Develop Reference

Reducing the number of times a helper function is run

I am trying to create a word cloud. In order to render text to the screen I am generating a random position for each word. This works perfectly, however there are a lot of overlapping words. In order to solve this I am storing the position and size of the elements in an array and then I created a helper function that checks for collisions, generates a new position for the element if it finds one, and then calls it's self again to check again from the start of the array. When I run my code the first 2-3 words render just fine but then I get an error saying Maximum call stack size exceeded. I saw there was already a post on this same issue on stack overflow.
I saw that the other person was using a forEach function and so was I so I converted it into a for loop like the answer suggested but it did not do anything. I think the issue boils down to the fact that there are so many collisions but I am not sure how to best approach the issue. Is there another way that I can generate unique positions for elements while still avoiding collisions?
Code:
function calculatePosition(parent, child) {
return Math.random() * parent - (child / 2)
}
// needed for rendering position of span elements
var ranges = []
var totalWidthOfWords = 0
var totalHeightOfWords = 0
// reposition element if there is a collision
function checkForCollisions(element, height, width, wordCloud, injectedSpan) {
for(var i = 0; i < ranges.length; i++) {
let current = ranges[i]
if(element.left >= current.width[0] && element.left <= current.width[1]) {
injectedSpan.style.left = calculatePosition(wordCloud.clientWidth, width) + "px";
checkForCollisions(element, height, width, wordCloud, injectedSpan)
}
if(element.top >= current.height[0] && element.top <= current.height[1]) {
injectedSpan.style.top = calculatePosition(wordCloud.clientHeight, height) + "px";
checkForCollisions(element, height, width, wordCloud, injectedSpan)
}
}
}
// Create content in DOM
const injectedContent = data.map(line => {
const injectedSpan = document.createElement("span")
const injectedWord = document.createElement("p")
const wordCloud = document.querySelector(".word-cloud")
// mod weight value to get more managable inputs
let weightValue = (line.weight * 100).toFixed(2)
// sets values of words and renders them to the screen
injectedWord.innerText = line.word
injectedSpan.appendChild(injectedWord)
wordCloud.appendChild(injectedSpan)
// sets style attribute based on weight value
injectedWord.setAttribute("style", `--i: ${weightValue}`)
// flips words
if(Math.random() > 0.75) {
injectedWord.style.writingMode = "vertical-rl";
}
// Entrance animation
let left = innerWidth * Math.random()
let top = innerHeight * Math.random()
if(Math.random() < 0.5) {
injectedWord.style.left = "-" + left + "px";
injectedSpan.style.left = calculatePosition(wordCloud.clientWidth, injectedSpan.clientWidth) + "px";
} else {
injectedWord.style.left = left + "px";
injectedSpan.style.left = calculatePosition(wordCloud.clientWidth, injectedSpan.clientWidth) + "px";
}
if(Math.random() < 0.5) {
injectedWord.style.top = "-" + top + "px";
injectedSpan.style.top = calculatePosition(wordCloud.clientHeight, injectedSpan.clientHeight) + "px";
} else {
injectedWord.style.top = top + "px";
injectedSpan.style.top = calculatePosition(wordCloud.clientWidth, injectedSpan.clientWidth) + "px";
}
// Get position of span and change coordinites if there is a collision
let spanPosition = injectedSpan.getBoundingClientRect()
console.log(spanPosition)
if(spanPosition) {
checkForCollisions(spanPosition, spanPosition.height, spanPosition.width, wordCloud, injectedSpan)
}
totalWidthOfWords += spanPosition.width
totalHeightOfWords += spanPosition.height
ranges.push({width: [spanPosition.left, spanPosition.right], height: [spanPosition.top, spanPosition.bottom]})
})
Link: https://jsfiddle.net/amotor/mdg7rzL1/4/

There is still a lot of work to do to make sure that it works properly, especially to make sure that the code does not produce any errors!
The general idea would be to follow IllsuiveBrian's comment to make sure, that checkForCollision only does the work of checking if there is a collision and that another function takes care of recalculating the position if necessary and then reevaluating a potential collision.
function checkForCollisions(element, wordCloud, injectedSpan) {
for(var i = 0; i < ranges.length; i++) {
let current = ranges[i];
// return true if there is a collision (you probably have to update the code you are using here to truly avoid collisions!)
if (collision) { return true; }
}
return false; // return false otherwise
}
Finally this part would take care of recalculating position and and rechecking for collision:
ranges.forEach(function(injectedSpan) {
// Get position of span and change coordinites if there is a collision
let spanPosition = injectedSpan.getBoundingClientRect();
if (spanPosition) {
while (checkForCollisions(spanPosition, wordCloud, injectedSpan)) {
injectedSpan.style.left = calculatePosition(wordCloud.clientWidth, element.width) + "px";
injectedSpan.style.top = calculatePosition(wordCloud.clientHeight, element.height) + "px";
}
}
});
Here is a quick idea on how to go into this direction: https://jsfiddle.net/euvbax1r/4/

setting a time delay between two frame when animation a sprite sheet

This is my jsfiddle :http://jsfiddle.net/Z7a5h/
As you can see the animation of the sprite sheet when the player is not moving is too fast so I was trying to make it slow by declaring two variable lastRenderTime: 0,RenderRate: 50000
but my code is not working and it seem I have a misunderstanding of the algorithm I am using so can anyone lay me a hand to how can I fix it?
if (!this.IsWaiting) {
this.IsWaiting = true;
this.Pos = 1 + (this.Pos + 1) % 3;
}
else {
var now = Date.now();
if (now - this.lastRenderTime < this.RenderRate) this.IsWaiting = false;
this.lastRenderTime = now;
}

Yes, your logic is wrong. You were using the wrong operator < instead of >. Also, you needed to update the lastRenderTime only when the condition is statisfied, otherwise it keeps getting updated and the value of now - this.lastRenderTime never ends up becoming more than 20 or so.
if (!this.IsWaiting) {
this.IsWaiting = true;
this.Pos = 1 + (this.Pos + 1) % 3;
}
else {
var now = Date.now();
if (now - this.lastRenderTime > this.RenderRate) {
this.IsWaiting = false;
this.lastRenderTime = now;
}
}
Here is your updated fiddle.

move div smoothly with javascript/jquery and an array of pos

I'm looking for a way to move a div from an array of position with javascript/jquery.
I have trying to do it with jquery.animate but he moved the div with a pause at each iteration of my array.
That could be something like move the div from 0,0 to 120px,230px passing by the 23px,35px;45px,50px etc...
That is for moving an game character on a Tile map
So as requested, some bit of code
First you have a global timer that call a function at short interval to see if it have any action to execute.
In this loop a routine look if some mobile tiles are waiting of any mouvement.
Mobiles are declared as Object class and have a sub function that do the deplacement like that
setPos:function(coord){
var pos = jQuery("#"+this.id).position();
var x = (coord[0] - 32 + this.screenOffX + this.xOffset) - pos.left;
var y =(coord[1] + this.yOffset) - pos.top;
//this.stopAnimation();
//this.startAnimation(this.walkingAnimation);
jQuery("#"+this.id).animate({
left: '+='+ x,
top: '+='+ y
}, 33, function() {
// Animation complete.
});
},
That is a bit messy cause i trying a lot of thing to do the smooth movement that i'm looking for.
so setPos is calling in another place like that
stepMobile:function(mobile){
var wp;/*TEST*/
mobile.changeState("idle");
var ind = mobile.getWayPointIndex();
while(ind < (mobile.getWayPoints()).length - 1){
if (ind < (mobile.getWayPoints()).length - 1) {
wp = (mobile.getWayPoints())[ind + 1];
if (getTime() > wp.time) {
mobile.setWayPointIndex(ind + 1);
ind = ind +1;
}
}
wp = (mobile.getWayPoints())[ind];
var x;
var y = 0;
var z;
x = this.tileWidth * (wp.getTile()).getCol();
z = this.tileHeight * (wp.getTile()).getRow();
var elapsed = getTime() - wp.getTime();
console.log(elapsed);
if (ind == (mobile.getWayPoints()).length - 1) {
console.log('checkForOnStopEvent()');
} else {
//x += 1 * mobile.getWalkSpeed() * mobile.getCosAngle();
//z += 1 * mobile.getWalkSpeed() * mobile.getSinAngle();
}
var coord = this.mapToScreen(x, y, -z);
mobile.setPos(coord);
ind = mobile.getWayPointIndex();
}
},
Again lot of junk code here cause i literally burned my brain but i didn't get any good result.
And you have that global function that run this function over all mobiles waiting for deplacement.

Detecting if two divs are too close or collide/overlap

I'm trying to detect if two given div's are too close or collide/overlap .
I have the below codepen which tries to generate 20 random div's and only append them to body if their position isn't too close to other existing div.
That's the idea but it doesn't work as expected where i get div's that get through with close/overlapping positions to existing divs. (run it multiple times if first time is perfect and you should come across it).
http://codepen.io/anon/pen/fHLzj
Can anyone see the mistake and way to make it work?

This is somewhat hard to explain and get..but here goes:
check every div against every div by running for loop.
x,y,h,w
x is top-left corner's distance from left.
y is top-left corner's distance from top.
h is div's height.
w is div's width.
Point to consider... you don't really need to check every div..consider this
there are 10 divs...
First you will check 1st against 9.
Second one against 8.
.............
Eight one against 2.
Ninth one against 1.
And don't the last one.
Also it's a good idea to assign values and check for collisions in data, before assigning them to dom. Dom should be just for rendering final result.
I'll assume you want to keep none of the two colliding divs.
Preview
http://jsfiddle.net/techsin/m4fSf/6/
as expected code is huge
var
div={},
number=10,
size=20,
m = ele('main');
mw= parseFloat(getComputedStyle(m).getPropertyValue("width"))-size,
mh= parseFloat(getComputedStyle(m).getPropertyValue("height"))-size,
f=true,
nn;
var i
for (i = 0; i < number; i++) {
div[i] = {};
var t = true, newX, newY, nn;
if (i!=0){
while (t) {
newX = rand(mw);
newY = rand(mh);
for (nn = 0; nn < i; nn++) {
if (!(((newX > div[nn].x + size+5) || (newY > div[nn].y + size+5)) ||
((newX + size+5 < div[nn].x) || (newY + size+5 < div[nn].y)))) {
break;
}
if (nn == i-1) t = false;
}}} else {
newX = rand(mw);
newY = rand(mh);
}
console.log(newX);
div[i].x = newX;
div[i].y = newY;
}
for (i = 0; i < number; i++) {
render(div[i]);
}
console.log(div);
function render(x){
var d=document.createElement('div');
d.style.position='absolute';
d.style.left=(x.x+'px');
d.style.top=(x.y+'px');
m.appendChild(d);
}
function rand(x) { return Math.random()*x;}
function ele(x){return document.getElementById(x);}
this code is from my collision site...ill try and put it in the code above, but this what's needed to avoid collisions and close gaps.
if (xpost+30>xx.left && xx.left>xpost && xx.top+30>ypost && xx.top<ypost+30) { xspeed = -speed; }
if (xpost<xx.left+30 && xx.left<xpost && xx.top+30>ypost && xx.top<ypost+30) { xspeed = speed; }
if (ypost+30>xx.top && xx.top>ypost && xx.left+30>xpost && xx.left<xpost+30) { yspeed = -speed; }
if (ypost<xx.top+30 && xx.top<ypost && xx.left+30>xpost && xx.left<xpost+30) { yspeed = speed; }

How about using one of these libraries to detect the collisions for you?
http://sourceforge.net/projects/jquerycollision/
http://gamequeryjs.com/

I changed the collision logic. It detects if an object is close to another object by comparing the distance between the objects. I wrapped the logic in a do-while loop as well, so that it will keep attempting to find a position to place the square and you'll have exactly 20 squares.
This works:
var positions = []; //stroe positions of appended divs
var divsize = 20;
var topGap = 40; // gap from top
var leftGap = 80; //gap from left
function generateRandomPositionedDiv(){
for(var c = 0; c < 20; c++){
var color = '#'+ Math.round(0xffffff * Math.random()).toString(16);
$newdiv = $('<div/>').css({
'width':divsize+'px',
'height':divsize+'px',
'background-color': color
});
var posLeft;
var posTop;
var checkObj;
var collide = false;
posLeft = Math.floor((Math.random() * ($(document).width() - divsize)));//.toFixed();
posTop = Math.floor((Math.random() * ($(document).height() - divsize)));//.toFixed();
checkObj = {x: posLeft, y: posTop};
collide = checkForCollisions(checkObj);
if(!collide) {
positions.push({x: posLeft, y: posTop});
$newdiv.css({
'position':'absolute',
'left':posLeft+'px',
'top':posTop+'px'
});
$('body').append($newdiv);
}
}
}
/*function getPositions(box) {
var $box = $(box);
var pos = $box.position();
var width = $box.width();
var height = $box.height();
return [ [ pos.left, pos.left + width + leftGap ], [ pos.top, pos.top + height + topGap ] ];
}*/
function comparePositions(obj1, obj2) {
if(Math.abs(obj1.x - obj2.x) <= (divsize + leftGap) && Math.abs(obj1.y - obj2.y) <= (divsize + topGap)) {
return true;
} else {
return false;
}
}
function checkForCollisions(posObj){
for(var i = 0; i < positions.length; i++){
var match = comparePositions(positions[i], posObj);
if (match) {
//return true if two positions are close or overlapping
return match;
}
}
}
generateRandomPositionedDiv();

JavaScript setTimeout() Method on Animation

I have three yellow bars and each of them needs to come from left to right. For that, I have produced this code, but it only works on the last one. Can anyone correct this code; I need to work with pure JavaScript. I am not using any framework. Thanks.
window.onload = function(){
var yellowTitles = document.getElementById('magazine-brief').getElementsByTagName('h2');
for(i=0; i< yellowTitles.length; i++) {
var header = yellowTitles[i];
var timer = i*500;
var yellowBar = setTimeout(animeYellowBar,timer);
function animeYellowBar(){
header.style.left= "0";
}
}
}

Here's how I'd solve the problem:
var yellows = document.getElementById('magazine-brief').getElementsByTagName('h2');
// this will force the header number to be bound correctly
// also animates the div across the page by tracking the current position of x
function createMotion(num){
var currPos = 0;//current x position
var delta = 10;//move by this amount
setInterval(function(){
currPos += delta
yellows[num].style.left = currPos;
}, num * 500);
}
for (var i = 1; i < yellows.length; i++)
{
createMotion(i);
}
Note the function "createMotion" - added so the number "i" is correctly reference in the setInterval function.

Shouldn't you be incrementing your CSS left value instead of just setting it to 0? Why have a timeout at all if you're just going to set the value without gradually incrementing or decrementing?
If you do actually want to use a gradual animation, look at this tutorial : http://www.schillmania.com/content/projects/javascript-animation-1/
Very descriptive and possibly what you want.

By the time your timeout function runs, header refers to your last h2.
Try editing your timeout function to this:
function animeYellowBar(){
var thisheader=header;
thisheader.style.left= "0";
}

var yellows = document.getElementById('magazine-brief').getElementsByTagName('h2');
for (var i = 0; i < yellows.length; i++)
{
(function(idx, el){
window.setTimeout(function(){
var interval = window.setInterval(function(){
el.style.left = parseInt(el.style.left) + 10; // adjust this movement step
if (parseInt(el.style.left) >= 0)
{
el.style.left = 0;
window.clearInterval(interval);
}
}, 100); // adjust this number for animation speed
}, (idx++) * 500);
})(i, yellows[i]);
}