----- Original Message ----- From: "Justin Couch" <[EMAIL PROTECTED]> To: "Fausto Mancini" <[EMAIL PROTECTED]> Sent: Tuesday, July 01, 2003 8:17 AM Subject: Re: [JAVA3D] [cyclic scene graph]
> Fausto Mancini wrote: > > > I am trying to manage a scene modeled by a graph. The problem is that the > > graph is cyclic (a node can have more than one parent). > > Having more than one parent does not define the graph as being cyclic. I think you are wrong here... Here is an example: A is parent of B. A is parent of C. D is parent of B. D is parent of A. This is a cyclic graph even if no node is parent of itself.... > Java3D allows you to create Directed Acyclic Graphs (DAG) of nodes in > the render. That means you cannot have a leaf become a parent of itself > in that graph. But, nowhere in your descriptions so far have you > indicated that this is a requirement. In fact, you've only been > describing DAG structures so far, which J3D can handle easily. In the official documentation it is stated that "A group node can have any number of children but only one parent. A leaf node can have one parent nad no children"; moreover: "The arcs of a tree form no cycles..." The same problem exists in VRML97. > Have a > look at the SharedGroup/Link combo. > This is not a solution... SharedGroups are referenced by one or more Link nodes and any modification of the SharedGroup affects all references to it (since SharedGroup is not directly added to the SceneGraph). The main purpose of SharedGroup/Link is the _re-use_ I think the problem is intrinsic in the j3d architecture (quoting: "Only one path exists from a root of the tree to each of the leaves..."). The same problem occurs when using DEF / USE bundle in VRML97. Thank you for the attention, Fausto. > -- > Justin Couch http://www.vlc.com.au/~justin/ > Java Architect & Bit Twiddler http://www.yumetech.com/ > Author, Java 3D FAQ Maintainer http://www.j3d.org/ > ------------------------------------------------------------------- > "Humanism is dead. Animals think, feel; so do machines now. > Neither man nor woman is the measure of all things. Every organism > processes data according to its domain, its environment; you, with > all your brains, would be useless in a mouse's universe..." > - Greg Bear, Slant > ------------------------------------------------------------------- > =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA3D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
