73 lines
1.7 KiB
JavaScript
73 lines
1.7 KiB
JavaScript
// JAVASCRIPT-3: SHOW & MOVE PADDLE
|
|
// © 2018, wbamberg
|
|
var canvas = document.getElementById("myCanvas");
|
|
var ctx = canvas.getContext("2d");
|
|
var ballRadius = 12;
|
|
var x = ballRadius;
|
|
var y = ballRadius;
|
|
var dx = 2;
|
|
var dy = -2;
|
|
var paddleHeight = 100;
|
|
var paddleWidth = 12;
|
|
var paddleY = (canvas.height-paddleHeight)/2;
|
|
var downPressed = false;
|
|
var upPressed = false;
|
|
|
|
function keyDownHandler(e) {
|
|
if(e.key == "Down" || e.key == "ArrowDown") {
|
|
downPressed = true;
|
|
}
|
|
else if(e.key == "Up" || e.key == "ArrowUp") {
|
|
upPressed = true;
|
|
}
|
|
}
|
|
|
|
function keyUpHandler(e) {
|
|
if(e.key == "Down" || e.key == "ArrowDown") {
|
|
downPressed = false;
|
|
}
|
|
else if(e.key == "Up" || e.key == "ArrowUp") {
|
|
upPressed = false;
|
|
}
|
|
}
|
|
|
|
function drawBall() {
|
|
ctx.beginPath();
|
|
ctx.arc(x, y, ballRadius, 0, 2 * Math.PI);
|
|
ctx.fillStyle = "#FF0000";
|
|
ctx.fill();
|
|
ctx.closePath();
|
|
}
|
|
function drawPaddle() {
|
|
ctx.beginPath();
|
|
ctx.rect(0, paddleY, paddleWidth, paddleHeight);
|
|
ctx.fillStyle = "#333";
|
|
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(downPressed && paddleY < canvas.height-paddleHeight) {
|
|
paddleY += 4;
|
|
}
|
|
else if(upPressed && paddleY > 4) {
|
|
paddleY -= 4;
|
|
}
|
|
|
|
x += dx;
|
|
y += dy;
|
|
}
|
|
|
|
document.addEventListener("keydown", keyDownHandler, false);
|
|
document.addEventListener("keyup", keyUpHandler, false);
|
|
setInterval(draw, 10); |