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| Index | -Introduction | -Contents | -Install | -Dependencies | -Demos | -Data | -Viewer | -Stereo | -Reference Guides | -
| Index | + +Introduction | + +Contents | + +Install | + +Dependencies | + +Demos | + +Data | + +Viewer | + +Stereo | + +Reference Guides | +
Welcome to OpenSceneGraph project! -
-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 -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. -
- --Robert Osfield, -Project Lead. -April 2002. -
- +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, scientific 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. +
Robert Osfield, Project Lead. April 2002.
+
Its a tree! Quite simply one the best and most reusable data structures invented.Typically drawn schematically as -root at the top, leaves at the bottom. It all starts with a topmost root node which -encompasses your whole virtual world, be it 2D or 3D. The world is then broken down -into hierachy of nodes representing either a spatial grouping of objects, -setting the position of objects, animating objects,. or define a logical relationship between objects such as to manage -the various states of a traffic light.The leaves of the graph represent the phyical objects -themselves, the drawable geometry and their material properties. -
- -A scene graph isn't a complete game or simulation engine, although may be one of the main -components of such an engine, it's primary focus is representing your 3d worlds, and rendering it efficiently. Physics models, collision detection and audio are left to other development libraries that a user will -integrate with.. The fact that scene graphs don't typically integrate all these features -is actually a really good thing, it aids interoprability with clients own applications -and tools they wish to use and allows them to serve many varied markets from games, visual -simulation, virtual reality, scientific and commerical visulasation, training thruogh to modelling -programs. -
- +A scene graph isn't a complete game or simulation engine, although may
+be one of the main components of such an engine, it's primary focus is
+representing your 3d worlds, and rendering it efficiently. Physics models,
+collision detection and audio are left to other development libraries that
+a user will integrate with.. The fact that scene graphs don't typically
+integrate all these features is actually a really good thing, it aids interoprability
+with clients own applications and tools they wish to use and allows them
+to serve many varied markets from games, visual simulation, virtual reality,
+scientific and commercial visualization, training through to modeling programs.
+
Performance - 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 -so that all similar objects are drawn together. Without culling the CPU, buses and -GPU will all become swamped by many times the amount of data tham they acual require.to represent -you work accurately. The hierachical structure of the scene graph makes this culling -process.very efficient.with whole town being culled with just a few operations! Without state storting, the the buses and GPU will thrash between -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. -
-Productivity - 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, -one of most powerfukl concepts in Object Orientated programming is that of object -compotsition, enshrined in Composite Design Pattern, which fits the scene graph -tree strucutre perfectly which makes it highly flexible and reusable design - in real terms -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 +
+Performance - scene graphs provide an excellent framework for +maximize graphics performance. A good scene graph employs two key techniques +- culling of the objects that won't be seen on screen, and state sorting +of properties such as textures and materials so that all similar objects +are drawn together. Without culling the CPU, buses and GPU will all become +swamped by many times the amount of data than they actually require to +represent you work accurately. The hierarchical structure of the scene +graph makes this culling process very efficient with whole town being culled +with just a few operations! Without state sorting, the the buses and GPU +will thrash between states, stalling the graphics and destroying graphics +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. +
+Productivity - scene graphs take much of the hard work required +to develop high performance 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, one of most powerful concepts +in Object Orientated programming is that of object composition, enshrined +in Composite Design Pattern, which fits the scene graph tree structure +perfectly which makes it highly flexible and reusable design - in real +terms this means that it can be easily adapted it to solve your problems. +Scene graph also often come additional utility 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 and create an interactive viewer! -
--Portability - 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. -
-+Portability - 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. +
+Scalability - along with being able to dynamic manage the complexity +of scenes automatically to account for differences in graphics performance +across a range of machines, scene graphs also make it much easier to manage +complex hardware configurations, such as clusters of graphics machines, +or multiprocessor/multipipe systems such as SGI's Onyx. A good scene graph +will allow the developer to concentrate on developing their own application +while the rendering framework of the scene graph handles the different +underlying hardware configurations. +
-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: -
- +Performance - 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. -
-Productivity - by combining lessons learned from established scene graph like -Performer and Open Inventor, with modern software engineering +
+Performance - supports view frustum culling, small feature culling, +Level 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 implementation of Continuos Level +of Detail (CLOD) meshes on top the scene graph, these allow the visualization +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. +
+Productivity - 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. -
--Portability - 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 makes 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. -
- -+Portability - The core scene graph has also been designed to +be have minimal platform specific dependency, 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 independent makes it easy for +users to add their own window specific libraries and applications on top. +In the distribution there is already the osgGLUT library, and in the Bazaar +found at openscenegrph.org/download/ once can find examples of how applications +written on top Qt, MFC, WxWindows and SDL. Users have also integrated it +with Motif, and X. +
+Scalability - 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 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 the Onyx and graphics clusters +
-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 -source or support which once you get stuck in you grow to appreciate. -
- --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 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. -
- +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, initiated 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 capacity providing consultancy and bespoke developments +on top the library, and are also collaborating 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 community, but this hasn't impacted +the quality of the source or support which once you get stuck in you grow +to appreciate. +The project is current in alpha, which means parts of the API are still
+to be developed, or subject to change, but the vast majority of the scene
+graph is there, and a beta will be published within the next few months,
+with a 1.0 release in late summer. Despite the alpha development status,
+the project has already earned the reputation the leading open source scene
+graph, and is establishing itself a viable alternative to the commercial
+scene graphs. Numerous companies, university researchers and graphics enthusiasts
+have already adopted their projects, and are from all over the world.
+
-The first thing is to select the distribution which suits you, there are binary, development and -source code distributions, these can be loaded from the -http://www.openscenegraph.org/download page. -The latest developments area available as via a nightly tarball or via cvs. -
- --The binary distribution contains just the libraries (.dll's /.so's) and demo executables. -This is suitable for using the OpenSceneGraph with an application that has already been compiled -but depends at runtime on the OpenSceneGraph. -
- --The development distribution contains the libraries (.dll's /.so's), demo executabls, include files, and source to -the demos. This is suitable for using the developers using the OpenSceneGraph. -
- --The source distribution contains the all the source and include files required to build the OpenSceneGraph from -sratch, and is ideal if you want to learn more about how the scene gaph works, how to extend it, and to track -down and fix any problems that you come across. -
- --If you are using a source disitribution then read the installation instructions -for how to get the OpenSceneGraph compiling and installed on your system. You may also need to download -libraries that parts of the OpenSceneGraph is dependant upon such as glut, check the -dependencies list for futher details. -
- - +The binary distribution contains just the libraries (.dll's /.so's) +and demo executables. This is suitable for using the OpenSceneGraph with +an application that has already been compiled but depends at runtime on +the OpenSceneGraph. +
The development distribution contains the libraries (.dll's /.so's), +demo executables, include files, and source to the demos. This is suitable +for using the developers using the OpenSceneGraph. +
The source distribution contains the all the source and include files +required to build the OpenSceneGraph from scratch, and is ideal if you +want to learn more about how the scene graph works, how to extend it, and +to track down and fix any problems that you come across. +
If you are using a source distribution then read the installation
+instructions for how to get the OpenSceneGraph compiling and installed
+on your system. You may also need to download libraries that parts of the
+OpenSceneGraph is dependent upon such as glut, check the
+dependencies
+list for further details.
+
-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 (details below).There is also the beginings of Wiki based FAQ -which may help answer a few of the common querries. - - -
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. -
- --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 concepts to the OpenSceneGraph, although Performer manuals is in C alas. -
- --The OpenSceneGraph uses OpenGL and does with a deliberately thin layer, making it easy to control the underlying -OpenGL and to extend it with OpenGL extensions. The close tie with OpenGL is also reflected in the nameing -of many of the OpenGL state related classes, the the parameters that they encapsulate and means that knowledge -of OpenGL itself will go a long way to understanding how to get the best out of the OpenSceneGraph. To this -end it is worth obtaining a copy of the OpenGL programming guide - `Red Book` -and OpenGL reference guide 'Blue Book'. The main OpenGL website is also a good source of links and further information. -
+A programming guide will be available in form of a OpenSceneGraph book +which is being written by Don Burns and Robert Osfield, parts of it will +be available online. +
Although not directly related to the OpenSceneGraph, once can learn +about scene graph technology from such sources as the Open +Inventor Mentor, and Performer +Programming Guides. The later is the closest in design concepts to +the OpenSceneGraph, although Performer manuals is in C alas. Also of use +as a background to some of the techniques used is a SIGGRAPH Vis-Sim +course. +
The OpenSceneGraph uses OpenGL and does with a deliberately thin layer,
+making it easy to control the underlying OpenGL and to extend it with OpenGL
+extensions. The close tie with OpenGL is also reflected in the naming of
+many of the OpenGL state related classes, the the parameters that they
+encapsulate and means that knowledge of OpenGL itself will go a long way
+to understanding how to get the best out of the OpenSceneGraph. To this
+end it is worth obtaining a copy of the OpenGL programming guide - `Red
+Book` and OpenGL reference guide 'Blue Book'. The main OpenGL
+website is also a good source of links and further information.
+
-For scene graph related questions, bug reports, bug fixes, and general design and development discussion one should -join the openscenegraph-news mailing list, -and check the the mailing list archives. -
--Professional support is also available in the form of confidential online, phone and onsite support and -consultancy, for details contact Robert Osfield at robert@openscenegraph.com.
+Professional support is also available in the form of confidential online, +phone and onsite support and consultancy, for details contact Robert Osfield +at robert@openscenegraph.com.