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--></style></head><body lang=EN-US link=blue vlink="#954F72"><div class=WordSection1><ul style='margin-top:0in' type=disc><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level1 lfo1'>> >as well as our "scene graph"</li></ul><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>VRML/X3D uses a special sort of scenegraph called a DAG. <o:p></o:p></p><p class=MsoNormal>This is important for x3d, notice how DEF/USE works. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Joe<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><div style='mso-element:para-border-div;border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='border:none;padding:0in'><b>From: </b><a href="mailto:michalis.kambi@gmail.com">Michalis Kamburelis</a><br><b>Sent: </b>Thursday, January 17, 2019 12:56 AM<br><b>To: </b><a href="mailto:iamhereintheworld@gmail.com">iam here</a><br><b>Cc: </b><a href="mailto:x3d-public@web3d.org">X3D Graphics public mailing list</a><br><b>Subject: </b>Re: [x3d-public] Beginner questions</p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>iam here <iamhereintheworld@gmail.com> wrote:</p><p class=MsoNormal>><o:p> </o:p></p><p class=MsoNormal>> Michalis Kamburelis said:</p><p class=MsoNormal>> >as well as our "scene graph"</p><p class=MsoNormal>><o:p> </o:p></p><p class=MsoNormal>> OK, I don't know what a "scene graph" is, but....does it have something to do with Graph Theory, as taught in Computer Science?</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>X3D represents 100% of the scene as a graph of nodes: you have a</p><p class=MsoNormal>"Transform" node, and as children it can have other "Transform" nodes,</p><p class=MsoNormal>or a "Shape" node, or many others. It is usually a simple tree (a</p><p class=MsoNormal>special case of a graph, probably the simplest one), but sometimes</p><p class=MsoNormal>it's more complicated (due to DEF / USE in X3D).</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>This concept is actually present in most (if not all?) of 3D APIs and</p><p class=MsoNormal>3D model formats.</p><p class=MsoNormal>- glTF also has a transformation hierarchy, which is a tree of</p><p class=MsoNormal>transformation nodes, IOW also a graph.</p><p class=MsoNormal>- Unity has a transformation hierarchy which is a tree of GameObject instances.</p><p class=MsoNormal>- Castle Game Engine exposes a graph of X3D nodes to the programmer</p><p class=MsoNormal>(and we also have a tree of TCastleTransform instances).</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Yes, the term "graph" means here the same thing as "graphs" they talk</p><p class=MsoNormal>about in the "Graph Theory" course :) But you don't really to know any</p><p class=MsoNormal>advanced theory to understand it. A graph is a set of "things"</p><p class=MsoNormal>(nodes), and some of those things are connected. That's it, in a</p><p class=MsoNormal>nutshell :)</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Regards,</p><p class=MsoNormal>Michalis</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>_______________________________________________</p><p class=MsoNormal>x3d-public mailing list</p><p class=MsoNormal>x3d-public@web3d.org</p><p class=MsoNormal>http://web3d.org/mailman/listinfo/x3d-public_web3d.org</p><p class=MsoNormal><o:p> </o:p></p></div></body></html>