Im pretty new to javascript and am currently working on a pong game. It's nearly finished, the only thing i still want to add is a slider that changes the bots movement speed, but for some reason when i set the bots speed value to that of the slider, the bot just vanishes. I did the same thing for the angle the bot hits the ball with and it worked fine, so i have no idea why the other slider isn't working. The code is in the "paddleLeft" function.
CSS / HTML
body{
width: 100vw;
height: 100vh;
}
<body onresize="resizeCanvas()">
Bot speed<input type="range" min="0" max="5" step="0.5" value="2.5" id="botSpeed">
<canvas id="canvas"></canvas>
<script>
</script>
</body>
JavaScript
var canvas, context;
canvas = document.getElementById("canvas");
context = canvas.getContext("2d");
var ballRadius;
var ballRadiusValue = .000005; // Radius of ball
var ballSpeed = 2.5; // Speed the ball moves with
var ballSpeedX;
var ballSpeedY;
var ballX;
var ballY;
var paddleWidth;
var paddleWidthValue = .01; // Width of paddles
var paddleHeight;
var paddleHeightValue = .125; // Height of paddles
var paddleMargin = .01; // Margin the paddles have from the wall
var paddleLeftX;
var paddleLeftY;
var angle = 5; // Angle the bot hits the ball with (lower number == higher difficulty)
var speed = 2.5; // Speed the bot follows the ball with (higher number == higher difficulty)
// Main function
window.onload = function() {
resizeCanvas();
startGame();
setInterval(drawCanvas, 1);
};
// Resizes the canvas depending on the screen resolution
function resizeCanvas() {
// Sets the canvas width and height to the users viewport
context.canvas.width = document.body.clientWidth;
context.canvas.height = document.body.clientHeight;
// Ball
ballRadius = (canvas.width * canvas.height) * ballRadiusValue;
ballX = (canvas.width / 2) - (ballRadius / 2); // Center of canvas width
ballY = (canvas.height / 2) - (ballRadius / 2); // center of canvas height
// Paddle
paddleWidth = canvas.width * paddleWidthValue;
paddleHeight = canvas.height * paddleHeightValue;
paddleLeftX = canvas.width * paddleMargin;
paddleLeftY = (canvas.height / 2) - (paddleHeight / 2); // Centers, center of paddle to height of canvas
}
// Draws everything that's displayed on the canvas
function drawCanvas() {
background();
paddleLeft();
ball();
ballMovement();
}
function background() {
context.clearRect(0, 0, canvas.width, canvas.height);
context.fillStyle = "transparent";
context.fillRect(0, 0, canvas.width, canvas.height);
}
// Bot
function paddleLeft() {
context.fillStyle = "red";
context.fillRect(paddleLeftX, paddleLeftY, paddleWidth, paddleHeight);
var botSpeed = document.getElementById("botSpeed");
speed = 2.5; // This works
speed = botSpeed.value; // This doesn't work, even though "botSpeed.value" is the same value
var paddleLeftCenter = paddleLeftY + (paddleHeight / 2);
// How fast and at what angle the bot follows the ball
if (paddleLeftCenter < ballY - (paddleHeight / angle) && (paddleLeftY + paddleHeight) <= canvas.height) // Paddle is above ball
{
paddleLeftY += speed; // Moves the paddle down
}
else if (paddleLeftCenter > ballY + (paddleHeight / angle) && paddleLeftY >= 0) // Paddle is below ball
{
paddleLeftY -= speed; // Moves the paddle up
}
}
// Initial speed
function ballMovement() {
ballX += ballSpeedX;
ballY += ballSpeedY;
}
function ball() {
context.fillStyle = "black";
context.beginPath();
context.arc(ballX, ballY, ballRadius, 0, Math.PI * 2, true);
context.fill();
// Collision with border
if (ballX + ballRadius <= 0 ) // Left side
{
resetBall();
}
if (ballY - ballRadius <= 0) // Top
{
ballSpeedY = -ballSpeedY;
}
else if (ballY + ballRadius >= canvas.height) // Bottom
{
ballSpeedY = -ballSpeedY;
}
}
// Moves the ball in a random direction on game start
function startGame() {
ballSpeedX = -ballSpeed;
ballSpeedY = ballSpeed;
var random = Math.random();
if (random <= .5) // Moves ball down
{
ballSpeedY = ballSpeedY;
}
else if (random <= 1) // Moves ball up
{
ballSpeedY = -ballSpeedY;
}
}
// Resets the ball to its original position
function resetBall() {
ballX = canvas.width / 2;
ballY = canvas.height / 2;
startGame();
}
Here is the full code if you need to look at it https://jsfiddle.net/Suppenteller/85y1j9zx/11/
Sorry for the long code, the relevant part is from line 129-178 in the Javascript section.
Edit: No error messages in the console, made a new JsFiddle link, maybe this one works
Ok, i got it to work. For some reason i can't just set the new value, i have to substract/add them...
Here is the new code.
var isMovingSlider = false; // Slider function will only get fired once on change
if (!isMovingSlider)
{
// Sets the "botSpeed" value
botSpeed.addEventListener("change", function () {
isMovingSlider = true;
if (botSpeed.value < 2.5)
{
// For every step the slider gets moved below 2.5, subtract 0.5 from "speed"
speed = 2.5;
speed -= (2.5 - botSpeed.value);
}
else if (botSpeed.value > 2.5)
{
// For every step the slider gets moved aboce 2.5, add 0.5 to "speed"
speed = 2.5;
speed += (botSpeed.value - 2.5);
}
else if (botSpeed.value == 2.5)
{
speed = 2.5;
}
});
isMovingSlider = false;
}
botSpeedValue.innerHTML = botSpeed.value; // Displays the value of "botSpeed"
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