I'm trying to create a ball hop game where the ball has to jump from one platform to another. However, I'm struggling with having the ball land on the platform and I think it might be because the platform itself is moving rather than the camera/background. Does anyone know a way I could move the camera, or a solution to the ball landing on the platform even if the platform is moving?
This is my code now.
let gravity = 1.5;
class Ball{
constructor(){
this.x = 0;
this.y= 200;
this.d = 30;
// constant velocity of the ball
this.v = 0.001;
this.xg = 0;
this.yg = 0;
}
draw() {
// stroke(0, 255, 255);
ellipse(this.x, this.y, this.d);
}
update() {
this.draw();
this.y += this.yg;
// ensures that ball doesnt go past screen
if (this.y + this.d + this.yg <= windowHeight) {
this.yg += gravity;
}
}
}
class Platform{
constructor({x,y}){
this.x = x;
this.y= y;
this.w = 30;
this.h = 30;
this.s = 1;
}
draw(){
push();
rectMode(CENTER);
rotateX(1.45);
rect(this.x,this.y,this.w,this.h);
pop();
}
move(){
this.y = this.y + this.s
this.s = this.s + 0.0001
}
}
let ball;
let plat;
let scrollOffset = 0;
function setup(){
createCanvas(710, 400, WEBGL);
ball = new Ball();
plat = [
(new Platform({x:0,y:200})),
(new Platform({x:50,y:100})),
(new Platform({x:0,y:0})),
(new Platform({x:-50,y:-100})),
(new Platform({x:0,y:-200})),
];
}
function draw(){
background(255);
ball.update();
plat.forEach((plat) => {
plat.draw();
plat.move();
});
plat.forEach((plat) => {
if (
ball.y + ball.d <= plat.y &&
ball.y + ball.d + ball.yg >= plat.y &&
ball.x + ball.d >= plat.x &&
ball.x <= plat.x + plat.w
) {
ball.yg = 0;
}
});
}
function keyPressed() {
if (keyCode === UP_ARROW) {
ball.yg -= 20;
}
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.5.0/p5.min.js"></script>
Hi guys i'm very new to p5/js and not quite good at OOP programming.
I want to drop a ball by changing its speed once the mouse is clicked.
After trying to write and edit the code many times, the p5 editor didn't show any error massages but there aren't anything shown up on the display. So, I need a hand and some advices to fix this kind of problem.
Thank you in advance (:
let ball1;
let circleX = 50;
let circleY = 50;
let xspeed = 0; // Speed of the shape
let yspeed = 0; // Speed of the shape
let xdirection = 1; // Left or Right
let ydirection = 1; // Top to Bottom
let rad =50;
function setup() {
createCanvas(400, 400);
ball1 = new Ball();
}
function draw() {
background(220);
ball1.x =20;
ball1.y = 50;
ball1.c = color(25,0,100)
ball1.body();
ball1.move();
ball1.bounce();
}
class Ball {
constructor(){
this.x = width/2;
this.y = height;
this.w = 30;
this.h = 30;
this.c = color(0,255,0);
this.xspeed = 0;
this.yspeed = 0;
}
body(){
noStroke();
fill(this.c);
ellipse(this.x, this.y, this.w, this.h);
}
move() {
//this.xpos = width / 2;
//this.ypos = height / 2;
this.x = this.x + this.xspeed * this.xdirection;
this.y = this.y + this.yspeed * this.ydirection;
}
bounce() {
if (this.x > width - rad || this.x < rad) {
this.xdirection *= -1;
}
if (this.y > height - rad || this.y < rad) {
this.ydirection *= -1;
}
}
if(mouseIsPressed) { // if the mouse is pressed
//set the new speed;
this.fill(0, 0, 0);
this.xspeed =1.5;
this.yspeed=1.5;
}
}
You've got some good beginnings to your code. I modified it just a bit to assist toward OOP programming. See the code at the end of my answer for the full source.
Solution
The main question you are asking involves setting the ball's speed when the mouse button is pressed. For that, you should declare a mousePressed() function in your code as such (borrowing from your if block):
function mousePressed() {
// if the mouse is pressed
// set the new speed;
ball.xspeed = 1.5;
ball.yspeed = 1.5;
}
That should set the speed of the ball and that should solve your problem.
Other thoughts
Some other steps I took to adjust your code to more working conditions include:
I created a reset() function to be used in the setup() function and potentially able to reset the animation whenever you would like.
I changed the rad variable declaration to const rad = 50 since it doesn't change
I changed the Ball constructor to include initial (x, y) coordinates when creating the ball (could be helpful if creating multiple balls)
If you want to create an arbitrary number of balls, create an array and use array.push(new Ball(x, y)) for each ball and loop through the array to move()/bounce()/body() each ball.
I'm assuming rad is meant to be the radius of the balls, so I set the this.w and this.h to rad * 2 since with and height would equate to the diameter.
let ball;
const rad = 50;
// let circleX = 50;
// let circleY = 50;
//let xspeed = 0; // Speed of the shape
//let yspeed = 0; // Speed of the shape
function setup() {
createCanvas(400, 400);
reset();
}
function draw() {
background(220);
ball.body();
ball.move();
ball.bounce();
}
function mousePressed() {
// if the mouse is pressed
//set the new speed;
ball.xspeed = 1.5;
ball.yspeed = 1.5;
}
function reset() {
ball = new Ball(width / 2, height / 2);
}
class Ball {
constructor(x, y) {
this.x = x;
this.y = y;
this.w = rad * 2;
this.h = rad * 2;
this.c = color(25, 0, 100);
this.xspeed = 0;
this.yspeed = 0;
this.xdirection = 1;
this.ydirection = 1;
}
body() {
noStroke();
fill(this.c);
ellipse(this.x, this.y, this.w, this.h);
}
move() {
this.x = this.x + this.xspeed * this.xdirection;
this.y = this.y + this.yspeed * this.ydirection;
}
bounce() {
if (this.x > width - rad || this.x < rad) {
this.xdirection *= -1;
}
if (this.y > height - rad || this.y < rad) {
this.ydirection *= -1;
}
}
}
<script src="https://cdn.jsdelivr.net/npm/p5#1.4.0/lib/p5.min.js"></script>
Numbers before code are line numbers, they might be wrong, but should be close enough...
You need to move the 64 if(mouseIsPressed){} into a function like 47 move().
Also you haven't declared and initialized 39 this.xdirection
in the constructor(){}.
I think 67 this.fill(0, 0, 0) should be fill(0).
Maybe 24 ball1.body(); should be after the other methods (24 -> 26 line).
I think the if() statements in bounce(){} are wrong, since they'd need to have AND or && instead of OR or ||.
Also you might want to make the if(mouseIsPressed) into function mousePressed(){} mouseIsPressed is a variable that is true if mouse button is down; mousePressed is a function that gets called once when user presses the mouse button.
function mousePressed(){
ball1.xSpeed = 1.5
ball1.ySpeed = 1.5
}
There might very well be other things i haven't noticed.
I'm caught in a logic knot with this game :(. I simply want to remove the explosions from the screen after say 1 second of each doing its loop. As you can see below they run at the frame rate of the game loop. This is the only way I could animate the explosion - by setting a sprite to move at the speed of the game loop (frame rate).
I don't understand how to connect a separate animation going at a different speed to this same canvas context that is being essentially cleared every frame.. I can't even figure out how to stop the explosion sprite loop.
I've tried creating a separate method drawExplosion() in the Explosion class and using setInterval in the Explosion constructor but it never likes the context I connect it to and throws this error:
Cannot read property 'drawImage' of undefined (i.e. the context is undefined)
If someone could just stop each explosion loop after 1 second I would understand where I went off course
The outline of the code is this:
class Entity
class Ball extends Entity
class Explosion extends Entity
class Enemy extends Entity
class Paddle extends Entity
class InputsManager
class mouseMoveHandler
class Game
const canvas = document.querySelector('canvas')
const game = new Game(canvas)
game.start()
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
body {
background-color: rgb(214, 238, 149);
height: 100vh;
display: flex;
justify-content: center;
align-items: center;
margin: 0;
padding: 0;
}
canvas {
background: url("https://picsum.photos/200");
width: 100%;
background-size: cover;
}
</style>
</head>
<body>
<canvas height="459"></canvas>
</body>
<script>
class Entity {
constructor(x, y) {
this.dead = false;
this.collision = 'none'
this.x = x
this.y = y
}
update() { console.warn(`${this.constructor.name} needs an update() function`) }
draw() { console.warn(`${this.constructor.name} needs a draw() function`) }
isDead() { console.warn(`${this.constructor.name} needs an isDead() function`) }
static testCollision(a, b) {
if (a.collision === 'none') {
console.warn(`${a.constructor.name} needs a collision type`)
return undefined
}
if (b.collision === 'none') {
d
console.warn(`${b.constructor.name} needs a collision type`)
return undefined
}
if (a.collision === 'circle' && b.collision === 'circle') {
return Math.sqrt((a.x - b.x) ** 2 + (a.y - b.y) ** 2) < a.radius + b.radius
}
if (a.collision === 'circle' && b.collision === 'rect' || a.collision === 'rect' && b.collision === 'circle') {
let circle = a.collision === 'circle' ? a : b
let rect = a.collision === 'rect' ? a : b
// this is a waaaaaay simplified collision that just works in this case (circle always comes from the bottom)
const topOfBallIsAboveBottomOfRect = circle.y - circle.radius <= rect.y + rect.height
const bottomOfBallIsBelowTopOfRect = circle.y + circle.radius >= rect.y - rect.height
const ballIsRightOfRectLeftSide = circle.x + circle.radius >= rect.x - rect.width / 4
const ballIsLeftOfRectRightSide = circle.x - circle.radius <= rect.x + rect.width
return topOfBallIsAboveBottomOfRect && bottomOfBallIsBelowTopOfRect && ballIsRightOfRectLeftSide && ballIsLeftOfRectRightSide
}
console.warn(`there is no collision function defined for a ${a.collision} and a ${b.collision}`)
return undefined
}
static testBallCollision(ball) {
const topOfBallIsAboveBottomOfRect = ball.y - ball.radius <= this.y + this.height / 2
const bottomOfBallIsBelowTopOfRect = ball.y + ball.radius >= this.y - this.height / 2
const ballIsRightOfRectLeftSide = ball.x - ball.radius >= this.x - this.width / 2
const ballIsLeftOfRectRightSide = ball.x + ball.radius <= this.x + this.width / 2
return topOfBallIsAboveBottomOfRect && bottomOfBallIsBelowTopOfRect && ballIsRightOfRectLeftSide && ballIsLeftOfRectRightSide
}
}
class Ball extends Entity {
constructor(x, y) {
super(x, y)
this.dead = false;
this.collision = 'circle'
this.speed = 300 // px per second
this.radius = 2.5 // radius in px
this.color = '#fff'
this.ballsDistanceY = 12
}
update({ deltaTime }) {
// Ball still only needs deltaTime to calculate its update
this.y -= this.speed * deltaTime / 1000 // deltaTime is ms so we divide by 1000
}
/** #param {CanvasRenderingContext2D} context */
draw(context) {
context.beginPath()
context.arc(this.x, this.y, this.radius, 0, 2 * Math.PI)
context.fillStyle = this.color;
context.fill()
context.beginPath()
context.arc(this.x, this.y + this.ballsDistanceY, this.radius, 0, 2 * Math.PI)
context.fillStyle = this.color;
context.fill()
context.beginPath()
context.arc(this.x, this.y - this.ballsDistanceY, this.radius, 0, 2 * Math.PI)
context.fillStyle = this.color;
context.fill()
}
isDead(enemy) {
const outOfBounds = this.y < 0 - this.radius
const collidesWithEnemy = Entity.testCollision(enemy, this)
if (outOfBounds) {
return true
}
if (collidesWithEnemy) {
//console.log('dead')
this.dead = true;
game.hitEnemy();
return true
}
}
}
class Explosion extends Entity {
constructor(x, y, contextFromGameObject){
super(x, y)
this.contextFromGameObject = contextFromGameObject
this.imgExplosion = new Image();
this.imgExplosion.src = "https://i.ibb.co/9Ggfzxr/explosion.png";
this.totalNumberOfFrames = 12 // ten images in the image (see the url above)
this.spriteFrameNumber = 0 // This is changed to make the sprite animate
this.widthOfSprite = 1200 // this.imgExplosion.width; // find the width of the image
this.heightOfSprite = 100 // this.imgExplosion.height; // find the height of the image
this.widthOfSingleImage = this.widthOfSprite / this.totalNumberOfFrames; // The width of each image in the spirite
//this.timerId = setInterval(this.explode.bind(this), 100)
this.scaleExplosion = 0.5
//this.timerId = setInterval(this.drawExplosion, 100);
}
// drawExplosion(){
// console.log(this.spriteFrameNumber)
// //ctx.clearRect(0, 0, 500, 500)
// this.spriteFrameNumber += 1; // changes the sprite we look at
// this.spriteFrameNumber = this.spriteFrameNumber % this.totalNumberOfFrames; // Change this from 0 to 1 to 2 ... upto 9 and back to 0 again, then 1...
// this.contextFromGameObject.drawImage(this.imgExplosion,
// this.spriteFrameNumber * this.widthOfSingleImage, 0, // x and y - where in the sprite
// this.widthOfSingleImage, this.heightOfSprite, // width and height
// this.x - 25, this.y - 25, // x and y - where on the screen
// this.widthOfSingleImage, this.heightOfSprite // width and height
// );
// if (this.spriteFrameNumber > 9) {
// clearInterval(this.timerId)
// };
// }
/** #param {CanvasRenderingContext2D} context */
draw(context, frameNumber) {
console.log(frameNumber)
//ctx.clearRect(0, 0, 500, 500)
this.spriteFrameNumber += 1; // changes the sprite we look at
this.spriteFrameNumber = this.spriteFrameNumber % this.totalNumberOfFrames; // Change this from 0 to 1 to 2 ... upto 9 and back to 0 again, then 1...
context.drawImage(this.imgExplosion,
this.spriteFrameNumber * this.widthOfSingleImage, 0, // x and y - where in the sprite
this.widthOfSingleImage, this.heightOfSprite, // width and height
this.x - 25, this.y - 25, // x and y - where on the screen
this.widthOfSingleImage, this.heightOfSprite // width and height
);
}
update() {
}
isDead(ball, isDead) {
if(isDead == 'true'){
clearTimeout(this.timerId);
return true
}
return false
}
}
class Enemy extends Entity {
constructor(x, y) {
super(x, y)
this.collision = 'rect'
this.height = 50;
this.width = 50;
this.speedVar = 4;
this.speed = this.speedVar;
this.color = '#EC3AC8';
this.color2 = '#000000';
this.y = y;
this.imgEnemy = new Image();
this.imgEnemy.src = "https://i.ibb.co/kgXsr66/question.png";
this.runCount = 1;
this.timerId = setInterval(this.movePosish.bind(this), 1000);
}
movePosish() {
//console.log(this.runCount)
// x 10 -> 240
// y 10 -> 300
switch (this.runCount) {
case 0:
this.x = 20; this.y = 200;
break
case 1:
this.x = 200; this.y = 300;
break
case 2:
this.x = 30; this.y = 20;
break
case 3:
this.x = 230; this.y = 150;
break
case 4:
this.x = 200; this.y = 20;
break
case 5:
this.x = 30; this.y = 90;
break
case 6:
this.x = 240; this.y = 20;
break
case 7:
this.x = 30; this.y = 150;
break
case 8:
this.x = 180; this.y = 170;
break
case 9:
this.x = 30; this.y = 50;
break
case 10:
this.x = 130; this.y = 170;
break
}
//if 10th image remove image and clear timer
this.runCount += 1;
if (this.runCount > 10) {
//clearInterval(this.timerId)
this.runCount = 0;
console.log('ya missed 10 of em')
};
}
update() {
// //Moving left/right
// this.x += this.speed;
// if (this.x > canvas.width - this.width) {
// this.speed -= this.speedVar;
// }
// if (this.x === 0) {
// this.speed += this.speedVar;
// }
}
/** #param {CanvasRenderingContext2D} context */
draw(context) {
// context.beginPath();
// context.rect(this.x, this.y, this.width, this.height);
// context.fillStyle = this.color2;
// context.fill();
// context.closePath();
context.drawImage(this.imgEnemy, this.x, this.y);
}
isDead(enemy) {
//// collision detection
// const collidesWithEnemy = Entity.testCollision(enemy, ball)
// if (collidesWithEnemy){
// console.log('enemy dead')
// game.hitEnemy();
// return true
// }
// if (ball.dead){
// console.log('enemy dead')
// game.hitEnemy();
// return true
// }
return false
}
}
class Paddle extends Entity {
constructor(x, width) {
super(x, width)
this.collision = 'rect'
this.speed = 200
this.height = 25
this.width = 30
this.color = "#74FCEF"
}
update({ deltaTime, inputs, mouse }) {
// Paddle needs to read both deltaTime and inputs
// if mouse inside canvas AND not on mobile
if (mouse.insideCanvas) {
this.x = mouse.paddleX
} else {
this.x += this.speed * deltaTime / 1000 * inputs.direction
// stop from going off screen
if (this.x < this.width / 2) {
this.x = this.width / 2;
} else if (this.x > canvas.width - this.width / 2) {
this.x = canvas.width - this.width / 2
}
}
}
/** #param {CanvasRenderingContext2D} context */
draw(context) {
context.beginPath();
context.rect(this.x - this.width / 2, this.y - this.height / 2, this.width, this.height);
context.fillStyle = this.color;
context.fill();
context.closePath();
context.beginPath();
context.rect(this.x - this.width / 12, this.y - this.height / 1.1, this.width / 6, this.height);
context.fillStyle = this.color;
context.fill();
context.closePath();
}
isDead() { return false }
}
class InputsManager {
constructor() {
this.direction = 0 // this is the value we actually need in out Game object
window.addEventListener('keydown', this.onKeydown.bind(this))
window.addEventListener('keyup', this.onKeyup.bind(this))
}
onKeydown(event) {
switch (event.key) {
case 'ArrowLeft':
this.direction = -1
break
case 'ArrowRight':
this.direction = 1
break
}
}
onKeyup(event) {
switch (event.key) {
case 'ArrowLeft':
if (this.direction === -1) // make sure the direction was set by this key before resetting it
this.direction = 0
break
case 'ArrowRight':
this.direction = 1
if (this.direction === 1) // make sure the direction was set by this key before resetting it
this.direction = 0
break
}
}
}
class mouseMoveHandler {
constructor() {
// this.paddleWidth = paddleWidth;
this.x = 0;
this.paddleX = 0;
//this.canvas = canvas;
document.addEventListener("mousemove", this.onMouseMove.bind(this), false);
}
//'relative to canvas width' mouse position snippet
getMousePos(canvas, evt) {
var rect = canvas.getBoundingClientRect(), // abs. size of element
scaleX = canvas.width / rect.width, // relationship bitmap vs. element for X
scaleY = canvas.height / rect.height; // relationship bitmap vs. element for Y
//console.log('canvas width = ' + canvas.width)
return {
x: (evt.clientX - rect.left) * scaleX, // scale mouse coordinates after they have
y: (evt.clientY - rect.top) * scaleY // been adjusted to be relative to element
}
}
onMouseMove(e) {
//console.log('moving')
//this.x = 100;
this.x = this.getMousePos(canvas, e).x; //relative x on canvas
this.y = this.getMousePos(canvas, e).y; //relative x on canvas
this.insideCanvas = false;
if (this.x > 0 && this.x < canvas.width) {
if (this.y > 0 && this.y < canvas.height) {
//console.log('inside')
this.insideCanvas = true;
} else {
this.insideCanvas = false;
}
}
if (this.x - 20 > 0 && this.x < canvas.width - 20) {
this.paddleX = this.x;
}
}
}
class Game {
/** #param {HTMLCanvasElement} canvas */
constructor(canvas) {
this.entities = [] // contains all game entities (Balls, Paddles, ...)
this.context = canvas.getContext('2d')
this.newBallInterval = 900 // ms between each ball
this.lastBallCreated = -Infinity // timestamp of last time a ball was launched
this.paddleWidth = 50
this.isMobile = false
this.frameNumber = 0;
}
endGame() {
//clear all elements, remove h-hidden class from next frame, then remove h-hidden class from the cta content
console.log('endgame')
const endGame = true;
game.loop(endGame)
}
hitEnemy() {
//this.timerId = setTimeout(endExplosion(), 500);
this.explosion = new Explosion(this.enemy.x, this.enemy.y, this.context)
this.entities.push(this.explosion)
}
start() {
this.lastUpdate = performance.now()
this.enemy = new Enemy(140, 220)
this.entities.push(this.enemy)
// we store the new Paddle in this.player so we can read from it later
this.player = new Paddle(150, 400)
// but we still add it to the entities list so it gets updated like every other Entity
this.entities.push(this.player)
//start watching inputs
this.inputsManager = new InputsManager()
//start watching mousemovement
this.mouseMoveHandler = new mouseMoveHandler()
//start game loop
this.loop()
}
update() {
// calculate time elapsed
const newTime = performance.now()
const deltaTime = newTime - this.lastUpdate
this.isMobile = window.matchMedia('(max-width: 1199px)');
// we now pass more data to the update method so that entities that need to can also read from our InputsManager
const frameData = {
deltaTime,
inputs: this.inputsManager,
mouse: this.mouseMoveHandler,
context: this.context
}
// update every entity
this.entities.forEach(entity => entity.update(frameData))
// other update logic (here, create new entities)
if (this.lastBallCreated + this.newBallInterval < newTime) {
// this is quick and dirty, you should put some more thought into `x` and `y` here
this.ball = new Ball(this.player.x, 360)
this.entities.push(this.ball)
this.lastBallCreated = newTime
}
// remember current time for next update
this.lastUpdate = newTime
}
cleanup() {
//console.log(this.entities[0])//Enemy
//console.log(this.entities[1])//Paddle
//console.log(this.entities[2])//Ball
//to prevent memory leak, don't forget to cleanup dead entities
this.entities.forEach(entity => {
if (entity.isDead(this.enemy)) {
const index = this.entities.indexOf(entity)
this.entities.splice(index, 1)
}
})
}
draw() {
//draw entities
this.entities.forEach(entity => entity.draw(this.context, this.frameNumber))
}
//main game loop
loop(endGame) {
this.myLoop = requestAnimationFrame(() => {
this.frameNumber += 1;
this.context.clearRect(0, 0, this.context.canvas.width, this.context.canvas.height)
if (endGame) {
cancelAnimationFrame(this.myLoop);
this.endGame()
return;
}
this.update()
this.draw()
this.cleanup()
this.loop()
})
}
}
const canvas = document.querySelector('canvas')
const game = new Game(canvas)
game.start()
</script>
</html>
What you might want to do is to use a boolean that stays true as long as your animation should be running, it will call the function that draws your explosion.
class Entity {
constructor(x, y) {
this.dead = false;
this.collision = 'none'
this.x = x
this.y = y
}
update() { console.warn(`${this.constructor.name} needs an update() function`) }
draw() { console.warn(`${this.constructor.name} needs a draw() function`) }
isDead() { console.warn(`${this.constructor.name} needs an isDead() function`) }
static testCollision(a, b) {
if (a.collision === 'none') {
console.warn(`${a.constructor.name} needs a collision type`)
return undefined
}
if (b.collision === 'none') {
d
console.warn(`${b.constructor.name} needs a collision type`)
return undefined
}
if (a.collision === 'circle' && b.collision === 'circle') {
return Math.sqrt((a.x - b.x) ** 2 + (a.y - b.y) ** 2) < a.radius + b.radius
}
if (a.collision === 'circle' && b.collision === 'rect' || a.collision === 'rect' && b.collision === 'circle') {
let circle = a.collision === 'circle' ? a : b
let rect = a.collision === 'rect' ? a : b
// this is a waaaaaay simplified collision that just works in this case (circle always comes from the bottom)
const topOfBallIsAboveBottomOfRect = circle.y - circle.radius <= rect.y + rect.height
const bottomOfBallIsBelowTopOfRect = circle.y + circle.radius >= rect.y - rect.height
const ballIsRightOfRectLeftSide = circle.x + circle.radius >= rect.x - rect.width / 4
const ballIsLeftOfRectRightSide = circle.x - circle.radius <= rect.x + rect.width
return topOfBallIsAboveBottomOfRect && bottomOfBallIsBelowTopOfRect && ballIsRightOfRectLeftSide && ballIsLeftOfRectRightSide
}
console.warn(`there is no collision function defined for a ${a.collision} and a ${b.collision}`)
return undefined
}
static testBallCollision(ball) {
const topOfBallIsAboveBottomOfRect = ball.y - ball.radius <= this.y + this.height / 2
const bottomOfBallIsBelowTopOfRect = ball.y + ball.radius >= this.y - this.height / 2
const ballIsRightOfRectLeftSide = ball.x - ball.radius >= this.x - this.width / 2
const ballIsLeftOfRectRightSide = ball.x + ball.radius <= this.x + this.width / 2
return topOfBallIsAboveBottomOfRect && bottomOfBallIsBelowTopOfRect && ballIsRightOfRectLeftSide && ballIsLeftOfRectRightSide
}
}
class Ball extends Entity {
constructor(x, y) {
super(x, y)
this.dead = false;
this.collision = 'circle'
this.speed = 300 // px per second
this.radius = 2.5 // radius in px
this.color = '#fff'
this.ballsDistanceY = 12
}
update({ deltaTime }) {
// Ball still only needs deltaTime to calculate its update
this.y -= this.speed * deltaTime / 1000 // deltaTime is ms so we divide by 1000
}
/** #param {CanvasRenderingContext2D} context */
draw(context) {
context.beginPath()
context.arc(this.x, this.y, this.radius, 0, 2 * Math.PI)
context.fillStyle = this.color;
context.fill()
context.beginPath()
context.arc(this.x, this.y + this.ballsDistanceY, this.radius, 0, 2 * Math.PI)
context.fillStyle = this.color;
context.fill()
context.beginPath()
context.arc(this.x, this.y - this.ballsDistanceY, this.radius, 0, 2 * Math.PI)
context.fillStyle = this.color;
context.fill()
}
isDead(enemy) {
const outOfBounds = this.y < 0 - this.radius
const collidesWithEnemy = Entity.testCollision(enemy, this)
if (outOfBounds) {
return true
}
if (collidesWithEnemy) {
//console.log('dead')
this.dead = true;
game.hitEnemy();
return true
}
}
}
class Explosion extends Entity {
constructor(x, y, contextFromGameObject){
super(x, y)
this.contextFromGameObject = contextFromGameObject
this.imgExplosion = new Image();
this.imgExplosion.src = "https://i.ibb.co/9Ggfzxr/explosion.png";
this.totalNumberOfFrames = 12 // ten images in the image (see the url above)
this.spriteFrameNumber = 0 // This is changed to make the sprite animate
this.widthOfSprite = 1200 // this.imgExplosion.width; // find the width of the image
this.heightOfSprite = 100 // this.imgExplosion.height; // find the height of the image
this.widthOfSingleImage = this.widthOfSprite / this.totalNumberOfFrames; // The width of each image in the spirite
//this.timerId = setInterval(this.explode.bind(this), 100)
this.scaleExplosion = 0.5
this.explosionHappened = 0;
//this.timerId = setInterval(this.drawExplosion, 100);
}
// drawExplosion(){
// console.log(this.spriteFrameNumber)
// //ctx.clearRect(0, 0, 500, 500)
// this.spriteFrameNumber += 1; // changes the sprite we look at
// this.spriteFrameNumber = this.spriteFrameNumber % this.totalNumberOfFrames; // Change this from 0 to 1 to 2 ... upto 9 and back to 0 again, then 1...
// this.contextFromGameObject.drawImage(this.imgExplosion,
// this.spriteFrameNumber * this.widthOfSingleImage, 0, // x and y - where in the sprite
// this.widthOfSingleImage, this.heightOfSprite, // width and height
// this.x - 25, this.y - 25, // x and y - where on the screen
// this.widthOfSingleImage, this.heightOfSprite // width and height
// );
// if (this.spriteFrameNumber > 9) {
// clearInterval(this.timerId)
// };
// }
/** #param {CanvasRenderingContext2D} context */
draw(context, frameNumber) {
//console.log(frameNumber)
if(this.explosionHappened)
{
//ctx.clearRect(0, 0, 500, 500)
this.spriteFrameNumber += 1; // changes the sprite we look at
this.spriteFrameNumber = this.spriteFrameNumber % this.totalNumberOfFrames; // Change this from 0 to 1 to 2 ... upto 9 and back to 0 again, then 1...
context.drawImage(this.imgExplosion,
this.spriteFrameNumber * this.widthOfSingleImage, 0, // x and y - where in the sprite
this.widthOfSingleImage, this.heightOfSprite, // width and height
this.x - 25, this.y - 25, // x and y - where on the screen
this.widthOfSingleImage, this.heightOfSprite // width and height
);
this.explosionHappened=this.spriteFrameNumber;
}
}
update() {
}
isDead(ball, isDead) {
if(isDead == 'true'){
clearTimeout(this.timerId);
return true
}
return false
}
}
class Enemy extends Entity {
constructor(x, y) {
super(x, y)
this.collision = 'rect'
this.height = 50;
this.width = 50;
this.speedVar = 4;
this.speed = this.speedVar;
this.color = '#EC3AC8';
this.color2 = '#000000';
this.y = y;
this.imgEnemy = new Image();
this.imgEnemy.src = "https://i.ibb.co/kgXsr66/question.png";
this.runCount = 1;
this.timerId = setInterval(this.movePosish.bind(this), 1000);
}
movePosish() {
//console.log(this.runCount)
// x 10 -> 240
// y 10 -> 300
switch (this.runCount) {
case 0:
this.x = 20; this.y = 200;
break
case 1:
this.x = 200; this.y = 300;
break
case 2:
this.x = 30; this.y = 20;
break
case 3:
this.x = 230; this.y = 150;
break
case 4:
this.x = 200; this.y = 20;
break
case 5:
this.x = 30; this.y = 90;
break
case 6:
this.x = 240; this.y = 20;
break
case 7:
this.x = 30; this.y = 150;
break
case 8:
this.x = 180; this.y = 170;
break
case 9:
this.x = 30; this.y = 50;
break
case 10:
this.x = 130; this.y = 170;
break
}
//if 10th image remove image and clear timer
this.runCount += 1;
if (this.runCount > 10) {
//clearInterval(this.timerId)
this.runCount = 0;
console.log('ya missed 10 of em')
};
}
update() {
// //Moving left/right
// this.x += this.speed;
// if (this.x > canvas.width - this.width) {
// this.speed -= this.speedVar;
// }
// if (this.x === 0) {
// this.speed += this.speedVar;
// }
}
/** #param {CanvasRenderingContext2D} context */
draw(context) {
// context.beginPath();
// context.rect(this.x, this.y, this.width, this.height);
// context.fillStyle = this.color2;
// context.fill();
// context.closePath();
context.drawImage(this.imgEnemy, this.x, this.y);
}
isDead(enemy) {
//// collision detection
// const collidesWithEnemy = Entity.testCollision(enemy, ball)
// if (collidesWithEnemy){
// console.log('enemy dead')
// game.hitEnemy();
// return true
// }
// if (ball.dead){
// console.log('enemy dead')
// game.hitEnemy();
// return true
// }
return false
}
}
class Paddle extends Entity {
constructor(x, width) {
super(x, width)
this.collision = 'rect'
this.speed = 200
this.height = 25
this.width = 30
this.color = "#74FCEF"
}
update({ deltaTime, inputs, mouse }) {
// Paddle needs to read both deltaTime and inputs
// if mouse inside canvas AND not on mobile
if (mouse.insideCanvas) {
this.x = mouse.paddleX
} else {
this.x += this.speed * deltaTime / 1000 * inputs.direction
// stop from going off screen
if (this.x < this.width / 2) {
this.x = this.width / 2;
} else if (this.x > canvas.width - this.width / 2) {
this.x = canvas.width - this.width / 2
}
}
}
/** #param {CanvasRenderingContext2D} context */
draw(context) {
context.beginPath();
context.rect(this.x - this.width / 2, this.y - this.height / 2, this.width, this.height);
context.fillStyle = this.color;
context.fill();
context.closePath();
context.beginPath();
context.rect(this.x - this.width / 12, this.y - this.height / 1.1, this.width / 6, this.height);
context.fillStyle = this.color;
context.fill();
context.closePath();
}
isDead() { return false }
}
class InputsManager {
constructor() {
this.direction = 0 // this is the value we actually need in out Game object
window.addEventListener('keydown', this.onKeydown.bind(this))
window.addEventListener('keyup', this.onKeyup.bind(this))
}
onKeydown(event) {
switch (event.key) {
case 'ArrowLeft':
this.direction = -1
break
case 'ArrowRight':
this.direction = 1
break
}
}
onKeyup(event) {
switch (event.key) {
case 'ArrowLeft':
if (this.direction === -1) // make sure the direction was set by this key before resetting it
this.direction = 0
break
case 'ArrowRight':
this.direction = 1
if (this.direction === 1) // make sure the direction was set by this key before resetting it
this.direction = 0
break
}
}
}
class mouseMoveHandler {
constructor() {
// this.paddleWidth = paddleWidth;
this.x = 0;
this.paddleX = 0;
//this.canvas = canvas;
document.addEventListener("mousemove", this.onMouseMove.bind(this), false);
}
//'relative to canvas width' mouse position snippet
getMousePos(canvas, evt) {
var rect = canvas.getBoundingClientRect(), // abs. size of element
scaleX = canvas.width / rect.width, // relationship bitmap vs. element for X
scaleY = canvas.height / rect.height; // relationship bitmap vs. element for Y
//console.log('canvas width = ' + canvas.width)
return {
x: (evt.clientX - rect.left) * scaleX, // scale mouse coordinates after they have
y: (evt.clientY - rect.top) * scaleY // been adjusted to be relative to element
}
}
onMouseMove(e) {
//console.log('moving')
//this.x = 100;
this.x = this.getMousePos(canvas, e).x; //relative x on canvas
this.y = this.getMousePos(canvas, e).y; //relative x on canvas
this.insideCanvas = false;
if (this.x > 0 && this.x < canvas.width) {
if (this.y > 0 && this.y < canvas.height) {
//console.log('inside')
this.insideCanvas = true;
} else {
this.insideCanvas = false;
}
}
if (this.x - 20 > 0 && this.x < canvas.width - 20) {
this.paddleX = this.x;
}
}
}
class Game {
/** #param {HTMLCanvasElement} canvas */
constructor(canvas) {
this.entities = [] // contains all game entities (Balls, Paddles, ...)
this.context = canvas.getContext('2d')
this.newBallInterval = 900 // ms between each ball
this.lastBallCreated = -Infinity // timestamp of last time a ball was launched
this.paddleWidth = 50
this.isMobile = false
this.frameNumber = 0;
}
endGame() {
//clear all elements, remove h-hidden class from next frame, then remove h-hidden class from the cta content
console.log('endgame')
const endGame = true;
game.loop(endGame)
}
hitEnemy() {
//this.timerId = setTimeout(endExplosion(), 500);
this.explosion = new Explosion(this.enemy.x, this.enemy.y, this.context)
this.explosion.explosionHappened=1;
this.entities.push(this.explosion)
}
start() {
this.lastUpdate = performance.now()
this.enemy = new Enemy(140, 220)
this.entities.push(this.enemy)
// we store the new Paddle in this.player so we can read from it later
this.player = new Paddle(150, 400)
// but we still add it to the entities list so it gets updated like every other Entity
this.entities.push(this.player)
//start watching inputs
this.inputsManager = new InputsManager()
//start watching mousemovement
this.mouseMoveHandler = new mouseMoveHandler()
//start game loop
this.loop()
}
update() {
// calculate time elapsed
const newTime = performance.now()
const deltaTime = newTime - this.lastUpdate
this.isMobile = window.matchMedia('(max-width: 1199px)');
// we now pass more data to the update method so that entities that need to can also read from our InputsManager
const frameData = {
deltaTime,
inputs: this.inputsManager,
mouse: this.mouseMoveHandler,
context: this.context
}
// update every entity
this.entities.forEach(entity => entity.update(frameData))
// other update logic (here, create new entities)
if (this.lastBallCreated + this.newBallInterval < newTime) {
// this is quick and dirty, you should put some more thought into `x` and `y` here
this.ball = new Ball(this.player.x, 360)
this.entities.push(this.ball)
this.lastBallCreated = newTime
}
// remember current time for next update
this.lastUpdate = newTime
}
cleanup() {
//console.log(this.entities[0])//Enemy
//console.log(this.entities[1])//Paddle
//console.log(this.entities[2])//Ball
//to prevent memory leak, don't forget to cleanup dead entities
this.entities.forEach(entity => {
if (entity.isDead(this.enemy)) {
const index = this.entities.indexOf(entity)
this.entities.splice(index, 1)
}
})
}
draw() {
//draw entities
this.entities.forEach(entity => entity.draw(this.context, this.frameNumber))
}
//main game loop
loop(endGame) {
this.myLoop = requestAnimationFrame(() => {
this.frameNumber += 1;
this.context.clearRect(0, 0, this.context.canvas.width, this.context.canvas.height)
if (endGame) {
cancelAnimationFrame(this.myLoop);
this.endGame()
return;
}
this.update()
this.draw()
this.cleanup()
this.loop()
})
}
}
const canvas = document.querySelector('canvas')
const game = new Game(canvas)
game.start()
body {
background-color: rgb(214, 238, 149);
height: 100vh;
display: flex;
justify-content: center;
align-items: center;
margin: 0;
padding: 0;
}
canvas {
background: url("https://picsum.photos/200");
width: 100%;
background-size: cover;
}
<canvas height="459"></canvas>
just for an additionnal information, i myself am a fan of ecs architecture and in order to achieve an explosion, or any other game mechanism cleanly you can use systems, there is an(experimental) firefox project that allows you to use entity component system architecture called ecsy
https://ecsy.io
I am trying to make a ping pong game. At the moment I got the ball moving and both paddles moving when keys pressed. But the ball does not bounce off the paddles. There is code to bounce off player2 paddle but it does not seem to work. It's a lot of code I know. Can you help me find out what is wrong?
"use strict";
// Variables
var c = document.getElementById("sCanvas");
var ctx = sCanvas.getContext("2d");
var cHeight = sCanvas.height;
var cWidth = sCanvas.width;
//Objects
//create paddle object
class Paddle {
constructor(x, y) {
this.colour = "red";
this.xPoss = x;
this.yPoss = y;
this.width = 12;
this.height = 60;
this.speed = 3;
}
drawMe() {
ctx.fillStyle = this.colour;
ctx.fillRect(this.xPoss, this.yPoss, this.width, this.height);
}
} // end paddle object
//create the sphere object
class Sphere {
constructor() {
this.radius = (10);
this.colour = "blue";
this.xPos = 65; //Math.random() * cWidth;
this.yPos = 100; //Math.random() * cHeight;
this.speedY = 5; //* Math.random();
this.speedX = 5; //* Math.random();
}
drawMe() {
//method to draw itself
ctx.beginPath();
ctx.arc(this.xPos, this.yPos, this.radius, 0, Math.PI * 2, true);
ctx.fillStyle = this.colour;
ctx.fill();
}
//method to move itself
moveMe() {
this.yPos += this.speedY;
this.xPos += this.speedX;
//bounce off the bottom wall
if (this.yPos > cHeight - this.radius) {
this.speedY = -this.speedY;
} //bounce off the top wall
else if (this.yPos < 0 + this.radius) {
this.speedY = -this.speedY;
}
//stop ball if hit right side
if (this.xPos > cWidth) {
this.speedX = 0;
this.speedY = 0;
}
//bounce off player 2 paddle
else if (this.xPos > player2.xPoss && (this.yPos > player2.yPoss && this.yPos < (player2.yPoss + player2.height))) {
this.speedX = -this.speedX;
}
}
//end moveMe function
} // end Sphere object
//******************
// create game objects
//******************
var ball = new Sphere();
var player1 = new Paddle(10, 150);
var player2 = new Paddle(580, 150);
//*********************
// Deal with key presses
// **********************
var keysDown = []; //empty array to store which keys are being held down
window.addEventListener("keydown", function(event) {
keysDown[event.keyCode] = true; //store the code for the key being pressed
});
window.addEventListener("keyup", function(event) {
delete keysDown[event.keyCode];
});
function checkKeys() {
if (keysDown[90]) {
if (player1.yPoss > 0) {
player1.yPoss = -player1.speed; //z
}
}
if (keysDown[88]) {
if (player1.yPoss < (cHeight - player1.height)) {
player1.yPoss += player1.speed; //x
}
}
if (keysDown[190]) {
if (player2.yPoss > 0) {
player2.yPoss = -player2.speed; //"."
}
}
if (keysDown[188]) {
if (player2.yPoss < (cHeight - player2.height)) {
player2.yPoss += player2.speed; //","
}
}
}
// your 2 new sets of code here for 2 more keys for player 2
//*********************
// Make the score board
// **********************
//*********************
// launch the ball from the centre, left and right, on space bar
// **********************
function render() {
requestAnimationFrame(render);
ctx.clearRect(0, 0, cWidth, cHeight);
ball.drawMe();
ball.moveMe();
player1.drawMe();
player2.drawMe();
checkKeys();
}
render(); //set the animation and drawing on canvas going
<canvas id="sCanvas" width="600" height="400" style="border: solid;"></canvas>
I added a simple hit box and detector and drawing the boxes in black to illustrate. Changed xPoss, yPoss to xPos, yPos for consistency. Changed = - to -= on the paddle movement (was snapping to top when moving up). Changed class and methods to JavaScript functions and prototype methods.
This should be enough to go on to see the how JavaScript does objects and how to do a simple hit detection. This isn't the only way to create objects but it is close to what you were trying to do.
update
Made some changes to hit/collision detection. Can now hit ball from bottom and top of paddle.
"use strict";
// Variables
var c = document.getElementById("sCanvas");
var ctx = sCanvas.getContext("2d");
var cHeight = sCanvas.height;
var cWidth = sCanvas.width;
//Objects
//create paddle object
function Paddle(x, y) {
this.colour = "red";
this.xPos = x;
this.yPos = y;
this.width = 12;
this.height = 60;
this.speed = 3;
}
Paddle.prototype.drawMe = function() {
ctx.fillStyle = this.colour;
ctx.fillRect(this.xPos, this.yPos, this.width, this.height);
}; // end paddle object
/***** BEGIN COLLISION DECTECTION FUNCTIONS *****/
// optimized collision of boxes - Does a hit b?
function hit(a, b) {
// Return immediately when the objects aren't touching.
if (
a.x2 < b.x || // a.right is before b.left
b.x2 < a.x || // b.right is before a.left
a.y2 < b.y || // a.bottom is before b.top
b.y2 < a.y // b.bottom is before a.top
) {
return false;
}
// The objects are touching. It is a hit or collision.
return true;
}
// does a hit the top of b?
function hitTop(a, b) {
return (a.y2 > b.y && a.y < b.y) ? true : false;
}
// does a hit the bottom of b?
function hitBottom(a, b) {
return (a.y < b.y2 && a.y2 > b.y2) ? true : false;
}
// Creates an obect of x, y, x2, y2 for hit detection.
function hitObj(obj) {
var h = {x:0, y:0, x2:0, y2:0};
if (obj.radius) {
h.x = obj.xPos - obj.radius;
h.x2 = obj.xPos + obj.radius;
h.y = obj.yPos - obj.radius;
h.y2 = obj.yPos + obj.radius;
} else {
h.x = obj.xPos;
h.x2 = obj.xPos + obj.width | (obj.radius * 2);
h.y = obj.yPos;
h.y2 = obj.yPos + obj.height | (obj.radius * 2);
}
// draw hit box - uncomment to see hit detection
/*
ctx.save();
ctx.strokeStyle = "#000000";
ctx.lineWidth = 5;
ctx.strokeRect(h.x, h.y, h.x2 - h.x, h.y2 - h.y);
ctx.restore();
*/
return h;
}
/***** END COLLISION DETECTION FUNCTIONS *****/
//create the sphere object
function Sphere() {
this.radius = (10);
this.colour = "blue";
this.xPos = 25; //Math.random() * cWidth;
this.yPos = 5; //Math.random() * cHeight;
this.speedY = 5; //* Math.random();
this.speedX = 5; //* Math.random();
}
Sphere.prototype.drawMe = function() {
//method to draw itself
ctx.beginPath();
ctx.arc(this.xPos, this.yPos, this.radius, 0, Math.PI * 2, true);
ctx.fillStyle = this.colour;
ctx.fill();
};
Sphere.prototype.moveMe = function() {
//method to move itself
// save start position. change back to start
// position when there's a hit so we don't
// get stuck in an object.
var pos = {
x: this.xPos,
y: this.yPos
};
// move
this.yPos += this.speedY;
this.xPos += this.speedX;
//bounce off the bottom wall
if (this.yPos > cHeight - this.radius) {
this.yPos = pos.y;
this.speedY = -this.speedY;
} //bounce off the top wall
else if (this.yPos < 0 + this.radius) {
this.yPos = pos.y;
this.speedY = -this.speedY;
}
/*
//stop ball if hit right side
if (this.xPos > cWidth) {
this.speedX = 0;
this.speedY = 0;
}
*/
// Bounce off left and right sides.
if ((this.xPos+this.radius) >= cWidth || this.xPos <= 0) {
this.xPos = pos.x;
this.speedX = -this.speedX;
}
//bounce off player paddle
else {
var pad1 = hitObj(player1);
var pad2 = hitObj(player2);
var ball = hitObj(this);
if (hit(ball, pad2)) {
// hit player2
this.xPos = pos.x;
this.speedX *= -1;
// if the ball travels down and hits top OR
// if the ball travels up and hits bottom then bounce back
if (
(this.speedY > 0 && hitTop(ball, pad2)) ||
(this.speedY < 0 && hitBottom(ball, pad2))
) {
this.yPos = pos.y;
this.speedY *= -1;
}
} else if (hit(ball, pad1)) {
// hit player1
this.xPos = pos.x;
this.speedX *= -1;
// if the ball travels down and hits top OR
// if the ball travels up and hits bottom then bounce back
if (
(this.speedY > 0 && hitTop(ball, pad1)) ||
(this.speedY < 0 && hitBottom(ball, pad1))
) {
this.yPos = pos.y;
this.speedY *= -1;
}
}
}
};
//end moveMe function
//******************
// create game objects
//******************
var ball = new Sphere();
var player1 = new Paddle(10, 150);
var player2 = new Paddle(580, 150);
//*********************
// Deal with key presses
// **********************
var keysDown = []; //empty array to store which keys are being held down
window.addEventListener("keydown", function(event) {
keysDown[event.keyCode] = true; //store the code for the key being pressed
});
window.addEventListener("keyup", function(event) {
delete keysDown[event.keyCode];
});
function checkKeys() {
if (keysDown[90]) {
if (player1.yPos > 0) {
player1.yPos -= player1.speed; //z
}
}
if (keysDown[88]) {
if (player1.yPos < (cHeight - player1.height)) {
player1.yPos += player1.speed; //x
}
}
if (keysDown[190]) {
if (player2.yPos > 0) {
player2.yPos -= player2.speed; //"."
}
}
if (keysDown[188]) {
if (player2.yPos < (cHeight - player2.height)) {
player2.yPos += player2.speed; //","
}
}
}
// your 2 new sets of code here for 2 more keys for player 2
//*********************
// Make the score board
// **********************
//*********************
// launch the ball from the centre, left and right, on space bar
// **********************
function render() {
requestAnimationFrame(render);
ctx.clearRect(0, 0, cWidth, cHeight);
ball.drawMe();
ball.moveMe();
player1.drawMe();
player2.drawMe();
checkKeys();
}
render(); //set the animation and drawing on canvas going
#sCanvas {
width: 300px;
height: 200px;
}
<canvas id="sCanvas" width="600" height="400" style="border: solid;"></canvas>
I'm creating a side-scrolling endless space themed game using canvas and JavaScript. I'm controlling a spaceship just by using the up and down arrows and I want to implement some kind of movement easing so that the ship doesn't just stop dead when I let go of the keys. I've looked around and haven't found anything plus my own attempts just aren't working. This is what I've tried.
Jet.prototype.checkDirection = function () {
if (this.isUpKey) {
this.drawY -= this.speed;
if (this.speed < 5) {
this.speed += 0.1;
}
}
if (this.isDownKey) {
this.drawY += this.speed;
if (this.speed < 5) {
this.speed += 0.1;
}
}
if (!this.isUpKey) {
if (!this.isDownKey) {
if (this.speed >= 0) {
this.drawY -= this.speed;
this.speed -= 1;
}
}
}
if (!this.isDownKey) {
if (!this.isUpKey) {
if (this.speed >= 0) {
this.drawY += this.speed;
this.speed -= 1;
}
}
}
You just want to apply some friction. Its pretty easy. You can do something like the following.
this.speed*=0.98;
The lower the value (0.8, 0.5, etc) the faster you will slow down.
I provided a demo where you can move around and will gradually slow down. Go ahead and play with the value and see how it affects it.
Live Demo
var canvas = document.getElementById("canvas"),
ctx = canvas.getContext("2d");
canvas.width = canvas.height = 300;
var x = 150, //initial x
y = 150, // initial y
velY = 0,
velX = 0,
speed = 2, // max speed
friction = 0.98, // friction
keys = [];
function update() {
requestAnimationFrame(update);
// check the keys and do the movement.
if (keys[38]) {
if (velY > -speed) {
velY--;
}
}
if (keys[40]) {
if (velY < speed) {
velY++;
}
}
if (keys[39]) {
if (velX < speed) {
velX++;
}
}
if (keys[37]) {
if (velX > -speed) {
velX--;
}
}
// apply some friction to y velocity.
velY *= friction;
y += velY;
// apply some friction to x velocity.
velX *= friction;
x += velX;
// bounds checking
if (x >= 295) {
x = 295;
} else if (x <= 5) {
x = 5;
}
if (y > 295) {
y = 295;
} else if (y <= 5) {
y = 5;
}
// do the drawing
ctx.clearRect(0, 0, 300, 300);
ctx.beginPath();
ctx.arc(x, y, 5, 0, Math.PI * 2);
ctx.fill();
}
update();
// key events
document.body.addEventListener("keydown", function (e) {
keys[e.keyCode] = true;
});
document.body.addEventListener("keyup", function (e) {
keys[e.keyCode] = false;
});
I think what I would do is on keyup don't stop the ship, just have a function that slows it down a little then call this function in setInterval at whatever interval gives you the desired effect and then once the speed of the ship is zero call clearInterval
So on keyup u basically setup setInterval(slowShip, 500)
You could try reducing the speed continuously on every frame
if(!playerUp && !playerDown && moveSpeed > 0){
moveSpeed--;
}