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Topic: Scene graph


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In the News (Mon 16 Nov 09)

  
  Scene graph - Wikipedia, the free encyclopedia
In vector-based graphics editing, each node in a scene graph represents some atomic unit of the document, usually a shape such as an ellipse or Bezier path.
Scene graphs are ideal for modern games using 3D graphics and increasingly large worlds or levels.
Very large drawings, or scene graphs that are generated solely at runtime (as happens in ray tracing rendering programs), require defining of group nodes in a more automated fashion.
en.wikipedia.org /wiki/Scene_graph   (2258 words)

  
 GameDev.net -- Understanding and Implementing Scene Graphs   (Site not responding. Last check: 2007-10-19)
The most popular question I get while explaining what a scene graph is - is: what is a scene graph?  Well a scene graph is a way of ordering your data into a hierarchy where parent nodes affect child nodes.
But scene graphs are a little bit more involved than a simple tree.  They represent some action to take place before proceeding to the children objects.  If this doesn't make sense now then don't worry it will all be explained in due time.
Now this scene graph is a lot more complex than what was originally presented, so let's go over the logical flow of the program now.
www.gamedev.net /reference/programming/features/scenegraph   (244 words)

  
 Dr. Dobb's | Understanding Scene Graphs | May 30, 2002
Scene graphs are data structures used to hierarchically organize and manage the contents of spatially oriented scene data.
Scene graph programming models support a variety of operations through traversals of the graph data structure that typically begin with the root node (root nodes are usually the entry point for scene rendering traversals).
Graph traversals are required for a number of operations, including rendering activities related to transformations, clipping and culling (preventing objects that fall outside of the user's view from being rendered), lighting, and interaction operations such as collision detection and picking.
www.ddj.com /184405094   (4431 words)

  
 System and method for encoding a scene graph - Patent 6243856
A typical scene graph is comprised of a plurality of nodes arranged in a tree structure, with invocation relationships defined among the nodes.
6 and 7, the scene is a teapot 600.
Generally speaking, according to this technique, the scene graph is traversed and where a USEFUNC defines a function in a context which was previously undefined or unused, a new cache or context is identified to maintain those results.
www.freepatentsonline.com /6243856.html   (16724 words)

  
 JTGame - Overview - Graphics and Scene Graph Architecture
Although the scene graph could be rendered directly from the scene graph by transversing the frame object hierarchy, there are a few reason why it is better not to do this, but to instead maintain a separate data structure I call a render engine.
For tying the scene graph node hierarchy together, the CGameFrame object stores a pointer to zero or one parent frames, depending on whether or not the frame is at the top of the hierarchy or not, and it stores an array of zero or more child frame object pointers.
In the scene graph, as described in the Visual Effect sections, during rendering, the complete set of render states for any particular node is determined by walking down the tree to that node via the OnRenderPrepare functions, applying render states by calling the OnRenderMember of any CGameRenderState objects found.
www.jtgame.com /jtovergraphics.html   (13546 words)

  
 Syzygy Documentation: Myriad Scene Graph
Python's internal reference counting mechanism is integrated with Myriad's, so that their combined operation is thread-safe (with respect, for instance, to node deletions from an external source, as in the case of a shared scene graph in peer-to-peer mode) and transparent to the programmer.
When reading this section, you'll first want to understand the basic design of the Myriad distributed scene graph, including how various kinds of state (lighting, texturing, coordinate arrays) are inherited to guide rendering where it actually takes place: at the "drawable" nodes.
The Myriad scene graph is thread-safe, for instance, with respect to drawing in multiple threads even with simultaneous deletions and other scene graph restructurings occur in still other threads.
www.isl.uiuc.edu /szg/doc/SceneGraph.html   (1659 words)

  
 J3D.ORG - Raw J3D: Chapter 1 - Scene Graph Basics
A scene graph is a hierarchical approach to describing objects and their relationship to each other.
Once you've added the branch graph to the locale, that branch graph, and anything you add to it, is considered live (we'll discuss the difference between live and dead scene graphs shortly).
If you have a scene graph that represents an arm with two transform groups, one each for elbow and wrist, setting the capability to write to the shoulder transform does not automatically allow you to write to the wrist or elbow transforms.
java3d.j3d.org /tutorials/raw_j3d/chapter1/scene_graph_basics.html   (3280 words)

  
 graph: netbeans.org : NetBeans Visual Library 2.0 - Documentation   (Site not responding. Last check: 2007-10-19)
When any widget is added/removed in the tree hierarchy of a scene or a widget is changed the way that affects its placement or boundary, then the widget (and the scene too) has to be validated again.
It is because the JComponent is not initialized yet and therefore the scene is not validated yet and therefore widget boundaries (which are usually required by the layout algorithms) are not resolved yet too.
Call this method after you have assigned all actions to the scene (since this action is internally added to the actions chain of the scene and the nature of the action is that it consumes all events while a mouse cursor is over the scene which usually happens all the time).
graph.netbeans.org /documentation.html   (9396 words)

  
 Aviatrix3D - Scenegraph Design Notes
One of the most important structures to scene graphs is the bounding box information that is used for culling, sorting, picking etc. Any change to a bounds low in the scenegraph can be quite costly forcing a large number of recalculations up the tree.
Firstly application code informs the scene graph that it would like to perform an update, and then at some point in the future the callback is made and the node will update the appropriate details.
Since we know which nodes of the scene graph had had their bounds altered, we can use this knowledge to optimise the updates without causing unnecessary recalculations for parts of the scene graph that have not changed.
aviatrix3d.j3d.org /impl/scenegraph.html   (1441 words)

  
 Computer Graphics : Java 3D : 13 / 35 : First look at the Scene Graph
The scene graph consists of superstructure components-a VirtualUniverse object and a Locale object-and a set of branch graphs.
Each branch graph is a subgraph that is rooted by a BranchGroup node that is attached to the superstructure.
Finally, the ViewPlatform is referenced by a View object that specifies all of the parameters needed to render the scene from the point of view of the ViewPlatform.
cs.anu.edu.au /escience/lecture/cg/Java3D/firstLook.en.html   (484 words)

  
 Introduction to Scene Graphs
The scene graph is assembled from objects to define the geometry, sound, lights, location, orientation, and appearance of visual and audio objects.
The path from the root of a scene graph to a specific leaf node is the leaf node’s scene graph path.
Since a scene graph path leads to exactly one leaf, there is one scene graph path for each leaf in the scene graph.
viz.aset.psu.edu /jack/java3d/intro.html   (730 words)

  
 Inverse Kinematics on the Java 3D(tm) Scene Graph
The scene graph is the emergent standard hierarchcal data structure for computer modeling of three dimensional worlds, but kinematic models of machines or mechanisms that have external constraints or constraints that span interior nodes do not sit comfortably on its open-branched tree topology.
The central failings of the bare scene graph are apparent from the figure.
Because a Constraint instance and its referenced Node each have particular positions in space by virtue of their positions on the scene graph, their relative positions (usually the mismatch between the current and desired displacements at the constraints) can be readily extracted by a few simple calls to Node geometry methods.
www.brockeng.com /VMech/IK/IKSG.htm   (2852 words)

  
 Game Object Structure: Scene Graphs Revisited
The effect is generated by adding a "fire" particle emitter as a child of the pine in the scene graph.
This is the most traditional form of scene graph, in which each node exists in the local space of its parent node.
In its loosest incarnation, a scene graph would simply be a tree of objects in which parents needed to be updated before children.
gamearchitect.net /Articles/GameObjects3.html   (790 words)

  
 Java3D- from Basics to Industrial Strength Application Building
A Scene graph which can be generically defined as an assembly of objects that have geometry, sound, light, location, orientation and appearance.
Assume a case where the scene is from a normal room of a house that contains a desk lamp and a book on a table and a clock on the adjoining wall.
First a scene graph is built from a Branch Group object, where a Cube object is attached to the branch group object.
www.geocities.com /kurienjoseph/Java3d.htm   (4566 words)

  
 Syzygy Documentation: Scene Graph Tutorial
This tutorial will walk you through working with the Syzygy scene graph from the Python prompt and introduce you to the concept of peer-to-peer reality.
This tutorial is complementary to the chapter describing the C++ scene graph API.
There are several scene graph examples written in Python.
www.isl.uiuc.edu /szg/doc/SceneGraphTutorial.html   (1422 words)

  
 Game Object Structure: Scene Graphs
Specifically, I'm concerned with the use of run-time hierarchy as used to represent a 3D scene in a scene graph.
A scene graph traditionally describes a particular physical universe in which every object moves rigidly in the space defined by its parent.
The scene graph thus acts outside the scope of a graphics engine and acts as a particularly limited physics engine, in which all constraints are absolute.
gamearchitect.net /Articles/GameObjects2.html   (1583 words)

  
 X3DToolKit: MESH scene graph API
The MESH scene graph is the re-ordered version of the X3D scene graph.
Moreover the scene graph is templated by the datas stored per vertex, edge, face and mesh, ensuring a fully customizable structure.
The translation of an X3D scene graph into a MESH scene graph conserves the global structure, but some differences are introduced.
artis.imag.fr /Software/X3D/doc/html/MESHSceneGraphAPI.html   (930 words)

  
 Scene Manager
The scene graph manager provides an API that the parser uses to create the nodes.
Because the scene graph manager is written mostly in Perl, except for the script language interfaces below, it will not be difficult to port FreeWRL to other operating systems or 3D APIs.
The routes are independent of the scene graph hierarchy.
www.perl.org /oscon/1998/User_Applications/FreeWRL/node5.html   (536 words)

  
 SCENE GRAPH
All 3D shapes, attributes, cameras, and light sources present in a scene are represented as nodes
Each field within a node is also a class, rather than a basic data type; for example, if a node needed to contain a single floating point value, it would have an SoSFFloat field data member rather than just a float, as in a C data structure.
"So" stands for scene object, and data types with this prefix are usually related to the scene graph; for example, all nodes have an "So" prefix.
web.mit.edu /1.125/www/OpenInv/scene_graph.html   (379 words)

  
 3D Theory - Using a scene graph for physics - Martin Baker
Below is a suggestion for new nodes to be added to a VRML-like scene graph to implement the behaviour proposed.
In addition to being updated from the acceleration field at every frame, velocity may be changed by the constraints and collision action nodes.
The reason for allowing a random factor is to allow a node to appear many times in a scene (by using DEF/USE, PROTO or Multiple Node) but to cause each instance of the node to start travelling in different directions.
www.euclideanspace.com /threed/games/data/usescenegraph/index.htm   (3625 words)

  
 osg File Loading   (Site not responding. Last check: 2007-10-19)
Load geometric models and add them to a scene, adjust the position of one of the models within the scene and view the scene by setting up a simulation loop.
Geometric models are represented as nodes of the scene graph.
So now we have a scene graph made up of a root node with two children, one is a geometric model of a cessna.
openscenegraph.org /documentation/NPSTutorials/osgFileLoading.htm   (579 words)

  
 NVSG SDK Details
The NVIDIA® Scene Graph (NVSG) Software Development Kit is an object-oriented programming library for creating scene graph-based applications.
Basically, a scene graph is a reusable, hierarchical data structure that describes the objects in a 3D scene—their size, position, orientation, visible properties, and relationships with one another.
Scene graphs can be used to display virtual scenes for a variety of purposes, including game engines, computer-aided design (CAD), scientific and commercial visualization, training, simulation, and modeling.
developer.nvidia.com /object/nvsg_details.html   (338 words)

  
 OpenRM - RM Library (rmscene.c)
When a non-NULL light source is assigned as a scene parameter, that light source becomes active, and has scope over the subtree rooted at the RMnode toModify within the scene graph.
The presence of a texture scene parameter will cause texture mapping to become active at the RMnode toModify, and will remain active using the supplied texture newTexture over the entire subtree rooted at the RMnode toModify, unless overridden by a different texture at a descendent node within the scene graph.
The viewport scene parameter defines a pixel rectangle in the window into which the final image is mapped.
www.openrm.org /docs/HTML/rmscene.c.html   (5070 words)

  
 Vega API
The Jolt software is further subdivided into three layers; a low-level library of basic utility functions (called psJlu), a scene graph management library (called psJlsg) that contains the actual OpenGL rendering code, and a thin compatibility layer (called psPf) that presents a Performer-like API to Vega.
The scene is the root node of our scene graph.
One we enter the simulation loop, the scene graph manager will traverse the scene graph and perform culling and drawing for us.
www.nps.navy.mil /cs/sullivan/MV4470/Tutorials/VegaSceneGraph.htm   (1099 words)

  
 Scene Graph Resources - GameDev.Net Discussion Forums   (Site not responding. Last check: 2007-10-19)
Posted - 10/6/2005 8:28:25 AM As scene graphs are a such an important and frequently questioned topic here (and else where) i decided to begin compiling a comprehensive listing of resource links about them for those interested in implementing/using them.
In the case of scene graphs implementated via the Composite pattern we have Grouping node types (they are the Composites) typically there will be an instantiable base Group node type who's sole purpose is child containment and
Observer - Scene Graphs are/use the Observer pattern implicitly without the developer realizing it but it can be used explicitly when scene graphs are DAGs because there maybe occasions where leaf nodes need to notify state changes to all parents (and there parent's parents and so on all the way upto the root/roots if necessary).
www.gamedev.net /community/forums/topic.asp?topic_id=349829   (1736 words)

  
 Open Scene Graph FAQ part 2 ( 51 thru 100 )
IThis unofficial Open Scene Graph (OSG) FAQ Part 2 (51 thru 100) is provided by Gordon Tomlinson, I hope you find the information contained with these FAQ's useful and helpful.
For example, a typical need is to obtain the current Height Above Terrain (HAT) information in a flight simulator or a driving simulator is determined by firing a vertical line segment from the aircraft or vehicle towards the terrain/ground and calculating the distance between the aircraft or vehicle and the intersection point on the ground.
The IntersectVisitor does ray/line segment intersections very efficiently by means of using the scene graph, node's bounding spheres and trivial rejection, all in the CPU, memory bound operations.
www.3dscenegraph.com /osg/osg_faq_2.htm   (4264 words)

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