Re: [JAVA3D] NURBS rendering in Java3D

[Andrew Phelps]

Anirban ,   I agree that there would substantial work involved in writing a comprehensive NURBS library, but a limited library with NURBS curve/surface creation and simple editing could be achieved fairly rapidly. (Correct me if I’m wrong, but the OGL does not support advanced NURBS functionality either - except for surface trimming). Granted – trimmed NURBS are a different kettle of fish (I have not looked at this in great detail, so can’t comment on the complexity) – and so I agree that it is probably easier to try and rap the OGL’s functionality (again I can’t comment on the complexity). As to whether I know of any good NURBS library that supports surface trimming I’m afraid I don’t.  Perhaps someone will fill the market soon?   Sorry I can’t help further.   Regards,   Andy Phelps       -----Original Message----- From: Anirban Bhadore [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 21, 2000 11:53 AM To: [EMAIL PROTECTED] Subject: Re: [JAVA3D] NURBS rendering in Java3D   Hi Andy,   Actually thats a huge task and the current project does not have that in scope.   Do you know any good NURBS facetter available which supports TRIMMED NURBS faceting. I am using Parasolid Library for that purpose right now, but its as heavy as 14MB !   Thanks a lot for your reply.   with regards, Anirban  ----- Original Message ----- From: Andrew Phelps To: [EMAIL PROTECTED] Sent: Tuesday, June 20, 2000 6:56 PM Subject: Re: [JAVA3D] NURBS rendering in Java3D   Anirban,   Have you thought about separating the NURBS engine from the Graphics engine and writing your own NURBS package?  You would then have full control over the NURBS implementation, and would be able to draw NURBS curves/surfaces on any context (awt, 2D, 3D) without having to access the OGL. The development time may be more costly, but I’m sure there are many people out there who would be keen to get their hands on a good package.   There is a good book: [‘The NURBS Book’, Les Pegl & Wayne Tiller, ISBN3-540-61545-8, Springer ] which contains a very good detailed description of NURBS.  It covers the maths behind NURBS and a number of operations (knot insertion/refinement, degree elevation, curve fitting etc), and contains pseudo code detailing some of the most popular NURBS algorithms.   Regards,   Andy Phelps freecom.net consulting ltd ================ Anirban,   I would write my own Java classes to decompose a NURB into a triangle strip which could then be part of a scenegraph. There is some sample code to do this in one of the Graphics Gems books that you could covert to Java.   Could be a fun project...     Daniel Selman [EMAIL PROTECTED]   Tornado Labs Ltd. http://www.tornadolabs.com   [Daniel Selman]  -----Original Message----- From: Discussion list for Java 3D API [mailto:[EMAIL PROTECTED]]On Behalf Of Anirban Bhadore Sent: Friday, June 16, 2000 5:55 AM To: [EMAIL PROTECTED] Subject: NURBS rendering in Java3D         Hi All,     Presently Java3D does not support NURBS surfaces as geometry. I want to handle NURBS surfaces in a Java3D Viewer, how do I handle picking and other stuff ( which are supported by Java3D on facets )?     What I tried was writing a class of my own extended from javax.media.j3d.Canvas3D and overloaded the postRender() where I call my JNI which in turn makes call to OpenGL Platform Libs. And I am able to render the NURBS surfaces separately by my own JNI and the surfaces are properly rendered to the Java3D Canvas. But These NURBS surfaces ARE NOT part of the Java3D Scene Graph. And that's why normal Java3D features are not supported on these surfaces. It seems difficult( if not impossible) to add them to the Java3D Scene Graph.     Does anybody have any experience in this? Any suggestion will be appreciated.     with thanks,   Anirban