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Addtional details on the OpenSceneGraph and support.

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Robert Osfield 2002-04-23 13:12:37 +00:00
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@ -13,7 +13,7 @@
</p>
<p>The OpenSceneGraph is an Open Source (LGPL), Cross Platform (Widows, Linux, Mac OSX, FreeBSD, Irix, Solaris),
Standard C++ and OpenGL based graphics development library, uses range from visual simulation, games,
virtual reality, sceintific visualization and graphics research. This pages introduces a
virtual reality, sceintific visualization and graphics research. This pages introduces
what scene graphs are, why graphics developers use them, and details about the OpenSceneGraph,
project, how to learn how to use it and contribute to the OpenSceneGraph community.
</p>
@ -47,6 +47,8 @@ programs.
<h2>Why use a Scene Graph - Performance, Productivity, Portability and Scalability.</h2>
<ol>
<li>
<p><i>Performance</i> - scene graphs provide an excellent framework for maximize graphics
performance. A good scene graph employs two key techinques - culling of the objects that won't
be seen on screen, and state sorting of properties such as textures and materials
@ -57,7 +59,8 @@ process.very efficient.with whole town being culled with just a few operations!
states, stalling the graphics and destroying graphisc throughout. As GPU's get faster and faster, the cost of
stalling the graphics is also going up, so scene graph are become ever more important.
</p>
</li>
<li>
<p><i>Productivity</i> - scene graphs take much of the hardwork required to develop
high perftomance graphics applications. The scene graphs manage all the graphics for you,
reducing what would be thousands of lines of OpenGL down to a few simple calls..Furthermoe,
@ -67,17 +70,21 @@ tree strucutre perfectly which makes it highly flexible and reusable design - in
this means that it can be easily adapted it to solve your problems. Scene graph also often come
additional utilitie libraries which range for helping users set up and manage graphics
windows to import of 3d modes and images. All this together allows the user to achieve
a great deal with very little coding.A dozen lines of code can be enough to load your data
a great deal with very little coding. A dozen lines of code can be enough to load your data
and create an interactive viewer!
</p>
</li>
<li>
<p>
<i>Portability</i> - scene graphs encapsulate much of the lower level tasks of rendering
graphics and reading and writing data, reducing or even eradicating the platform specific
coding that you require in your own application. If the underlying scene graph is portable
then moving from platform to platform can be a simple as recompiling your source code.
</p>
</li>
<li>
</p>
<i>Scalability</i> - along with being able to dynamic manage the complexity of scenes
automatically to account for differences in graphics performance across a range of machines,
@ -86,19 +93,94 @@ of graphics machines, or multiprocessor/multipipe systems such as SGI's Onyx. A
will allow the developer to concentrate on developing their own application while the rendering
framework of the scene graph handles the differnt underlying hardware configurations.
</p>
</li>
</ol>
<hr>
<h2>So what about the OpenSceneGraph project?</h2>
<p>
The OpenSceneGraph is Open Source, all the source to is published under the
GNU Library General Public License (LGPL) which allows both open source and closed source
projects to use, modify and distribute it freely as long its usage complies with the
LGPL. The project has been developed over the last four years, initliated by Don Burns, and
then taken over by Robert Osfield who leads the continues to lead project, there are many
other contributors to the library, for a full list check out the AUTHORS file. Both Robert
and Don now work on the OpenSceneGraph in a professional capaciity provide consultancy
The OpenSceneGraph is an Open Source Scene Graph, and our goal is make the benifits
of scene gaph technology available to all. Our scene gaph is still in development,
but has already gained a great deal of respect amoungst the development community
for its high performance, cleaness of design and portability. Written entitely in
Standard C++ and OpenGL, it makes full use of STL and Design Patterns, and leverages
the open source development model to provide a development library that is legacy
free and well focused on the solving the task. The OpenSceneGraph delivers on
the four key benifits of scene graph techonolgy outlined above using the following
features:
</p>
<ol>
<li>
<p><i>Performance</i> - supports view frustum culling, small feature culling,
Leval Of Details (LOD') nodes, state sorting, vertex arrays and display list
as part of the core scene graph, these together make the OpenSceneGraph one
highest performance scene graph available. User feedback is that performance
surpasses much more established scene graphs such as Performer, VTee,
Vega Scene Graph and Jave3D! The OpenSceneGraph also supports easy customization
of the drawing process, which has allowed implemention of Continous Level of
Detail (CLOD) meshes ontop the scene graph, these allow the visualisation of
massive terrain databases interactively, examples of this approach can be
found at both Vterrain.org and TerrainEngine.com which both integrate with the
OpenSceneGraph.
</p>
</li>
</li>
<li>
<p><i>Productivity</i> - by combining lessons learned from established scene graph like
Performer and Open Inventor, with modern software engineering
methodologies like Design Patterns and a great deal of feedback early on
in the development cycle, it has been possible to design a design that clean
and highly interporable. This has made it easy for user to adopt to the
OpenSceneGraph and to integrate with their own applications. With a full
feature set in the core scene graph, utilities to set up the scene graph and
viewers and a wide range of loaders it is possible to create an application
and bring in user data with a very small amount of code.
</p>
</li>
<li>
<p>
<i>Portability</i> - The core scene graph has also been designed to be have minimal
platform speciific dependancy, requiring little more than Standard C++ and OpenGL.
The has allowed the scene graph to be rapidly ported on wide range of platforms -
originally developed on IRIX, then ported to Linux, then to Windows, then FreeBSD, then Mac OSX
and most recently Solaris! Being completely windowing system independant it easy
for users to add their own window specific libraries and applications on top.
In the distribution there is aleady the osgGLUT library, and in the Bazaar found
at openscenegrph.org/download/ once can find examples of how applications written
ontop Qt, MFC, WxWindows and SDL. Users have also integrated it with Motif, and X.
</p>
</p>
</li>
<li>
</p>
<i>Scalability</i> - the scene graph not only runs from portables all the way up
to Onyx Infinite Reality Monsters, it supports the multiple graphics subsystems
found on the machines like the a mulitpipe Onyx. This is possible since the core scene
graph supports multiple graphics context for both OpenGL DisplayLists and texture objects,
and the cull and draw traversals have been designed to cache rendering data locally and
use the scene gaph almost entirely as a read only operation. This allows multiple
cull-draw pairs to run on multiple CPU's which are bound to multiple graphics subsystems.
This has been demonstrated using the OpenSceneGraph in conjunction with sgi's OpenGL
multipipe SDK. We also have osgMP in development which will be cross platform and
transparently support multiple multipipe systems like th Onyx and gaphics clusters.
</p>
</li>
</ol>
<p>
All the source to is published under the GNU Library General Public License (LGPL)
which allows both open source and closed source projects to use, modify and
distribute it freely as long its usage complies with the LGPL. The project has been
developed over the last four years, initliated by Don Burns, and then taken over
by Robert Osfield who continues to lead project today, there are many other
contributors to the library, for a full list check out the AUTHORS file. Both Robert
and Don now work on the OpenSceneGraph in a professional capaciity providing consultancy
and bespoke developments ontop the library, and are also colloborating on the book.Work on
the core scene graph and support of public mailing list remains unpaid as are the
contributions of the rest of the communinity, but this hasn't impacted the quality of the
@ -106,13 +188,11 @@ source or support which once you get stuck in you grow to appreciate.
</p>
<p>
The project itself is written entitely in Standard C++ and OpenGL, makes full use of STL
and Design Patterns, and leverages the open source development model to provide clean, highly portable,
and flexible scene graph. The project is current in alpha, which means parts of the API are still to be
The project is current in alpha, which means parts of the API are still to be
developerd, or subjec to change, but the vast majority of the scene graph is there, and a beta will
be published within the next few months, wiht a 1.0 release in late summer. Despite the
alpha development status, the project has alrady earned the reputation as one of the leading
open source scene graphs, and is establishing itself a vialbe alternative to the commericial
alpha development status, the project has alrady earned the reputation the leading
open source scene graph, and is establishing itself a vialbe alternative to the commericial
scene graphs. Numerous companies, university researchers and graphics enthusasts have
already adopted their projects, and are from all over the world.
</p>
@ -120,9 +200,29 @@ already adopted their projects, and are from all over the world.
<hr>
<h2>How to learn to use the OpenSceneGraph</h2>
<p>
The OpenSceneGraph distribution comes with a reference guide for each of the componet libraries - osg, osgDB,
osgUtil, osgText and osgGLUT, a set of demos - the source of which can be found in src/Demos/.For questions
or help which can't be easily be answered by the reference guide and demo source, one should join the openscene
gaph mailing list. A programming guide will be avaialbe in form of a OpenSceneGraph book which is being
written by Don Burns and Robert Osfield, parts of it will be available.online.
</p>
<p>
Although not directly releated to the OpenSceneGraph, once can learn about scene graph technolgy from
such sources as the Open Inventor Mentor, and Performer Programming Guides. The later is the closest
in design/API structure to the OpenSceneGraph.</p>
<hr>
<h2>Support and discussion - the OpenSceneGraph-news mailing list</h2>
<p>
For scene graph related questions, bug reports, bug fixes, and general design and development discussion one should
join the OpenSceneGraph-news mailing list.
</p>
<p>
Professional support is also available in the form of confidential online, phone and onsite support and
consultancy, for details contact robert@openscengraph.com.</p>
</body>
</html>