回転行列の公式（x’ = cosθ * x – sinθ * y, y’ = sinθ * x + cosθ * y）を使って、Canvasに描いたオブジェクトをマウスの方向に回転させる。
オブジェクトをマウスの方向に、回転行列（Rotating Matrix）を使って回転させる（HTML5, JavaScript, CSS3） : デモ
オブジェクトをマウスの方向に、回転行列（Rotating Matrix）を使って回転させる（HTML5, JavaScript, CSS3） : ZIPファイル（6kb）
1.HTML
<!DOCTYPE html> <html lang="jp"> <head> <meta charset="UTF-8" /> <title>マウスの方向に回転行列｜Rotate Matrix to Mouse</title> <link href="css/base.css" rel="stylesheet" type="text/css"> <script src="js/base.js"></script> <script src="js/devicecheck.js"></script> </head> <body> <div id="contents"> <canvas id="canvas" width="300" height="300"> </canvas> </div> </body> </html>
2.CSS
@charset "utf-8";
body
{
margin:0;
padding:0;
background-color: #fff;
font-family:Helvetica, HiraKakuProN-W3, sans-serif;
font-size:12px;
color:#000;
}
#contents
{
position: absolute;
top: 0;
left: 0;
width: 300px;
height:300px;
border: 1px solid #000;
overflow:hidden;
}
#canvas
{
position: absolute;
top: 0;
left: 0;
width: 300px;
height:300px;
}
3.JavaScript
devicecheck.js
var g_mobiledevice = false; //iPhone、iPad、Androidのときtrue
var g_browsername = 'unknown';
var g_browserver = -1;
if(checkUserAgent() == false)
{
window.alert('このブラウザは対象外です');
}
function checkUserAgent()
{
var ua = navigator.userAgent;
//iPhoneか？
var mstr = ua.match(/iPhone OS \d+/);
if(mstr != null){
var vstr = mstr[0].match(/\d+/);
if(parseInt(vstr[0]) >= 3)
{
g_mobiledevice = true;
g_browsername = 'iPhone';
//alert('major-version ' + vstr);
return true;
}
}
//iPadか？
if(ua.indexOf('iPad') > -1)
{
mstr = ua.match(/CPU OS \d+/);
if(mstr != null)
{
var vstr = mstr[0].match(/\d+/);
if(parseInt(vstr[0]) >= 3) {
g_mobiledevice = true;
g_browsername = 'iPad';
//alert('major-version ' + vstr);
return true;
}
}
}
//Androidか？
var mstr = ua.match(/Android \d+\.\d+/);
if(mstr != null)
{
g_browsername = 'Android';
var vstr = mstr[0].match(/\d+\.\d+/);
g_browserver = parseFloat(vstr[0]);
g_mobiledevice = true;
if(pg_browserver > 2.1)
{
//alert('version ' + vstr);
return true;
}
}
//Chromeか？
mstr = ua.match(/Chrome\/\d+/);
if(mstr != null)
{
g_browsername = 'Chrome';
var vstr = mstr[0].match(/\d+/);
g_browserver = parseInt(vstr[0]);
if(g_browserver >= 9)
{
//alert('major-version ' + vstr);
return true;
}
}
//Safariか？
if(ua.indexOf('Safari') > -1)
{
mstr = ua.match(/Version\/\d+/);
if(mstr != null){
var vstr = mstr[0].match(/\d+/);
if(parseInt(vstr[0]) >= 5)
{
g_browsername = 'Safari';
//alert('major-version ' + vstr);
return true;
}
}
}
//Internet Explorerか？
mstr = ua.match(/MSIE \d+/);
if(mstr != null)
{
var vstr = mstr[0].match(/\d+/);
if(parseInt(vstr[0]) >= 9)
{
g_browsername = 'MSIE';
//alert('major-version ' + vstr);
return true;
}
}
//Firefoxか？
mstr = ua.match(/Firefox\/\d+/);
if(mstr != null){
var vstr = mstr[0].match(/\d+/);
if(parseInt(vstr[0]) >= 4)
{
g_browsername = 'Firefox';
//alert('major-version ' + vstr);
return true;
}
}
//Operaか？
if(ua.indexOf('Opera') > -1)
{
mstr = ua.match(/Version\/\d+/);
if(mstr != null){
var vstr = mstr[0].match(/\d+/);
if(parseInt(vstr[0]) >= 11)
{
g_browsername = 'Opera';
//alert('major-version ' + vstr);
return true;
}
}
}
return false;
}
base.js
window.addEventListener("load", init, false);
var centerX;
var centerY;
var theCanvas;
var ctx;
var currentX0;
var currentY0;
var currentX1;
var currentY1;
var currentX2;
var currentY2;
var points = new Array();
var mouseX;
var mouseY;
function init()
{
document.getElementById('canvas').addEventListener('touchstart', function()
{
event.preventDefault();
});
document.getElementById('canvas').addEventListener('touchmove', function()
{
event.preventDefault();
});
document.getElementById('canvas').addEventListener('touchend', function()
{
event.preventDefault();
});
//ボタンタイプ
if(g_mobiledevice==true)
{
buttonStart = 'touchstart';
buttonMove = 'touchmove';
buttonEnd = 'touchend';
}
else
{
buttonStart = 'mousedown';
buttonMove = 'mousemove';
buttonEnd = 'mouseup';
}
theCanvas = document.getElementById("contents");
centerX = (theCanvas.currentStyle || document.defaultView.getComputedStyle(theCanvas,'')).width;
centerX = Number(centerX.replace('px',''));
centerX = centerX / 2;
centerY = (theCanvas.currentStyle || document.defaultView.getComputedStyle(theCanvas,'')).height;
centerY = Number(centerY.replace('px',''));
centerY = centerY / 2;
theCanvas = document.getElementById("canvas");
theCanvas.addEventListener(buttonMove, mouseDownHandler, false);
function mouseDownHandler(e)
{
if(g_mobiledevice)
{
var rect = event.currentTarget.getBoundingClientRect();
mouseX = event.touches[0].pageX - rect.left - centerX;
mouseY = event.touches[0].pageY - rect.top - centerY;
}
else
if(g_browsername == 'MSIE' || g_browsername == 'Opera')
{
rect = document.getElementById("canvas").getBoundingClientRect();
mouseX = event.clientX - rect.left - centerX;
mouseY = event.clientY - rect.top - centerY;
}
else
if(g_browsername == 'Firefox')
{
rect = document.getElementById("canvas").getBoundingClientRect();
mouseX = e.clientX - rect.left - centerX;
mouseY = e.clientY - rect.top - centerY;
}
else
{
rect = event.currentTarget.getBoundingClientRect();
mouseX = event.clientX - rect.left - centerX;
mouseY = event.clientY - rect.top - centerY;
}
set(mouseX, mouseY);
}
ctx = theCanvas.getContext("2d");
var x = Math.cos(18*Math.PI/180)*50*1.62;
var y = Math.sin(18*Math.PI/180)*50*1.62;
points.push({x:-(x/2),y:-y});
points.push({x:x/2,y:0});
points.push({x:-(x/2),y:y});
set(0,0);
}
function set(mx,my)
{
var mx = mx;
var my = my;
ctx.clearRect(0,0,300,300);
var dx = mx;
var dy = my;
var radian = Math.atan2(dy,dx);
var i=0;
var currentX0 = Math.cos(radian)*points[i].x-Math.sin(radian)*points[i].y;
var currentY0 = Math.sin(radian)*points[i].x+Math.cos(radian)*points[i].y;
i=1;
var currentX1 = Math.cos(radian)*points[i].x-Math.sin(radian)*points[i].y;
var currentY1 = Math.sin(radian)*points[i].x+Math.cos(radian)*points[i].y;
i=2;
var currentX2 = Math.cos(radian)*points[i].x-Math.sin(radian)*points[i].y;
var currentY2 = Math.sin(radian)*points[i].x+Math.cos(radian)*points[i].y;
draw(currentX0,currentY0,currentX1,currentY1,currentX2,currentY2);
}
function draw(currentX0,currentY0,currentX1,currentY1,currentX2,currentY2)
{
ctx.strokeStyle="#000000";
ctx.lineWidth=1;
ctx.beginPath();
ctx.moveTo(centerX+currentX0, centerY+currentY0);
ctx.lineTo(centerX+currentX1, centerY+currentY1);
ctx.lineTo(centerX+currentX2, centerY+currentY2);
ctx.lineTo(centerX+currentX0, centerY+currentY0);
ctx.stroke();
}