关键字：WebGL，STL，ThreeJS，Chrome，Viewer，Python3.4， HTML5，Canvas。
OS：Windows 10。
本文介绍如何使用ThreeJS来实现一个WebGL的Viewer，用来浏览STL文件。
STL 文件是在计算机图形应用系统中，用于表示三角形网格的一种文件格式。 它的文件格式非常简单， 应用很广泛。
STL是最多快速原型系统所应用的标准文件类型。STL是用三角网格来表现3D CAD模型。
1.新建一个STL.html文件如下：
<!DOCTYPE html>
<html lang="en">
<head>
<title>WebViewer - STL</title>
<meta charset="utf-8">
</head>
<body>
<script src="threejs/three.min.js"></script>
<script src="threejs/loaders/STLLoader.js"></script>
<script src="threejs/OrbitControls.js"></script>
<script>
var container;
var camera, cameraTarget, scene, renderer;
var cameraType = 1;
var perspectiveAngle = 45;
var cameraPosX = 200;
var cameraPosY = 200;
var cameraPosZ = 200;
var cameraTargetX = 0;
var cameraTargetY = 0;
var cameraTargetZ = 0;
var upVectorX = 0;
var upVectorY = 1;
var upVectorZ = 0;
var cameralScale = 5;
init();
animate();
function getQueryStringByName(name){
var result = location.search.match(new RegExp("[\?\&]" + name+ "=([^\&]+)","i"));
if(result == null || result.length < 1){
return "";
}
return result[1];
}
function init() {
container = document.createElement( ‘div‘ );
document.body.appendChild( container );
// set camera
var cameraTypeStr = getQueryStringByName(‘cameraType‘);
cameraType = cameraTypeStr == "" ? cameraType : parseInt(cameraTypeStr);
var perspectiveAngleStr = getQueryStringByName(‘perspectiveAngle‘);
perspectiveAngle = perspectiveAngleStr == "" ? perspectiveAngle : parseFloat(perspectiveAngleStr);
var cameraPosXStr = getQueryStringByName(‘cameraPosX‘);
cameraPosX = cameraPosXStr == "" ? cameraPosX : parseFloat(cameraPosXStr) * cameralScale;
var cameraPosYStr = getQueryStringByName(‘cameraPosY‘);
cameraPosY = cameraPosYStr == "" ? cameraPosY : parseFloat(cameraPosYStr) * cameralScale;
var cameraPosZStr = getQueryStringByName(‘cameraPosZ‘);
cameraPosZ = cameraPosZStr == "" ? cameraPosZ : parseFloat(cameraPosZStr) * cameralScale;
var cameraTargetXStr = getQueryStringByName(‘cameraTargetX‘);
cameraTargetX = cameraTargetXStr == "" ? cameraTargetX : parseFloat(cameraTargetXStr) * cameralScale;
var cameraTargetYStr = getQueryStringByName(‘cameraTargetY‘);
cameraTargetY = cameraTargetYStr == "" ? cameraTargetY : parseFloat(cameraTargetYStr) * cameralScale;
var cameraTargetZStr = getQueryStringByName(‘cameraTargetZ‘);
cameraTargetZ = cameraTargetZStr == "" ? cameraTargetZ : parseFloat(cameraTargetZStr) * cameralScale;
var upVectorXStr = getQueryStringByName(‘upVectorX‘);
upVectorX = upVectorXStr == "" ? upVectorX : parseFloat(upVectorXStr) * cameralScale;
var upVectorYStr = getQueryStringByName(‘upVectorY‘);
upVectorY = upVectorYStr == "" ? upVectorY : parseFloat(upVectorYStr) * cameralScale;
var upVectorZStr = getQueryStringByName(‘upVectorZ‘);
upVectorZ = upVectorZStr == "" ? upVectorZ : parseFloat(upVectorZStr) * cameralScale;
if(cameraType == 0) {
camera = new THREE.OrthographicCamera( window.innerWidth / - 2, window.innerWidth / 2, window.innerHeight / 2, window.innerHeight / - 2, 1, 10000 );
}
else {
camera = new THREE.PerspectiveCamera( perspectiveAngle, window.innerWidth / window.innerHeight, 1, 10000 );
}
camera.position.set( cameraPosX, cameraPosY, cameraPosZ);
camera.up.set(upVectorX, upVectorY, upVectorZ);
cameraTarget = new THREE.Vector3( cameraTargetX, cameraTargetY, cameraTargetZ );
camera.lookAt( cameraTarget );
scene = new THREE.Scene();
scene.fog = new THREE.Fog( 0xffffff, 1, 10000 );
// load file
var loader = new THREE.STLLoader();
var modelName = getQueryStringByName(‘modelName‘);
loader.load( ‘../Models/‘ + modelName, function ( geometry ) {
var material = new THREE.MeshPhongMaterial( { color: 0x808080, specular: 0x111111, shininess: 200 } );
var mesh = new THREE.Mesh( geometry, material );
mesh.castShadow = true;
mesh.receiveShadow = true;
scene.add( mesh );
} );
// lights
scene.add( new THREE.AmbientLight( 0x333333 ) );
addDirectionalLight(-1, 1, 1, 0xFFFFFF, 1.35);
addDirectionalLight(1, -1, -1, 0xFFFFFF, 1);
// renderer
renderer = new THREE.WebGLRenderer( { antialias: true } );
renderer.setClearColor( scene.fog.color );
renderer.setSize( window.innerWidth, window.innerHeight );
renderer.gammaInput = true;
renderer.gammaOutput = true;
renderer.shadowMapEnabled = true;
renderer.shadowMapCullFace = THREE.CullFaceBack;
container.appendChild( renderer.domElement );
// orbit control
control = new THREE.OrbitControls( camera, renderer.domElement );
// events
window.addEventListener( ‘resize‘, onWindowResize, false );
}
function addDirectionalLight( x, y, z, color, intensity ) {
var directionalLight = new THREE.DirectionalLight( color, intensity );
directionalLight.position.set( x, y, z )
scene.add( directionalLight );
}
function onWindowResize() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize( window.innerWidth, window.innerHeight );
}
function animate() {
requestAnimationFrame( animate );
render();
}
function render() {
// var timer = Date.now() * 0.0005;
//
// camera.position.x = Math.cos( timer ) * 3;
// camera.position.z = Math.sin( timer ) * 3;
renderer.render( scene, camera );
}
</script>
</body>
</html>
2.直接用Chrome打开文件STL.html，将会看到一下错误，那是因为不能打开本地模型文件，需要创建一个http server。
XMLHttpRequest cannot load file:///D:/L/Dev/WebViewer/Models/. Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, https, chrome-extension-resource.THREE.XHRLoader.load @ three.min.js:258
three.min.js:258 Uncaught NetworkError: Failed to execute ‘send‘ on ‘XMLHttpRequest‘: Failed to load ‘file:///D:/L/Dev/WebViewer/Models/‘.
3.本文使用python来创建一个http server，新建localServer.py文件，内容如下：
from threading import Thread
import webbrowser, http.server, socketserver
import time;
port_number = 8000
server = None
def startServer(port):
Handler = http.server.SimpleHTTPRequestHandler
global server
server = socketserver.TCPServer(("", port), Handler)
print("Start server at port", port)
server.serve_forever()
def start(port):
thread = Thread(target=startServer, args=[port])
thread.start()
startTime = int(time.time())
while not server:
if int(time.time()) > startTime + 60:
print("Time out")
break
return server
def stop():
if server:
server.shutdown()
def openUrl():
url = "http://localhost:" + str(port_number)
webbrowser.open(url)
print(url + " is opened in browser")
if __name__ == "__main__":
start(port_number)
openUrl()
4.文件夹结构如下：
Models - 模型文件夹，放置模型文件，例如bike_frame.stl。
threejs - threejs文件夹，放置threejs相关的库文件
5. 双击运行LocalServer.py启动一个http服务器。
6.在Chrome里面打开http://localhost:8000/WebGLViewer/STL.html?modelName=bike_frame.stl，如下图。
源代码地址：https://github.com/ldlchina/Sample-of-WebGL-with-STL-loader
相关链接: http://threejs.org/
时间： 2024-08-02 06:38:07