Move dimension lines away from a polygon - javascript

So I have multiple points which creates a polygon. I have calculated the center point of the polygon and used that to create dimension lines for each side of a polygon. My problem is that some dimension lines don't move to a new position that I calculated. To have a better view here's an image of what I have and what I want to happen.
What I have:
What I want to achieve:
I added a red circle to the issue I'm having it should move to new point which is the blue lines.
Here's code snippet:
var viewHeight = window.innerHeight / 2;
var viewWidth = window.innerWidth / 2;
var scene = new THREE.Scene();
var camera = new THREE.OrthographicCamera(
viewWidth / - 2, viewWidth / 2, viewHeight / 2, viewHeight / - 2, 1, 1000);
camera.translateZ(15);
camera.updateProjectionMatrix();
scene.add(camera);
var points = [
{
start: {x: -99.74425000000002, y: 68.61000000000001},
end: {x: -99.74425000000002, y: -37.87599999999999}
},
{
start: {x: -99.74425000000002, y: -37.87599999999999},
end: {x: 69.22574999999995, y: -37.87599999999999}
},
{
start: {x: 69.22574999999995, y: -37.87599999999999},
end: {x: 69.22574999999995, y: -1.2999999999999832}
},
{
start: {x: 69.22574999999995, y: -1.2999999999999832},
end: {x: 120.02574999999996, y: -1.2999999999999827}
},
{
start: {x: 120.02574999999996, y: -1.2999999999999827},
end: {x: 120.02574999999996, y: 68.61000000000001}
},
{
start: {x: 120.02574999999996, y: 68.61000000000001},
end: {x: -99.74425000000002, y: 68.61000000000001}
}
];
var vertices = [];
for (var i in points) {
var line = points[i];
vertices.push(new THREE.Vector2(line.start.x, line.start.y));
};
// build floor
var floor = buildFloor(vertices);
scene.add(floor);
// get center point of floor
var center = findCentroid(vertices);
// build dimension lines
for (var i in points) {
var line = points[i];
var lineCenterPoint = findLineCenterPoint(line.start, line.end);
var degrees = getAngle(center.x, center.y, lineCenterPoint.x, lineCenterPoint.y);
var radians = degrees * Math.PI / 180;
var startX = line.start.x;
var startY = line.start.y;
var endX = line.end.x;
var endY = line.end.y;
if (startY == endY) {
// horizontal
// move point y outward to a new point
var newY = startY + Math.sin(radians) * 20;
startY = newY;
endY = newY;
} else if (startX == endX) {
// vertical
// move point x outward to a new point
var x = startX + Math.cos(radians) * 20;
startX = x;
endX = x;
} else {
// todo diagonal lines
// don't know what should be the formula for this
}
var from = new THREE.Vector3(startX, startY, 0);
var to = new THREE.Vector3(endX, endY, 0);
var direction = to.clone().sub(from);
var length = direction.length();
var hex = 0x0;
var arrorGroupHelper = new THREE.Group();
arrorGroupHelper.add(new THREE.ArrowHelper(direction.normalize(), from, length, hex, 1, 10));
arrorGroupHelper.add(new THREE.ArrowHelper(direction.negate(), to, length, hex, 1, 10));
scene.add(arrorGroupHelper);
var text = document.createElement('div');
text.style.position = 'absolute';
text.style.zIndex = 5;
text.style.backgroundColor = "ffffff";
text.innerHTML = length.toFixed(2);
let interiorCenter = to.clone().add(from).multiplyScalar(0.5);
let textPos = interiorCenter.project( camera );
var widthHalf = viewWidth;
var heightHalf = viewHeight;
var style = 'translate(-50%,-50%) translate(' + ( textPos.x * widthHalf + widthHalf ) + 'px,' + ( - textPos.y * heightHalf + heightHalf ) + 'px)';
text.style.transform = style;
document.getElementById('container').append(text);
}
var threejsCanvas = document.getElementById('threejs-canvas');
var renderer = new THREE.WebGLRenderer({
canvas : threejsCanvas,
alpha : true
});
renderer.autoClear = false;
renderer.setSize( window.innerWidth, window.innerHeight );
renderer.render( scene, camera );
animate();
window.addEventListener( 'resize', onWindowResize, false );
function onWindowResize() {
var width = window.innerWidth / 2;
var height = window.innerHeight / 2;
camera.left = -width / 2;
camera.right = width / 2
camera.top = height / 2;
camera.bottom = -height / 2;
camera.updateProjectionMatrix();
renderer.setSize( window.innerWidth, window.innerHeight );
}
function animate() {
requestAnimationFrame( animate );
render();
}
function render() {
renderer.clear();
renderer.render( scene, camera );
}
function findLineCenterPoint(a, b) {
return { x: (b.x - a.x) / 2 + a.x, y: (b.y - a.y) / 2 + a.y };
}
function findCentroid (arr) {
var minX, maxX, minY, maxY;
for (var i = 0; i < arr.length; i++)
{
var x = arr[i]['x'], y = arr[i]['y'];
minX = (x < minX || minX == null) ? x : minX;
maxX = (x > maxX || maxX == null) ? x : maxX;
minY = (y < minY || minY == null) ? y : minY;
maxY = (y > maxY || maxY == null) ? y : maxY;
}
return {x:(minX + maxX) / 2, y:(minY + maxY) / 2};
}
function buildFloor(vertices) {
var material = new THREE.MeshBasicMaterial({
color: 0xcccccc,
});
var shape = new THREE.Shape(vertices);
var geometry = new THREE.ShapeGeometry(shape);
var floor = new THREE.Mesh(geometry, material);
return floor;
}
function getAngle(originX, originY, targetX, targetY) {
var dx = originX - targetX;
var dy = originY - targetY;
var theta = Math.atan2(-dy, -dx);
theta *= 180 / Math.PI;
if (theta < 0) theta += 360;
return theta;
}
#container {
position: relative;
}
#threejs-canvas {
position:absolute;
z-index: 2;
}
<script src="//cdn.rawgit.com/mrdoob/three.js/master/build/three.min.js"></script>
<div id="container">
<canvas id="threejs-canvas"></canvas>
</div>
Here's my question:
How do I move the dimension lines encircled on red on the image above to the new points which is the blue lines.
Thanks. Hope someone could shed a light on this.

Related

Draw Heart using JavaScript in any postion(X,Y)

I have seen a good animation in codepen.io Link Here . Its really amazing. But instead of red-arrow i thought to change it to Heart(Love symbol). So i started to debug the code and i found the function drawArrow, where they are drawing the arrow. There i have tried to implement heart draw(got the code from here).
var ctx = _pexcanvas.getContext("2d");
var d = 20; //The Size of the hearting
var k =150; // The Position of the heart
ctx.moveTo(k, k + d / 4);
ctx.quadraticCurveTo(k, k, k + d / 4, k);
ctx.quadraticCurveTo(k + d / 2, k, k + d / 2, k + d / 4);
ctx.quadraticCurveTo(k + d / 2, k, k + d * 3/4, k);
ctx.quadraticCurveTo(k + d, k, k + d, k + d / 4);
ctx.quadraticCurveTo(k + d, k + d / 2, k + d * 3/4, k + d * 3/4);
ctx.lineTo(k + d / 2, k + d);
ctx.lineTo(k + d / 4, k + d * 3/4);
ctx.quadraticCurveTo(k, k + d / 2, k, k + d / 4);
But while using the above code i can't change the starting position of the heart, means if i increase the K value its placing the heart in the linear position(Like heart will appear only in the linear scope of (-x,y) to (x,-y)),
But i like to place to heart in anywhere in the screen, but i can't achieve it. Give me right direction to fix it.
Note: I am not an JavaScript Dev, i have a basic knowledge in java.
Thanks in advance.

You just need to add the new function to draw hearts instead of arrow, the solution you are referred will draw a stable heart.
Width and height can be use as per your requirement.
Add the following function:
function drawHeart(fromx, fromy, tox, toy,lw,hlen,color) {
var x = fromx;
var y = fromy;
var width = lw ;
var height = hlen;
ctx.save();
ctx.beginPath();
var topCurveHeight = height * 0.3;
ctx.moveTo(x, y + topCurveHeight);
// top left curve
ctx.bezierCurveTo(
x, y,
x - width / 2, y,
x - width / 2, y + topCurveHeight
);
// bottom left curve
ctx.bezierCurveTo(
x - width / 2, y + (height + topCurveHeight) / 2,
x, y + (height + topCurveHeight) / 2,
x, y + height
);
// bottom right curve
ctx.bezierCurveTo(
x, y + (height + topCurveHeight) / 2,
x + width / 2, y + (height + topCurveHeight) / 2,
x + width / 2, y + topCurveHeight
);
// top right curve
ctx.bezierCurveTo(
x + width / 2, y,
x, y,
x, y + topCurveHeight
);
ctx.closePath();
ctx.fillStyle = color;
ctx.fill();
ctx.restore();
}
Below is the working solution for same.
"use strict"
var stage = {
w:1280,
h:720
}
var _pexcanvas = document.getElementById("canvas");
_pexcanvas.width = stage.w;
_pexcanvas.height = stage.h;
var ctx = _pexcanvas.getContext("2d");
var pointer = {
x:0,
y:0
}
var scale = 1;
var portrait = true;
var loffset = 0;
var toffset = 0;
var mxpos = 0;
var mypos = 0;
// ------------------------------------------------------------------------------- Gamy
function drawArrow(fromx, fromy, tox, toy,lw,hlen,color) {
var dx = tox - fromx;
var dy = toy - fromy;
var angle = Math.atan2(dy, dx);
ctx.fillStyle=color;
ctx.strokeStyle=color;
ctx.lineCap = "round";
ctx.lineWidth = lw;
ctx.beginPath();
ctx.moveTo(fromx, fromy);
ctx.lineTo(tox, toy);
ctx.stroke();
ctx.beginPath();
ctx.moveTo(tox, toy);
ctx.lineTo(tox - hlen * Math.cos(angle - Math.PI / 6), toy - hlen * Math.sin(angle - Math.PI / 6));
ctx.lineTo(tox - hlen * Math.cos(angle)/2, toy - hlen * Math.sin(angle)/2);
ctx.lineTo(tox - hlen * Math.cos(angle + Math.PI / 6), toy - hlen * Math.sin(angle + Math.PI / 6));
ctx.closePath();
ctx.stroke();
ctx.fill();
}
function drawHeart(fromx, fromy, tox, toy,lw,hlen,color) {
var x = fromx;
var y = fromy;
var width = lw ;
var height = hlen;
ctx.save();
ctx.beginPath();
var topCurveHeight = height * 0.3;
ctx.moveTo(x, y + topCurveHeight);
// top left curve
ctx.bezierCurveTo(
x, y,
x - width / 2, y,
x - width / 2, y + topCurveHeight
);
// bottom left curve
ctx.bezierCurveTo(
x - width / 2, y + (height + topCurveHeight) / 2,
x, y + (height + topCurveHeight) / 2,
x, y + height
);
// bottom right curve
ctx.bezierCurveTo(
x, y + (height + topCurveHeight) / 2,
x + width / 2, y + (height + topCurveHeight) / 2,
x + width / 2, y + topCurveHeight
);
// top right curve
ctx.bezierCurveTo(
x + width / 2, y,
x, y,
x, y + topCurveHeight
);
ctx.closePath();
ctx.fillStyle = color;
ctx.fill();
ctx.restore();
}
var colors = ['#1abc9c','#1abc9c','#3498db','#9b59b6','#34495e','#16a085','#27ae60','#2980b9','#8e44ad','#2c3e50','#f1c40f','#e67e22','#e74c3c','#95a5a6','#f39c12','#d35400','#c0392b','#bdc3c7','#7f8c8d'];
ctx.clearRect(0,0,stage.w,stage.h);
for (var i =0;i<200;i++) {
var angle = Math.random()*Math.PI*2;
var length = Math.random()*250+50;
var myx=360+Math.sin(angle)*length;
var myy=360-Math.cos(angle)*length;
drawArrow(myx,myy,myx+length/6*Math.sin(angle),myy-length/6*Math.cos(angle),length/30,length/30,'#c0392b');
}
var explode = new Image();
explode.src = canvas.toDataURL("image/png");
ctx.clearRect(0,0,stage.w,stage.h);
for (var i =0;i<200;i++) {
var angle = Math.random()*Math.PI-Math.PI/2;
var length = Math.random()*480+50;
var myx=stage.w/2+Math.sin(angle)*length;
var myy=stage.h-Math.cos(angle)*length;
drawArrow(myx,myy,myx+length/6*Math.sin(angle),myy-length/6*Math.cos(angle),length/30,length/30,'#2c3e50');
}
var explodeb = new Image();
explodeb.src = canvas.toDataURL("image/png");
ctx.clearRect(0,0,stage.w,stage.h);
ctx.fillStyle = "rgba(236,240,241,1)";
ctx.fillRect(0,0,stage.w,stage.h);
for (var i =0;i<200;i++) {
var angle = Math.random()*Math.PI/Math.PI*180;
var length = Math.random()*250+50;
var myx=Math.random()*stage.w;
var myy=Math.random()*stage.h;
drawArrow(myx,myy,myx+length/6*Math.sin(angle),myy-length/6*Math.cos(angle),length/30,length/30,colors[Math.floor(Math.random()*colors.length)]);
}
ctx.fillStyle = "rgba(236,240,241,0.9)";
ctx.fillRect(0,0,stage.w,stage.h);
var back = new Image();
back.src = canvas.toDataURL("image/png");
var angle=0;
var ai = true;
var ait = 0;
var btm=0;
var bullets = [];
function Bullet() {
this.x=stage.w/2-Math.sin(angle)*150;
this.y=stage.h-Math.cos(angle)*150;
this.r=angle;
}
var enemies = [];
function Enemy() {
this.r = Math.random()*Math.PI/(2.5/2)-Math.PI/2.5;
this.dis = Math.random()*1280+720;
this.x=stage.w/2-Math.sin(this.r)*this.dis;
this.y=stage.h-Math.cos(this.r)*this.dis;
}
for(var i=0;i<10;i++) {
enemies.push(new Enemy());
enemies[i].x += Math.sin(enemies[i].r)*300;
enemies[i].y += Math.cos(enemies[i].r)*300;
}
var explosions = [];
function Explosion(x,y,ty) {
this.x=x;
this.y=y;
this.t=30;
this.ty=ty;
}
var eturn = 0;
var cold = [];
function enginestep() {
ctx.drawImage(back,0,0);
if (!ai&&ait<Date.now()-3000) {
ai = true;
}
btm++;
if(btm>8){
btm=0;
bullets.push(new Bullet());
}
for (var i=0;i<bullets.length;i++) {
bullets[i].x -= Math.sin(bullets[i].r)*20;
bullets[i].y -= Math.cos(bullets[i].r)*20;
drawArrow(bullets[i].x+Math.sin(bullets[i].r)*50,bullets[i].y+Math.cos(bullets[i].r)*50,bullets[i].x,bullets[i].y,8,8,'#2980b9');
if(bullets[i].x<-100||bullets[i].x>stage.w+100){
bullets.splice(i,1);
}
if(bullets[i].y<-100||bullets[i].y>stage.h+100){
bullets.splice(i,1);
}
}
for(var i=0;i<enemies.length;i++) {
enemies[i].x += Math.sin(enemies[i].r)*3;
enemies[i].y += Math.cos(enemies[i].r)*3;
drawHeart(enemies[i].x-Math.sin(enemies[i].r)*100,enemies[i].y-Math.cos(enemies[i].r)*100,enemies[i].x,enemies[i].y,15,15,"#c0392b");
if (enemies[i].y>stage.h) {
enemies[i] = new Enemy();
explosions.push(new Explosion(stage.w/2,stage.h,2));
shake = true;
shaket=0;
}
for (var b=0;b<bullets.length;b++) {
var dx = enemies[i].x-bullets[b].x;
var dy = enemies[i].y-bullets[b].y;
var dis = dx*dx+dy*dy;
if (dis<20*20) {
explosions.push(new Explosion(enemies[i].x,enemies[i].y,1));
enemies[i] = new Enemy();
bullets.splice(b,1);
}
}
}
if (ai) {
for(var l=0;l<enemies.length;l++) {
var dx = enemies[l].x-stage.w/2;
var dy = enemies[l].y-stage.h;
var dis = Math.floor(Math.sqrt(dx*dx+dy*dy));
var val1 = 100000+dis;
var val2 = 1000+l;
cold[l]=val1+'x'+val2;
}
cold.sort();
eturn = parseInt(cold[0].slice(8,11));
if (parseInt(cold[0].slice(1,6))<800) {
angle += (enemies[eturn].r-angle)/8;
}
} else {
var dx = pointer.x-stage.w/2;
var dy = pointer.y-stage.h;
angle = Math.atan(dx/dy);
}
drawArrow(stage.w/2,stage.h,stage.w/2-Math.sin(angle)*150,stage.h-Math.cos(angle)*150,30,20,'#2c3e50');
for(var e=0;e<explosions.length;e++) {
if (explosions[e].ty==1) {
var myimg = explode;
ctx.globalAlpha=1-(explosions[e].t/stage.h);
ctx.drawImage(myimg,explosions[e].x-explosions[e].t/2,explosions[e].y-explosions[e].t/2,explosions[e].t*stage.w/stage.h,explosions[e].t);
ctx.globalAlpha=1;
} else {
var myimg = explodeb;
ctx.globalAlpha=1-(explosions[e].t/stage.h);
ctx.drawImage(myimg,explosions[e].x-explosions[e].t*stage.w/stage.h/2,stage.h-explosions[e].t,explosions[e].t*stage.w/stage.h,explosions[e].t);
ctx.globalAlpha=1;
}
}
for(var e=0;e<explosions.length;e++) {
explosions[e].t += 20;
if (explosions[e].t>stage.h) {
explosions.splice(e,1);
}
}
}
// ------------------------------------------------------------------------------- events
// ------------------------------------------------------------------------------- events
// ------------------------------------------------------------------------------- events
// ------------------------------------------------------------------------------- events
function toggleFullScreen() {
var doc = window.document;
var docEl = doc.documentElement;
var requestFullScreen = docEl.requestFullscreen || docEl.mozRequestFullScreen || docEl.webkitRequestFullScreen || docEl.msRequestFullscreen;
var cancelFullScreen = doc.exitFullscreen || doc.mozCancelFullScreen || doc.webkitExitFullscreen || doc.msExitFullscreen;
if(!doc.fullscreenElement && !doc.mozFullScreenElement && !doc.webkitFullscreenElement && !doc.msFullscreenElement) {
requestFullScreen.call(docEl);
}
else {
cancelFullScreen.call(doc);
}
}
function motchstart(e) {
mxpos = (e.pageX-loffset)*scale;
mypos = (e.pageY-toffset)*scale;
}
function motchmove(e) {
mxpos = (e.pageX-loffset)*scale;
mypos = (e.pageY-toffset)*scale;
pointer.x = mxpos;
pointer.y = mypos;
ai = false;
ait = Date.now();
}
function motchend(e) {
}
window.addEventListener('mousedown', function(e) {
motchstart(e);
}, false);
window.addEventListener('mousemove', function(e) {
motchmove(e);
}, false);
window.addEventListener('mouseup', function(e) {
motchend(e);
}, false);
window.addEventListener('touchstart', function(e) {
e.preventDefault();
motchstart(e.touches[0]);
}, false);
window.addEventListener('touchmove', function(e) {
e.preventDefault();
motchmove(e.touches[0]);
}, false);
window.addEventListener('touchend', function(e) {
e.preventDefault();
motchend(e.touches[0]);
}, false);
// ------------------------------------------------------------------------ stager
// ------------------------------------------------------------------------ stager
// ------------------------------------------------------------------------ stager
// ------------------------------------------------------------------------ stager
function _pexresize() {
var cw = window.innerWidth;
var ch = window.innerHeight;
if (cw<=ch*stage.w/stage.h) {
portrait = true;
scale = stage.w/cw;
loffset = 0;
toffset = Math.floor(ch-(cw*stage.h/stage.w))/2;
_pexcanvas.style.width = cw + "px";
_pexcanvas.style.height = Math.floor(cw*stage.h/stage.w) + "px";
_pexcanvas.style.marginLeft = loffset +"px";
_pexcanvas.style.marginTop = toffset +"px";
} else {
scale = stage.h/ch;
portrait = false;
loffset = Math.floor(cw-(ch*stage.w/stage.h))/2;
toffset = 0;
_pexcanvas.style.height = ch + "px";
_pexcanvas.style.width = Math.floor(ch*stage.w/stage.h) + "px";
_pexcanvas.style.marginLeft = loffset +"px";
_pexcanvas.style.marginTop = toffset +"px";
}
}
window.requestAnimFrame = (function(){
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function( callback ){
window.setTimeout(callback, 1000 / 60);
};})();
function sfps(iny) {
return(Math.floor(smoothfps)/60*iny);
}
var timebomb=0;
var lastCalledTime;
var fpcount = 0;
var fpall = 0;
var smoothfps = 60;
var thisfps = 60;
function fpscounter() {
timebomb ++;
if (!lastCalledTime) {
lastCalledTime = Date.now();
return;
}
var delta = (Date.now()-lastCalledTime)/1000;
lastCalledTime = Date.now();
var fps = 1/delta;
fpcount ++;
fpall += fps;
if (timebomb>30) {
thisfps = parseInt(fpall/fpcount*10)/10;
fpcount = 0;
fpall = 0;
timebomb = 0;
}
}
var shake = false;
var shaket = 0;
function animated() {
requestAnimFrame(animated);
if (shake) {
var trax = Math.random()*60-30;
var tray = Math.random()*60-30;
ctx.translate(trax,tray);
}
// fpscounter();
//ctx.clearRect(0,0,_pexcanvas.width,_pexcanvas.height);
enginestep()
// ctx.fillStyle='#8e44ad';
// ctx.font = "24px arial";
// ctx.textAlign = "left";
// ctx.fillText(thisfps,20,50);
// smoothfps += (thisfps-smoothfps)/100;
// ctx.fillText(cold[0].slice(1,6),20,80);
// ctx.beginPath();
// ctx.arc(pointer.x, pointer.y, 50, 0, Math.PI*2,false);
// ctx.closePath();
// ctx.fill();
if (shake) {
ctx.translate(-trax,-tray);
shaket ++;
if (shaket>20) {
shaket=0;
shake=false;
}
}
}
_pexresize();
animated();
body {background:#000000;margin:0;padding:0}
canvas {background:#ecf0f1;}
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="description" content="Pex.Js Engine">
<meta name="author" content="Ahmad Faisal Jawed">
<title>Arrows</title>
</head>
<body onresize='_pexresize()'>
<canvas id='canvas' width=1280 height=720></canvas>
</body>
</html>

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>

Drag Bound with Konva.Layer

I am using KonvaJs in my project. I need to implement drag bound to Konva.Layer. My layer has so many other shapes and images. I need to restrict the movement of layer up to 50% of it's width and height. The way I have done in this plunkr. The problem arises when user zoom-in or zoom-out the layer using mouse wheel. After the zoom, I don't know why the drag bound is behaving differently. Seems like I am not able to do the Math correctly. I need to have the same behavior i.e. the way movement of layer is restricted when user does not perform zoom. This is what I am doing:
//... a helper object for zooming
var zoomHelper = {
stage: null,
scale: 1,
zoomFactor: 1.1,
origin: {
x: 0,
y: 0
},
zoom: function(event) {
event.preventDefault();
var delta;
if (navigator.userAgent.toLowerCase().indexOf('firefox') > -1) {
if (event.originalEvent.detail > 0) {
//scroll down
delta = 0.2;
} else {
//scroll up
delta = 0;
}
} else {
if (event.originalEvent.wheelDelta < 0) {
//scroll down
delta = 0.2;
} else {
//scroll up
delta = 0;
}
}
var evt = event.originalEvent,
mx = evt.clientX - zoomHelper.stage.getX(),
my = evt.clientY - zoomHelper.stage.getY(),
zoom = (zoomHelper.zoomFactor - delta),
newscale = zoomHelper.scale * zoom;
zoomHelper.origin.x = mx / zoomHelper.scale + zoomHelper.origin
.x - mx / newscale;
zoomHelper.origin.y = my / zoomHelper.scale + zoomHelper.origin
.y - my / newscale;
zoomHelper.stage.setOffset({
x: zoomHelper.origin.x,
y: zoomHelper.origin.y
});
zoomHelper.stage.setScale({
x: newscale,
y: newscale
});
zoomHelper.stage.draw();
zoomHelper.scale *= zoom;
preCalculation();
}
};
// Code goes here
var w = window.innerWidth;
var h = window.innerHeight;
var height, minX, minY, maxX, maxY;
var stage = new Konva.Stage({
container: 'container',
width: w,
height: h
});
zoomHelper.stage =stage;
var layer = new Konva.Layer({
draggable: true,
dragBoundFunc: function(pos) {
console.log('called');
var X = pos.x;
var Y = pos.y;
if (X < minX) {
X = minX;
}
if (X > maxX) {
X = maxX;
}
if (Y < minY) {
Y = minY;
}
if (Y > maxY) {
Y = maxY;
}
return ({
x: X,
y: Y
});
}
});
stage.add(layer);
function preCalculation(){
// pre-calc some bounds so dragBoundFunc has less calc's to do
height = layer.getHeight();
minX = stage.getX() - layer.getWidth() / 2;
maxX = stage.getX() + stage.getWidth() - layer.getWidth() / 2;
minY = stage.getY() - layer.getHeight() / 2;
maxY = stage.getY() + stage.getHeight() - layer.getHeight() / 2;
console.log(height, minX, minY, maxX, maxY);
}
preCalculation();
var img = new Image();
img.onload = function() {
var floorImage = new Konva.Image({
image: img,
width: w,
height: h
});
layer.add(floorImage);
layer.draw();
};
img.src = 'https://s.yimg.com/pw/images/coverphoto02_h.jpg.v3';
$(stage.container).on('mousewheel DOMMouseScroll', zoomHelper.zoom);

While using dragBoundFunc you have to return absolute position of layer. As you are changing attributes of top node (stage) it can be hard to maintain absolute position. So you can try to set bound function inside 'dragmove' event:
layer.on('dragmove', function() {
var x = Math.max(minX, Math.min(maxX, layer.x()));
var y = Math.max(minY, Math.min(maxY, layer.y()));
layer.x(x);
layer.y(y);
});
http://plnkr.co/edit/31MUmOjXBUVuaHVJsL3c?p=preview

Rectangle Coordinate Projection into another Rectangle

So I would like to project coordinates from one rectangle in javascript to another, in essence, scaling coordinates from one rectangle to another. How would I do that?
function Rectangle(maxX, minX, maxY, minY) {
this.maxX = maxX;
this.minX = minX;
this.maxY = maxY;
this.minY = minY;
}
So 2 Rectangles with different size and coordinates. I want to draw into one rectangle and scale that proportionally into the other rectangle.

Something like this?
var src = new Rectangle(6, 0, 6, 2);
var dst = new Rectangle(4, 2, 8, 0);
function Rectangle(maxX, minX, maxY, minY) {
this.maxX = maxX;
this.minX = minX;
this.maxY = maxY;
this.minY = minY;
}
var canvas = document.querySelector("canvas");
var width = canvas.width, height = canvas.height;
var w = width / 2 + 0.5, h = height / 2 + 0.5;
var sx = width / 20, sy = height / 20;
var context = canvas.getContext("2d");
context.strokeStyle = "#808080";
context.fillStyle = "#000080";
tween(src, dst, 25, 1, 1000);
function tween(src, dst, fps, seconds, delay) {
var frames = fps * seconds;
var srcMaxX = src.maxX;
var srcMinX = src.minX;
var srcMaxY = src.maxY;
var srcMinY = src.minY;
var maxX = dst.maxX - srcMaxX;
var minX = dst.minX - srcMinX;
var maxY = dst.maxY - srcMaxY;
var minY = dst.minY - srcMinY;
drawRectangle(srcMaxX, srcMinX, srcMaxY, srcMinY);
setTimeout(function loop(frame, delay) {
var dstMaxX = srcMaxX + maxX * frame / frames;
var dstMinX = srcMinX + minX * frame / frames;
var dstMaxY = srcMaxY + maxY * frame / frames;
var dstMinY = srcMinY + minY * frame / frames;
drawRectangle(dstMaxX, dstMinX, dstMaxY, dstMinY);
if (frame < frames) setTimeout(loop, delay, frame + 1, delay);
}, delay, 1, 1000 / fps);
}
function drawRectangle(maxX, minX, maxY, minY) {
context.clearRect(0, 0, width, height);
drawLine(0, h, width, h);
drawLine(w, 0, w, height);
var x = w + sx * minX;
var y = h - sy * maxY;
var wth = sx * (maxX - minX);
var hgt = sy * (maxY - minY);
context.fillRect(x, y, wth, hgt);
}
function drawLine(x1, y1, x2, y2) {
context.beginPath();
context.moveTo(x1, y1);
context.lineTo(x2, y2);
context.stroke();
}
canvas {
border: 1px solid #000000;
}
<canvas width="400" height="400"></canvas>
Hope this helps.

With these functions:
function Point(x, y) {
this.x = x;
this.y = y;
}
function Rect(xMin, xMax, yMin, yMax) {
this.xMin = xMin;
this.xMax = xMax;
this.yMin = yMin;
this.yMax = yMax;
}
Rect.prototype.width = function() {
return this.xMax - this.xMin;
};
Rect.prototype.height = function() {
return this.yMax - this.yMin;
};
function RectProjection(a, b) {
var xScale = b.width() / a.width();
var yScale = b.height() / a.height();
var xOffset = b.xMin - xScale * a.xMin;
var yOffset = b.yMin - yScale * a.yMin;
return function (p) {
return Point(xScale * p.x + xOffset, yScale * p.y + yOffset);
};
}
You can then do something like this:
var proj = projection(new Rectangle(0, 2, 0, 3), new Rectangle(2, 6, 2, 8));
var q = proj(new Point(1, 2));
Where q is Point(4, 6).

How to constrain movement within the area of a circle

This might be more a geometry related question, but I'm trying to constrain a controller within an area of a circle. I know I have to touch the Math.sin() and Math.cos() methods, but my attemps so far have been fruitless so far.
Here is the jsfiddle:
So far I've been able to constrain it to an invisible square. http://jsfiddle.net/maGVK/

So I finally was able to complete this with a bit of everyone's help.
var pointerEl = document.getElementById("pointer");
var canvasEl = document.getElementById("canvas");
var canvas = {
width: canvasEl.offsetWidth,
height: canvasEl.offsetHeight,
top: canvasEl.offsetTop,
left: canvasEl.offsetLeft
};
canvas.center = [canvas.left + canvas.width / 2, canvas.top + canvas.height / 2];
canvas.radius = canvas.width / 2;
window.onmousemove = function(e) {
var result = limit(e.x, e.y);
pointer.style.left = result.x + "px";
pointer.style.top = result.y + "px";
}
function limit(x, y) {
var dist = distance([x, y], canvas.center);
if (dist <= canvas.radius) {
return {x: x, y: y};
}
else {
x = x - canvas.center[0];
y = y - canvas.center[1];
var radians = Math.atan2(y, x)
return {
x: Math.cos(radians) * canvas.radius + canvas.center[0],
y: Math.sin(radians) * canvas.radius + canvas.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));
}
You can see the result here:
http://jsfiddle.net/7Asn6/

var pointerEl = document.getElementById("pointer");
var canvasEl = document.getElementById("canvas");
var canvas = {
width: canvasEl.offsetWidth,
height: canvasEl.offsetHeight,
top: canvasEl.offsetTop,
left: canvasEl.offsetLeft
};
canvas.center = [canvas.left + canvas.width / 2, canvas.top + canvas.height / 2];
canvas.radius = canvas.width / 2;
window.onmousemove = function(e) {
var result = limit(e.x, e.y);
if (!result.limit) {
pointer.style.left = result.x + "px";
pointer.style.top = result.y + "px";
}
}
function limit(x, y) {
var dist = distance([x, y], canvas.center);
if (dist <= canvas.radius) {
return {x: x, y: y};
} else {
return {limit: true};
}
}
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));
}
this could do the work, though the movement is not smooth....that will need more geometry knowledge...
fiddle: http://jsfiddle.net/cRxMa/

This arithmetic is trivial as long as you normalize each data point (prospective position), which i have tried to do in the function below:
function locatePoint(canvas_size, next_position) {
// canvas_size & next_position are both 2-element arrays
// (w, h) & (x, y)
dist = function(x, y) {
return Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
};
x = next_position[0];
y = next_position[1];
rescaledX = x/(canvas_size[0]/2);
rescaledY = y/(canvas_size[1]/2);
if (distance(x, y) <= 1) {
// the base case; position is w/in the circle
}
else {
// position is outside the circle, so perhaps
// do something like random select a new position, then
// call this function again (recursively) passing in
// that new position
}
}
so in the simple diagram below, i have just inscribed a unit circle (r=1) inside a square whose sides are r*2. Your canvas dimensions do not have to be square though. To further simplify the calculation, you only need to consider one of the four quadrants--the upper right quadrant, let's say. The reason is that the Euclidean distance formula squares each coordinate value, so negative values become positive.
Put another way, the simplest way is to imagine a circle inscribed in your canvas and whose center is also the center of your canvas (so (0, 0) is the center not the upper left-hand corner); next, both canvas and circle are shrunk until the circle has radius = 1. Hopefully i have captured this in the function above.

Hi and thanks for sharing your solution.
Your jsfiddle helps me a lot to constraint the movement of a rotation handle.
Here's my solution using jQuery :
function getBall(xVal, yVal, dxVal, dyVal, rVal, colorVal) {
var ball = {
x: xVal,
lastX: xVal,
y: yVal,
lastY: yVal,
dx: dxVal,
dy: dyVal,
r: rVal,
color: colorVal,
normX: 0,
normY: 0
};
return ball;
}
var canvas = document.getElementById("myCanvas");
var xLabel = document.getElementById("x");
var yLabel = document.getElementById("y");
var dxLabel = document.getElementById("dx");
var dyLabel = document.getElementById("dy");
var ctx = canvas.getContext("2d");
var containerR = 200;
canvas.width = containerR * 2;
canvas.height = containerR * 2;
canvas.style["border-radius"] = containerR + "px";
var balls = [
getBall(containerR, containerR * 2 - 30, 2, -2, 20, "#0095DD"),
getBall(containerR, containerR * 2 - 50, 3, -3, 30, "#DD9500"),
getBall(containerR, containerR * 2 - 60, -3, 4, 10, "#00DD95"),
getBall(containerR, containerR * 2 / 5, -1.5, 3, 40, "#DD0095")
];
function draw() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
for (var i = 0; i < balls.length; i++) {
var curBall = balls[i];
ctx.beginPath();
ctx.arc(curBall.x, curBall.y, curBall.r, 0, Math.PI * 2);
ctx.fillStyle = curBall.color;
ctx.fill();
ctx.closePath();
curBall.lastX = curBall.x;
curBall.lastY = curBall.y;
curBall.x += curBall.dx;
curBall.y += curBall.dy;
var dx = curBall.x - containerR;
var dy = curBall.y - containerR;
var distanceFromCenter = Math.sqrt(dx * dx + dy * dy);
if (distanceFromCenter >= containerR - curBall.r) {
var normalMagnitude = distanceFromCenter;
var normalX = dx / normalMagnitude;
var normalY = dy / normalMagnitude;
var tangentX = -normalY;
var tangentY = normalX;
var normalSpeed = -(normalX * curBall.dx + normalY * curBall.dy);
var tangentSpeed = tangentX * curBall.dx + tangentY * curBall.dy;
curBall.dx = normalSpeed * normalX + tangentSpeed * tangentX;
curBall.dy = normalSpeed * normalY + tangentSpeed * tangentY;
}
xLabel.innerText = "x: " + curBall.x;
yLabel.innerText = "y: " + curBall.y;
dxLabel.innerText = "dx: " + curBall.dx;
dyLabel.innerText = "dy: " + curBall.dy;
}
requestAnimationFrame(draw);
}
draw();
canvas { background: #eee; }
<div id="x"></div>
<div id="y"></div>
<div id="dx"></div>
<div id="dy"></div>
<canvas id="myCanvas"></canvas>
Hope this help someone.

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