很多購物網站現在都支持360實物全景圖像，可以360度任意選擇查看樣品，這樣對購買者來說是一個很好的消費體驗，網上有很多這樣的插件都是基于jQuery實現的有收費的也有免費的，其實很好用的一個叫3deye.js的插件。該插件支持桌面與移動終端iOS與Android， 它的demo程序：http://www.voidcanvas.com/demo/28823deye/
1. 首先需要對實物拍照，間隔是每張照片旋轉15度，所以需要23張照片。
2.照片準備好了以后，盡量選擇JPG格式，裁剪到適當大小。
3.JavaScript中預加載所有照片，可以配合進度條顯示加載精度
4.創建/獲取Canvas對象，加上鼠標監聽事件，當鼠標左右移動時候，適度的繪制不同幀。大致的原理就是這樣，簡單吧！
<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8">
<title>Full 360 degree View</title>
<script>
var ctx = null; // global variable 2d context
var frame = 1; // 23
var width = 0;
var height = 0;
var started = false;
var images = new Array();
var startedX = -1;
window.onload = function() {
var canvas = document.getElementById("fullview_canvas");
canvas.width = 440;// window.innerWidth;
canvas.height = 691;//window.innerHeight;
width = canvas.width;
height = canvas.height;
var bar = document.getElementById('loadProgressBar');
for(var i=1; i<24; i++)
{
bar.value = i;
if(i<10)
{
images[i] = new Image();
images[i].src = "0" + i + ".jpg";
}
else
{
images[i] = new Image();
images[i].src = i + ".jpg";
}
}
ctx = canvas.getContext("2d");
// mouse event
canvas.addEventListener("mousedown", doMouseDown, false);
canvas.addEventListener('mousemove', doMouseMove, false);
canvas.addEventListener('mouseup', doMouseUp, false);
// loaded();
// frame = 1
frame = 1;
images[frame].onload = function() {
redraw();
bar.style.display = 'none';
}
}
function doMouseDown(event) {
var x = event.pageX;
var y = event.pageY;
var canvas = event.target;
var loc = getPointOnCanvas(canvas, x, y);
console.log("mouse down at point( x:" + loc.x + ", y:" + loc.y + ")");
startedX = loc.x;
started = true;
}
function doMouseMove(event) {
var x = event.pageX;
var y = event.pageY;
var canvas = event.target;
var loc = getPointOnCanvas(canvas, x, y);
if (started) {
var count = Math.floor(Math.abs((startedX - loc.x)/30));
var frameIndex = Math.floor((startedX - loc.x)/30);
while(count > 0)
{
console.log("frameIndex = " + frameIndex);
count--;
if(frameIndex > 0)
{
frameIndex--;
frame++;
} else if(frameIndex < 0)
{
frameIndex++;
frame--;
}
else if(frameIndex == 0)
{
break;
}
if(frame >= 24)
{
frame = 1;
}
if(frame <= 0)
{
frame = 23;
}
redraw();
}
}
}
function doMouseUp(event) {
console.log("mouse up now");
if (started) {
doMouseMove(event);
startedX = -1;
started = false;
}
}
function getPointOnCanvas(canvas, x, y) {
var bbox = canvas.getBoundingClientRect();
return { x: x - bbox.left * (canvas.width / bbox.width),
y: y - bbox.top * (canvas.height / bbox.height)
};
}
function loaded() {
setTimeout( update, 1000/8);
}
function redraw()
{
// var imageObj = document.createElement("img");
// var imageObj = new Image();
var imageObj = images[frame];
ctx.clearRect(0, 0, width, height)
ctx.drawImage(imageObj, 0, 0, width, height);
}
function update() {
redraw();
frame++;
if (frame >= 23) frame = 1;
setTimeout( update, 1000/8);
}
</script>
</head>
<body>
<progress id="loadProgressBar" value="0" max="23"></progress>
<canvas id="fullview_canvas"></canvas>
<button onclick="loaded()">Auto Play</button>
</body>
</html>
