Project

General

Profile

Wiki » History » Version 72

Josip Almasi, 08/24/2022 11:08 AM

1 4 Josip Almasi
{{toc}}
2
3 1 Josip Almasi
h1. Welcome!
4 2 Josip Almasi
5 18 Josip Almasi
h2. External resources
6 4 Josip Almasi
7 14 Josip Almasi
Demo site: https://www.vrspace.org/
8
9 15 Josip Almasi
Github project page: https://github.com/jalmasi/vrspace
10 2 Josip Almasi
11 63 Josip Almasi
OpenSource.com articles: 
12
https://opensource.com/article/20/12/virtual-reality-server
13
https://opensource.com/article/22/1/open-source-metaverse
14 3 Josip Almasi
15 15 Josip Almasi
VR Days video (features, technologies): https://vimeo.com/475142708
16 3 Josip Almasi
17 70 Josip Almasi
Open Source Metaverse video: https://www.youtube.com/watch?v=lIQd_3935Gk&list=PLbzoR-pLrL6rr72M1w7pTYw-X8FduLz1v&index=10
18
19 15 Josip Almasi
Youtube channel: https://www.youtube.com/channel/UCLdSg22i9MZ3u7ityj_PBxw
20 1 Josip Almasi
21 16 Josip Almasi
Facebook page: https://fb.com/vrspace.org
22 14 Josip Almasi
23
Client API jsdoc: https://www.vrspace.org/docs/jsdoc/index.html
24
25
Server javadoc: https://www.vrspace.org/docs/javadoc/index.html?overview-summary.html
26 4 Josip Almasi
27 72 Josip Almasi
London talk video: https://www.youtube.com/watch?v=lIQd_3935Gk
28
29 23 Josip Almasi
h2. Playgrounds
30
31
Multi-user interaction, shared objects: https://playground.babylonjs.com/#ZBK155
32
Multi-user world: https://playground.babylonjs.com/#Y6ILJ5
33
Avatar selection, portals: https://playground.babylonjs.com/#HDV7LA
34 24 Josip Almasi
VR Avatar template world: https://www.babylonjs-playground.com/#VXA0R3
35 23 Josip Almasi
36 17 Josip Almasi
h1. Frequently Asked Questions
37
38
h2. Is this open source, free to use and share?
39
40
Yes, it's all free and open. Server and client code is published under Apache 2 license, all 3D models published by their respective authors under Creative Commons Attribution license.
41
42
h2. Is there any documentation?
43
44
This is good place to start, this page links to all available resources.
45
46 45 Josip Almasi
h2. I want to build my space, where do I start?
47
48 46 Josip Almasi
This question prompted writing Getting Started section of this wiki, but set up basic development environment first.
49
You don't need to modify any of the server code, but you need to be able to get it from github and build it.
50
Once you do, start it up, and everything else is html 5 and javascript ES6.
51 45 Josip Almasi
52 66 Josip Almasi
h2. How do I create my own world(s)?
53
54
You can use any authoring tool that exports glTF: Blender, Unity, Unreal, to name a few. You will likely need some glTF exporter plugin.
55 67 Josip Almasi
Export your model in a folder under vrspace/content/worlds, vrspace server automatically picks it up, and creates another portal for it.
56 68 Josip Almasi
Save a screenshot of your world as jpg file in vrspace/content/worlds, and it will be used as portal texture.
57 66 Josip Almasi
58 17 Josip Almasi
h2. How many users can share a “world/space” simultaneously?
59
60
By default, number of users per space is not limited. There is a server parameter to limit that (org.vrspace.server.maxSessions) that can be specified either in config file or command line. Users that hit the limit remain in the queue for configurable timeout (org.vrspace.server.sessionStartTimeout, zero by default) until someone leaves. An error is raised on timeout.
61
62 39 Josip Almasi
h2. How can I implement custom authentication and/or authorization?
63 1 Josip Almasi
64 39 Josip Almasi
Typically you will authenticate users on your web server, before they enter the world. 
65
If that's not enough, you can implement your own "ClientFactory":https://github.com/jalmasi/vrspace/blob/master/server/src/main/java/org/vrspace/server/core/ClientFactory.java and configure it in "application.properties":https://github.com/jalmasi/vrspace/blob/master/server/src/main/resources/application.properties file.
66 1 Josip Almasi
This allows you to do your own database queries, REST calls or whatever else you may need to identify your users.
67
68 39 Josip Almasi
h2. How is that different from a game server?
69 38 Josip Almasi
70 40 Josip Almasi
It's not all that different, though the emphasis is different: vrspace.org is not focused on games specifically. It's more about multi-user 3D web, in particular WebXR, open standards and open source.
71 39 Josip Almasi
So while game servers usually don't bother with video/audio streaming, vrspace.org provides it out of the box, using WebRTC. On the other hand, there's nothing like game level in vrspace.org.
72 59 Josip Almasi
Basic difference is that, while game servers focus on sharing the state of the game, vrspace.org server shares the state of any number of objects. No object in particular special in any way, there's no 'game loop' object.
73 38 Josip Almasi
74 42 Josip Almasi
h2. How does inverse kinematics and motion tracking work in vrspace.org characters?
75 41 Josip Almasi
76 62 Josip Almasi
Everything is encapsulated "Avatar class":https://github.com/jalmasi/vrspace/blob/master/babylon/js/ui/avatar.js, but relies on observed glTF avatar structure. Heuristics used to analyze the character structure is explained in depth in "this research paper":https://www.researchgate.net/publication/356987355_TOWARDS_AUTOMATIC_SKELETON_RECOGNITION_OF_HUMANOID_3D_CHARACTER.
77 41 Josip Almasi
78 56 Josip Almasi
h2. Why websockets?
79
80
Since death of internet explorer, websockets just work, in any browser. Some reliable multicast protocol would do better job for object state distribution, but no such protocol is supported by web browsers. WebRTC on the other hand is widely supported, but is unreliable, and requires complex development environment setup.
81
82 60 Josip Almasi
h2. Can I make/buy and use my own unique avatar?
83
84
Sure you can, but note that technically you can't prevent anybody else from copying and using it. Using video avatar is the only practical option to have unique appearance.
85
86 64 Josip Almasi
h2. How to enable https?
87
88 65 Josip Almasi
The server comes bundled with self-signed certificate, so all you need to do to enable SSL is change *server.ssl.enabled* property in "application.properties":https://github.com/jalmasi/vrspace/blob/master/server/src/main/resources/application.properties to true. You may also want to set *server.port* to 443.
89 64 Josip Almasi
90 47 Josip Almasi
h1. Getting started
91
92
So, you're new to VRSpace, and you want to make yourself a new virtual world.
93
You will not need to change any of the server code, but you need to get it from github, build it, and start it.
94
Once done, familiarize yourself with directory structure, and especially with template world, as this is intended stating point.
95
96
h2. Directory structure
97
98
h3. server
99
100
Contains the server code and configuration. Generally you don't need to change the code, but you may want to change the configuration. Main configuration file is in src/main/resources/application.properties, have a look at what you can change.
101 50 Josip Almasi
The server executable is a jar file in target subdirectory.
102 47 Josip Almasi
103
h3. babylon
104
105
This is reference Babylon.js client implementation. You don't really need any of it, but it is highly recommended to build on top of it, using javascript code provided there.
106
Html files there implement and/or test different functions available, like avatar loading and movement, video/audio streaming etc.
107
Most important one is avatar-selection.html, this is main entry point that allows user to select avatar and enter a world.
108
109
h3. web
110
111
This is the actual web site that's available online on vrspace.org, your final web site will probably look somewhat like this.
112
113
h3. content
114
115
Actual web content used to build virtual worlds, with self-explanatory directory names. Two of these contain special attention though:
116
117
h4. char
118
119
Characters, under female, male and other subdirectories. These directories are listed and presented by avatar-selection.html, you will probably to change how it works eventually.
120 48 Josip Almasi
But adding or removing characters is as simple as dropping them here.
121 47 Josip Almasi
122
h4. worlds
123
124 48 Josip Almasi
Available worlds, also listed by avatar-selection.html, and displayed as portals. Every subdirectory contains one world, and also note there's an image with the same name - that's thumbnail displayed on the portal.
125 49 Josip Almasi
Every world has some specific features.
126
Paris is huge, a real-life model.
127
Persian city and Aladin both feature the same procedural terrain and plants.
128 1 Josip Almasi
Cave is an actual game level, and utilizes floors built with vrspace.org floor editor.
129 50 Josip Almasi
Classrooom allows for sharing screen.
130
But the template is where you start - copy it over to another directory, and edit to suit your needs.
131
132
h2. Your first world
133
134 51 Josip Almasi
So with the server running, copy the template directory to your own. This world is immediately listed at http://localhost:8080/content/worlds/ and also available in http://localhost:8080/babylon/avatar-selection.html as a portal.
135 1 Josip Almasi
All you need to do to replace that dolphin with your own world is to replace this.file='dolphin.glb' in world.js with your own file name. Or really, delete the entire constructor, and save your world as scene.gltf in the same directory.
136 51 Josip Almasi
Hit reload button/key in your web browser, changes become visible immediately.
137 50 Josip Almasi
138
There are two files there, a html and a js, but html also contains some javascript.
139 52 Josip Almasi
The idea behind this separation of concerns is that world.js contains all programming logic that relates to the world itself, it should not depend on any server functionality. So build your world first, then add multi-user functions to it. Javascript in the world.html file shows some basic multiuser functions. As these grow, you'll probably want them in another javascript file, but these are minimum to get started.
140 50 Josip Almasi
141 51 Josip Almasi
Hopefully comments world.js and world.html explain enough to get started. As you need more functionality, look at other worlds and copy it over.
142 47 Josip Almasi
143 4 Josip Almasi
h1. Setting up development environment
144
145
Here's all you need to start development on Windows.
146 20 Josip Almasi
Linux distributions include all these tools as native packages, so no additional downloads should be required.
147 4 Josip Almasi
148
h2. Basic setup
149
150
h3. Git bash
151
152
IDEs can work with github directly, but whatever you ask, you'll get a command line answer.
153
Command line git is simply a must have. Bash also includes a lot of goodies like ssh.
154
155
https://git-scm.com/downloads
156
157
h3. Java
158
159 21 Josip Almasi
Java 8 will work, java 11 recommended. JDK is required to build the server.
160
Get it either from Oracle or elsewhere, e.g. Zulu OpenJDK: https://www.azul.com/downloads/zulu-community/?package=jdk
161 4 Josip Almasi
162
h3. Node.js
163
164
Node is used by IDE to evaluate javascript. You'll also may need it if you modify any of babylon.js source.
165
Mind that IDE will complain if you installed unsupported version of Node; should that happen, remove Node, and install latest one supported.
166
167
Get it from https://nodejs.org/
168
169 19 Josip Almasi
h3. Maven
170
171
Apache Maven is used to build the server from command prompt.
172
173
Get it from https://maven.apache.org/download.cgi
174
175
176 4 Josip Almasi
h3. IDE
177
178
Eclipse for Java developers (not enterprise), with Spring and Web plugins:
179
180
Download eclipse here: https://www.eclipse.org/
181
182
And then go to Help -> Eclipse Marketplace
183
Search and install Spring Tools 4 and Wild Web Developer plugins.
184
185 6 Josip Almasi
You'll also need to download and install https://projectlombok.org/
186 8 Josip Almasi
Once done, restart the eclipse.
187 6 Josip Almasi
188 5 Josip Almasi
h2. Import and start the project
189
190 22 Josip Almasi
h3. IDE
191
192 5 Josip Almasi
In Eclipse, you can use either default or new workspace for the project.
193
Assuming you have cloned the project from the github, 
194
Go to File -> Open Projects From the Filesystem
195
Then choose vrspace directory.
196
197
This will import vrspace folders and project subfolders, click Finish.
198
199
In vrspace project folder, in src/main/java, there's org.vrspace.server.ServerApplication.java.
200
Open it, then right click on the code.
201
From the menu, choose either Run as or Debug as -> Spring Boot App.
202
203
Open http://localhost:8080/babylon/connect.html with two browsers, and navigate around.
204
205
That's all, you're all set!
206 22 Josip Almasi
207
h3. git bash
208
209
git clone https://github.com/jalmasi/vrspace.git
210
cd vrspace
211
mvn clean install
212 69 Nick Naglich
java -jar target/server-0.4.5-SNAPSHOT.jar
213 4 Josip Almasi
214
h2. Advanced setup
215
216 12 Josip Almasi
h3. SSL
217 4 Josip Almasi
218 12 Josip Almasi
HTTPS is required for pretty much everything - WebXR, camera, mic access.
219
By default, the server runs on 8080 port with plain HTTP. To enable HTTPS, edit application.properties (found in src/main/resources), and change following properties:
220 1 Josip Almasi
221 12 Josip Almasi
<pre>
222
server.ssl.enabled=false
223
# default port 8080
224
#server.port=8443
225 13 Josip Almasi
</pre>
226 12 Josip Almasi
227
h3. Apache
228
229
Apache reverse proxy setup, linux, windows, TBD
230 4 Josip Almasi
231
h3. Docker and OpenVidu
232
233
OpenVidu voice/video chat server runs as docker image. This is only required for development of voice chat functions.
234
235 71 Josip Almasi
Modify openvidu.publicurl and openvidu.secret in application.properties, or run server.jar with -Dopenvidu.publicurl=YOUR_URL and -Dopenvidu.secret=YOUR_SECRET
236
237
h4. Local execution (development)
238
239 1 Josip Almasi
docker run -p 4443:4443 --rm -e OPENVIDU_SECRET=YOUR_SECRET -e DOMAIN_OR_PUBLIC_IP=YOUR_IP openvidu/openvidu-server-kms:2.17.0
240
241 71 Josip Almasi
Enter a space. You may get
242
WebSocket connection to 'wss://YOUR_IP:4443/openvidu?sessionId=cave' failed: Error in connection establishment: net::ERR_CERT_AUTHORITY_INVALID
243
in the console. To get rid of it, open https://YOUR_IP:4443/ and accept the cert.
244
(using localhost as YOUR_IP may not work)
245
246
h4. Running on server
247
248 11 Josip Almasi
https://docs.openvidu.io/en/2.17.0/deployment/deploying-on-premises/
249
250 25 Josip Almasi
251
h1. Software Architecture
252 26 Josip Almasi
253
!https://redmine.vrspace.org/attachments/download/15/vrspace-diagram.png!
254
255
h2. Client-Server Communication
256
257 31 Josip Almasi
Clients communicate with server by sending JSON messages over "WebSockets":https://en.wikipedia.org/wiki/WebSocket. Reference javascript implementation of client communication layer is in "VRSpace.js":https://www.vrspace.org/docs/jsdoc/VRSpace.html.
258 26 Josip Almasi
259
General approach to communication is rather obscure Half-Object pattern: server-side and client-side object have same properties, but different implementations.
260
Whenever an object's property changes in (any) client's address space, it's transmitted to the server, that broadcasts it to all clients currently 'watching' the object.
261
262
Whenever a client wants to perform any change to any object in the space, it has to go through the VRSpace server.
263
Clients may or may not communicate directly, but this is out of the scope of VRSpace server.
264
265
h2. Server Responsibilities
266
267
Sole responsibility of VRSpace server is management of 3D space: persisting space objects, tracking their properties, processing and distributing events from/to objects.
268 27 Josip Almasi
Whenever we talk about objects, that includes clients, i.e. users - a client is a special case of an object.
269
The server does not even handle the authentication - it is assumed to be responsibility of web app serving the space.
270
3D geometry is also not in server's scope, it's just another property of an object (mesh).
271
272
h2. Server design
273
274
Key concepts here are Active Objects, Actor model, and Live distributed object.
275
276 53 Josip Almasi
"VRObject":https://github.com/jalmasi/vrspace/blob/master/server/src/main/java/org/vrspace/server/obj/VRObject.java is a basic shared object, with some basic properties like position and rotation, and of course, mesh. It essentially a "Business object":https://en.wikipedia.org/wiki/Business_object acting as a "Live distributed object":https://en.wikipedia.org/wiki/Live_distributed_object.
277 27 Josip Almasi
278 28 Josip Almasi
"Client":https://github.com/jalmasi/vrspace/blob/master/server/src/main/java/org/vrspace/server/obj/Client.java extends VRObject, and adds capabilities to communicate over web sockets, and listen to changes to other objects. Typically, a client represents a remote user, but it can also represent a robot connected over a web socket, or be a base class for a server-side robot.
279
A Client can be thought of as "Active Object":https://en.wikipedia.org/wiki/Active_object or an "Actor":https://en.wikipedia.org/wiki/Actor_model, 
280 27 Josip Almasi
281
Server relies on Spring Boot and embedded Tomcat to handle all I/O and threads.
282 29 Josip Almasi
283 55 Josip Almasi
Design does not require websockets in particular, in fact some reliable multicast protocol would surely fit better. Websockets work in web browsers.
284
285 33 Josip Almasi
h3. Client
286 29 Josip Almasi
287 30 Josip Almasi
Each "Client":https://github.com/jalmasi/vrspace/blob/master/server/src/main/java/org/vrspace/server/obj/Client.java has it's own "Scene":https://github.com/jalmasi/vrspace/blob/master/server/src/main/java/org/vrspace/server/core/Scene.java that tracks all shared objects - including other clients - visible by the client. The scene is initially populated once the client logs in to the server, and starts the session. Scene is refreshed periodically, after a movement, or explicitly.
288 29 Josip Almasi
289
Scene maintains the event model, by adding the Client as listener to all other active objects (usually other users) in the scene.
290 1 Josip Almasi
291 30 Josip Almasi
Client simply notifies it's own listeners on any changes to any of it's own properties. As a listener, it propagates any observed change on any other object over the network, to the user.
292
293
Client has just a couple of persistent properties, like position, rotation and name. The name must be unique.
294
All other properties are transient.
295
296 33 Josip Almasi
"ClientFactory":https://github.com/jalmasi/vrspace/blob/master/server/src/main/java/org/vrspace/server/core/ClientFactory.java allows for customization of Client class and instances.
297 1 Josip Almasi
298 33 Josip Almasi
h3. Events and messages
299
300 30 Josip Almasi
Typically events exchanged are changes to properties of active objects, e.g. user moves around, changing own position and rotation. However, an object may emit any event, and the event gets propagated to all listeners.
301 1 Josip Almasi
This is to simplify client development: simply emit any custom event you want.
302 32 Josip Almasi
All distributed events are encapsulated in "VREvent":https://github.com/jalmasi/vrspace/blob/master/server/src/main/java/org/vrspace/server/dto/VREvent.java class.
303
304
However, there are other types of messages that are not distributed to other clients: commands and their return values, and errors.
305 1 Josip Almasi
Client will typically execute at least one command during the session - "Session":https://github.com/jalmasi/vrspace/blob/master/server/src/main/java/org/vrspace/server/dto/Session.java start. It will not receive any messages before that.
306
Should any server-side exception occur during the session, errors are sent to the client as simple JSON maps.
307 33 Josip Almasi
308
"WorldManager":https://github.com/jalmasi/vrspace/blob/master/server/src/main/java/org/vrspace/server/core/WorldManager.java manages clients and event distribution between them.
309
310
h3. Worlds
311
312
A server can host many worlds, i.e. shared spaces. A world contains users and other objects that are shared only within the world. It can be thought of as a chatroom, but mind the difference: being in the same world does not mean that users can see and talk to each other.
313
Client can enter another world by issuing "Enter":https://github.com/jalmasi/vrspace/blob/master/server/src/main/java/org/vrspace/server/dto/Enter.java command.
314
315 35 Josip Almasi
h3. Ownership and privacy
316
317
A class can be annotated as Owned, and all of instances automatically become owned as they are created. An owned object does not receive events from anyone by owner(s). A Client is owned, and nobody but himself can change his name.
318
On the other hand, a generic VRObject is public, and receives events from anyone. Like a door, anybody can open and close it. But even public objects can have some properties annotated as Owned, that can't be change by anyone but owner.
319
Fields of a class can be annotated as Private, and their contents will never be published.
320
321
"Dispatcher":https://github.com/jalmasi/vrspace/blob/master/server/src/main/java/org/vrspace/server/core/Dispatcher.java takes care of it before property changes are applied, and before they are published to listeners.
322
323 33 Josip Almasi
h3. Package structure
324
325
Package "org.vrspace.server":https://github.com/jalmasi/vrspace/tree/master/server/src/main/java/org/vrspace/server contains only main application class. Under it,
326
- config package contains server configuration classes that are executed only on server statup
327
- core is the core of the server
328 34 Josip Almasi
- dto is misnomer that stands Data Transfer Objects, though this package contains all objects that are not shared nor persisted
329 33 Josip Almasi
- obj contains persistent objects, most importantly Client and VRObject
330
- types are custom types used elsewhere, be it interfaces or annotations
331
- web is a primitive admin interface, disabled by default
332 54 Josip Almasi
- api contains REST controllers