We Keep Coding

How can I make the score run in seconds instead of miliseconds?

I'm coding a basic game and in that game, the score is based on how long you survive. However, the score isn't recording how long the player survives in seconds, instead it's doing so in milliseconds (I presume). How can I fix this so the score keeps track in seconds?
I've tried using setInterval([insert parameter], 1000) but still my code ran in milliseconds.
/*Down below I am bringing the canvas into JavaScript so we can code and "draw" our canvas.*/
var thecanvas = document.getElementById("thecanvas").getContext("2d");
thecanvas.font = "30px Arial";
var HEIGHT = 500;
var WIDTH = 500;
var TimeWhenTheGameStarted = Date.now(); /*This will return the time in miliseconds.*/
var CountofTheFrames = 0;
var TheScore = 0;
/*The Player - Variable will be the object, as indicated by the {}*/
var player = {
x: 50,
speedX: 30,
y: 40,
speedY: 5,
name: "P",
hp: 10,
width: 20,
height: 20,
color: "blue",
};
var enemyList = {};
gettingDistanceBetweenEntities = function(entity1, entity2) {
/*Return Distance (number)*/
var vx = entity1.x - entity2.x;
var vy = entity1.y - entity2.y;
return Math.sqrt(vx * vx + vy * vy);
};
testingCollisionOfEntities = function(entity1, entity2) {
/*Return if colliding (true.false)*/
var rectangle1 = {
x: entity1.x - entity1.width / 2,
y: entity1.y - entity1.height / 2,
width: entity1.width,
height: entity1.height,
};
var rectangle2 = {
x: entity2.x - entity2.width / 2,
y: entity2.y - entity2.height / 2,
width: entity2.width,
height: entity2.height,
};
return testingCollusionofRectangles(rectangle1, rectangle2);
};
Enemy = function(id, x, y, speedX, speedY, width, height) {
var theenemy = {
x: x,
speedX: speedX,
y: y,
speedY: speedY,
name: "E",
id: id,
width: width,
height: height,
color: "red",
};
enemyList[id] = theenemy;
};
UpdatingTheEntity = function(entityParameter) {
UpdatingTheEntityPosition(entityParameter);
DrawingTheEntity(entityParameter);
};
document.onmousemove = function(mouse) {
var mouseX =
mouse.clientX -
document.getElementById("thecanvas").getBoundingClientRect().left;
var mouseY =
mouse.clientY -
document.getElementById("thecanvas").getBoundingClientRect().top;
/*Makes sure that the mouse does not go out of bounds of the canvas.*/
if (mouseX < player.width / 2) mouseX = player.width / 2;
if (mouseX > WIDTH - player.width / 2) mouseX = WIDTH - player.width / 2;
if (mouseY < player.height / 2) mouseY = player.height / 2;
if (mouseY > HEIGHT - player.height / 2) mouseY = HEIGHT - player.height / 2;
player.x = mouseX;
player.y = mouseY;
};
/*Speed of the Entities*/
UpdatingTheEntityPosition = function(entityParameter) {
entityParameter.x += entityParameter.speedX;
entityParameter.y += entityParameter.speedY;
if (entityParameter.x < 0 || entityParameter.x > WIDTH) {
entityParameter.speedX = -entityParameter.speedX;
}
if (entityParameter.y < 0 || entityParameter.y > HEIGHT) {
entityParameter.speedY = -entityParameter.speedY;
}
};
testingCollusionofRectangles = function(rectangle1, rectangle2) {
return (
rectangle1.x <= rectangle2.x + rectangle2.width &&
rectangle2.x <= rectangle1.x + rectangle1.width &&
rectangle1.y <= rectangle2.y + rectangle2.height &&
rectangle2.y <= rectangle1.y + rectangle1.height
);
};
/*Physical Appearance of the Entities*/
DrawingTheEntity = function(entityParameter) {
thecanvas.save();
thecanvas.fillStyle = entityParameter.color;
thecanvas.fillRect(
entityParameter.x - entityParameter.width / 2,
entityParameter.y - entityParameter.height / 2,
entityParameter.width,
entityParameter.height,
);
thecanvas.restore(); /*So we do not override the color of HP*/
};
runningTheCode = function() {
thecanvas.clearRect(0, 0, WIDTH, HEIGHT);
/*Increase by 1*/
CountofTheFrames++;
TheScore++;
CountofTheFrames = CountofTheFrames + 1;
/*This will generate more random enemies over time*/
if (CountofTheFrames % 300 === 0)
/*Only when the frame count reaches 300, it will generate new enemies every 8 seconds*/
RandomlyGeneratingEnemies();
for (var id in enemyList) {
UpdatingTheEntity(enemyList[id]);
var isColliding = testingCollisionOfEntities(player, enemyList[id]);
if (isColliding) {
player.hp = player.hp - 1;
if (player.hp <= 0) {
var TimeSurvived = Date.now() - TimeWhenTheGameStarted;
console.log(
"You lost! You survived for " + TimeSurvived + " miliseconds!",
);
//TimeWhenTheGameStarted = Date.now(); /*Restarts*/
player.hp = 10;
StartingNewGame();
}
}
}
DrawingTheEntity(player);
thecanvas.fillText(player.hp + "HP", 0, 30);
thecanvas.fillText("Score: " + TheScore, 325, 30);
};
RandomlyGeneratingEnemies = function() {
/* Math.random () returns a number between 0 and 1 by default*/
var id = Math.random();
var x = Math.random() * WIDTH;
var y = Math.random() * HEIGHT;
var height = 24 + Math.random() * 10;
var width = 10 + Math.random() * 23;
var speedX = 4 + Math.random() * 6;
var speedY = 4 + Math.random() * 6;
Enemy(id, x, y, speedX, speedY, height, width);
};
StartingNewGame = function() {
player.hp = 10;
TimeWhenTheGameStarted = Date.now();
CountofTheFrames = 0;
TheScore = 0;
enemyList = {};
RandomlyGeneratingEnemies();
RandomlyGeneratingEnemies();
RandomlyGeneratingEnemies();
};
setInterval(
runningTheCode,
40,
); /*Meaning, the code will run every [blank] miliseconds, 40 = 22 frames*/
<center><h1>Dodge Box: The Game</h1></center>
<center><canvas id="thecanvas" width="500" height="500" style="border: 4px solid #000000;"></canvas></center>
When running the code, the score will run in seconds, not in milliseconds.

Divide milliseconds by 1000 to get seconds.
var TimeSurvived = (Date.now() - TimeWhenTheGameStarted) / 1000;

adding custom animation in canvas html5

this might be somewhat difficult but i wil still ask, so i made a starfield ,now what i want to do is to have my stars( a pair each) connected to eachother by a line ,now this line will expand as the stars move forward and disappear when the stars move out of the canvas .any help would be appreciated here this is difficult i have the logic but i seem unable to follow the correct way to implement it
function randomRange(minVal, maxVal) {
return Math.floor(Math.random() * (maxVal - minVal - 1)) + minVal;
}
function initStars() {
for (var i = 0; i < stars.length; i++) {
stars[i] = {
x: randomRange(-25, 25),
y: randomRange(-25, 25),
z: randomRange(1, MAX_DEPTH)
}
}
}
function degToRad(deg) {
radians = (deg * Math.PI / 180) - Math.PI / 2;
return radians;
}
function animate() {
var halfWidth = canvas.width / 2;
var halfHeight = canvas.height / 2;
ctx.fillStyle = "rgb(0,0,0)";
ctx.fillRect(0, 0, canvas.width, canvas.height);
for (var i = 0; i < stars.length; i++) {
stars[i].z -= 0.2;
if (stars[i].z <= 0) {
stars[i].x = randomRange(-25, 25);
stars[i].y = randomRange(-25, 25);
stars[i].z = MAX_DEPTH;
}
var k = 128.0 / stars[i].z;
var px = stars[i].x * k + halfWidth;
var py = stars[i].y * k + halfHeight;
if (px >= 0 && px <= 1500 && py >= 0 && py <= 1500) {
var size = (1 - stars[i].z / 32.0) * 5;
var shade = parseInt((1 - stars[i].z / 32.0) * 750);
ctx.fillStyle = "rgb(" + shade + "," + shade + "," + shade + ")";
ctx.beginPath();
ctx.arc(px, py, size, degToRad(0), degToRad(360));
ctx.fill();
}
}
}
function animate() {
var halfWidth = canvas.width / 2;
var halfHeight = canvas.height / 2;
ctx.fillStyle = "rgb(0,0,0)";
ctx.fillRect(0, 0, canvas.width, canvas.height);
for (var i = 0; i < stars.length; i++) {
stars[i].z -= 0.2;
if (stars[i].z <= 0) {
stars[i].x = randomRange(-25, 25);
stars[i].y = randomRange(-25, 25);
stars[i].z = MAX_DEPTH;
}
var k = 128.0 / stars[i].z;
var px = stars[i].x * k + halfWidth;
var py = stars[i].y * k + halfHeight;
if (px >= 0 && px <= 1500 && py >= 0 && py <= 1500) {
var size = (1 - stars[i].z / 32.0) * 5;
var shade = parseInt((1 - stars[i].z / 32.0) * 750);
ctx.fillStyle = "rgb(" + shade + "," + shade + "," + shade + ")";
ctx.beginPath();
ctx.arc(px, py, size, degToRad(0), degToRad(360));
ctx.fill();
}
}
}
<!DOCTYPE html5>
<html>
<head>
<title>stars</title>
<script src="convergis.js"></script>
<script>
MAX_DEPTH = 32;
var canvas, ctx;
var stars = new Array(500);
window.onload = function() {
canvas = document.getElementById("tutorial");
if( canvas && canvas.getContext ) {
ctx = canvas.getContext("2d");
initStars();
setInterval(animate,17);
}
}
</script>
</head>
<body>
<canvas id='tutorial' width='1500' height='1500'>
</canvas>
</body>
</html>

You could just say you want a lightspeed effect!
One way very cheap way to do it is to paint the background with some transparency. You can also render a set of points close together in order to make the illusion of the effect.
The good way to do it is shaders since they will allow you to add glow and some other nice image trickery that will make it look better. Here is a good example: https://www.shadertoy.com/view/Xdl3D2
Below I used the canvas api lineTo and even with a fixed line width, it's a pretty good final result.
var MAX_DEPTH = 64;
var LINELENGTH = 0.1;
var stars = new Array(500);
var canvas = document.getElementById("tutorial");
canvas.width = innerWidth;
canvas.height = innerHeight;
var ctx = canvas.getContext("2d");
initStars();
setInterval(animate,17);
function randomRange(minVal, maxVal) {
return Math.floor(Math.random() * (maxVal - minVal - 1)) + minVal;
}
function initStars() {
for (var i = 0; i < stars.length; i++) {
stars[i] = {
x: randomRange(-25, 25),
y: randomRange(-25, 25),
z: randomRange(1, MAX_DEPTH)
}
}
}
function degToRad(deg) {
radians = (deg * Math.PI / 180) - Math.PI / 2;
return radians;
}
function animate() {
var halfWidth = canvas.width / 2;
var halfHeight = canvas.height / 2;
ctx.fillStyle = "rgba(0,0,0,1)";
ctx.fillRect(0, 0, canvas.width, canvas.height);
for (var i = 0; i < stars.length; i++) {
stars[i].z -= 0.5;
if (stars[i].z <= 0) {
stars[i].x = randomRange(-25, 25);
stars[i].y = randomRange(-25, 25);
stars[i].z = MAX_DEPTH;
}
var k = 254.0 / stars[i].z;
var px = stars[i].x * k + halfWidth;
var py = stars[i].y * k + halfHeight;
if (px >= 0 && px <= 1500 && py >= 0 && py <= 1500) {
var size = (1 - stars[i].z / 32.0) * 2;
var shade = parseInt((1 - stars[i].z / 32.0) * 750);
ctx.strokeStyle = "rgb(" + shade + "," + shade + "," + shade + ")";
ctx.lineWidth = size;
ctx.beginPath();
ctx.moveTo(px,py);
var ox = size * (px - halfWidth) * LINELENGTH;
var oy = size * (py - halfHeight) * LINELENGTH;
ctx.lineTo(px + ox, py + oy);
ctx.stroke();
}
}
}
<canvas id='tutorial' width='1500' height='1500'></canvas>

How can i customize the lines of this canvas?

I started to work on this animation and got the base from another animation, i have pretty much customized it all to my needs besides the lines. Currently the lines are pointy and i have gone through the code multiple times trying to find what creates these spiky lines. I would appreciate if someone could check both the provided code and the external code and identify what it is. All help is appreciated thanks.
// Settings
var particleCount = 35,
flareCount = 0,
motion = 0.05,
tilt = 0,
particleSizeBase = 1,
particleSizeMultiplier = 0.5,
flareSizeBase = 100,
flareSizeMultiplier = 100,
glareAngle = -60,
glareOpacityMultiplier = 0.4,
renderParticles = true,
renderParticleGlare = true,
renderFlares = false,
renderLinks = false,
renderMesh = false,
flicker = false,
flickerSmoothing = 15, // higher = smoother flicker
blurSize = 0,
orbitTilt = true,
randomMotion = true,
noiseLength = 1000,
noiseStrength = 3;
document.querySelectorAll('.stars').forEach(canvas => {
var context = canvas.getContext('2d'),
color = canvas.dataset['color'],
mouse = { x: 0, y: 0 },
m = {},
r = 0,
c = 1000, // multiplier for delaunay points, since floats too small can mess up the algorithm
n = 0,
nAngle = (Math.PI * 2) / noiseLength,
nRad = 100,
nScale = 1,
nPos = {x: 0, y: 0},
points = [],
vertices = [],
triangles = [],
links = [],
particles = [],
flares = [];
function init() {
var i, j, k;
// requestAnimFrame polyfill
window.requestAnimFrame = (function(){
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
function( callback ){
window.setTimeout(callback, 1000 / 60);
};
})();
// Size canvas
resize();
mouse.x = canvas.clientWidth / 2;
mouse.y = canvas.clientHeight / 2;
// Create particle positions
for (i = 0; i < particleCount; i++) {
var p = new Particle();
particles.push(p);
points.push([p.x*c, p.y*c]);
}
vertices = Delaunay.triangulate(points);
var tri = [];
for (i = 0; i < vertices.length; i++) {
if (tri.length == 2) {
triangles.push(tri);
tri = [];
}
tri.push(vertices[i]);
}
// Tell all the particles who their neighbors are
for (i = 0; i < particles.length; i++) {
// Loop through all tirangles
for (j = 0; j < triangles.length; j++) {
// Check if this particle's index is in this triangle
k = triangles[j].indexOf(i);
// If it is, add its neighbors to the particles contacts list
if (k !== -1) {
triangles[j].forEach(function(value, index, array) {
if (value !== i && particles[i].neighbors.indexOf(value) == -1) {
particles[i].neighbors.push(value);
}
});
}
}
}
var fps = 60;
var now;
var then = Date.now();
var interval = 1000/fps;
var delta;
// Animation loop
(function animloop(){
requestAnimFrame(animloop);
now = Date.now();
delta = now - then;
if (delta > interval) {
then = now - (delta % interval);
resize();
render();
}
})();
}
function render() {
if (randomMotion) {
n++;
if (n >= noiseLength) {
n = 0;
}
nPos = noisePoint(n);
}
if (renderParticles) {
// Render particles
for (var i = 0; i < particleCount; i++) {
particles[i].render();
}
}
}
function resize() {
canvas.width = window.innerWidth * (window.devicePixelRatio || 1);
canvas.height = canvas.width * (canvas.clientHeight / canvas.clientWidth);
}
// Particle class
var Particle = function() {
this.x = random(-0.1, 1.1, true);
this.y = random(-0.1, 1.1, true);
this.z = random(0,4);
this.color = color;
this.opacity = random(0.1,1,true);
this.flicker = 0;
this.neighbors = []; // placeholder for neighbors
};
Particle.prototype.render = function() {
var pos = position(this.x, this.y, this.z),
r = ((this.z * particleSizeMultiplier) + particleSizeBase) * (sizeRatio() / 1000),
o = this.opacity;
context.fillStyle = this.color;
context.globalAlpha = o;
context.beginPath();
context.fill();
context.closePath();
if (renderParticleGlare) {
context.globalAlpha = o * glareOpacityMultiplier;
context.ellipse(pos.x, pos.y, r * 100, r, (glareAngle - ((nPos.x - 0.5) * noiseStrength * motion)) * (Math.PI / 180), 0, 2 * Math.PI, false);
context.fill();
context.closePath();
}
context.globalAlpha = 1;
};
// Utils
function noisePoint(i) {
var a = nAngle * i,
cosA = Math.cos(a),
sinA = Math.sin(a),
rad = nRad;
return {
x: rad * cosA,
y: rad * sinA
};
}
function position(x, y, z) {
return {
x: (x * canvas.width) + ((((canvas.width / 2) - mouse.x + ((nPos.x - 0.5) * noiseStrength)) * z) * motion),
y: (y * canvas.height) + ((((canvas.height / 2) - mouse.y + ((nPos.y - 0.5) * noiseStrength)) * z) * motion)
};
}
function sizeRatio() {
return canvas.width >= canvas.height ? canvas.width : canvas.height;
}
function random(min, max, float) {
return float ?
Math.random() * (max - min) + min :
Math.floor(Math.random() * (max - min + 1)) + min;
}
// init
if (canvas) init();
});
html,
body {
margin: 0;
padding: 0;
height: 100%;
}
body {
background: #000;
background-image: linear-gradient(-180deg, rgba(0, 0, 0, 0.00) 0%, #000000 100%);
height: 100%;
}
#stars {
display: block;
position: relative;
width: 100%;
height: 100vh;
z-index: 1;
position: absolute;
}
<script src="https://rawgit.com/ironwallaby/delaunay/master/delaunay.js"></script>
<script src="http://requirejs.org/docs/release/2.1.15/minified/require.js"></script>
<canvas id="Stars" class="stars" width="300" height="300" data-color="#fff"></canvas>

// Tell all the particles who their neighbors are
for (i = 0; i < particles.length; i++) {
// Loop through all tirangles
for (j = 0; j < triangles.length; j++) {
// Check if this particle's index is in this triangle
k = triangles[j].indexOf(i);
// If it is, add its neighbors to the particles contacts list
if (k !== -1) {
triangles[j].forEach(function(value, index, array) { // <----- missing ')' here
if (value !== i && particles[i].neighbors.indexOf(value) == -1) {
particles[i].neighbors.push(value);
}
});
}
}
}

The reason you are getting spikes is the radius of the ellipse is too large so the ends are so small they look like points but it's just a small radius.
context.ellipse(pos.x, pos.y, r * 100, r, (glareAngle - ((nPos.x - 0.5) * noiseStrength * motion)) * (Math.PI / 180), 0, 2 * Math.PI, false);
After experimenting with different shapes like rect() and arc():
The code below instead of using ellipse uses a rotated rectangle. Since the shape is different the algorithm for getting the angle you wanted will need more work but this code solves the problem of the pointy ends.
//context.ellipse(pos.x, pos.y, r * 100, r, (glareAngle - ((nPos.x - 0.5) * noiseStrength * motion)) * (Math.PI / 180), 0, 2 * Math.PI, false);
context.rotate((glareAngle - ((nPos.x - 0.5) * noiseStrength * motion)) * (Math.PI / 180));
context.fillRect(pos.x, pos.y, r * 100, r)
context.closePath();
It will take more work to align them to match the first code, but the pointy ends are gone.
Also, rotate() is actually rotating the canvas not the rectangles so keep that in mind. I would start with a simple 45 degree angle and see what that generates.

Why circles are vibrating on collision (Canvas)

I have been creating a clone of agar.io and I don't understand why the circles start vibrating when they touch each other. Below is my code:
var
canvas,
ctx,
width = innerWidth,
height = innerHeight,
mouseX = 0,
mouseY = 0;
var
camera = {
x: 0,
y: 0,
update: function(obj) {
this.x = obj.x - width / 2;
this.y = obj.y - height / 2;
}
},
player = {
defaultMass: 54,
x: 0,
y: 0,
blobs: [],
update: function() {
for (var i = 0; i < this.blobs.length; i++) {
var x = mouseX + camera.x - this.blobs[i].x;
var y = mouseY + camera.y - this.blobs[i].y;
var length = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
var speed = 54 / this.blobs[i].mass;
this.blobs[i].velX = x / length * speed * Math.min(1, Math.pow(x / this.blobs[i].mass, 2));
this.blobs[i].velY = y / length * speed * Math.min(1, Math.pow(x / this.blobs[i].mass, 2));
this.blobs[i].x += this.blobs[i].velX;
this.blobs[i].y += this.blobs[i].velY;
for (var j = 0; j < this.blobs.length; j++) {
if (j != i && this.blobs[i] !== undefined) {
var blob1 = this.blobs[i];
var blob2 = this.blobs[j];
var dist = Math.sqrt(Math.pow(blob2.x - blob1.x, 2) + Math.pow(blob2.y - blob1.y, 2));
if (dist < blob1.mass + blob2.mass) {
if (this.blobs[i].x < this.blobs[j].x) {
this.blobs[i].x--;
} else if (this.blobs[i].x > this.blobs[j].x) {
this.blobs[i].x++;
}
if (this.blobs[i].y < this.blobs[j].y) {
this.blobs[i].y--;
} else if ((this.blobs[i].y > this.blobs[j].y)) {
this.blobs[i].y++;
}
}
}
}
}
this.x += (mouseX - width / 2) / (width / 2) * 1;
this.y += (mouseY - height / 2) / (height / 2) * 1
},
split: function(cell) {
cell.mass /= 2;
this.blobs.push({
x: cell.x,
y: cell.y,
mass: cell.mass
});
},
draw: function() {
for (var i = 0; i < this.blobs.length; i++) {
ctx.fillStyle = "red";
ctx.beginPath();
ctx.arc(-camera.x + this.blobs[i].x, -camera.y + this.blobs[i].y, this.blobs[i].mass, 0, Math.PI * 2);
ctx.fill();
ctx.closePath();
}
}
};
function handleMouseMove(e) {
mouseX = e.clientX;
mouseY = e.clientY;
}
function setup() {
canvas = document.getElementById("game");
ctx = canvas.getContext("2d");
canvas.width = width;
canvas.height = height;
addEventListener("mousemove", handleMouseMove);
player.blobs.push({
x: 0,
y: 0,
mass: player.defaultMass
});
player.blobs.push({
x: 100,
y: 100,
mass: player.defaultMass / 2
});
player.blobs.push({
x: 100,
y: 100,
mass: player.defaultMass * 2
});
var loop = function() {
update();
draw();
requestAnimationFrame(loop);
}
requestAnimationFrame(loop);
}
function update() {
camera.update(player.blobs[0]);
player.update();
}
function draw() {
ctx.fillStyle = "#fff";
ctx.fillRect(0, 0, width, height);
player.draw();
}
setup();
body {
margin: 0;
padding: 0;
}
<canvas id="game">kindly update your browser.</canvas>

Separating circles
Your separation code was not correct. Use the vector between them to get the new pos.
The vector between them
To find if two circles are intercepting find the length of the vector from one to the next
The two circles.
var cir1 = {x : 100, y : 100, r : 120}; // r is the radius
var cir2 = {x : 250, y : 280, r : 150}; // r is the radius
The vector from cir2 to cir1
var vx = cir2.x - cir1.x;
var vy = cir2.y - cir1.y;
The length of the vector
var len = Math.sqrt(x * x + y * y);
// or use the ES6 Math.hypot function
/* var len = Math.hypot(x,y); */
The circles overlap if the sum of the radii is greater than the length of the vector between them
if(cir1.r + cir2.r > len){ // circles overlap
Normalise the vector
If they overlap you need to move one away from the other. There are many ways to do this, the simplest way is to move one circle along the line between them.
First normalise the vector from cir1 to cir2 by dividing by its (vector) length.
vx \= len;
vy \= len;
Note that the length could be zero. If this happens then you will get NaN in further calculations. If you suspect you may get one circle at the same location as another the easiest way to deal with the zero move one circle a little.
// replace the two lines above with
if(len === 0){ // circles are on top of each other
vx = 1; // move the circle (abstracted into the vector)
}else{
vx \= len; // normalise the vector
vy \= len;
}
Move circle/s to just touch
Now you have the normalised vector which is 1 unit long you can make it any length you need by multiplying the two scalars vx, vy with the desired length which in this case is the sum of the two circles radii.
var mx = vx * (cir1.r + cir2.r); // move distance
var my = vy * (cir1.r + cir2.r);
.Only use one of the following methods.
You can now position one of the circles the correct distance so that they just touch
// move cir1
cir1.x = cir2.x - mx;
cir1.y = cir2.y - my;
Or move the second circle
cir2.x = cir1.x + mx;
cir2.y = cir1.y + my;
Or move both circles but you will have to first find the proportional center between the two
var pLen = cir1.r / (cir1.r + cir2.r); // find the ratio of the radii
var cx = cir1.x + pLen * vx * len; // find the proportional center between
var cy = cir1.y + pLen * vy * len; // the two circles
Then move both circles away from that point by their radii
cir1.x = cx - vx * cir1.r; // move circle 1 away from the shared center
cir1.y = cy - vy * cir1.r;
cir2.x = cx + vx * cir2.r; // move circle 2 away from the shared center
cir2.y = cy + vy * cir2.r;
DEMO
Copy of OP's snippet with mods to fix problem by moving the the first circle blob1 away from the second blob2 and assuming they will never be at the same spot (no divide by zero)
var
canvas,
ctx,
width = innerWidth,
height = innerHeight,
mouseX = 0,
mouseY = 0;
var
camera = {
x: 0,
y: 0,
update: function(obj) {
this.x = obj.x - width / 2;
this.y = obj.y - height / 2;
}
},
player = {
defaultMass: 54,
x: 0,
y: 0,
blobs: [],
update: function() {
for (var i = 0; i < this.blobs.length; i++) {
var x = mouseX + camera.x - this.blobs[i].x;
var y = mouseY + camera.y - this.blobs[i].y;
var length = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
var speed = 54 / this.blobs[i].mass;
this.blobs[i].velX = x / length * speed * Math.min(1, Math.pow(x / this.blobs[i].mass, 2));
this.blobs[i].velY = y / length * speed * Math.min(1, Math.pow(x / this.blobs[i].mass, 2));
this.blobs[i].x += this.blobs[i].velX;
this.blobs[i].y += this.blobs[i].velY;
for (var j = 0; j < this.blobs.length; j++) {
if (j != i && this.blobs[i] !== undefined) {
var blob1 = this.blobs[i];
var blob2 = this.blobs[j];
var x = blob2.x - blob1.x; // get the vector from blob1 to blob2
var y = blob2.y - blob1.y; //
var dist = Math.sqrt(x * x + y * y); // get the distance between the two blobs
if (dist < blob1.mass + blob2.mass) { // if the distance is less than the 2 radius
// if there is overlap move blob one along the line between the two the distance of the two radius
x /= dist; // normalize the vector. This makes the vector 1 unit long
y /= dist;
// multiplying the normalised vector by the correct distance between the two
// and subtracting that distance from the blob 2 give the new pos of
// blob 1
blob1.x = blob2.x - x * (blob1.mass + blob2.mass);
blob1.y = blob2.y - y * (blob1.mass + blob2.mass);
}
}
}
}
this.x += (mouseX - width / 2) / (width / 2) * 1;
this.y += (mouseY - height / 2) / (height / 2) * 1
},
split: function(cell) {
cell.mass /= 2;
this.blobs.push({
x: cell.x,
y: cell.y,
mass: cell.mass
});
},
draw: function() {
for (var i = 0; i < this.blobs.length; i++) {
ctx.fillStyle = "red";
ctx.beginPath();
ctx.arc(-camera.x + this.blobs[i].x, -camera.y + this.blobs[i].y, this.blobs[i].mass, 0, Math.PI * 2);
ctx.fill();
ctx.closePath();
}
}
};
function handleMouseMove(e) {
mouseX = e.clientX;
mouseY = e.clientY;
}
function setup() {
canvas = document.getElementById("game");
ctx = canvas.getContext("2d");
canvas.width = width;
canvas.height = height;
addEventListener("mousemove", handleMouseMove);
player.blobs.push({
x: 0,
y: 0,
mass: player.defaultMass
});
player.blobs.push({
x: 100,
y: 100,
mass: player.defaultMass / 2
});
player.blobs.push({
x: 100,
y: 100,
mass: player.defaultMass * 2
});
var loop = function() {
update();
draw();
requestAnimationFrame(loop);
}
requestAnimationFrame(loop);
}
function update() {
camera.update(player.blobs[0]);
player.update();
}
function draw() {
ctx.fillStyle = "#fff";
ctx.fillRect(0, 0, width, height);
player.draw();
}
setup();
body {
margin: 0;
padding: 0;
}
<canvas id="game">kindly update your browser.</canvas>

var
canvas,
ctx,
width = innerWidth,
height = innerHeight,
mouseX = 0,
mouseY = 0;
var
camera = {
x: 0,
y: 0,
update: function(obj) {
this.x = obj.x - width / 2;
this.y = obj.y - height / 2;
}
},
player = {
defaultMass: 54,
x: 0,
y: 0,
blobs: [],
update: function() {
for (var i = 0; i < this.blobs.length; i++) {
var x = mouseX + camera.x - this.blobs[i].x;
var y = mouseY + camera.y - this.blobs[i].y;
var length = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
var speed = 54 / this.blobs[i].mass;
this.blobs[i].velX = x / length * speed * Math.min(1, Math.pow(x / this.blobs[i].mass, 2));
this.blobs[i].velY = y / length * speed * Math.min(1, Math.pow(x / this.blobs[i].mass, 2));
this.blobs[i].x += this.blobs[i].velX;
this.blobs[i].y += this.blobs[i].velY;
for (var j = 0; j < this.blobs.length; j++) {
if (j != i && this.blobs[i] !== undefined) {
var blob1 = this.blobs[i];
var blob2 = this.blobs[j];
var dist = Math.sqrt(Math.pow(blob2.x - blob1.x, 2) + Math.pow(blob2.y - blob1.y, 2));
if (dist < blob1.mass + blob2.mass) {
if (this.blobs[i].x < this.blobs[j].x) {
this.blobs[i].x--;
} else if (this.blobs[i].x > this.blobs[j].x) {
this.blobs[i].x++;
}
if (this.blobs[i].y < this.blobs[j].y) {
this.blobs[i].y--;
} else if ((this.blobs[i].y > this.blobs[j].y)) {
this.blobs[i].y++;
}
}
}
}
}
this.x += (mouseX - width / 2) / (width / 2) * 1;
this.y += (mouseY - height / 2) / (height / 2) * 1
},
split: function(cell) {
cell.mass /= 2;
this.blobs.push({
x: cell.x,
y: cell.y,
mass: cell.mass
});
},
draw: function() {
for (var i = 0; i < this.blobs.length; i++) {
ctx.fillStyle = "red";
ctx.beginPath();
ctx.arc(-camera.x + this.blobs[i].x, -camera.y + this.blobs[i].y, this.blobs[i].mass, 0, Math.PI * 2);
ctx.fill();
ctx.closePath();
}
}
};
function handleMouseMove(e) {
mouseX = e.clientX;
mouseY = e.clientY;
}
function setup() {
canvas = document.getElementById("game");
ctx = canvas.getContext("2d");
canvas.width = width;
canvas.height = height;
addEventListener("mousemove", handleMouseMove);
player.blobs.push({
x: 0,
y: 0,
mass: player.defaultMass
});
player.blobs.push({
x: 100,
y: 100,
mass: player.defaultMass / 2
});
player.blobs.push({
x: 100,
y: 100,
mass: player.defaultMass * 2
});
var loop = function() {
update();
draw();
requestAnimationFrame(loop);
}
requestAnimationFrame(loop);
}
function update() {
camera.update(player.blobs[0]);
player.update();
}
function draw() {
ctx.fillStyle = "#fff";
ctx.fillRect(0, 0, width, height);
player.draw();
}
setup();
body {
margin: 0;
padding: 0;
}
<canvas id="game">kindly update your browser.</canvas>

How to make this HTML5 canvas script to full screen?

I am having trouble trying to set the canvas to fill the whole window. It is currently set to 500x500.. I am new to coding and would really appreciate any help! Thank you.
Here is the code:
<!DOCTYPE html>
<html>
<head>
<title>Starfield effect done in HTML 5</title>
<script>
window.onload = function() {
/* --- config start --- */
var starfieldCanvasId = "starfieldCanvas", // id of the canvas to use
framerate = 60, // frames per second this animation runs at (this is not exact)
numberOfStarsModifier = 0.15, // Number of stars, higher numbers have performance impact
flightSpeed = 0.003; // speed of the flight, the higher this number the faster
/* ---- config end ---- */
var canvas = document.getElementById(starfieldCanvasId),
context = canvas.getContext("2d"),
width = canvas.width,
height = canvas.height,
numberOfStars = width * height / 1000 * numberOfStarsModifier,
dirX = width / 2,
dirY = height / 2,
stars = [],
TWO_PI = Math.PI * 2;
// initialize starfield
for(var x = 0; x < numberOfStars; x++) {
stars[x] = {
x: range(0, width),
y: range(0, height),
size: range(0, 1)
};
}
// when mouse moves over canvas change middle point of animation
canvas.onmousemove = function(event) {
dirX = event.offsetX,
dirY = event.offsetY;
}
// start tick at specified fps
window.setInterval(tick, Math.floor(1000 / framerate));
// main routine
function tick() {
var oldX,
oldY;
// reset canvas for next frame
context.clearRect(0, 0, width, height);
for(var x = 0; x < numberOfStars; x++) {
// save old status
oldX = stars[x].x;
oldY = stars[x].y;
// calculate changes to star
stars[x].x += (stars[x].x - dirX) * stars[x].size * flightSpeed;
stars[x].y += (stars[x].y - dirY) * stars[x].size * flightSpeed;
stars[x].size += flightSpeed;
// if star is out of bounds, reset
if(stars[x].x < 0 || stars[x].x > width || stars[x].y < 0 || stars[x].y > height) {
stars[x] = {
x: range(0, width),
y: range(0, height),
size: 0
};
}
// draw star
context.strokeStyle = "rgba(255, 255, 255, " + Math.min(stars[x].size, 1) + ")";
context.lineWidth = stars[x].size;
context.beginPath();
context.moveTo(oldX, oldY);
context.lineTo(stars[x].x, stars[x].y);
context.stroke();
}
}
// get a random number inside a range
function range(start, end) {
return Math.random() * (end - start) + start;
}
};
</script>
</head>
<body style="background:#000;">
<canvas width="500" height="500" id="starfieldCanvas"></canvas>
</body>
</html>
Original code and credit to: https://www.timewasters-place.com/starfield-animation-done-in-html-5/

I assume you mean that you want your script to determine the screen size automatically, and then to set the canvas to be the full screen instead of the hardcoded 500 x 500 currently.
You can determine the viewport size programatically using the following where the width and height are as follows respectively. (Source):
var width = window.innerWidth
|| document.documentElement.clientWidth
|| document.body.clientWidth;
var height = window.innerHeight
|| document.documentElement.clientHeight
|| document.body.clientHeight;
Then you can set the dimensions of your canvas as follows:
canvas.width = width;
canvas.height = height;
So, this would be the full code in your case:
<!DOCTYPE html>
<html>
<head>
<title>Starfield effect done in HTML 5</title>
<script>
window.onload = function() {
/* --- config start --- */
var starfieldCanvasId = "starfieldCanvas", // id of the canvas to use
framerate = 60, // frames per second this animation runs at (this is not exact)
numberOfStarsModifier = 0.15, // Number of stars, higher numbers have performance impact
flightSpeed = 0.003; // speed of the flight, the higher this number the faster
var width = window.innerWidth
|| document.documentElement.clientWidth
|| document.body.clientWidth;
var height = window.innerHeight
|| document.documentElement.clientHeight
|| document.body.clientHeight;
/* ---- config end ---- */
var canvas = document.getElementById(starfieldCanvasId),
context = canvas.getContext("2d"),
stars = [],
TWO_PI = Math.PI * 2;
canvas.width = width;
canvas.height = height;
numberOfStars = width * height / 1000 * numberOfStarsModifier;
dirX = width / 2;
dirY = height / 2;
// initialize starfield
for(var x = 0; x < numberOfStars; x++) {
stars[x] = {
x: range(0, width),
y: range(0, height),
size: range(0, 1)
};
}
// when mouse moves over canvas change middle point of animation
canvas.onmousemove = function(event) {
dirX = event.offsetX,
dirY = event.offsetY;
}
// start tick at specified fps
window.setInterval(tick, Math.floor(1000 / framerate));
// main routine
function tick() {
var oldX,
oldY;
// reset canvas for next frame
context.clearRect(0, 0, width, height);
for(var x = 0; x < numberOfStars; x++) {
// save old status
oldX = stars[x].x;
oldY = stars[x].y;
// calculate changes to star
stars[x].x += (stars[x].x - dirX) * stars[x].size * flightSpeed;
stars[x].y += (stars[x].y - dirY) * stars[x].size * flightSpeed;
stars[x].size += flightSpeed;
// if star is out of bounds, reset
if(stars[x].x < 0 || stars[x].x > width || stars[x].y < 0 || stars[x].y > height) {
stars[x] = {
x: range(0, width),
y: range(0, height),
size: 0
};
}
// draw star
context.strokeStyle = "rgba(255, 255, 255, " + Math.min(stars[x].size, 1) + ")";
context.lineWidth = stars[x].size;
context.beginPath();
context.moveTo(oldX, oldY);
context.lineTo(stars[x].x, stars[x].y);
context.stroke();
}
}
// get a random number inside a range
function range(start, end) {
return Math.random() * (end - start) + start;
}
};
</script>
</head>
<body style="background:#000;">
<canvas id="starfieldCanvas"></canvas>
</body>
</html>
I also tested this on Fiddle. Here's the link: Fiddle
Hope this helps! Let me know if it works.