Using buttons as touchscreen controls for javascript game - javascript

I'm making a webpage that is just a place to take a break, and a lot of my users are on touchscreen, so I'm trying to implement touchscreen controls into the games, but it's not working and I cannot for the life of me figure out why. The arrow key controls still work, but not the buttons.
<canvas id="myCanvas" width="480" height="320" ></canvas>
<script>
function playGame() { var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
var x = canvas.width/2;
var y = canvas.height-30;
var dx = 2;
var dy = -2;
var ballRadius = 10;
var paddleHeight = 10;
var paddleWidth = 75;
var paddleX = (canvas.width-paddleWidth) / 2;
var rightPressed = false;
var leftPressed = false;
var difficulty = 10
var score = 0
var gameRunning = false
var paused = false
function paddleMoveLeft(){ paddleX -= 5;
if (paddleX < 0){
paddleX = 0;
}}
function paddleMoveRight(){ paddleX += 5;
if (paddleX + paddleWidth > canvas.width){
paddleX = canvas.width - paddleWidth;
}}
function playPause(){
if(paused === true){paused = false}
else {paused = true}
}
function drawBall() {
ctx.beginPath();
ctx.arc(x, y, ballRadius, 0, Math.PI*2);
ctx.fillStyle = "#0095DD";
ctx.fill();
ctx.closePath();
}
function drawPaddle() {
ctx.beginPath();
ctx.rect(paddleX, canvas.height-paddleHeight, paddleWidth, paddleHeight);
ctx.fillStyle = "#0095DD";
ctx.fill();
ctx.closePath();
}
function drawScore() {
ctx.font = "24px ";
ctx.fillStyle = "#0095DD";
ctx.fillText("Score: "+score, 8, 20);
}
function draw() {
if (paused === false){
ctx.clearRect(0, 0, canvas.width, canvas.height);
drawBall();
drawPaddle();
drawScore();
x += dx;
y += dy;
if(x + dx > canvas.width-ballRadius || x + dx < ballRadius) {
dx = -dx;
}
if(y + dy < ballRadius) {
dy = -dy;
} else if(y + dy > canvas.height-ballRadius) {
if(x > paddleX && x < paddleX + paddleWidth) {
dy = -dy;
difficulty = difficulty + 0.5;
score = score + 1;
}
else {
alert("GAME OVER! you scored " + score);
ctx.clearRect(0, 0, canvas.width, canvas.height);
clearInterval(interval);
canvas.style.display = 'none';
}
}
if(rightPressed) {
paddleMoveRight();
}
else if(leftPressed) {
paddleMoveLeft();
}
}
}
document.addEventListener("keydown", keyDownHandler, false);
document.addEventListener("keyup", keyUpHandler, false);
function keyDownHandler(e) {
if(e.key == "Right" || e.key == "ArrowRight") {
rightPressed = true;
}
else if(e.key == "Left" || e.key == "ArrowLeft") {
leftPressed = true;
}
}
function keyUpHandler(e) {
if(e.key == "Right" || e.key == "ArrowRight") {
rightPressed = false;
}
else if(e.key == "Left" || e.key == "ArrowLeft") {
leftPressed = false;
}
}
var interval = setInterval(draw, difficulty);}
</script>
<div style = 'width: 30%; margin: auto;'>
<button style = 'font-size:large;' onclick = 'paddleMoveLeft()'> left</button>
<button style = 'font-size: large;' onclick = 'paddleMoveRight()'> right</button>
</div>
Any idea what's wrong?

Just by opening the console, it will tells you what's wrong.
So far, you call paddleMoveLeft in html but it's not globally defined, as it is inside the playGame method. About scope

Related

Game doesn't work, but my code looks fine

I've been following an online tutorial for making a Breakout Game using JS, but it doesn't work. Even something as simple as an alert popup doesn't work. All of this started happening after I created the keyboard controls, and all of the errors are in that section as well. But it looks fine, i've compared the sample code with mine and everything's identical. What am I doing wrong?
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Gamedev</title>
<style>
* {
padding: 0;
margin: 0;
}
canvas {
background:rgba(104, 10, 93, 0.61);
display: block;
margin: 0 auto;
}
</style>
</head>
<body>
<canvas id="myCanvas" width="480" height="320"></canvas>
</body>
<script>
// JS goes here
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
var ballRadius = 10;
var x = canvas.width/2;
var y = canvas.height-30;
var dx = 2;
var dy = -2;
var paddleHeight = 10;
var paddleWidth = 75;
var paddleX = (canvas.width-paddleWidth)/2;
var rightPressed = false;
var leftPressed = false;
document.addEventListener("keydown", keyDownHandler, false);
document.addEventListener("keyup", keyUphandler, false);
alert('test')
function keyDownHandler(e) {
if(e.key == "Right" || e.key == "ArrowRight") {
rightPressed = true;
}
elseif(e.key == "Left" || e.key == "ArrowLeft") {
leftPressed = true;
}
}
function keyUpHandler(e) {
if(e.key -- "Right" || e.key == "ArrowRight") {
rightPressed = false;
}
elseif(e.key-- "Left" || e.key == "ArrowLeft") {
leftPressed = false;
}
}
function drawBall() {
ctx.beginPath();
ctx.arc(x, y, ballRadius, 0, Math.PI * 2);
ctx.fillStyle = "#EE82EE";
ctx.fill();
ctx.closePath();
}
function drawPaddle() {
ctx.beginPath();
ctx.rect(paddleX, canvas.height - paddleheight, paddleWidth, paddleHeight);
ctx.fillStyle = "#9400D3";
ctx.fill();
ctx.closePath();
}
function draw() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
drawBall();
drawPaddle();
if(x + dx > canvas.width - ballRadius || x + dx < ballRadius) {
dx = -dx;
}
if (y + dy > canvas.height - ballRadius || y + dy < ballRadius) {
dy = -dy;
}
if(rightPressed) {
paddleX += 7;
if (paddleX + paddleWidth > canvas.width){
paddleX = canvas.width - paddleWidth;
}
}
else if(leftPressed) {
paddleX -= 7;
if (paddleX < 0){
paddleX = 0;
}
x += dx;
y += dy;
}
}
setInterval(draw, 10);
</script>
</body>
</html>
You have numerous typos in your code. This version should work better (at least it does not generate any errors):
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Gamedev</title>
<style>
* {
padding: 0;
margin: 0;
}
canvas {
background:rgba(104, 10, 93, 0.61);
display: block;
margin: 0 auto;
}
</style>
</head>
<body>
<canvas id="myCanvas" width="480" height="320"></canvas>
</body>
<script>
// JS goes here
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
var ballRadius = 10;
var x = canvas.width/2;
var y = canvas.height-30;
var dx = 2;
var dy = -2;
var paddleHeight = 10;
var paddleWidth = 75;
var paddleX = (canvas.width-paddleWidth)/2;
var rightPressed = false;
var leftPressed = false;
document.addEventListener("keydown", keyDownHandler, false);
document.addEventListener("keyup", keyUpHandler, false);
alert('test')
function keyDownHandler(e) {
if(e.key == "Right" || e.key == "ArrowRight") {
rightPressed = true;
}
else if(e.key == "Left" || e.key == "ArrowLeft") {
leftPressed = true;
}
}
function keyUpHandler(e) {
if (e.key == "Right" || e.key == "ArrowRight") {
rightPressed = false;
}
else if(e.key == "Left" || e.key == "ArrowLeft") {
leftPressed = false;
}
}
function drawBall() {
ctx.beginPath();
ctx.arc(x, y, ballRadius, 0, Math.PI * 2);
ctx.fillStyle = "#EE82EE";
ctx.fill();
ctx.closePath();
}
function drawPaddle() {
ctx.beginPath();
ctx.rect(paddleX, canvas.height - paddleHeight, paddleWidth, paddleHeight);
ctx.fillStyle = "#9400D3";
ctx.fill();
ctx.closePath();
}
function draw() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
drawBall();
drawPaddle();
if(x + dx > canvas.width - ballRadius || x + dx < ballRadius) {
dx = -dx;
}
if (y + dy > canvas.height - ballRadius || y + dy < ballRadius) {
dy = -dy;
}
if (rightPressed) {
paddleX += 7;
if (paddleX + paddleWidth > canvas.width){
paddleX = canvas.width - paddleWidth;
}
}
else if(leftPressed) {
paddleX -= 7;
if (paddleX < 0){
paddleX = 0;
}
x += dx;
y += dy;
}
}
setInterval(draw, 10);
</script>
</html>

Creating a pong game in Netbeans

I really hope that you might be able to able me. I am a total novice and so I am simply trying to learn. I am trying to create a pong game.
My problem is now that there is no collision between the paddles and balls.
Here is my code. It is messy I must admit.
</head>
<body>
<canvas id="canvas" width="500" height="500" style="border:1px solid #000000;"></canvas>
<script type="text/javascript">
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var gradientMag = 375;
var gradient = ctx.createLinearGradient(0,0,0, gradientMag);
var ball_x = canvas.width/2;
var ball_y = canvas.height-30;
var dx = -2;
var dy = -2;
var ballRadius = 5;
var p_Height = 100;
var p_Width = 10;
var player1x = (canvas.width-p_Width);
var player1y = canvas.height-p_Height;
var player2y = 0;
var player2x = 0;
var player2Right = false;
var player2Left = false;
var player1Right = false;
var player1Left = false;
var startScreen = true;
var gameRunning = false;
var player1wins = false;
var player2wins = false;
document.addEventListener("keydown", keyDownHandler, false);
document.addEventListener("keyup", keyUpHandler, false);
function keyDownHandler(e) {
if(e.keyCode == 40) {
player1Right = true;
} if(e.keyCode == 38) {
player1Left = true;
} if(e.keyCode == 83) {
player2Right = true;
} else if(e.keyCode == 87) {
player2Left = true;
} }
function keyUpHandler(e) {
if(e.keyCode == 40) {
player1Right = false;
} if(e.keyCode == 38) {
player1Left = false;
} if(e.keyCode == 83) {
player2Right = false;
} if(e.keyCode == 87) {
player2Left = false;
}
else if (e.keyCode == 13){
gameRunning = true;
startScreen = false;
player1wins = false;
player2wins = false;
}
}
/*
function loadGame(){
if (startScreen){
var gradient = ctx.createLinearGradient(0,0,0,gradientMag);
gradient.addColorStop(0,blue );
gradient.addColorStop(1,red);
ctx.fillStyle = gradient;
ctx.fillRect(0,0, 500, 500);
ctx.font = "40px Verdana";
ctx.fillstyle = "blue";
ctx.fillText("Press Enter to begin", 150, 110);
}
}
*/
function ball() {
ctx.beginPath();
ctx.arc(ball_x, ball_y, ballRadius, 0, Math.PI*2);
ctx.fillStyle = "red";
ctx.fill();
ctx.closePath();
}
function paddle() {
ctx.beginPath();
ctx.rect(player1x, player1y, p_Width, p_Height);
ctx.fillStyle = "green";
ctx.fill();
ctx.closePath();
}
function player2() {
ctx.beginPath();
ctx.rect(player2x, player2y, p_Width, p_Height);
ctx.fillStyle = "blue";
ctx.fill();
ctx.closePath();
}
function draw() {
if (startScreen){
/*var gradient = ctx.createLinearGradient(0,0,0,gradientMag);
gradient.addColorStop(0,blue );
gradient.addColorStop(1,red);
ctx.fillStyle = gradient;
ctx.fillRect(0,0, 500, 500);
*/
ctx.font = "20px Verdana";
ctx.fillstyle = "blue";
ctx.fillText("Press Enter to begin", 100, 90);
}
if (gameRunning){
ctx.clearRect(0, 0, canvas.width, canvas.height);
ball();
paddle();
player2();
//bounce of the walls
if(ball_y + dy > canvas.width-ballRadius || ball_y+dy < ballRadius){
dy = -dy;
}
//if the ball hits the top
if(ball_x + dx < ballRadius) {
//if the ball hits the paddle of player 2
if(ball_x + dx < player2x + p_Height && ball_y > player2y && ball_y < player2y + p_Width){
console.log("hit the paddle");
dx = -dx;
}
//if the ball hits the top - do this first
else if(ball_x + dx < canvas.height)
{
//alert("Player 1 Wins!");
//document.location.reload();
player1wins = true;
gameRunning = false;
}
}
//if the ball hits the bottom
if(ball_x + dx > canvas.height-ballRadius) {
//the ball hits the paddle
if(ball_x + dx > player1x && ball_y > player1y && ball_y < player1y + p_Width){
dx = -dx;
}
//the ball hits the base
else if(ball_x + dx > canvas.height)
{
//alert("Player 2 Wins!");
//document.location.reload();
player2wins = true;
gameRunning = false;
}
}
if(player1Right && player1y < canvas.width-p_Width) {
player1y += 5;
}else if(player1Left && player1y > 0) {
player1y -= 5;
}
if(player2Right && player2y < canvas.width-p_Width) {
player2y += 5;
}else if(player2Left && player2y > 0) {
player2y -= 5;
}
ball_y += dy;
ball_x += dx;
}
else if (player1wins) {
ctx.clearRect(0, 0, canvas.width, canvas.height);
//background();
ctx.font = "20px Verdana";
ctx.fillstyle = "blue";
ctx.fillText("Well done player 1, you win!", 100, 90);
ctx.fillText("Hit F5 to play again!", 100, 110);
} else if (player2wins) {
ctx.clearRect(0, 0, canvas.width, canvas.height);
//background();
ctx.font = "20px Verdana";
ctx.fillstyle = "blue";
ctx.fillText("Well done player 2, you win!", 100, 90);
ctx.fillText("Hit F5 to play again!", 100, 110);
}
}
setInterval(draw, 10);
//loadGame();
</script>
</body>
</html>
Your choice of y to signify width hurts a bit, however, it seems to me you're only checking collision once the ball has passed the player paddle? (ball_x + dx > player1x)
Shouldn't it be the other way around? ball_x + dx < player1x

How do you move a drawing in javascript up down right and left

I was wondering how to move the red ball right and left (I already did, but its not working) and also how to move it up and down.
<canvas id="canvas" width="480" height="320"></canvas>
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var ball;
var obstacle;
var x = canvas.width / 2;
var y = canvas.height / 2;
var dx = 2;
var dy = -2;
var redballRadius = 10;
var ballRadius = 20;
var rightpressed = false;
var leftpressed = false;
var ballX = (canvas.width - redballDiameter) / 2;
var redballDiameter = redballRadius * 2;
function startGame() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
ball = new drawBall(30, 30, 'red', 20, 10);
obstacle = new drawObstacle(40, 30, 'blue', 15, 10);
if (x + dx > canvas.width - ballRadius || x + dx < ballRadius) {
dx = -dx;
}
if (y + dy > canvas.height - ballRadius || y + dy < ballRadius) {
dy = -dy;
}
if(rightpressed && ballX < canvas.width-redballDiameter) {
ballX += 7;
}
else if(leftpressed && ballX > 0) {
ballX -= 7;
}
}
//keyboard controls
document.addEventListener('keydown', keyDownHandler, false);
document.addEventListener('keyup', keyUpHandler, false);
function keyDownHandler(e) {
if(e.keyCode == 39) {
rightpressed = true;
}
else if(e.keyCode == 37) {
leftpressed = true;
}
}
function keyUpHandler(e) {
if(e.keyCode == 39) {
rightpressed = false;
}
else if (e.keyCode == 37) {
leftpressed = false;
}
}
function drawBall() {
ctx.beginPath();
ctx.arc(30, 30, 15, 0, 2 * Math.PI);
ctx.fillStyle = 'red';
ctx.fill();
ctx.closePath();
}
function drawObstacle() {
x += dx;
y += dy;
ctx.beginPath();
ctx.arc(x, y, 20, 10, 1 * Math.PI);
ctx.fillStyle = 'blue';
ctx.fill();
ctx.closePath();
}
setInterval(startGame, 10);
I am basically wondering how to move it up down right and left with the keys. Thanks
I took a look at your code. In your life cycle, you are calling drawBall, now sure what you are trying to do with the new there. anyways, I updated the function to use the ballX your key handling logic updates.
function drawBall() {
ctx.beginPath();
ctx.arc(ballX, 30, 15, 0, 2 * Math.PI);
ctx.fillStyle = 'red';
ctx.fill();
ctx.closePath();
}
here is the working code pen. http://codepen.io/poda/pen/aNPPEp
move a ball to up, down, right and left.
it would be better to use object than use global variable of x_pos and y_pos of ball
function drawBall() {
this.ball_x = 30;
this.ball_y = 30;
this.draw = function() {
ctx.beginPath();
ctx.arc(this.ball_x, this.ball_y, 15, 0, 2 * Math.PI);
ctx.fillStyle = 'red';
ctx.fill();
ctx.closePath();
},
this.move = function() {
if(rightpressed && this.ball_x < canvas.width-redballDiameter) {
this.ball_x += 5;
}
else if(leftpressed && this.ball_x > redballDiameter) {
this.ball_x -= 5;
}
else if(uppressed && this.ball_y > redballDiameter) {
this.ball_y -= 5;
}
else if(downpressed && this.ball_y < canvas.height - redballDiameter) {
this.ball_y += 5;
}
},
this.collision = function() {
//stuff
}
}
Here's a fiddle

How to make the ball move faster when it hits paddle?

How to make the ball move faster when it hits paddle !
var canvas = document.getElementById("myCanvas");var ctx = canvas.getContext("2d");
var dx = 2;var dy = -2;
var w = canvas.width, h = canvas.height;
var x = w/2;var y = h-30;
var ballRadius = 10;
var color = getColor();
var paddleHeight = 10;var paddleWidth = 75;var paddleX = (w-paddleWidth)/2;
var rightPressed = false;
var leftPressed = false;
document.addEventListener("keydown", keyDownHandler,false);
document.addEventListener("keyup", keyUpHandler,false);
function keyDownHandler(e) {
if(e.keyCode == 39) {
rightPressed = true;
}
else if(e.keyCode == 37) {
leftPressed = true;
}
}
function keyUpHandler(e) {
if(e.keyCode == 39) {
rightPressed = false;
}
else if(e.keyCode == 37) {
leftPressed = false;
}
}
function getColor() {
var letters = '0123456789ABCDEF'.split('');
var color = '#';
for (var i = 0; i < 6; i++ ) {
color += letters[Math.floor(Math.random() * 16)];
}
return color;
}
function drawBall() {
ctx.beginPath();
ctx.arc(x, y, ballRadius, 0, Math.PI*2);
ctx.fillStyle = color;
ctx.fill();
ctx.closePath();
}
function drawPaddle() {
ctx.beginPath();
ctx.rect(paddleX, h-paddleHeight, paddleWidth, paddleHeight);
ctx.fillStyle = "#eee";
ctx.fill();
ctx.closePath();
}
function draw() {
ctx.clearRect(0,0,w,h);
drawBall();
drawPaddle();
if(x + dx < ballRadius || x + dx > w-ballRadius) {
dx = -dx;
color = getColor();
}
if(y + dy < ballRadius) {
dy = -dy;
color = getColor();
}else if(y + dy > h-ballRadius) {
if(x > paddleX && x < paddleX + paddleWidth) {
dy = -dy;
}
else {
alert("GAME OVER");
}
}
if(rightPressed && paddleX < w-paddleWidth) {
paddleX += 7;
}
else if(leftPressed && paddleX > 0) {
paddleX -= 7;
}
x += dx;
y += dy;
}
setInterval(draw, 10);
/*left arrow: 37
up arrow: 38
right arrow: 39
down arrow: 40*/
* {
background-color: #224;
padding: 0; margin: 0;
}
canvas {
background: #555;
display: block;
margin: 10px auto;
}
<canvas id="myCanvas" width="480px" height="320px"></canvas>
Modify the bounce code in the draw function:
if(y + dy < ballRadius) {
dy = -dy;
color = getColor();
}
else if(y + dy > h-ballRadius) {
if(x > paddleX && x < paddleX + paddleWidth) {
dy = -dy * 1.1;
}
Note the last line:
dy = -dy * 1.1;
This means that dy will be increased by 10% each time the paddle hits the ball. You could change 1.1 to modify the scaling factor.

Moving up and down on javascript based canvas game

I am making game based on this tutorial: https://developer.mozilla.org/en-US/docs/Games/Workflows/2D_Breakout_game_pure_JavaScript
I think i understand how the paddle moves right and left. But when i try to make it move up and down, its not working at all. I have literally tried everyting but still its not working. So the question is how i can make it move up and down?
Here is the whole code:
<script>
var canvas = document.getElementById("tausta");
var ctx = canvas.getContext("2d");
var ballRadius = 10;
var x = canvas.width/2;
var y = canvas.height-30;
var dx = 2;
var dy = -2;
var paddleHeight = 10;
var paddleWidth = 75;
var paddleX = (canvas.width-paddleWidth)/2;
var paddleY = canvas.height-paddleHeight;
var rightPressed = false;
var leftPressed = false;
var upPressed = false;
var downPressed = false;
document.addEventListener("keydown", keyDownHandler, false);
document.addEventListener("keyup", keyUpHandler, false);
function keyDownHandler(e) {
if(e.keyCode == 39) {
rightPressed = true;
}
if(e.keyCode == 37) {
leftPressed = true;
}
if(e.keycode == 38){
upPressed = true;
}
if(e.keycode == 40){
downPressed = true;
}
}
function keyUpHandler(e) {
if(e.keyCode == 39) {
rightPressed = false;
}
if(e.keyCode == 37) {
leftPressed = false;
}
if(e.keycode == 38){
upPressed = false;
}
if(e.keycode == 40){
downPressed = false;
}
}
function drawBall() {
ctx.beginPath();
ctx.arc(x, y, ballRadius, 0, Math.PI*2);
ctx.fillStyle = "#0095DD";
ctx.fill();
ctx.closePath();
}
function drawPaddle() {
ctx.beginPath();
ctx.rect(paddleX, paddleY, paddleWidth, paddleHeight);
ctx.fillStyle = "#0095DD";
ctx.fill();
ctx.closePath();
}
function draw() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
drawBall();
drawPaddle();
if(x + dx > canvas.width-ballRadius || x + dx < ballRadius) {
dx = -dx;
}
if(y + dy > canvas.height-ballRadius || y + dy < ballRadius) {
dy = -dy;
}
if(rightPressed && paddleX < canvas.width-paddleWidth) {
paddleX += 5;
}
if(leftPressed && paddleX > 0) {
paddleX -= 5;
}
if(upPressed && paddleY < canvas.height-paddleHeight) {
paddleY += 5;
}
if(downPressed && paddleY > 0) {
paddleY -= 5;
}
x += dx;
y += dy;
}
setInterval(draw, 10);
</script>
Turns out it was a simple mistake.
You typed
if(e.keycode == 38){
if(e.keycode == 40){
But it should be
if(e.keyCode== 38){
if(e.keyCode== 40){
capital C
http://jsfiddle.net/cagwyd6m/4/

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