TSP implementation seems to ignore if statement - javascript

Just for fun I am creating a basic JavaScript implementation of the traveling salesman problem.
It will basically create an array of cities with random coordinates, plot them on a canvas, then show the path between them. I then have a button which launches a 'findBetterRoute' function, which simply swaps two cities over, and if the path is better it will pass the new route back, if it's worse it will pass the original back. However, I am finding that the last part isn't working - it will sometimes plot a route that is longer than the original and I can't for the life of me fathom what I am doing wrong.
Here is my code:
<html>
<head>
<title>The Traveling Salesman Problem</title>
</head>
<body onload="drawInitial()">
<canvas id="TSP" width="1000" height="1000" style="border:1px solid #000000;"></canvas>
<script>
var canvas = document.getElementById("TSP");
var ctx = canvas.getContext("2d");
var numberofCities = 5;
let city = [numberofCities];
for (i = 0; i < numberofCities; i++) {
city[i] = [Math.random() * 1000 + 1, Math.random() * 1000 + 1];
}
function drawInitial() {
drawPath(city);
}
function drawPath(cityarray) {
ctx.moveTo(cityarray[0][0], cityarray[0][1]);
for (i = 0; i < cityarray.length; i++) {
if (i != 0) {
ctx.lineTo(cityarray[i][0], cityarray[i][1]);
ctx.stroke();
}
ctx.beginPath();
ctx.arc(cityarray[i][0], cityarray[i][1], 2, 0, Math.PI * 2, true);
ctx.fill();
}
ctx.lineTo(city[0][0], city[0][1]);
ctx.stroke();
ctx.font = "30px Arial";
ctx.fillText("Path Length: " + parseInt(calculatePathLength(city)), 10, 50);
}
function calculatePathLength(cityarray) {
let pathLength = 0;
for (i = 0; i < (cityarray.length - 1); i++) {
pathLength = pathLength + Math.sqrt((Math.pow((cityarray[i][0] - cityarray[i + 1][0]), 2)) + (Math.pow((cityarray[i][1] - cityarray[i + 1][1]), 2)))
}
pathLength = pathLength + Math.sqrt((Math.pow((cityarray[numberofCities - 1][0] - cityarray[0][0]), 2)) + (Math.pow((cityarray[numberofCities - 1][1] - cityarray[0][1]), 2)))
return pathLength;
}
function swap2RandomCities(cityarray) {
var city1 = 1;
var city2 = 2;
do {
city1 = parseInt(Math.random() * numberofCities);
city2 = parseInt(Math.random() * numberofCities);
} while (city1 == city2);
var swapArray = [];
swapArray[0] = [cityarray[city1][0], cityarray[city1][1]];
swapArray[1] = [cityarray[city2][0], cityarray[city2][1]];
cityarray[city1] = swapArray[1];
cityarray[city2] = swapArray[0];
return cityarray;
}
function findBetterRoute(cityArray) {
var currentlength = calculatePathLength(cityArray);
var newRoute = swap2RandomCities(cityArray);
if (calculatePathLength(newRoute) < currentlength) {
return newRoute;
} else {
return cityArray;
}
}
function ButtonClick() {
city = findBetterRoute(city);
ctx.clearRect(0, 0, canvas.width, canvas.height);
drawPath(city);
}
</script>
<button onclick="ButtonClick()">Find Better Route</button>
</body>
</html>

Related

How to animate several dots moving here and there in html canvas

I have a requirement to move many dots here and there inside a canvas.
Hence I created several arcs with different radius and placed them at random places.
var context = document.getElementById('stage').getContext('2d');
var radian = Math.PI / 180;
var x = 40;
var y = 40;
var r = 20;
var colorPoints = [];
var frames = 50;
var currentFrame = 0;
var toggle = false;
var iconsLoaded = false;
context.beginPath();
context.arc(x,y, r, 0 * radian, 360 * radian, false)
context.fill();
var drawMultipleCurves = function(ctx){
if(!iconsLoaded){
for (let i = 0; i < 600; i++) {
ctx.beginPath();
ctx.filter = 'blur(5px)';
ctx.fillStyle = '#B835FF';
colorPoints.push({x: Math.floor((Math.random() * 700) + 0), xMove: Math.floor((Math.random() * 2) + 0) , yMove: Math.floor((Math.random() * 2) + 0) , y: Math.floor((Math.random() * 700) + 0), radius: Math.floor((Math.random() * 20) + 5)});
ctx.arc(colorPoints[colorPoints.length - 1].x, colorPoints[colorPoints.length - 1].y, colorPoints[colorPoints.length - 1].radius, 0 * radian, 360 * radian, false);
ctx.fill();
ctx.closePath();
iconsLoaded = true;
}
}
else{
for(let i =0;i< colorPoints.length; i++){
if(frames === currentFrame ){
toggle = !toggle;
currentFrame = 0;
}
if(!toggle){
colorPoints[i].xMove === 1 ? colorPoints[i].x = colorPoints[i].x + 5 : colorPoints[i].x = colorPoints[i].x - 5;
colorPoints[i].yMove === 1 ? colorPoints[i].y = colorPoints[i].y + 5 : colorPoints[i].y = colorPoints[i].y - 5;
}
else{
colorPoints[i].xMove === 1 ? colorPoints[i].x = colorPoints[i].x - 5 : colorPoints[i].x = colorPoints[i].x + 5;
colorPoints[i].yMove === 1 ? colorPoints[i].y = colorPoints[i].y - 5 : colorPoints[i].y = colorPoints[i].y + 5;
}
ctx.beginPath();
ctx.arc(colorPoints[i].x, colorPoints[i].y, colorPoints[i].radius, 0 * radian, 360 * radian, false);
context.closePath( );
ctx.fill();
currentFrame = currentFrame + 1;
}
}
}
var animate = function(){
setTimeout(()=>{
context.clearRect(0,0,400,400);
context.beginPath();
drawMultipleCurves(context);
context.fill();
requestAnimationFrame(animate)
}, 1000/30)
}
requestAnimationFrame(animate)
<canvas id="stage" width="400" height="400">
<p>Your browser doesn't support canvas.</p>
</canvas>
Above is the code that I have tried.
I have first created and placed several dots at random places with random radius.
When I created them I saved all these random places in an array 'colorPoints'
Now I'm looping into this array and moving all the dots everytime 'requestAnimation' is called.
I'm able to achieve my animation of moving the dots randomly but as I have used 800 dots and then saving them into an array and then again looping them to move their position, the animation is not looking smooth.
It looks like it is moving and strucking. How can I achieve this animation smoothly?
Thanks in advance :)
Render "fill" once per style
Your code is slowing down due to where you placed fill (same if you use stroke)
When you have many objects with the same style call fill only once per frame for each object.
You had something like
for (const c of circles) {
ctx.beginPath();
ctx.arc(c.x, c.y, c.r, 0, TAU)
ctx.fill();
}
With a filter active the fill command forces the filter to be reset, which for blur is complex.
Rather add all the arcs then fill.
ctx.beginPath();
for (const c of circles) {
ctx.moveTo(c.x + c.r, c.y);
ctx.arc(c.x, c.y, c.r, 0, TAU)
}
ctx.fill();
The move ctx.moveTo(c.x + c.r, c.y); is used to close the previous arc.
You can also close the arc with ctx.closePath but this can be a lot slower when you have many arcs in the path buffer.
// slower than using moveTo
ctx.beginPath();
for (const c of circles) {
ctx.arc(c.x, c.y, c.r, 0, TAU)
ctx.closePath();
}
ctx.fill();
Example
Example draws 600 arcs using the blur filter as it only calls fill once per frame. This should run smooth on all but the most low end devices.
See function drawCircles
requestAnimationFrame(animate);
const ctx = canvas.getContext('2d');
const W = canvas.width;
const BLUR = 5;
const CIRCLE_COUNT = 600;
const MIN_RADIUS = BLUR;
const MAX_RADIUS = 30;
const MAX_DELTA = 1;
const MAX_CIR_R = MAX_RADIUS + BLUR;
const MOVE_SIZE = MAX_CIR_R * 2 + W;
const TAU = 2 * Math.PI;
const setOf = (c, cb, i = 0, a = []) => { while(i < c) { a.push(cb(i++)) } return a };
const rnd = (m, M) => Math.random() * (M - m) + m;
const style = {
filter: "blur(" + BLUR + "px)",
fillStyle: '#B835FF',
};
var currentStyle;
function setStyle(ctx, style) {
if (currentStyle !== style) {
Object.assign(ctx, style);
currentStyle = style;
}
}
const circle = {
get x() { return rnd(-MAX_CIR_R, W + MAX_CIR_R) },
get y() { return rnd(-MAX_CIR_R, W + MAX_CIR_R) },
get dx() { return rnd(-MAX_DELTA, MAX_DELTA) },
get dy() { return rnd(-MAX_DELTA, MAX_DELTA) },
get r() { return rnd(MIN_RADIUS, MAX_RADIUS) },
move() {
var x = this.x + this.dx + MOVE_SIZE + MAX_CIR_R;
var y = this.y + this.dy + MOVE_SIZE + MAX_CIR_R;
this.x = x % MOVE_SIZE - MAX_CIR_R;
this.y = y % MOVE_SIZE - MAX_CIR_R;
}
};
const circles = setOf(CIRCLE_COUNT, () => Object.assign({}, circle));
function drawCircles(circles, ctx, style) {
setStyle(ctx, style);
ctx.beginPath();
for (const c of circles) {
ctx.moveTo(c.x + c.r, c.y);
ctx.arc(c.x, c.y, c.r, 0, TAU);
}
ctx.fill();
}
function updateCircles(circles) {
for (const c of circles) { c.move(); }
}
function animate() {
ctx.clearRect(0,0,W, W);
updateCircles(circles);
drawCircles(circles, ctx, style);
requestAnimationFrame(animate);
}
<canvas id="canvas" width="600" height="600"> </canvas>
If you have several colors, group all the same colors so you can keep the number of fill calls as low as possible.
There are many ways to get the same effect with many colors (each circle a different color) but will need more setup code.
The CanvasRenderingContext2D blur filter is quite heavy - especially if you use it on a canvas consisting of 600 circles. That means on every screen update it has to re-draw 600 circles and apply a blur filter afterwards.
The usual approach is a little different. Initially you create a master texture with a blurred circle. This texture can then be re-used and drawn onto the canvas using the drawImage() method. To vary the size of the circles there is no radius anymore though. We can get the same effect by using a scale instead.
Here's an example:
var context = document.getElementById('stage').getContext('2d');
var radian = Math.PI / 180;
var x = 40;
var y = 40;
var r = 20;
var colorPoints = [];
var frames = 50;
var currentFrame = 0;
var toggle = false;
var iconsLoaded = false;
var texture = document.createElement("canvas");
var textureContext = texture.getContext("2d");
texture.width = 80;
texture.height = 80;
textureContext.filter = 'blur(5px)';
textureContext.fillStyle = '#B835FF';
textureContext.arc(texture.width / 2, texture.height / 2, 25, 0 * radian, 360 * radian, false);
textureContext.fill();
textureContext.closePath();
var drawMultipleCurves = function(ctx) {
if (!iconsLoaded) {
for (let i = 0; i < 600; i++) {
colorPoints.push({
x: Math.floor((Math.random() * 700) + 0),
xMove: Math.floor((Math.random() * 2) + 0),
yMove: Math.floor((Math.random() * 2) + 0),
y: Math.floor((Math.random() * 700) + 0),
scale: 0.2 + Math.random() * 0.8
});
iconsLoaded = true;
}
} else {
for (let i = 0; i < colorPoints.length; i++) {
if (frames === currentFrame) {
toggle = !toggle;
currentFrame = 0;
}
if (!toggle) {
colorPoints[i].xMove === 1 ? colorPoints[i].x = colorPoints[i].x + 5 : colorPoints[i].x = colorPoints[i].x - 5;
colorPoints[i].yMove === 1 ? colorPoints[i].y = colorPoints[i].y + 5 : colorPoints[i].y = colorPoints[i].y - 5;
} else {
colorPoints[i].xMove === 1 ? colorPoints[i].x = colorPoints[i].x - 5 : colorPoints[i].x = colorPoints[i].x + 5;
colorPoints[i].yMove === 1 ? colorPoints[i].y = colorPoints[i].y - 5 : colorPoints[i].y = colorPoints[i].y + 5;
}
ctx.drawImage(texture, colorPoints[i].x, colorPoints[i].y, texture.width * colorPoints[i].scale, texture.height * colorPoints[i].scale);
currentFrame = currentFrame + 1;
}
}
}
var animate = function() {
setTimeout(() => {
context.clearRect(0, 0, 400, 400);
context.beginPath();
drawMultipleCurves(context);
context.fill();
requestAnimationFrame(animate)
})
}
requestAnimationFrame(animate)
<canvas id="stage" width="400" height="400">
<p>Your browser doesn't support canvas.</p>
</canvas>

Need help optimizing my Javascript for canvas rendering

I've written this quick script for random moving lines for the background for my portfolio. It works smoothly alone but when I start working with other CSS animations and stuff, there's a frame drop at the beginning (later it runs smooth). At least on my PC, struggles on low-end PC.
Some tips to optimize it would be helpful.
Here's my code:
/*Random Line Render Script aka Mini Browser Crasher */
/*XD Can't Revise This Script. Rofl Drains Memory. May crash low-end pc :V */
var c = document.getElementById("graph");
var dimension = [document.documentElement.clientWidth, document.documentElement.clientHeight];
c.width = dimension[0];
var ctx = c.getContext("2d");
var ctx2 = c.getContext("2d");
var posx = [100, 200, 150, 100, 0];
var posy = [100, 200, 300, 100, -100];
var posx2 = [600, 400, 200, 600];
var posy2 = [500, 200, 100, 150, 500, 500];
var posx3 = [];
var posy3 = [];
/*Generate random values for array( random starting point ) */
for (var i = 0; i < 2; i++) {
posx2.push(500 + Math.round(Math.random() * 700));
posy2.push(Math.round(Math.random() * 900));
}
for (var i = 0; i < 5; i++) {
posx3.push(1000 + Math.round(Math.random() * 300));
posy3.push(0 + Math.round(Math.random() * 1000));
}
var posx_len = posx.length;
var posx2_len = posx2.length;
var posx3_len = posx3.length;
var xa, ya;
var opa = 1;
var amount = 0.01;
var sinang = 0;
var distance1 = 0;
var distance2 = 0;
document.body.addEventListener('mousemove', (function(event) {
xa = event.clientX;
ya = event.clientY;
}));
/*Render Lines */
function draw() {
ctx.clearRect(0, 0, 10000, 10000);
ctx.beginPath();
ctx.moveTo(posx[0], posy[0]);
for (var i = 0; i < posx_len; i++) {
ctx.lineTo(posx[i], posy[i]);
ctx.strokeStyle = 'rgba(255,255,255,' + opa + ')';
ctx.stroke();
ctx.arc(posx[i], posy[i], 5, 0, 2 * Math.PI, false);
}
if (opa > 1) {
amount = -0.01 * Math.random();
}
if (opa < 0) {
amount = 0.01 * Math.random();
}
opa = opa + amount;
ctx.moveTo(posx2[0], posy2[0]);
for (var i = 0; i < posx2_len; i++) {
ctx.lineTo(posx2[i], posy2[i]);
ctx.strokeStyle = 'rgba(255,255,255,' + opa + ')';
ctx.stroke();
ctx.arc(posx2[i], posy2[i], 5, 0, 2 * Math.PI, false);
}
ctx.moveTo(posx3[0], posy3[0]);
for (var i = 0; i < posx3_len; i++) {
ctx.lineTo(posx3[i], posy3[i]);
ctx.strokeStyle = 'rgba(255,255,255,' + opa + ')';
ctx.stroke();
ctx.arc(posx3[i], posy3[i], 5, 0, 2 * Math.PI, false);
}
sinang = sinang + 0.01;
/*Frame Render Ends here*/
/*Calculation for next frame*/
for (var i = 0; i < posx_len; i++) {
posx[i] = posx[i] + (Math.cos(sinang) * i) / 2; /* Sin curve for smooth value transition. Smooth assss Butter */
posy[i] = posy[i] + (Math.cos(sinang) * i) / 2;
/* Can't believe Distance Formula is useful ahaha */
distance1 = Math.sqrt(Math.pow((posx[i] - xa), 2) + Math.pow((posy[i] - ya), 2));
if (distance1 <= 500) {
ctx.moveTo(posx[i], posy[i]);
ctx.lineTo(xa, ya);
}
for (var j = 0; j < posx2_len; j++) {
distance12 = Math.sqrt(Math.pow((posx[i] - posx2[j]), 2) + Math.pow((posy[i] - posy2[j]), 2));
if (distance12 <= 500) {
ctx.moveTo(posx[i], posy[i]);
ctx.lineTo(posx2[j], posy2[j]);
}
}
for (var j = 0; j < posx3_len; j++) {
distance13 = Math.sqrt(Math.pow((posx[i] - posx3[j]), 2) + Math.pow((posy[i] - posy3[j]), 2));
if (distance13 <= 500) {
ctx.moveTo(posx[i], posy[i]);
ctx.lineTo(posx3[j], posy3[j]);
}
}
}
posx[posx.length - 1] = posx[0];
posy[posy.length - 1] = posy[0];
/*Repeat Above Steps. Should have done this in Multi-dimensional array. Ugh I feel sad now*/
for (var i = 0; i < posx2_len; i++) {
posx2[i] = posx2[i] + (Math.sin(sinang) * i) / 2;
posy2[i] = posy2[i] - (Math.sin(sinang) * i) / 2;
distance2 = Math.sqrt(Math.pow((posx2[i] - xa), 2) + Math.pow((posy2[i] - ya), 2));
if (distance2 <= 500) {
ctx.moveTo(posx2[i], posy2[i]);
ctx.lineTo(xa, ya);
}
for (var j = 0; j < posx3_len; j++) {
distance22 = Math.sqrt(Math.pow((posx2[i] - posx3[j]), 2) + Math.pow((posy2[i] - posy3[j]), 2));
if (distance22 <= 500) {
ctx.moveTo(posx2[i], posy2[i]);
ctx.lineTo(posx3[j], posy3[j]);
}
}
}
posx2[posx2.length - 1] = posx2[0];
posy2[posy2.length - 1] = posy2[0];
for (var i = 0; i < posx3_len; i++) {
posx3[i] = posx3[i] - (Math.sin(sinang) * i) / 1.2;
posy3[i] = posy3[i] - (Math.sin(sinang) * i) / 1.2;
distance2 = Math.sqrt(Math.pow((posx3[i] - xa), 2) + Math.pow((posy3[i] - ya), 2));
if (distance2 <= 500) {
ctx.moveTo(posx3[i], posy3[i]);
ctx.lineTo(xa, ya);
}
}
posx3[posx3.length - 1] = posx3[0];
posy3[posy3.length - 1] = posy3[0];
ctx.restore();
ctx.stroke();
window.requestAnimationFrame(draw);
}
window.requestAnimationFrame(draw);
body {
background: #1f1f1f;
}
<canvas height="1080px" width="1100px" id="graph">
</canvas>
So, what I've done is used square colliders instead of circular(distance formula) and it has faster runtime now. (not much but still)
<html>
<head>
</head>
<style>
body{
background: #1f1f1f;
}
canvas{
}
</style>
<body >
<canvas height="1080px" width="1100px" id="graph">
</canvas>
</body>
<script>
/*Random Line Render Script aka Mini Browser Crasher */
/*XD Can't Revise This Script. Rofl Drains Memory. May crash low-end pc :V */
var c = document.getElementById("graph");
var dimension = [document.documentElement.clientWidth, document.documentElement.clientHeight];
c.width = dimension[0];
var ctx = c.getContext("2d");
var posx = [100,200,150,100,0];
var posy = [100,200,300,100,-100];
var posx2 = [600,400,200,600];
var posy2 = [500,200,100,150,500,500];
var posx3 = [];
var posy3 = [];
/*Generate random values for array( random starting point ) */
for(var i=0; i<2;i++){
posx2.push(500+Math.round(Math.random()*700));
posy2.push(Math.round(Math.random()*900));
}
for(var i=0; i<5;i++){
posx3.push(1000+Math.round(Math.random()*300));
posy3.push(0+Math.round(Math.random()*1000));
}
var posx_len = posx.length;
var posx2_len = posx2.length;
var posx3_len = posx3.length;
var xa,ya;
var opa =1;
var amount = 0.01;
var sinang = 0;
var distance1 = 0;
var distance2 = 0;
var t1, t2;
document.body.addEventListener('mousemove', (function (event) {
xa = event.clientX;
ya = event.clientY;
}));
/*Render Lines */
function draw(){
t1 =performance.now();
ctx.clearRect(0, 0, 1920,1080);
ctx.beginPath();
ctx.moveTo(posx[0], posy[0]);
for(var i= 0; i<posx_len;i++){
ctx.lineTo(posx[i], posy[i]);
ctx.arc(posx[i],posy[i], 5, 0, 2 * Math.PI, false);
}
if(opa>1){
amount = -0.01*Math.random();
}
if(opa<0){
amount =0.01*Math.random();
}
opa =opa +amount;
ctx.moveTo(posx2[0], posy2[0]);
for(var i = 0; i<posx2_len;i++){
ctx.lineTo(posx2[i], posy2[i]);
ctx.arc(posx2[i],posy2[i], 5, 0, 2 * Math.PI, false);
}
ctx.moveTo(posx3[0], posy3[0]);
for(var i = 0; i<posx3_len;i++){
ctx.lineTo(posx3[i], posy3[i]);
ctx.arc(posx3[i],posy3[i], 5, 0, 2 * Math.PI, false);
}
sinang = sinang+0.01;
/*Frame Render Ends here*/
/*Calculation for next frame*/
for(var i = 0;i<posx_len;i++){
posx[i] = posx[i]+ (Math.cos(sinang)*i)/2;/* Sin curve for smooth value transition. Smooth assss Butter */
posy[i] = posy[i]+ (Math.cos(sinang)*i)/2;
/* Can't believe Distance Formula is useful ahaha */
if(Math.abs(posx[i]-xa)<500 && Math.abs(posy[i]-ya)<500){
ctx.moveTo(posx[i],posy[i]);
ctx.lineTo(xa, ya);
}
for(var j = 0;j<posx2_len;j++){
if(Math.abs(posx[i]-posx2[j])<500 && Math.abs(posy[i]-posy2[j])<500){
ctx.moveTo(posx[i],posy[i]);
ctx.lineTo(posx2[j], posy2[j]);
}
}
for(var j = 0;j<posx3_len;j++){
if(Math.abs(posx[i]-posx3[j])<500 && Math.abs(posy[i]-posy3[j])<500){
ctx.moveTo(posx[i],posy[i]);
ctx.lineTo(posx3[j], posy3[j]);
}
}
}
posx[posx.length-1]=posx[0];
posy[posy.length-1] = posy[0];
/*Repeat Above Steps. Should have done this in Multi-dimensional array. Ugh I feel sad now*/
for(var i = 0;i<posx2_len;i++){
posx2[i] = posx2[i]+ (Math.sin(sinang)*i)/2;
posy2[i] = posy2[i]-(Math.sin(sinang)*i)/2;
if(Math.abs(posx2[i]-xa)<500 && Math.abs(posy2[i]-ya)<500){
ctx.moveTo(posx2[i],posy2[i]);
ctx.lineTo(xa, ya);
}
for(var j = 0;j<posx3_len;j++){
if(Math.abs(posx2[i]-posx3[j])<500 && Math.abs(posy2[i]-posy3[j])<500){
ctx.moveTo(posx2[i],posy2[i]);
ctx.lineTo(posx3[j], posy3[j]);
}
}
}
posx2[posx2.length-1]=posx2[0];
posy2[posy2.length-1] = posy2[0];
for(var i = 0;i<posx3_len;i++){
posx3[i] = posx3[i]- (Math.sin(sinang)*i)/1.2;
posy3[i] = posy3[i]-(Math.sin(sinang)*i)/1.2;
if(Math.abs(posx3[i]-xa)<500 && Math.abs(posy3[i]-ya)<500){
ctx.moveTo(posx3[i],posy3[i]);
ctx.lineTo(xa, ya);
}
}
posx3[posx3.length-1]=posx3[0];
posy3[posy3.length-1] = posy3[0];
ctx.restore();
ctx.strokeStyle = 'rgba(255,255,255,'+opa+')';
ctx.stroke();
window.requestAnimationFrame(draw);
t2=performance.now();
console.log(t2-t1);
}
window.requestAnimationFrame(draw);
</script>
</html>

How to have two different text elements moving randomly on a page in Javascript

So I've been reading this post which I found is the closest to what I want. Basically, I want two different text elements (two different words) moving around the page randomly and also bouncing off each other when they come in contact.
I have tried to edit the code so that it's black and have only one text element. However how can I also include a second text element (a different word) moving randomly as well?
Also how can I change it to Roboto Mono font?
// Return random RGB color string:
function randomColor() {
var hex = Math.floor(Math.random() * 0x1000000).toString(16);
return "#" + ("000000" + hex).slice(0);
}
// Poor man's box physics update for time step dt:
function doPhysics(boxes, width, height, dt) {
for (let i = 0; i < boxes.length; i++) {
var box = boxes[i];
// Update positions:
box.x += box.dx * dt;
box.y += box.dy * dt;
// Handle boundary collisions:
if (box.x < 0) {
box.x = 0;
box.dx = -box.dx;
} else if (box.x + box.width > width) {
box.x = width - box.width;
box.dx = -box.dx;
}
if (box.y < 0) {
box.y = 0;
box.dy = -box.dy;
} else if (box.y + box.height > height) {
box.y = height - box.height;
box.dy = -box.dy;
}
}
// Handle box collisions:
for (let i = 0; i < boxes.length; i++) {
for (let j = i + 1; j < boxes.length; j++) {
var box1 = boxes[i];
var box2 = boxes[j];
var dx = Math.abs(box1.x - box2.x);
var dy = Math.abs(box1.y - box2.y);
// Check for overlap:
if (2 * dx < (box1.width + box2.width ) &&
2 * dy < (box1.height + box2.height)) {
// Swap dx if moving towards each other:
if ((box1.x > box2.x) == (box1.dx < box2.dx)) {
var swap = box1.dx;
box1.dx = box2.dx;
box2.dx = swap;
}
// Swap dy if moving towards each other:
if ((box1.y > box2.y) == (box1.dy < box2.dy)) {
var swap = box1.dy;
box1.dy = box2.dy;
box2.dy = swap;
}
}
}
}
}
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
// Initialize random boxes:
var boxes = [];
for (var i = 0; i < 1; i++) {
var box = {
x: Math.floor(Math.random() * canvas.width),
y: Math.floor(Math.random() * canvas.height),
width: 50,
height: 20,
dx: (Math.random() - 0.5) * 0.3,
dy: (Math.random() - 0.5) * 0.3
};
boxes.push(box);
}
// Initialize random color and set up interval:
var color = randomColor();
setInterval(function() {
color = randomColor();
}, 450);
// Update physics at fixed rate:
var last = performance.now();
setInterval(function(time) {
var now = performance.now();
doPhysics(boxes, canvas.width, canvas.height, now - last);
last = now;
}, 50);
// Draw animation frames at optimal frame rate:
function draw(now) {
context.clearRect(0, 0, canvas.width, canvas.height);
for (let i = 0; i < boxes.length; i++) {
var box = boxes[i];
// Interpolate position:
var x = box.x + box.dx * (now - last);
var y = box.y + box.dy * (now - last);
context.beginPath();
context.fillStyle = color;
context.font = "40px 'Roboto Mono'";
context.textBaseline = "hanging";
context.fillText("motion", x, y);
context.closePath();
}
requestAnimationFrame(draw);
}
requestAnimationFrame(draw);
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
<!DOCTYPE html>
<html>
<body>
<head>
<link rel="stylesheet" href="test.css">
<meta charset="utf-8">
<meta name="viewport" content="initial-scale=1">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title></title>
</head>
<canvas id="canvas"></canvas>
<script src="test.js"></script>
</body>
</html>
Multiple text boxes is easy :
Change the initialize boxes part to include more than one.
// Initialize random boxes:
var boxes = [];
var boxCount = 2
for (var i = 0; i < boxCount; i++) {
Second your random color is flawed , try this :
function randomColor() {
var hex = Math.floor(Math.random() * 0x1000000).toString(16);
return "#" + ("000000" + hex).substr(hex.length);
}
I don't think that roboto is available in the canvas element. (I could be wrong)
monospace is available though.
Edit
If you want different words you could use another array for them:
var words = ['motion','designer']
for (var i = 0; i < words.length; i++) {
as you create boxes use the words array.
You can't hard code the size of the box if you want have the words to collide. Height should be at least the font height 40px and if you want to get the width of the text box there is a context helping function :
box.width = context.measureText(words[i]).width;
See the snippet for usage :
// Return random RGB color string:
function randomColor() {
var hex = Math.floor(Math.random() * 0x1000000).toString(16);
return "#" + ("000000" + hex).substr(hex.length);
}
// Poor man's box physics update for time step dt:
function doPhysics(boxes, width, height, dt) {
for (let i = 0; i < boxes.length; i++) {
var box = boxes[i];
// Update positions:
box.x += box.dx * dt;
box.y += box.dy * dt;
// Handle boundary collisions:
if (box.x < 0) {
box.x = 0;
box.dx = -box.dx;
} else if (box.x + box.width > width) {
box.x = width - box.width;
box.dx = -box.dx;
}
if (box.y < 0) {
box.y = 0;
box.dy = -box.dy;
} else if (box.y + box.height > height) {
box.y = height - box.height;
box.dy = -box.dy;
}
}
// Handle box collisions:
for (let i = 0; i < boxes.length; i++) {
for (let j = i + 1; j < boxes.length; j++) {
var box1 = boxes[i];
var box2 = boxes[j];
var dx = Math.abs(box1.x - box2.x);
var dy = Math.abs(box1.y - box2.y);
// Check for overlap:
if (2 * dx < (box1.width + box2.width ) &&
2 * dy < (box1.height + box2.height)) {
// Swap dx if moving towards each other:
if ((box1.x > box2.x) == (box1.dx < box2.dx)) {
var swap = box1.dx;
box1.dx = box2.dx;
box2.dx = swap;
}
// Swap dy if moving towards each other:
if ((box1.y > box2.y) == (box1.dy < box2.dy)) {
var swap = box1.dy;
box1.dy = box2.dy;
box2.dy = swap;
}
}
}
}
}
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
// Initialize random boxes:
var boxes = [];
var words = ["designer","motion","hi"]
for (var i = 0; i < words.length; i++) {
var box = {
x: Math.floor(Math.random() * canvas.width),
y: Math.floor(Math.random() * canvas.height),
width: 50, // Will be dynamic
height: 42,
dx: (Math.random() - 0.5) * 0.3,
dy: (Math.random() - 0.5) * 0.3
};
boxes.push(box);
}
// Initialize random color and set up interval:
var color = randomColor();
setInterval(function() {
color = randomColor();
}, 450);
// Update physics at fixed rate:
var last = performance.now();
setInterval(function(time) {
var now = performance.now();
doPhysics(boxes, canvas.width, canvas.height, now - last);
last = now;
}, 50);
// Draw animation frames at optimal frame rate:
function draw(now) {
context.clearRect(0, 0, canvas.width, canvas.height);
for (let i = 0; i < boxes.length; i++) {
var box = boxes[i];
// Interpolate position:
var x = box.x + box.dx * (now - last);
var y = box.y + box.dy * (now - last);
box.width = context.measureText(words[i]).width;
context.beginPath();
context.fillStyle = color;
context.font = "normal 40px monospace";
context.textBaseline = "hanging";
context.fillText(words[i], x, y);
context.closePath();
}
requestAnimationFrame(draw);
}
requestAnimationFrame(draw);
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
<!DOCTYPE html>
<html>
<body>
<head>
<link rel="stylesheet" href="test.css">
<meta charset="utf-8">
<meta name="viewport" content="initial-scale=1">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title></title>
</head>
<canvas id="canvas"></canvas>
<script src="test.js"></script>
</body>
</html>

Update function in Conway's game of life is not working

I am trying to make Conway's Game of Life in JavaScript, but cannot find what is wrong with a specific function after hours of debugging.
The program works by making a 2d array based of global "row" and "column" variables, and then pushes "Square" objects to each space in the array. The program then sets an interval for the "draw" function for a specific interval, (the global variable "rate").
I apologize if this is hard to understand, but basically, every specific time interval, like every 1000 milliseconds, the program checks every "Square" object in the array, updates the amount of neighbors it has, and then draws it on the screen.
This is where I am stuck; the update function is supposed to check all 8 neighbors that a square has, (or 3-5 if it is an edge square) but it will only check 4 neighbors. No matter what I do, if I click a square to populate it, only the top, top left, top right, and left neighbors of the now populated square will register that their neighbor has become populated.
Other than this bug the code is working fine, and i'm 99% sure the problem is in this one function, because the code will still function as a cellular automata currently, just not as Conway's Game of Life.
var canvas = document.getElementById("life");
var ctx = canvas.getContext('2d');
var timer;
var rate = 1000;
var rows = 20;
var columns = 20;
var width = 20;
var clickX;
var clickY;
var board;
var running = false;
var checkArray = [
[-1, 0, 1, 1, 1, 0, -1, -1],
[-1, -1, -1, 0, 1, 1, 1, 0]
];
var visuals = true;
var gridColor = "#000000";
/*
live cell with < 2 neighbors = death
live cell with 2 or 3 neighbors = live for 1 generation
live cell with > 4 neighbors = death
dead cell with 3 neighbors = live for 1 generation
0 = death
1 = death
2 = continues life if alive
3 = continues life if alive OR brings to life if dead
4 = death
5 = death
6 = death
7 = death
8 = death
*/
window.onload = function() {
makeBoard();
var timer = setInterval(draw, rate);
window.addEventListener("mousedown", clickHandler);
// for(var i = 0; i < 8; i++){
// var checkIndexX = checkArray[0][i];
// var checkIndexY = checkArray[1][i];
// console.log(checkIndexX, checkIndexY);
// }
}
function makeBoard() {
board = new Array(columns);
for (var i = 0; i < rows; i++) {
var intRow = new Array(rows);
for (var j = 0; j < columns; j++) {
intRow[j] = new Square(false, j, i);
}
board[i] = intRow;
}
}
function draw() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
for (var y = 0; y < rows; y++) {
for (var x = 0; x < columns; x++) {
if (running) {
board[y][x].update();
}
board[y][x].draw();
if (visuals) {
board[y][x].visuals();
}
}
}
drawRunButton();
}
function Square(alive, PARX, PARY) {
this.alive = false;
this.X = PARX;
this.Y = PARY;
this.neighbors = 0;
this.update = function() {
this.neighbors = 0;
for (var i = 0; i < 8; i++) {
var checkIndexX = checkArray[0][i];
var checkIndexY = checkArray[1][i];
if ((this.X + checkIndexX) >= 0 && (this.X + checkIndexX) < columns &&
(this.Y + checkIndexY) >= 0 && (this.Y + checkIndexY) < rows) {
var check = board[this.Y + checkIndexY][this.X + checkIndexX];
// console.log(this.X, this.Y, check.X, check.Y, checkIndexX, checkIndexY);
if (check.alive) {
this.neighbors++;
}
}
}
if (this.alive) {
if (this.neighbors < 2 || this.neighbors > 3) {
this.alive = false;
}
} else {
if (this.neighbors == 3) {
this.alive = true;
}
}
};
this.visuals = function() {
drawVisuals(this.neighbors, this.X * width, this.Y * width);
};
this.draw = function(alive) {
drawSquare(this.alive, this.X * width, this.Y * width, width);
}
}
function clickHandler(e) {
var clickX = e.screenX - 68;
var clickY = e.screenY - 112;
mapClick(clickX, clickY);
manageRun(clickX, clickY);
}
function mapClick(x, y) {
var indexX = Math.floor(x / width);
var indexY = Math.floor(y / width);
if (indexX >= 0 && indexX < columns && indexY >= 0 && indexY < rows) {
board[indexY][indexX].alive = true;
}
}
function manageRun(x, y) {
if (x >= (columns * width) + 5 && x <= (columns * width) + 45 && y >= 5 && y <= 45) {
if (running) {
running = false;
} else {
running = true;
}
console.log(running);
}
}
function drawRunButton() {
drawSquare(false, (columns * width) + 5, 5, 40)
}
function drawSquare(fill, x, y, width) {
ctx.beginPath();
ctx.moveTo(x, y);
ctx.lineTo(x + width, y);
ctx.lineTo(x + width, y + width);
ctx.lineTo(x, y + width);
ctx.lineTo(x, y);
if (fill) {
ctx.fillStyle = gridColor;
ctx.fill();
} else {
ctx.strokeStyle = gridColor;
ctx.stroke();
}
}
function drawVisuals(neighbors, x, y) {
ctx.beginPath();
ctx.fillStyle = "#ff0000";
ctx.font = '20px serif';
ctx.fillText(neighbors, x + (width / 3), y + (width / 1.25));
}
<!DOCTYPE html>
<html>
<head>
<title>template.com</title>
<link href="style.css" type="text/css" rel="stylesheet">
</head>
<body>
<canvas id="life" width="1400" height="700" style="border: 1px solid black"></canvas>
</body>
</html>

How would I create a trail behind my shapes in canvas?

Right now I have some shapes (I only included the triangle as they're all generated the same way) that are generated when the user spins the mouse wheel. I want to leave a trail behind the shapes that slowly disappear. I've looked around and tried a few different ways but I can't seem to get any of them to work. Here's the code:
<html>
<head>
<script>
var canvas;
var context;
var triangles = [];
var timer;
function init() {
canvas = document.getElementById('canvas');
context = canvas.getContext("2d");
resizeCanvas();
window.addEventListener('resize', resizeCanvas, false);
window.addEventListener('orientationchange', resizeCanvas, false);
canvas.onwheel = function(event) {
handleClick(event.clientX, event.clientY);
};
var timer = setInterval(resizeCanvas, 30);
}
function Triangle(x,y,triangleColor) {
this.x = x;
this.y = y;
this.triangleColor = triangleColor;
this.vx = Math.random() * 30 - 15;
this.vy = Math.random() * 30 - 15;
this.time = 100;
}
function handleClick(x,y) {
var colors = [[0,170,255], [230,180,125], [50,205,130]];
var triangleColor = colors[Math.floor(Math.random()*colors.length)];
triangles.push(new Triangle(x,y,triangleColor));
for (var i=0; i<triangles.length; i++) {
drawTriangle(triangles[i]);
}
}
function drawTriangle(triangle) {
context.beginPath();
context.moveTo(triangle.x,triangle.y);
context.lineTo(triangle.x+25,triangle.y+25);
context.lineTo(triangle.x+25,triangle.y-25);
var c = triangle.triangleColor
context.fillStyle = 'rgba(' + c[0] + ', ' + c[1] + ', ' + c[2] + ', ' + (triangle.time / 100) + ')';
context.fill();
}
function resizeCanvas() {
canvas.width = window.innerWidth-20;
canvas.height = window.innerHeight-20;
fillBackgroundColor();
for (var i=0; i<triangles.length; i++) {
var t = triangles[i];
drawTriangle(t);
if (t.x + t.vx > canvas.width || t.x + t.vx < 0)
t.vx = -t.vx
if (t.y + t.vy > canvas.height || t.y + t.vy < 0)
t.vy = -t.vy
if (t.time === 0) {
triangles.splice(i,1);
}
t.time -= 1;
t.x += t.vx;
t.y += t.vy;
}
}
function fillBackgroundColor() {
context.fillStyle = "black";
context.fillRect(0,0,canvas.width,canvas.height);
}
window.onload = init;
</script>
</head>
<body>
<canvas id="canvas" width="500" height="500"></canvas>
</body>
</html>
The way I managed to do this is by storing past locations of my objects (for example 10 past locations, and draw line from one to the next one.
1.Add arrays pastX and pastY to your triangle object.
this.pastX = [];
this.pastY = [];
2.Each tick put every element 1 place further and add current location as first.
Right before you update triangle positions
for(var k = t.pastX.length; k > 0; k--){
if(k < 10){
t.pastX[k] = pastX[k-1];
t.pastY[k] = pastY[k-1];
}
t.pastX[0] = t.x;
t.pastY[0] = t.y;
draw lines between them like this (from 0 to 1, from 1 to 2 and so on);
for(var k = 0; k < t.pastX.length - 1; k++){
//draw line from pastX[k], pastY[k] to pastX[k + 1], pastY[k + 1]
}
Hope I helped you.

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