I did the assessment and checked a code of the final version.
I amended a little bit, but still I cannot fix it.
(Evil circle appears, but the balls doesn’t appear anymore).
Could you let me know what is wrong with my code?
Here is my code…
const para = document.querySelector(‘p’);
let count = 0;
const canvas = document.querySelector(‘canvas’);
const ctx = canvas.getContext(‘2d’);
const width = canvas.width = window.innerWidth;
const height = canvas.height = window.innerHeight;
function random(min, max)
{
const num = Math.floor(Math.random() * (max - min + 1)) + min;
return num;
}
function Shape(x, y, velX, velY, exists)
{
this.x = x;
this.y = y;
this.velX = velX;
this.velY = velY;
this.exists = exists;
}
class Ball extends Shape
{
constructor(x, y, velX, velY,exists, size, color)
{
super(x, y, velX, velY, exists)
this.size = size;
this.color = color;
}
}
Ball.prototype = Object.create(Shape.prototype);
Ball.prototype.constructor = Ball;
Ball.prototype.draw = function()
{
ctx.beginPath();
ctx.fillStyle = this.color;
ctx.arc(this.x, this.y, this.size, 0, 2 * Math.PI);
ctx.fill();
}
Ball.prototype.update = function()
{
if ((this.x + this.size) >= width) {
this.velX = -(this.velX);
}
if ((this.x - this.size) <= 0) {
this.velX = -(this.velX);
}
if ((this.y + this.size) >= height) {
this.velY = -(this.velY);
}
if ((this.y - this.size) <= 0) {
this.velY = -(this.velY);
}
this.x += this.velX;
this.y += this.velY;
}
Ball.prototype.collisionDetect = function() {
for (let j = 0; j < balls.length; j++) {
if (!(this === balls[j])) {
const dx = this.x - balls[j].x;
const dy = this.y - balls[j].y;
const distance = Math.sqrt(dx * dx + dy * dy);
if (distance < this.size + balls[j].size) {
balls[j].color = this.color = 'rgb(' + random(0, 255) + ',' + random(0, 255) + ',' + random(0, 255) +')';
}
}
}
}
function EvilCircle(x, y, velX, velY, exists, size, color)
{
Shape.call(this, x, y, 20, 20, exists);
this.size = 10;
this.color = ‘white’;
}
EvilCircle.prototype = Object.create(Shape.prototype);
EvilCircle.prototype.constructor = EvilCircle;
EvilCircle.prototype.draw = function() {
ctx.beginPath();
ctx.strokeStyle = this.color;
ctx.lineWidth = 3;
ctx.arc(this.x, this.y, this.size, 0, 2 * Math.PI);
ctx.stroke();
};
EvilCircle.prototype.checkBounds = function()
{
if ((this.x + this.size) >= width)
{
this.x -= this.size;
}
if ((this.x - this.size) <= 0)
{
this.x += this.size;
}
if ((this.y + this.size) >= height)
{
this.y -+ this.size;
}
if ((this.y - this.size) <= 0)
{
this.y += this.size;
}
}
EvilCircle.prototype.setControls = function()
{
let _this = this;
window.onkeydown = function(e) {
if (e.key === ‘a’) {
_this.x -= _this.velX;
} else if (e.key === ‘d’) {
_this.x += _this.velX;
} else if (e.key === ‘w’) {
_this.y -= _this.velY;
} else if (e.key === ‘s’) {
_this.y += _this.velY;
}
}
}
EvilCircle.prototype.collisionDetect = function ()
{
for (let j = 0; j < balls.length; j++)
{
if (balls[j].exists)
{
const dx = this.x - balls[j].x;
const dy = this.y - balls[j].y;
const distance = Math.sqrt(dx * dx + dy * dy);
if (distance < this.size + balls[j].size)
{
balls[j].exists = false;
count--;
para.textContent = 'Ball Count: ' + count;
}
}
}
};
const balls = [];
while (balls.length < 25) {
let size = random(10,20);
let ball = new Ball(
// ball position always drawn at least one ball width
// away from the edge of the canvas, to avoid drawing errors
random(0 + size,width - size),
random(0 + size,height - size),
random(-7,7),
random(-7,7),
true,
size,
‘rgb(’ + random(0,255) + ‘,’ + random(0,255) + ‘,’ + random(0,255) +’)’
);
balls.push(ball);
count++;
para.textContent = 'Ball count:' + count;
}
let evil = new EvilCircle(random(0, width), random(0, height), true);
evil.setControls();
function loop()
{
ctx.fillStyle = ‘rgba(0, 0, 0, 0.25)’;
ctx.fillRect(0, 0, width, height);
for (let i = 0; i < balls.length; i++)
{
if (balls[i].exists)
{
balls[i].draw();
balls[i].update();
balls[i].collisionDetect();
}
}
evil.draw();
evil.update();
evil.collisionDetect();
requestAnimationFrame(loop);
}
