<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style type="text/css">
canvas {
border: 2px dotted #ddd
}
</style>
</head>
<body>
<canvas id="canvas1" width="400" height="400"></canvas>
<canvas id="canvas2" width="400" height="400"></canvas>
<script>
var canvas1 = document.getElementById('canvas1')
var context1 = canvas1.getContext('2d')
function randomFromTo(from, to) {
return Math.floor(Math.random() * (to - from) + from)
}
function Circle(x, y, radius, color) {
this.x = x
this.y = y
this.radius = radius
this.color = color
this.isSelected = false
}
var circles = []
function addRandomCircle() {
var radius = randomFromTo(10, 60)
var x = randomFromTo(0, canvas1.width)
var y = randomFromTo(0, canvas1.height)
var colors = ['green', 'blue', 'red', 'yellow', 'magenta', 'orange', 'brown', 'purple', 'pink']
var color = colors[randomFromTo(0, 8)]
var circle = new Circle(x, y, radius, color)
circles.push(circle)
}
function drawCircles() {
context1.clearRect(0, 0, canvas1.width, canvas1.height)
context1.globalAlpha = 0.85
context1.strokeStyle = 'black'
for (var i = 0, l = circles.length; i < l; i++) {
var circle = circles[i]
if (circle.isSelected) {
context1.lineWidth = 5
} else {
context1.lineWidth = 1
}
context1.beginPath()
context1.arc(circle.x, circle.y, circle.radius, 0, Math.PI*2)
context1.fillStyle = circle.color
context1.fill()
context1.stroke()
}
}
var previousSelectedCircle = null
function canvasClick(e) {
var clickX = e.pageX - canvas1.offsetLeft
var clickY = e.pageY - canvas1.offsetTop
for (var i = circles.length; i > 0; i--) {
var circle = circles[i - 1]
var distanceFromCenter = Math.sqrt(Math.pow(circle.x - clickX, 2) + Math.pow(circle.y - clickY, 2))
if (distanceFromCenter <= circle.radius) {
if (previousSelectedCircle != null) {
previousSelectedCircle.isSelected = false
}
previousSelectedCircle = circle
circle.isSelected = true
drawCircles()
return
}
}
}
addRandomCircle()
addRandomCircle()
addRandomCircle()
addRandomCircle()
addRandomCircle()
addRandomCircle()
addRandomCircle()
addRandomCircle()
drawCircles()
canvas1.onclick = canvasClick
var canvas2 = document.getElementById('canvas2')
var context2 = canvas2.getContext('2d')
var squarePosition_y = 0
var squarePosition_x = 10
function drawFrame() {
context2.clearRect(0, 0, canvas2.width, canvas2.height)
context2.beginPath()
context2.rect(squarePosition_x, squarePosition_y, 10, 10)
context2.lineStyle = 'black'
context2.lineWidth = 1
context2.stroke()
if (squarePosition_y > canvas2.height) {
squarePosition_y = 0
} else {
squarePosition_y += 1
}
setTimeout('drawFrame()', 20)
}
setTimeout('drawFrame()', 20)
</script>
</body>
</html>
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<canvas id="canvas" width="600" height="400" style="border:1px solid #ddd;"></canvas>
<button id="add">Add Ball</button>
<button id="clear">Clear Canvas</button>
<input id="ballSize" type="number">
<input id="connectedBalls" type="checkbox">
Connect Balls
<script>
function Ball(x, y, dx, dy, radius) {
this.x = x
this.y = y
this.dx = dx
this.dy = dy
this.radius = radius
this.color = 'red'
}
var balls = []
function addBall() {
var radius = parseFloat(document.getElementById('ballSize').value)
var ball = new Ball(50, 50, 1, 1, radius)
balls.push(ball)
}
function clearBall() {
balls = []
}
document.getElementById('add').onclick = addBall
document.getElementById('clear').onclick = clearBall
var canvas = document.getElementById('canvas')
var context = canvas.getContext('2d')
setTimeout('drawFrame()', 20)
function drawFrame() {
context.clearRect(0, 0, canvas.width, canvas.height)
context.beginPath()
for (var i = 0; i < balls.length; i++) {
var ball = balls[i]
ball.x += ball.dx
ball.y += ball.dy
if (ball.y < canvas.height) ball.dy += 0.22
ball.dx = ball.dx * 0.998
if ((ball.x + ball.radius > canvas.width) || (ball.x - ball.radius < 0)) {
ball.dx = -ball.dx
}
if ((ball.y + ball.radius > canvas.height) || (ball.y - ball.radius < 0)) {
ball.dy = -ball.dy * 0.96
}
if (!document.getElementById('connectedBalls').checked) {
context.beginPath()
context.fillStyle = ball.color
} else {
context.fillStyle = 'white'
}
context.arc(ball.x, ball.y, ball.radius, 0, Math.PI*2)
context.lineWidth = 1
context.fill()
context.stroke()
}
setTimeout('drawFrame()', 20)
}
</script>
</body>
</html>
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