Processes for optimizing canvas animations - javascript

I've got a small web app in development to simulate the Ising model of magnetism. I've found that the animation slows down considerably after a few seconds of running, and it also doesn't loop after 5 seconds like I want it to with the command:
setInteval(main, 500)
I've added start and stop buttons. When I stop the animation, and then restart it, it begins fresh at the usual speed, but again slows down.
My question is: what steps can I take to troubleshoot and optimize the performance of my canvas animation? I hope to reduce or mitigate this slowing effect.
JS code:
window.onload = function() {
var canvas = document.getElementById("theCanvas");
var context = canvas.getContext("2d");
var clength = 100;
var temperature = 2.1;
var playAnim = true;
canvas.width = clength;
canvas.height = clength;
var imageData = context.createImageData(clength, clength);
document.getElementById("stop").addEventListener("click",function(){playAnim=false;});
document.getElementById("start").addEventListener("click",function(){playAnim=true;});
function init2DArray(xlen, ylen, factoryFn) {
//generates a 2D array of xlen X ylen, filling each element with values defined by factoryFn, if called.
var ret = []
for (var x = 0; x < xlen; x++) {
ret[x] = []
for (var y = 0; y < ylen; y++) {
ret[x][y] = factoryFn(x, y)
}
}
return ret;
}
function createImage(array, ilen, jlen) {
for (var i = 0; i < ilen; i++) {
for (var j = 0; j < jlen; j++) {
var pixelIndex = (j * ilen + i) * 4;
if (array[i][j] == 1) {
imageData.data[pixelIndex] = 0; //r
imageData.data[pixelIndex+1] = 0; //g
imageData.data[pixelIndex+2] = 0; //b
imageData.data[pixelIndex+3] = 255; //alpha (255 is fully visible)
//black
} else if (array[i][j] == -1) {
imageData.data[pixelIndex] = 255; //r
imageData.data[pixelIndex+1] = 255; //g
imageData.data[pixelIndex+2] = 255; //b
imageData.data[pixelIndex+3] = 255; //alpha (255 is fully visible)
//white
}
}
}
}
function dU(i, j, array, length) {
var m = length-1;
//periodic boundary conditions
if (i == 0) { //top row
var top = array[m][j];
} else {
var top = array[i-1][j];
}
if (i == m) { //bottom row
var bottom = array[0][j];
} else {
var bottom = array[i+1][j];
}
if (j == 0) { //first in row (left)
var left = array[i][m];
} else {
var left = array[i][j-1];
}
if (j == m) { //last in row (right)
var right = array[i][0];
} else {
var right = array[i][j+1]
}
return 2.0*array[i][j]*(top+bottom+left+right); //local magnetization
}
function randInt(max) {
return Math.floor(Math.random() * Math.floor(max));
}
var myArray = init2DArray(clength, clength, function() {var c=[-1,1]; return c[Math.floor(Math.random()*2)]}); //creates a 2D square array populated with -1 and 1
function main(frame) {
if (!playAnim){return;} // stops
window.requestAnimationFrame(main);
createImage(myArray, clength, clength);
context.clearRect(0,0,clength,clength);
context.beginPath();
context.putImageData(imageData,0,0);
for (var z = 0; z < 10*Math.pow(clength,2); z++) {
i = randInt(clength-1);
j = randInt(clength-1);
var deltaU = dU(i, j, myArray, clength);
if (deltaU <= 0) {
myArray[i][j] = -myArray[i][j];
} else {
if (Math.random() < Math.exp(-deltaU/temperature)) {
myArray[i][j] = -myArray[i][j];
}
}
}
}
var timer = setInterval(main, 500);
}

Related

Paint bucket getting "Maximum Call Stack Size Exceeded" error

This is the code of the paint bucket tool in my drawing app using the p5.js library. The function self.floodFill always get "Maximum Call Stack Size Exceeded" because of recursion and I want to know the way to fix it. I am thinking if changing the function to a no recursion function would help or not. Any help would be appreciated.
function BucketTool(){
var self = this;
//set an icon and a name for the object
self.icon = "assets/bucket.jpg";
self.name = "Bucket";
var d = pixelDensity();
var oldColor;
var searchDirections = [[1,0],[-1,0],[0,1],[0,-1]];
var pixelsToFill = [];
var positionArray = new Array(2);
self.checkBoundary = function(currentX, currentY, localOldColor) {
if (self.getPixelAtXYPosition(currentX,currentY).toString() != localOldColor.toString() || currentX < 0 || currentY < 0 || currentX > width || currentY > height || pixelsToFill.indexOf(currentX+" "+currentY) != -1) {
return false;
}
return true;
};
self.floodFill = function(currentX, currentY, localOldColor, localSearchDirections) {
if (self.checkBoundary(currentX, currentY, localOldColor)){
pixelsToFill.push(currentX+" "+currentY);
} else {
return;
}
for (var i = 0; i < searchDirections.length; i++){
self.floodFill(currentX + searchDirections[i][0], currentY + searchDirections[i][1], localOldColor, localSearchDirections);
}
};
self.getPixelAtXYPosition = function(x, y) {
var colour = [];
for (var i = 0; i < d; i++) {
for (var j = 0; j < d; j++) {
// loop over
index = 4 * ((y * d + j) * width * d + (x * d + i));
colour[0] = pixels[index];
colour[1] = pixels[index+1];
colour[2] = pixels[index+2];
colour[3] = pixels[index+3];
}
}
return colour;
}
self.drawTheNeededPixels = function(){
for(var i = 0; i < pixelsToFill.length; i++){
positionArray = pixelsToFill[i].split(" ");
point(positionArray[0],positionArray[1]);
}
}
self.draw = function () {
if(mouseIsPressed){
pixelsToFill = [];
loadPixels();
oldColor = self.getPixelAtXYPosition(mouseX, mouseY);
self.floodFill(mouseX, mouseY, oldColor, searchDirections);
self.drawTheNeededPixels();
}
};
}
This problem is well documented on the wikipedia page and the shortfalls of the different types of algorithms to perform flood filling. You've gone for the stack-based recursive implementation.
To prevent a stackoverflow — Maximum Call Stack Exceeded — the first step would be to use a data structure. Using queues/stacks rather than having the function call itself.
The code below creates an empty stack where we put a new object containing the x and y where the user has chosen to fill. This is then added to the pixelsToFill array. We then loop the stack until it's completely empty, at which point we are ready to display the filled pixels.
In the while loop we pop an element off the stack and then find its children — the directions up, down, left, right denoted by the searchDirections array you created. If we've not seen the child before and it's within the boundary we add it to the pixelsToFill array and add it to the stack to repeat the process:
self.floodFill = function (currentX, currentY, localOldColor, localSearchDirections) {
let stack = [];
stack.push({ x: currentX, y: currentY });
pixelsToFill.push(currentX + " " + currentY);
while (stack.length > 0) {
let current = stack.pop();
for (var i = 0; i < searchDirections.length; i++) {
let child = {
x: current.x + searchDirections[i][0],
y: current.y + searchDirections[i][1],
localOldColor,
};
if (self.checkBoundary(child.x, child.y, localOldColor)) {
pixelsToFill.push(child.x + " " + child.y);
stack.push(child);
}
}
}
};
This code may stop the stackoverflow but there are still a lot of optimisations that can be made. Once again, it's worth checking out the Wikipedia page and potentially take a look at Span filling.
let bucketTool;
function setup() {
createCanvas(400, 400);
bucketTool = new BucketTool();
}
function draw() {
background(220);
strokeWeight(5);
circle(width / 2, height / 2, 100);
frameRate(1);
bucketTool.draw();
}
function BucketTool() {
var self = this;
//set an icon and a name for the object
// self.icon = "assets/bucket.jpg";
// self.name = "Bucket";
var d = pixelDensity();
var oldColor;
var searchDirections = [
[1, 0],
[-1, 0],
[0, 1],
[0, -1],
];
var pixelsToFill = [];
var positionArray = new Array(2);
self.checkBoundary = function (currentX, currentY, localOldColor) {
if (
self.getPixelAtXYPosition(currentX, currentY).toString() !=
localOldColor.toString() ||
currentX < 0 ||
currentY < 0 ||
currentX > width ||
currentY > height ||
pixelsToFill.indexOf(currentX+" "+currentY) != -1
) {
return false;
}
return true;
};
self.floodFill = function (currentX, currentY, localOldColor, localSearchDirections) {
let stack = [];
stack.push({ x: currentX, y: currentY });
pixelsToFill.push(currentX + " " + currentY);
while (stack.length > 0) {
let current = stack.pop();
for (var i = 0; i < searchDirections.length; i++) {
let child = {
x: current.x + searchDirections[i][0],
y: current.y + searchDirections[i][1],
localOldColor,
};
if (self.checkBoundary(child.x, child.y, localOldColor)) {
pixelsToFill.push(child.x + " " + child.y);
stack.push(child);
}
}
}
};
self.getPixelAtXYPosition = function (x, y) {
var colour = [];
for (var i = 0; i < d; i++) {
for (var j = 0; j < d; j++) {
// loop over
index = 4 * ((y * d + j) * width * d + (x * d + i));
colour[0] = pixels[index];
colour[1] = pixels[index + 1];
colour[2] = pixels[index + 2];
colour[3] = pixels[index + 3];
}
}
return colour;
};
self.drawTheNeededPixels = function () {
for (var i = 0; i < pixelsToFill.length; i++) {
positionArray = pixelsToFill[i].split(" ");
point(positionArray[0], positionArray[1]);
}
};
self.draw = function () {
if (mouseIsPressed) {
pixelsToFill = [];
loadPixels();
oldColor = self.getPixelAtXYPosition(mouseX, mouseY);
self.floodFill(mouseX, mouseY, oldColor, searchDirections);
console.log(pixelsToFill.length);
self.drawTheNeededPixels();
}
};
}
html, body {
margin: 0;
padding: 0;
}
canvas {
display: block;
}
<!DOCTYPE html>
<html lang="en">
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.1/p5.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.1/addons/p5.sound.min.js"></script>
<link rel="stylesheet" type="text/css" href="style.css">
<meta charset="utf-8" />
</head>
<body>
<main>
</main>
<script src="sketch.js"></script>
</body>
</html>
Shameless plug, but relevant: I've created a blog comparing the different flood fill algorithms using p5.js.

Drawing different colors of circles depending if a number exists in a variable or not

So I got this jackpot coding. First it finds 7 unique random numbers between 1-36:
function RandomTal(Limit)
{
var RandomLottoTal
var Cont = true
while(Cont)
{
RandomLottoTal=Math.round(Math.random()*100+1)
if (RandomLottoTal <= Limit)
{
Cont = false
}
}
return RandomLottoTal;
}
function FindLottoTal()
{
var min = 1
var RandomTalNy
var LottoTal = []
for (var i=min; i<=7; i++)
{
RandomTalNy = RandomTal(36)
if(LottoTal.indexOf(RandomTalNy)<0)
{
LottoTal[i] = RandomTalNy
}
else
{
i--
}
}
DineLottoTal.value = LottoTal
return i;
}
Then when I have to draw the circle something doesn't work. What I want it to do is it checks all numbers from 1-36 and if it is the same as one of my 7 random jackpot numbers, it has to draw a red circle, else it has to draw a white circle.
Circle coding:
function TegnCirkel()
{
var canvas = document.getElementById("LottoPlade")
var ctx = canvas.getContext("2d")
var LottoTalNy = FindLottoTal()
for (var j=1; j<=4; j++)
{
var Tæller = 0
for (var i=1; i<=9; i++)
{
Tæller = Tæller + 1
XPos = i*100-50
YPos = j*100-50
if (LottoTalNy.indexOf(Tæller)<0)
{
// Color for white not yet added
ctx.beginPath()
ctx.arc(XPos,YPos,20,0,2*Math.PI)
ctx.stroke()
}
else
{
// Color for red not yet added
ctx.beginPath()
ctx.arc(XPos,YPos,20,0,2*Math.PI)
ctx.stroke()
}
}
}
}
Anyone know what's wrong or a fix.
Help is appreciated a lot :)
maybe it helps, but I did not have much time to understand what you wanted to do
jsfiddle
function TegnCirkel()
{
var canvas = document.getElementById("LottoPlade")
var ctx = canvas.getContext("2d")
var LottoTalNy = FindLottoTal()
for (var j=1; j<=4; j++)
{
var Tæller = 0
for (var i=1; i<=9; i++)
{
Tæller = Tæller + 1
XPos = i*100-50
YPos = j*100-50
if (LottoTalNy.toString().indexOf(Tæller)<0)
{
ctx.beginPath()
ctx.arc(XPos,YPos,20,0,2*Math.PI)
ctx.stroke()
}
else
{
ctx.beginPath()
ctx.arc(XPos,YPos,20,0,2*Math.PI)
ctx.stroke()
}
}
}
}
function RandomTal(Limit)
{
var RandomLottoTal
var Cont = true
while(Cont)
{
RandomLottoTal=Math.round(Math.random()*100+1)
if (RandomLottoTal <= Limit)
{
Cont = false
}
}
return RandomLottoTal;
}
function FindLottoTal()
{
var min = 1
var RandomTalNy
var LottoTal = []
for (var i=min; i<=7; i++)
{
RandomTalNy = RandomTal(36)
if(LottoTal.indexOf(RandomTalNy)<0)
{
LottoTal[i] = RandomTalNy
}
else
{
i--
}
}
FindLottoTal.value = LottoTal
return i;
}

PIXI.JS - Gradually Remove Slot Game Reels

I'm in the process learning to code a slot game, I have the below code which handles the spinning of the game. I want to add a border to the reels and have the sprites gradually disappear behind the border before they are removed and returned to the top.
function spingame(){
spin.interactive = false;
if (reelcount === 2){
if((reel[0].y >= 10) && (reel[5].y >= 400) && (reel[10].y >= renderer.height / 790)){
cancelAnimationFrame(spingame);
reelcount = 0;
console.log(reelarray);
checkwinnings();
balanceUpdate();
spin.interactive = true;
refresh();
}
else{
for (var i = 0; i < 15; i++){
reel[i].y += anispeed;
}
requestAnimationFrame(spingame);
refresh();
}
}
else if (reel[0].y >= 790) {
cancelAnimationFrame(spingame);
rowNo = 5;
reelSet();
for (var i = 0; i < 5; i++) {
reel[i].y = 10;
}
refresh();
spingame();
reelcount = reelcount + 1;
}
else if (reel[5].y >= 790) {
cancelAnimationFrame(spingame);
rowNo = 10;
reelSet();
for (var i = 5; i < 10; i++) {
reel[i].y = 10;
}
refresh();
spingame();
}
else if (reel[10].y >= 790) {
cancelAnimationFrame(spingame);
rowNo = 15;
reelSet();
for (var i = 10; i < 15; i++) {
reel[i].y = 10;
}
refresh();
spingame();
}
else{
for (var i = 0; i < 15; i++) {
reel[i].setTexture(symb[reelarray[i]]);
reel[i].y += anispeed;
}
requestAnimationFrame(spingame);
refresh();
}
What should I be looking for?
I've tried making the Sprites a child of the border but they're still visible when they move outside of the border.
Turns out I was looking in the wrong place. Assign a mask to a rectangle in the center of the screen and it's now working
var masksContainer = new PIXI.Container();
stage.addChild(masksContainer);
var mask = new PIXI.Graphics();
mask.beginFill(0xffffff);
mask.drawRect(renderer.width / 6 , renderer.height / 7, renderer.width / 1.6 , renderer.height / 1.3);
mask.endFill();
masksContainer.addChild(mask);
for (var i = 0 ; i < 15; i++){
masksContainer.addChild(reel[i]);
reel[i].mask = mask;
refresh();
}

Javascript game of life array gets reset

For a fun little project I decided to program conway's game of life in javascript. My logic seems to make sense and each individual function does its job however I still dont get my intended result. I have an array called grid, which stores the value of all the cells, and if they are alive or dead. I check each individual cell, then check all 8 surrounding cells to count neighbors, repeat for every other cell. At some point my grid no longer stores the correct value and resets. At this point I'm starting to think it's a javascript problem.
<body>
<style>
* {
padding: 0;
margin: 0;
}
body {
overflow: hidden;
}
canvas {
background: #FFFFFF;
display: block;
margin: 0 auto;
}
</style>
<canvas id="canvas" style="border:1px solid #000000;"></canvas>
</body>
<script>
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext('2d');
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
var Game = {};
var nextGrid, emptyGrid, grid;
Game.horCells = 30;
Game.cellSize = canvas.width / Game.horCells;
Game.verCells = Math.floor(canvas.height / Game.cellSize);
Game.startLives = 80;
config();
//setInterval(run, 1000);
function config() {
console.log("in config");
emptyGrid = newGrid(Game.horCells, Game.verCells);
grid = emptyGrid;
nextGrid = emptyGrid;
//Manual Setup
for (var i = 0; i < Game.startLives; i++) {
//grid[getRandomInt(0, Game.horCells - 1)][getRandomInt(0, Game.verCells - 1)] = true;
}
grid[0][3] = true;
grid[1][3] = true;
grid[2][3] = true;
}
function run() {
console.log("gread" + grid[3][3]);
draw();
update();
}
function draw() {
console.log("Draw");
ctx.fillStyle = "#FFFFFF";
ctx.fillRect(0, 0, canvas.width, canvas.height);
for (var i = 0; i < Game.horCells; i++) {
for (var j = 0; j < Game.verCells; j++) {
if (grid[i][j] === false) {
ctx.fillStyle = "#FFFFFF";
} else if (grid[i][j] === true) {
console.log("drawing live");
ctx.fillStyle = "#000000";
}
ctx.fillRect(i * Game.cellSize, j * Game.cellSize, Game.cellSize, Game.cellSize);
}
}
}
function update() {
for (var p = 0; p < Game.horCells; p++) {
for (var k = 0; k < Game.verCells; k++) {
nextGrid[p][k] = survival(p, k);
}
}
}
function survival(x, y) {
var neighbours = 0;
for (var l = 0; l < 3; l++) {
for (var m = 0; m < 3; m++) {
var sx = (x - 1) + l;
var sy = (y - 1) + m;
//Check bounds
if (inBounds(sx, sy) === true && grid[sx][sy]) {
neighbours++;
}
}
}
if (grid[x][y]) {
neighbours--;
if (neighbours === 2 || neighbours === 3) {
return true;
} else if (neighbours < 2 || neighbours > 3) {
console.log("DIED");
return false;
}
} else if (grid[x][y] === false && neighbours === 3) {
return true;
} else {
console.log("DIED");
return false;
}
}
function inBounds(x, y) {
return (x >= 0 && x < Game.horCells && y >= 0 && y < Game.horCells);
}
function newGrid(xCells, yCells) {
var gridd = new Array(xCells);
for (var i = 0; i < xCells; i++) {
gridd[i] = new Array(yCells);
}
for (var j = 0; j < xCells; j++) {
for (var k = 0; k < yCells; k++) {
gridd[j][k] = false;
}
}
return gridd;
}
function getRandomInt(min, max) {
return Math.floor(Math.random() * (max - min + 1)) + min;
}
</script>
emptyGrid = newGrid(Game.horCells, Game.verCells);
grid = emptyGrid;
nextGrid = emptyGrid
Creates 1 grid, then assigns grid and nextGrid to the same object. Again, grid and nextGrid are the same object. Any changes you make to 1 will happen to the other.
Create 2 separate grids so they can be changed independently:
grid = newGrid(Game.horCells, Game.verCells);
nextGrid = newGrid(Game.horCells, Game.verCells);
Or, to neaten it up slightly:
var g = () => newGrid(Game.horCells, Game.verCells);
grid = g();
nextGrid = g();
Just to clear up the question in the comments:
var g = () => newGrid(Game.horCells, Game.verCells);
Is (basically) the same thing as:
var g = function() {
return newGrid(Game.horCells, Game.verCells);
}
It's known as a "fat-arrow" function.
Both bits do the same thing though: they create a function that returns a new grid. This has the benefit of not needing to write newGrid(Game.horCells, Game.verCells); twice.
I used an arrow function instead of the function keyword because the latter is giant and ugly, which takes away from the goal of cleaning up the code.

Adding to a scoreboard on canvas platform

I'm doing something a bit different, instead of putting the scoreboard outside of the Canvas, its inside it and associated with the canvas properties.
It's fully functional but I don't understand why it does not add to the score whenever a row is cleared.
Here's that part:
var totalPoints = 0;
function erase() {
for ( var y = rows - 1; y >= 0; y--) {
var full = true;
for (var x = 0; x < columns; x++) {
if (board[y][x] == 0) {
full = false;
totalPoints--;
break;
}
}
if (full) {
totalPoints++;
for ( var j = y; j > 0; j--) {
for ( var x = 0; x < columns; x++) {
board[j][x] = board[j-1][x]
}
}
++y;
}
}
}
function showOnload(){
c.fillStyle = "black";
c.fillText("scores", 200, 100);
c.fillText(totalPoints, 200, 140);
}
Note:
I've the showOnload function as a body onload for my HTML page, does this have anything to do with why it doesn't change?
Update score each time it is changed.
var totalPoints = 0;
function erase() {
for ( var y = rows - 1; y >= 0; y--) {
var full = true;
for (var x = 0; x < columns; x++) {
if (board[y][x] == 0) {
full = false;
totalPoints--;
showOnload(); //HERE
break;
}
}
if (full) {
totalPoints++;
showOnload(); //HERE
for ( var j = y; j > 0; j--) {
for ( var x = 0; x < columns; x++) {
board[j][x] = board[j-1][x]
}
}
++y;
}
}
}
function showOnload(){
c.fillStyle = "black";
c.fillText("scores", 200, 100);
c.fillText(totalPoints, 200, 140);
}

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