Examples for NURBS surface rendering in X3D
Joe D Williams
From: "Vincent Marchetti" <vmarc...@ameritech.net>
To: "X3D-Public" <x3d-p...@web3d.org>
Sent: Thursday, September 01, 2011 9:03 AM
Subject: [X3D-Public] Examples for NURBS surface rendering in X3D
> To the group:
>
> I have been surveying the current implementations of the NURBS Component among
> readily available browsers, to support work I've been doing on generating X3D
> models from of STEP (CAD) files (see http://www.kshell.com/pages/x3d_cad/ ).
> I've developed some test files giving demonstrations of the NurbsPatchSurface
> and NurbsTrimmedSurface nodes. I've found the following browsers that render
> some or all of these models:
> -- Octaga Player
> -- Instant Player
> -- BS Contact
> -- view3dscene (part of the Kambi game engine)
>
> I'd like to make the demo files and results of my survey available for
> comment; at http://www.kshell.com/pages/nurbs_surface_demo/
>
> One thing I've found is that there is a divergence among these implementations
> as to how the parametric coordinate system is mapped onto the rendered
> surface, leading to a difference among the browsers in how they handle
> texturing and trimming.
>
> I look forward to discussing these results, I'd be particularly interested in
> finding out about any other implementations of the NURBS Component of X3D.
>
> Thanks for your interest,
>
> Vincent Marchetti
> KShell Analysis
>
> vmarc...@ameritech.net
>
>
>
>
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Joerg Scheurich aka MUFTI
> > NurbsPatchSurface
> > and NurbsTrimmedSurface nodes. I've found the following browsers that
> > render
> > some or all of these models:
> > -- Octaga Player
> > -- Instant Player
> > -- BS Contact
> > -- view3dscene (part of the Kambi game engine)
Does Kambi support the NurbsTrimmedSurface ?
NurbsPatchSurface nodes can be converted to IndexedFaceSets (including
morphing animation) with programs like white_dune.
> > One thing I've found is that there is a divergence among these
> > implementations
> > as to how the parametric coordinate system is mapped onto the rendered
> > surface, leading to a difference among the browsers in how they handle
> > texturing and trimming.
> 27.4.1 Contour2D
...
> The 2D coordinates used by the node shall be interpreted to lie in
> the (u, v) coordinate space defined by the NURBS surface.
Do you think, this sentence is clear without ambiguity ?
What scale of the 2D coordinates do you expect, according to this sentence ?
When you have
Shape
{
appearance Appearance { material Material { } }
geometry NurbsPatchSurface
{
uDimension 2
vDimension 2
uKnot [ 0 0 1 1 ]
vKnot [ 0 0 1 1 ]
uOrder 2
vOrder 2
controlPoint Coordinate
{
point
[
-2 0 -2
-2 0 2
2 0 -2
2 0 2
]
}
weight [ 1 1 1 1 ]
}
}
where is n/v = (1, 1) ?
so long
MUFTI
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