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c05.html
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c05.html
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<!DOCTYPE html>
<html>
<head>
<title>Example</title>
<style>
body {
background: #dddddd;
}
#canvas {
background: #ffffff;
border: thin inset #aaaaaa;
}
</style>
</head>
<body>
<canvas id='canvas' width="800" height="600">
Canvas not supported
</canvas>
<script>
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
function windowToCanvas(x, y) {
var bbox = canvas.getBoundingClientRect();
return { x : x - bbox.left, y : y - bbox.top }
}
function Ball() {
this.x = 0;
this.y = 0;
this.radius = 10;
this.color = "red";
this.angle = 0;
}
Ball.prototype = {
draw : function() {
context.save();
context.beginPath();
context.translate(this.x, this.y);
context.rotate(this.angle);
context.arc(0, 0, this.radius, 0, Math.PI * 2);
//context.fillRect(0, 0, 30, 5);
context.fillStyle = this.color;
context.fill();
context.restore();
}
}
var ball = new Ball();
var vx = 0;
var vy = 0;
var time = +new Date();
var duration = 1000;
var startX = 0;
var startY = 0;
ball.x = 0;
ball.y = 100;
//ball.angle = 45 * Math.PI / 180;
canvas.onmousedown = function(e) {
var loc = windowToCanvas(e.clientX, e.clientY);
targetX = loc.x;
targetY = loc.y;
startX = ball.x;
startY = ball.y;
time = +new Date();
requestAnimationFrame(loop);
};
function loop() {
context.clearRect(0, 0, canvas.width, canvas.height);
var elapsed = +new Date() - time;
var per = bounce(elapsed / duration);
if(elapsed >= duration) {
ball.x = targetX;
ball.y = targetY;
render();
return;
}
ball.x = startX + (targetX - startX) * per;
ball.y = startY + (targetY - startY) * per;
render();
requestAnimationFrame(loop);
}
function easeIn(per) {
return Math.pow(per, 2);
}
function easeOut(per) {
return 1 - Math.pow(1- per, 2);
}
function easeInOut(per) {
return per - Math.sin(per * 2 * Math.PI) / (2 * Math.PI);
}
function elastic(per) {
return ((1- Math.cos(per * Math.PI * 8)) * (1 - per) ) + per;
}
function bounce(per) {
per = elastic(per);
return per <= 1 ? per : 2 - per;
}
function render() {
ball.draw();
}
</script>
</body>
</html>