JavaScript: Intro to Web Game Development - Part 7: add title screen and settings

As of the previous article, the game can be considered to be in a “complete” state, but I want to add a few features, such as a title screen, some options such as score to win, ball speed, and game colors. I also want to add a link back to the title screen from the winner screen, so this will entail some logic for navigation between pages. Here is the previous article in the series:

JavaScript: Intro to Web Game Development – Part 6: add win screen and replay

Here is what the game’s title screen with options looks like:

Here are the coding steps to make all of these new features work:

Step 1: Add some new global variables

var GAME_COLOR = "black"; // default
var startNewGame = false;
var mouseClickX, mouseClickY;
var mouseClicked = false;
var box_1_selected = true; // default
var box_2_selected = false;
var box_3_selected = true; // default
var box_4_selected = false;
var box_5_selected = false;
var box_6_selected = true; // default
var box_7_selected = false;
var box_8_selected = false;
var linkText, linkText2;
var link1, link2;
var linkX2, linkY2;
var mousePosition = {x:0, y:0}
var mousePos;

Step 2: Update the game loop in the window.onload function

    // game loop - begin ------------
    var framesPerSecond = 30;
    setInterval(
        function() {

            if (startNewGame == true) {
                startGame();
            } else if (showGameOverScreen) {
                gameOverScreen();
            } else {
                titlePage();
            }

        }, 1000/framesPerSecond);
    // game loop - end  ------------

Notice the new function calls to startGame() and titlePage(). The startGame() function looks like this:

function startGame() {
    ballMovement();
    drawComponents();
}

Step 3: Enhance mousedown event listener in the window.onload function

    canvas.addEventListener('mousedown',
    function(evt) {
        mousePos = calculateMousePos(evt);
        mouseClickX = mousePos.x;
        mouseClickY = mousePos.y;
        // console.log(mousePos);
        // console.log("mouseClickX: ", mouseClickX, "mouseClickY: ", mouseClickY);
        mouseClicked = true;
    });

mouseClickX and mouseClickY are new variables that will help with determining if a button or link is clicked.

Step 4: Create new function for detecting button and link clicks

function isPointInsideRect(pointX, pointY, rectX, rectY, rectWidth, rectHeight) {
    // returns true if point is inside rect
    return  (rectX <= pointX) &&
            (rectX + rectWidth >= pointX) &&
            (rectY <= pointY) &&
            (rectY + rectHeight >= pointY);
}

This function will return true if a mouse click is within the rectangle of a button or link. Otherwise it will return false.

Step 5: Move the code for drawing the scores into it’s own function

function drawScores() {
    // Left side score - make room for more digits
    canvasContext.font="40px monospace";
    if (player1Score < 10) {
        canvasContext.fillText(player1Score, (canvas_width/2)-60, 40);
    } else if (player1Score > 99) {
        canvasContext.fillText(player1Score, (canvas_width/2)-100, 40);
    } else {
        canvasContext.fillText(player1Score, (canvas_width/2)-80, 40);
    }

    // Right side score
    canvasContext.fillText(player2Score, (canvas_width/2)+35, 40);
}

Step 6: Update the gameOverScreen() function

The winner screen has been updated with the following:

[settings] has been added to the bottom of both the left and right pages
both the play again and [settings] text now act as links that change the pointer when the mouse hovers over them
code has been added to make the mouseover code work
boxes have been created to make clicking on the the text links detectable
actions have been defined for when a link has been clicked

Here is an example of what the new winner screens look like. Both the “play again” and “[settings]” text are now links that change the pointer on hover and have specific actions when clicked. I also made sure the score and net were left on the screen.

Here is what the new gameOverScreen() looks like:

function gameOverScreen() {

    canvasContext.fillStyle = 'white';
    drawScores();
    drawNet();

    if(player1Score >= WINNING_SCORE) {

        canvasContext.font="54px monospace";
        canvasContext.fillText("Winner", canvas_width/8, canvas_height/4);
        canvasContext.font="44px monospace";
        canvasContext.fillText("Left Player", canvas_width/12, canvas_height/3);

        linkText = "begin game";
        linkX = (canvas_width/10);
        linkY = canvas_height/2;
        boxY = (canvas_height/2)- 50;
        var link1 = {x:65, y:235, width:280, height:60};
        // canvasContext.fillStyle = 'gray';
        // canvasContext.fillRect(link1.x, link1.y, link1.width, link1.height);
        canvasContext.fillStyle = 'white';
        canvasContext.fillText("play again", linkX, linkY);


        // options link
        canvasContext.font="38px monospace";
        linkText2 = "[settings]";
        linkX2 = canvas_width/8;
        linkY2 = canvas_height-70;
        var link2 = {x:90, y:445, width:235, height:55};
        // canvasContext.fillStyle = 'gray';
        // canvasContext.fillRect(link2.x, link2.y, link2.width, link2.height);
        canvasContext.fillStyle = 'white';
        canvasContext.fillText(linkText2, linkX2, linkY2);


    } else if(player2Score >= WINNING_SCORE) {
        canvasContext.font="54px monospace";
        canvasContext.fillText("Winner", (canvas_width/2 + canvas_width/8), (0 + canvas_height/4));
        canvasContext.font="44px monospace";
        canvasContext.fillText("Right Player", (canvas_width/2 + canvas_width/24), (0 + canvas_height/3));

        linkX = (canvas_width/2 + canvas_width/16);
        linkY = canvas_height/2;
        var link1 = {x:415, y:235, width:280, height:60};
        // canvasContext.fillStyle = 'gray';
        // canvasContext.fillRect(link1.x, link1.y, link1.width, link1.height);
        canvasContext.fillStyle = 'white';
        canvasContext.fillText("play again", linkX, linkY);


        // options link
        canvasContext.font="38px monospace";

        linkText2 = "[settings]";
        linkX2 = (canvas_width/2 + canvas_width/12);
        linkY2 = canvas_height-70;
        var link2 = {x:435, y:445, width:235, height:55};
        // canvasContext.fillStyle = 'gray';
        // canvasContext.fillRect(link2.x, link2.y, link2.width, link2.height);
        canvasContext.fillStyle = 'white';
        canvasContext.fillText(linkText2, linkX2, linkY2);

    }
    var x = mousePosition.x;
    var y = mousePosition.y;

    onlink2 = isPointInsideRect(x, y, link1.x, link1.y, link1.width, link1.height);
    onlink3 = isPointInsideRect(x, y, link2.x, link2.y, link2.width, link2.height);
    if (onlink2 == true || onlink3 == true) {
        document.body.style.cursor = "pointer";
    } else {
        document.body.style.cursor = "";
    }

    if (mouseClicked) {
        link1_clicked = isPointInsideRect(mouseClickX, mouseClickY, link1.x, link1.y, link1.width, link1.height);
        if (link1_clicked == true) {
            link1_selected = true;
            link2_selected = false;
            startNewGame = true;
            player1Score = 0;
            player2Score = 0;
            showGameOverScreen = false;
            document.body.style.cursor = "";
            startGame();
        }

        link2_clicked = isPointInsideRect(mouseClickX, mouseClickY, link2.x, link2.y, link2.width, link2.height);
        if (link2_clicked == true) {
            link1_selected = false;
            link2_selected = true;
            startNewGame = false;
            player1Score = 0;
            player2Score = 0;
            showGameOverScreen = false;
            box_1_selected = true;
            mouseClicked = false;
            titlePage();
        }

    }
    // reset to false so that the mouse click only registers once in the game loop
    mouseClicked = false;
}

Step 7: Update the computer paddle A.I. for the new ball speeds

Since there are now two new options for ball speeds (2x and 3x), I decided to update the computer A.I. so that the game will be a little more challenging. (Otherwise the computer would almost certainly always lose.)

function computerPaddleAI() {
    var paddle2YCenter = paddle2Y + (PADDLE_HEIGHT/2);

    var normal = 6;
    var fast = 10; // just a little less than 2x
    var crazy = 16;
    var moveSpeed;

    if (ballSpeedX == 20 ){
        moveSpeed = fast;
    } else if (ballSpeedX > 20 ){
        moveSpeed = crazy;
    } else {
        moveSpeed = normal
    }

    if(paddle2YCenter < ballY - 35) {
	paddle2Y = paddle2Y + moveSpeed;
    } else if(paddle2YCenter > ballY + 35) {
	paddle2Y = paddle2Y - moveSpeed;
    }
}

Step 8: Create the titlePage() function

function titlePage() {

    if(showGameOverScreen) {
        return;
    }

    // clear the game screen
    canvasContext.fillStyle = GAME_COLOR;
    canvasContext.roundRect(0, 0, canvas_width, canvas_height, 40, GAME_COLOR, 0);

    // draw the pong title
    canvasContext.fillStyle = 'white';
    canvasContext.font="120px monospace";
    canvasContext.fillText("pong", 230, 120);

    //draw the begin game link
    canvasContext.font="44px monospace";
    linkText = "begin game";
    linkX = 230;
    linkY = 500;
    var begin_game_link = {x:210, y:455, width:300, height:60};
    // A gray box around the text link for debugging
    // canvasContext.fillStyle = 'gray';
    // canvasContext.fillRect(begin_game_link.x, begin_game_link.y, begin_game_link.width, begin_game_link.height);
    canvasContext.fillStyle = 'white';
    canvasContext.fillText(linkText, linkX, linkY);


    // ---- Game options ----

    // ----------------------- Score limit ----------------------- //
    canvasContext.fillStyle = 'white';
    canvasContext.font="20px monospace";
    canvasContext.fillText("score limit", 100, 225);
    var bt = 28; // distance text is to the right of the box

    // box 1
    var box1 = {x:100, y:240, width:20, height:20};
    canvasContext.fillText("3", box1.x + bt, 257);
    canvasContext.fillRect(box1.x, box1.y, box1.width, box1.height);
    canvasContext.fillStyle = GAME_COLOR;
    canvasContext.fillRect(102, 242, 16, 16);

    if (box_1_selected == true) {
        canvasContext.fillStyle = 'white';
        canvasContext.fillRect(104, 244, 12, 12);
    }

    // box 2
    var box2 = {x:180, y:240, width:20, height:20};
    canvasContext.fillStyle = 'white';
    canvasContext.fillText("10", box2.x + bt, 257);
    canvasContext.fillRect(box2.x, box2.y, box2.width, box2.height);
    canvasContext.fillStyle = GAME_COLOR;
    canvasContext.fillRect(182, 242, 16, 16);

    // box 2 selected
    if (box_2_selected == true) {
        canvasContext.fillStyle = 'white';
        canvasContext.fillRect(184, 244, 12, 12);
    }

    // ----------------------- color options ----------------------- //
    canvasContext.fillStyle = 'white';
    canvasContext.font="20px monospace";
    canvasContext.fillText("game color", 450, 225);

    // box 3
    var box3 = {x:450, y:240, width:20, height:20};
    canvasContext.fillText("black & white", box3.x + bt, 257);
    canvasContext.fillRect(box3.x, box3.y, box3.width, box3.height);
    canvasContext.fillStyle = GAME_COLOR;
    canvasContext.fillRect(452, 242, 16, 16);

    if (box_3_selected == true) {
        canvasContext.fillStyle = 'white';
        canvasContext.fillRect(454, 244, 12, 12);
    }

    // box 4
    var box4 = {x:450, y:267, width:20, height:20};
    canvasContext.fillStyle = 'white';
    canvasContext.fillText("retro green", box4.x + bt, 282);
    canvasContext.fillRect(box4.x, box4.y, box4.width, box4.height);
    canvasContext.fillStyle = GAME_COLOR;
    canvasContext.fillRect(452, 269, 16, 16);

    // box 4 selected
    if (box_4_selected == true) {
        canvasContext.fillStyle = 'white';
        canvasContext.fillRect(454, 271, 12, 12);
    }

    // box 5
    var box5 = {x:450, y:294, width:20, height:20};
    canvasContext.fillStyle = 'white';
    canvasContext.fillText("cool blue", box5.x + bt, 309);
    canvasContext.fillRect(box5.x, box5.y, box5.width, box5.height);
    canvasContext.fillStyle = GAME_COLOR;
    canvasContext.fillRect(452, 296, 16, 16);

    // box 5 selected
    if (box_5_selected == true) {
        canvasContext.fillStyle = 'white';
        canvasContext.fillRect(454, 298, 12, 12);
    }

    // ----------------------- ball speed ----------------------- //
    canvasContext.fillStyle = 'white';
    canvasContext.font="20px monospace";
    canvasContext.fillText("ball speed", 100, 325);

    // box 6
    var box6 = {x:100, y:340, width:20, height:20};
    canvasContext.fillText("normal", box6.x + bt, 355);
    canvasContext.fillRect(box6.x, box6.y, box6.width, box6.height);
    canvasContext.fillStyle = GAME_COLOR;
    canvasContext.fillRect(102, 342, 16, 16);

    if (box_6_selected == true) {
        canvasContext.fillStyle = 'white';
        canvasContext.fillRect(104, 344, 12, 12);
    }

    // box 7
    var box7 = {x:100, y:367, width:20, height:20};
    canvasContext.fillStyle = 'white';
    canvasContext.fillText("fast 2x", box7.x + bt, 382);
    canvasContext.fillRect(box7.x, box7.y, box7.width, box7.height);
    canvasContext.fillStyle = GAME_COLOR;
    canvasContext.fillRect(102, 369, 16, 16);

    // box 7 selected
    if (box_7_selected == true) {
        canvasContext.fillStyle = 'white';
        canvasContext.fillRect(104, 371, 12, 12);
    }

    // box 8
    var box8 = {x:100, y:394, width:20, height:20};
    canvasContext.fillStyle = 'white';
    canvasContext.fillText("crazy 3x", box8.x + bt, 409);
    canvasContext.fillRect(box8.x, box8.y, box8.width, box8.height);
    canvasContext.fillStyle = GAME_COLOR;
    canvasContext.fillRect(102, 396, 16, 16);

    // box 7 selected
    if (box_8_selected == true) {
        canvasContext.fillStyle = 'white';
        canvasContext.fillRect(104, 398, 12, 12);
    }

    // check to see if the mouse is over the begin game link
    // if so, change the pointer to a hand, indicating a link
    var x = mousePosition.x;
    var y = mousePosition.y;

    onlink1 = isPointInsideRect(x, y, begin_game_link.x, begin_game_link.y, begin_game_link.width, begin_game_link.height);
    if (onlink1) {
        document.body.style.cursor = "pointer";
    } else {
        document.body.style.cursor = "";
    }

    // handle the case of a mouse click
    if (mouseClicked) {
        // check to see if the mouse clicked box1
        box_1_clicked = isPointInsideRect(mouseClickX, mouseClickY, box1.x, box1.y, box1.width, box1.height);
        if (box_1_clicked == true) {
            box_1_selected = true;
            box_2_selected = false;
            WINNING_SCORE = 3;
        }
        // check to see if the mouse clicked box 2
        box_2_clicked = isPointInsideRect(mouseClickX, mouseClickY, box2.x, box2.y, box2.width, box2.height);
        if (box_2_clicked == true) {
            box_1_selected = false;
            box_2_selected = true;
            WINNING_SCORE = 10;
        }

        // check to see if the mouse clicked box 3
        box_3_clicked = isPointInsideRect(mouseClickX, mouseClickY, box3.x, box3.y, box3.width, box3.height);
        if (box_3_clicked == true) {
            box_3_selected = true;
            box_4_selected = false;
            box_5_selected = false;
            GAME_COLOR = "black";
        }

        // check to see if the mouse clicked box 4
        box_4_clicked = isPointInsideRect(mouseClickX, mouseClickY, box4.x, box4.y, box4.width, box4.height);
        if (box_4_clicked == true) {
            box_3_selected = false;
            box_4_selected = true;
            box_5_selected = false;
            GAME_COLOR = "#003300";
        }

        // check to see if the mouse clicked box 5
        box_5_clicked = isPointInsideRect(mouseClickX, mouseClickY, box5.x, box5.y, box5.width, box5.height);
        if (box_5_clicked == true) {
            box_3_selected = false;
            box_4_selected = false;
            box_5_selected = true;
            GAME_COLOR = "#004080";
        }

        // check to see if the mouse clicked box 6
        box_6_clicked = isPointInsideRect(mouseClickX, mouseClickY, box6.x, box6.y, box6.width, box6.height);
        if (box_6_clicked == true) {
            box_6_selected = true;
            box_7_selected = false;
            box_8_selected = false;
            ballSpeedX = 10;
            ballSpeedY = 4;
        }

        // check to see if the mouse clicked box 7
        box_7_clicked = isPointInsideRect(mouseClickX, mouseClickY, box7.x, box7.y, box7.width, box7.height);
        if (box_7_clicked == true) {
            box_6_selected = false;
            box_7_selected = true;
            box_8_selected = false;
            ballSpeedX = 20;
            ballSpeedY = 8;
        }

        // check to see if the mouse clicked box 8
        box_8_clicked = isPointInsideRect(mouseClickX, mouseClickY, box8.x, box8.y, box8.width, box8.height);
        if (box_8_clicked == true) {
            box_6_selected = false;
            box_7_selected = false;
            box_8_selected = true;
            ballSpeedX = 30;
            ballSpeedY = 12;
        }

        // check to see if the mouse clicked the begin game link
        begin_game_link_clicked = isPointInsideRect(mouseClickX, mouseClickY, begin_game_link.x, begin_game_link.y, begin_game_link.width, begin_game_link.height);
        if (begin_game_link_clicked == true) {
            box_1_selected = false;
            box_2_selected = false;
            startNewGame = true;
            player1Score = 0;
            player2Score = 0;
            showGameOverScreen = false;
            document.body.style.cursor = "";
            startGame();
        }

    }
    // reset to false so that the mouse click only registers once in the game loop
    mouseClicked = false;

}

Notice that each box is defined as an object with x, y, width, height:

var box8 = {x:100, y:394, width:20, height:20};

And then the isPointInsideRect() function is used in conjunction with mouse click coordinates to determine if a box has been clicked:

box_8_clicked = isPointInsideRect(mouseClickX, mouseClickY, box8.x, box8.y, box8.width, box8.height);

At this point, the game is essentially complete. The only other things I can think of to add are sound effects and perhaps options for changing the computer AI player from the right to the left and maybe adding a two player option that uses keyboard arrows.

Here is the game as it stands at this point:

Chris Nielsen Code Walk

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JavaScript: Intro to Web Game Development – Part 7: add title screen and settings