Scene Management-Scene Graph

Scene GraphTherefore, it is a scenario diagram, or a "Graph" data structure used to organize a scenario. It is usually based on a logical relationship (such as the overall-Data is divided. Of course, data is divided by other relationships (such as spatial relationships and States. It is characterized by a hierarchical structure. The advantage of a hierarchical structure is that the data scale at a certain level can be greatly reduced compared with the overall data, and the scale-down can certainly improve efficiency. CommonScene GraphImplement a directed non-cyclic graph (Dag), Undirected non-circular connected graph (UdcgThat isTree.

 

To see how to useSGWhat are the benefits? Let's take a look at another one.Scene Graph.

 

Wildmagic (ver 1.07):

 

Features:

• Scenario diagram structure:Tree, That isNodeYes0-1ItemsParent node,0 -*ItemsChild Node

• Advantage: UseTree, Very concise and clear, convenientTraverse, From top to bottom, from bottom to top.
• disadvantages: node and geometry inherited from spatial , it is easy to cause expansion of the base class spatial , whether it is a member or an interface, in fact, some node spatial there are not many attributes, such as light .
• disadvantages: use the tree to node share is troublesome, for example, geometry entity share , class geometry parent only one of them can be shared. geometry , multiple geometry mount to different nodes .

• ry entity NO node , hanging on node lower
• How to crop cull :include BVl
• processing rendering status: not Supported state sort
• other details:

• TransformNoNode
• LightYesNode
• CameraNoNode

 

 

OSG (ver 2.8.1):

Features:

• Scenario diagram structure:DagTo achieve,NodeYes0 -*ItemsParent node,Group NodeYes0 -*ItemsChild Node

• Advantage: UseDagTo facilitate sharing.NodeEasy to expand. For example:Geometry.
• Disadvantage: MultipleParent nodesInconvenientTraversal.

• ry entity NO node , hanging on node lower
• How to crop cull :include BVl
• processing rendering status: state sort supported state cache

• Advantages:State sort, SameState setTo reduce rendering.StateOverhead of switchover.
• Advantages:State Cache, InStateUpdate and reduce when necessaryStateFrequent switchover and query.

• Other details:

• TransformYesNode

• Advantages:TransformAsNodeYesShare transform data, ReducedNode.

 

• LightYesNode
• CameraYesNode

 

 

Ogre (Ver: v1-4-7):

 

 

Features:

• Scenario diagram structure:TreeToTree, That isNodeYes0-1ItemsParent node,0 -*ItemsChild Node

• Advantage: UseTree, Very concise and clear, convenientTraverse, From top to bottom, from bottom to top.

• Relationship between ry and scene map:Geometry entityNoNode, HangingNode,GeometryCan be easily differentNodeShare.
• How to cropCull: IncludeBVl
• Processing of rendering status: supportedState sort

• Advantage: Upper Layer SupportRender strategyOfSort, Underlying supportMaterial/texture nameOfSort

• Other details:

• TransformYesNode

• Advantages:TransformAsNodeYesShare transform data, ReducedNode.

 

• light Yes node
• camera Yes node