Develop Reference

javascript game - joystick issue

Note: I've asked this question again because I was not be able to edit my old question. (No idea if this was a SO bug or a bug with my beta safari.)
So I want to generate a joystick, as it is used in many games. The joystick stands out of a background and a movable billet. The billet may only be moved within the background.
Here you can find both images
let background = new Image()
let stick = new Image()
let enableMaxDistance = false
background.onload = function() {
$(this).css({
position: "absolute",
left: "2%",
bottom: "2%",
width: "30%"
}).appendTo(document.body)
}
stick.onload = function() {
$(this).css({
position: "absolute",
left: "2%",
bottom: "2%",
width: "30%"
}).appendTo(document.body)
let zeroPosition = $(this).offset()
$(this).draggable({
drag: function(e, ui) {
let distance = Math.sqrt(Math.pow(zeroPosition.top - $(this).offset().top, 2) + Math.pow(zeroPosition.left - $(this).offset().left, 2));
if (distance > 60 && enableMaxDistance) {
e.preventDefault();
}
},
scroll: false
})
}
background.src = "https://i.stack.imgur.com/5My6q.png"
stick.src = "https://i.stack.imgur.com/YEoJ4.png"
html, body {
overflow: hidden;
height: 100%;
}
input {
margin-top: 10%;
margin-left: 50%;
}
<script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.min.js"></script>
<input onclick="enableMaxDistance = !enableMaxDistance " value="toggle maximum distance" type="button"/>
But while implementing this joystick some problems occurred:
My idea was to make the stick maneuverable by using jqueryUI and to calculate its distance to the origin with each drag event. If the distance is too large, the event will be stopped (not executed) using e.preventDefault();. --> If the distance in the frame, the stick is wearable.
The problem is that ...
The stick is no longer draggable after moving out the maximum distance.
The stick should be just be movable inside the bounds without canceling the event so that I have to grab the stick again and again if I'm touching the bounds (going out of the maximum distance).
How to implement a working joystick using jQuery + jQueryUI?

The issue with your logic is that as soon as the drag event is prevented the distance value will be over 60 due to the inherent delays in JS processing time. Therefore the logic in the next drag is immediately cancelled as the distance > 60 check is immediately hit. While it would be possible to fix this, a much better solution would be to not allow the value to ever be greater than the limit you set.
To achieve this I would not recommend using jQueryUI. You can do it quite easily using native methods which give you more direct control of the positioning without having to fight against any built in logic.
It's also slightly more performant, which is vital when dealing with game mechanics; especially when dealing with direct user input which needs to be as responsive as possible.
With that said, you can use modify the basic logic as laid out in Twisty's comment on this question. Then it simply becomes a question of changing the size of the relevant elements, which is a trivial task. Try this:
var $canvas = $('#background');
var $pointer = $('#stick');
var $window = $(window);
var settings = {
width: $canvas.prop('offsetWidth'),
height: $canvas.prop('offsetHeight'),
top: $canvas.prop('offsetTop'),
left: $canvas.prop('offsetLeft')
};
settings.center = [settings.left + settings.width / 2, settings.top + settings.height / 2];
settings.radius = settings.width / 2;
let mousedown = false;
$window.on('mouseup', function() { mousedown = false; });
$pointer.on('mousedown', function() { mousedown = true; });
$pointer.on('mouseup', function() { mousedown = false; });
$pointer.on('dragstart', function(e) { e.preventDefault(); });
$window.on('mousemove', function(e) {
if (!mousedown)
return;
var result = limit(e.clientX, e.clientY);
$pointer.css('left', result.x + 'px');
$pointer.css('top', result.y + 'px');
});
function limit(x, y) {
var dist = distance([x, y], settings.center);
if (dist <= settings.radius) {
return {
x: x,
y: y
};
} else {
x = x - settings.center[0];
y = y - settings.center[1];
var radians = Math.atan2(y, x)
return {
x: Math.cos(radians) * settings.radius + settings.center[0],
y: Math.sin(radians) * settings.radius + settings.center[1]
}
}
}
function distance(dot1, dot2) {
var x1 = dot1[0],
y1 = dot1[1],
x2 = dot2[0],
y2 = dot2[1];
return Math.sqrt(Math.pow(x1 - x2, 2) + Math.pow(y1 - y2, 2));
}
html,
body {
height: 100%;
}
#background {
background-image: url('https://i.stack.imgur.com/5My6q.png');
position: absolute;
height: 200px;
width: 200px;
top: 50%;
left: 50%;
margin: -100px 0 0 -100px;
border-radius: 200px;
border: dashed #ccc 1px;
}
#stick {
background: transparent url('https://i.stack.imgur.com/YEoJ4.png') 50% 50%;
position: absolute;
width: 100px;
height: 100px;
border-radius: 100px;
margin: -50px 0 0 -50px;
top: 50%;
left: 50%;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="background"></div>
<div id="stick"></div>

Creating an effect wherever mouse goes

So I have been trying endlessly to try and do something similar too what this site is doing (http://whois.domaintools.com/). I'm trying to get a webpage, so wherever the mouse moves over the webpage, that kind of effect follows it (I'm sorry I don't know what I would call the effect).
I've read how to ask questions on here, but I don't know what too look for so it's difficult for me to attempt this. So far this link (http://p5js.org/learn/demos/Hello_P5_Drawing.php) I've used the code from this and played around with it but i'm just puzzled as too how I would go about doing this.
Thanks for any help, I've been banging my head against a brick wall for a good couple of days now.

This seems to be some kind of particle system. I would start the following way: First create a class for a particle, it should have a random x and y coordinate, and it should change it's postion periodically to a random new postion. Then create a lot of instances of the particle and distribute them over the page.
http://jsfiddle.net/aggoh0s1/3/
/* each particle will move in a 100px100px square */
var gutterWidth = 100;
/* class definition */
var Particle = function(x, y) {
var t = this;
t.x = x;
t.y = y;
t.elem = $('<div class="particle" />');
t.elem.css({ left: x+"px", top: y+"px"});
$('body').append(t.elem);
/* create a new position every 500-1000 milliseconds */
var milliSecs = 500 + Math.random() * 500;
t.ptinterval = setInterval(function() {
var dx = Math.round(Math.random() * gutterWidth);
var dy = Math.round(Math.random() * gutterWidth);
t.elem.animate({left: (t.x + dx)+"px", top: (t.y + dy) + "px"}, 600);
}, milliSecs);
};
/* create a 1000px1000px area where particles are placed each 100px */
var particles = [];
var newParticle;
for(var x = 0; x < 1000; x = x + gutterWidth) {
for(var y = 0; y < 1000; y = y + gutterWidth) {
newParticle = new Particle(x,y);
particles.push(newParticle);
}
}
CSS:
.particle {
width: 2px;
height: 2px;
background-color: black;
position: absolute;
}
Using this logic, you could also use a canvas to display the particles instead of a html div like it is done on whois.domaintools.com. The next step should be to connect the particles with lines to each other, and after that some code should hide all particles that are some distance away from the mouse position.

I've developed the following solution for the effect which you are referring. This is done using jQuery using the event mousemove(). Bind this event to your body where the content is.
Method :
Create an element with the following css on your body. You can create the element onthefly using jQuery as well.
<div class='hover'></div>
CSS
.hover{
position:absolute;
width:100px;
height:100px;
background-color:#fff;
}
The add the following code to your page.
$('body').mousemove(function(event){
$('.hover').css({
'top' : event.pageY,
'left': event.pageX
})
});
The above code will bind an event to your mouse move and I change the element position according to the mouse coordinates.
This fiddle shows a running example
I've given you the basic idea of the solution! You will have to medle with the css and jquery to add the looks and feels of the effect which you refer to.

See the simple example
<img id="imgMove" src="Images/img1.jpg" height="100" width="100" style="position: absolute;" />
JQuery
$(document).ready(function () {
$(document).mousemove(function (e) {
$("#imgMove").css({ "top": e.pageY - 50, "left": e.pageX - 50 }); // e.pageX - Half of Image height, width
})
})

How to correctly resize an element by dragging?

I have two divs serving as two panels one to the left and one to the right.
They take 70% and 30% of the area.
I have a separator between them.
When I drag the separator to the left or right, I want that to remain as the position of the separator. i.e., I should be able to dynamically resize the left and right divs by dragging.
Here is the code I have:
http://jsbin.com/witicozi/1/edit
HTML:
<!DOCTYPE html>
<html>
<head>
<body>
<div style='height: 100px'>
<div id='left'>...</div>
<div id='separator'></div>
<div id='right'>...</div>
</div>
</body>
</html>
CSS:
#left {
float: left;
width: 70%;
height: 100%;
overflow: auto;
}
#separator {
float: left;
width: 3px;
height: 100%;
background-color: gray;
cursor: col-resize;
}
#right {
height: 100%;
overflow: auto;
}
JavaScript:
document.querySelector('#separator').addEventListener('drag', function (event) {
var newX = event.clientX;
var totalWidth = document.querySelector('#left').offsetWidth;
document.querySelector('#left').style.width = ((newX / totalWidth) * 100) + '%';
});
The problems:
The resizing happens, but the separator jumps around randomly. It even falls down many times. I have no idea what's happening.
The mouse cursor changes to a hand when the dragging begins. I want it to remain a col-resize.
It is very hard to drag.
No JQuery please.

If you use console.log(event), it shows that event.clientX doesn't return exactly what you are looking for. The following JavaScript worked for me in chrome.
document.getElementById('separator').addEventListener('drag', function(event) {
var left = document.getElementById('left');
var newX = event.offsetX + left.offsetWidth;
left.style.width = newX + 'px';
});
The event.offsetX value that it is returning is the location (in px) of the upper left hand corner of the left div. This will give you the same result but using percentages so that when the resize the window the columns adjust:
document.getElementById('separator').addEventListener('drag', function(event) {
var left = document.getElementById('left');
var newX = event.offsetX + left.offsetWidth;
left.style.width = (newX / window.innerWidth * 100) + '%';
});

Taking a bit of a different approach: rather than using the drag and drop functionality, I used some coupled mouse down and mouse up listeners. This has better cross-browser compatibility (at least as far as my testing goes) and it has the added benefit of being able to easily control the cursor.
var resize = function(event) {
var newX = event.clientX;
document.getElementById('left').style.width = (newX / window.innerWidth * 100) + '%';
};
document.getElementById('separator').addEventListener('mousedown', function(event) {
document.addEventListener('mousemove', resize);
document.body.style.cursor = 'col-resize';
});
document.addEventListener('mouseup', function(event) {
document.removeEventListener('mousemove', resize);
document.body.style.cursor = '';
});

video on canvas keeps resizing

I'm having trouble resizing this canvas that is displaying a video. After resizing, it continually jerks all around into different sizes between the "before" and "after" window sizes.
I tried this posts' idea, and that seemed to calm down Chrome a little, but had no affect on Firefox.
This other post gave me some ideas, but still didn't fix it. It seems like I'm either calling resize multiple times in a loop (which I don't see), or the canvas's context doesn't know how to settle on the final size. Any ideas?
<!DOCTYPE html>
<html>
<head>
<title>overflow</title>
<style>
#c {
position: absolute;
top: 0;
bottom: 0;
left: 0;
right: 0;
width: 100%;
height: 100%;
z-index: 1;
}
#hold {
position: fixed;
}
#v {
position: absolute;
height: auto;
width: 100%;
z-index: 0;
}
#see {
position: relative;
top: 0;
bottom: 0;
left: 0;
right: 0;
z-index: 2;
}
</style>
</head>
<body>
<canvas id=c></canvas>
<div id=hold>
<video id=v>
</video>
</div>
<canvas id=see></canvas>
<script>
window.onload = start;
function start() {
var v = document.getElementById('v');
var house = document.getElementById('hold');
var base = document.getElementById('c');
var canvas = base.getContext('2d');
var cover = document.getElementById('see');
var canvastwo = cover.getContext('2d');
v.src=("keyed.ogv")
v.load();
v.play();
resize();
function resize() {
var wth = (window.innerWidth * 0.65);
house.width = wth;
house.height = (wth * 9/16);
house.style.marginTop=((window.innerHeight/2) - (house.height/2) + "px");
house.style.marginLeft=((window.innerWidth/2) - (house.width/2) + "px");
cover.width = (wth/2);
cover.height = (house.height/2);
cover.style.marginTop=((window.innerHeight/2) - (cover.height/2) + "px");
cover.style.marginLeft=((window.innerWidth/2) - (cover.width/2) + "px");
var rw = cover.width;
var rh = cover.height;
canvastwo.clearRect(0, 0, rw, rh);
draw(v, canvastwo, rw, rh);
}
window.onresize = resize;
function draw(o,j,w,h) {
if(v.paused || v.ended) return false;
j.drawImage(o,0,0,w,h);
setTimeout(draw,20,o,j,w,h);
}
}
</script>
</body>
</html>

You seem to lock in the old values you use for the setTimeout function the way you are using it here, as the context changes. So when you re-size the loop still uses the old values which no longer corresponds with the new sizes and results in the video toggle between these sizes.
Try to more "globalize" the values so that the loop call is clean when it comes to arguments. This way you are sure the variables contains the correct values for each round.
Also change setTimeout with requestAnimationFrame to make the loop more low-level (efficient) and fluid as this syncs to the monitor's vblank gap. This is particular important with video as you otherwise will get skipped frames as setTimeout is not able to sync with monitor.
Here is the essential code you need to change:
/// put these into you start block to keep them "global"
/// for the functions within it.
var w, h;
Change this part in the resize function:
/// ...
w = cover.width;
h = cover.height;
canvastwo.clearRect(0, 0, w, h);
/// argument free call to draw:
draw();
And finally the loop:
function draw() {
if(v.paused || v.ended) return false;
canvastwo.drawImage(v,0,0,w,h);
requestAnimationFrame(draw);
}
This will remove the jerking video and also make the update in sync to the monitor like the video element itself does.
ONLINE DEMO

How can I animate DIVs moving from a central point to off-screen?

Is it possible to have divs located around a central point and then on hover for them to whisk off screen and return when the mouse is gone?
This what the layout:
http://pena-alcantara.com/aramael/wp-content/uploads/2010/04/Paper-Browser.8.5x11.Horizontal3.jpg
is looking like, the idea is for the green "leaves" to whisk off to show the branches and the menus. Would this be possible with JavaScript and PHP?

Any chance I could convince you to not design a site this way?
I suppose not, so the answer is to use jQuery. Here is the jQuery reference for animation, which you'll need to study carefully.

You are going to need to combine a few jQuery features.
The animation feature at: http://api.jquery.com/animate/
The mouse over feature: http://api.jquery.com/mouseover/
The mouse out feature: http://api.jquery.com/mouseout/
Have "dummy divs" where the mouse over is detected that move their ID's real div out of view using animate it, and bring it back with mouseout
I found this interesting so coded it for myself... I did it as below:
<style type="text/css">
body {
overflow:hidden;
}
.leaf {
position:relative;
background-color:#0F0;
height: 100px;
width: 100px;
}
.branch {
display:inline-block;
background-color:#F00;
height: 100px;
width: 100px;
}
</style>
<script type="text/javascript">
$(function(){
var w = $(document).width();
var h = $(document).height();
var r = 250;
$(".branch").hover(function() {
var rand = Math.random();
var x,y;
if(rand<0.25) {
x = w;
y = h*Math.random();
} else if(rand<0.5) {
x = -w;
y = h*Math.random();
} else if(rand<0.75) {
x = w*Math.random();
y = h;
} else {
x = w*Math.random();
y = -h;
}
$(this).children().animate({left: x, top: y});
}, function () {
$(this).children().animate({left: '0', top: '0'});
})
});
</script>
<div class="wrap">
<div class="branch"><div class="leaf"></div></div><!-- etc -->
</div>