;
    var ballSpeedX=8,ballSpeedY=4.8;

    var player1score=0,player2score=0;
    const WIN_SCORE = 15;

    var paddle1=250,paddle2=250;
    const PADDLE_HEIGHT = 100; // constant value
    const PADDLE_THICKESS = 10;

    var showingWinScreen = false;

    function calcMousePos(evt)
    {
        var rect=canvas.getBoundingClientRect();
        var root=document.documentElement;
        var mouseX=evt.clientX-rect.left-root.scrollLeft;
        var mouseY=evt.clientY-rect.top-root.scrollTop;
        return {
            x:mouseX,
            y:mouseY
        }; // returning the current position of mouse
    }

    function ballReset()
    {

        if(player1score>=WIN_SCORE)
            {
                alert("Player 1 has won!");
                player1score=player2score=0;
            }
        else if(player2score>=WIN_SCORE)
            {
                alert("Player 2 has won!");
                player1score=player2score=0;
            }

            ballSpeedX=-ballSpeedX;
            ballX=canvas.width/2;
            ballY=canvas.height/2;
    }

    window.onload=function()
    {
        console.log("Finished Loading page");
        canvas=document.getElementById('gameCanvas');
        canvasContext=canvas.getContext('2d');

        var framesPerSecond=30;
        setInterval(function(){
            moveEverything();
            drawEverything();
        } ,1000/framesPerSecond);


        canvas.addEventListener('mousemove',
                   function(evt){
                var mousePos=calcMousePos(evt);
                paddle1=mousePos.y-(PADDLE_HEIGHT/2);

        });
    }

    function computerMovement()
    {
        // computer controls !
        var paddle2centre=paddle2+(PADDLE_HEIGHT/2);

        if(paddle2centre<ballY-34)
        {
            paddle2+=5.8;
        }
        else if(paddle2centre>ballY+34)
        {
            paddle2-=5.9;
        }

    }


    function moveEverything()
    {
        computerMovement();

        ballX+=ballSpeedX;
        ballY+=ballSpeedY;

        if(ballX<=0) {
            // bouncing off the paddle
            if(ballY>paddle1 && ballY<paddle1+PADDLE_HEIGHT){
                ballSpeedX=-ballSpeedX;
                // use collision principles for better controls!
                var deltaY=ballY-(paddle1+PADDLE_HEIGHT/2);
                ballSpeedY=deltaY*0.33;
            } else { // reset the ball if missed
                player2score++; ballReset();
            }
        }
        // Right controls
        if(ballX>=canvas.width) {
            // bouncing off the paddle
            if(ballY>paddle2 && ballY<paddle2+PADDLE_HEIGHT){
                ballSpeedX=-ballSpeedX;
                // use collision principles for better controls!
                var deltaY=ballY-(paddle2+PADDLE_HEIGHT/2);
                ballSpeedY=deltaY*0.30;
            } else { // reset the ball if missed
                player1score++; ballReset();
            }
        }

        if(ballY<=0) {
            ballSpeedY=-ballSpeedY;
        }

        if(ballY>=canvas.height) {
            ballSpeedY=-ballSpeedY;
        }
    }

    function drawNet()
    {
        for(var i=0;i<=canvas.height;i+=30)
        {
            colorRect(canvas.width/2-1,i,2,20,'white');
        }
    }

    function drawEverything()
    {
        // blanks out the canvas
        colorRect(0,0,canvas.width,canvas.height,'black');
        // net in the middle
        drawNet();
        // for the player paddle: Left
        colorRect(2,paddle1,PADDLE_THICKESS,
                  PADDLE_HEIGHT,'yellow');
        // for the computer paddle: Right
        colorRect(canvas.width-PADDLE_THICKESS-2,paddle2,
                  PADDLE_THICKESS,PADDLE_HEIGHT,'lightgreen');
        // drawing the ball
        colorCircle(ballX,ballY,10,'hotpink');
        // finally, put in the text for updating scores
        canvasContext.font='20px Georgia'
        canvasContext.fillStyle='yellow'
        canvasContext.fillText(player1score,100,50);
        canvasContext.fillText(player2score,canvas.width-100,50);
    }

    function colorRect(leftX,topY,width,height,drawColor)
    {
        canvasContext.fillStyle=drawColor;
        canvasContext.fillRect(leftX,topY,width,height);
    }

    function colorCircle(centreX,centreY,radius,drawColor)
    {
        canvasContext.fillStyle=drawColor;
        canvasContext.beginPath();
        canvasContext.arc(centreX,centreY,radius,0,Math.PI*2,
                          true);
        canvasContext.fill();
    }


    </script>


</html>