[x3d-public] Nurbs patch coloring

[Joseph D Williams]

With all NURBS, please note the value in hanim where we may want some skin to be NURBS. How to animate (deform) skin in terms of skeleton driven or displacer driven animations where the animation target is one or more points of a target mesh that the animator needs to know in advance?

Thanks,
Joe

From: Andreas Plesch
Sent: Wednesday, April 22, 2020 9:43 AM
To: Michail Vidiassov
Cc: X3D Graphics public mailing list
Subject: Re: [x3d-public] Nurbs patch coloring

Right, the spec, at

https://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/lighting.html#Lightingmodel

only says 'interpolated' but not how to interpolate.

So Nurbs vertex coloring may not be well defined between control
points. But I do think that if there is color for a control point,
including an internal (non-cornerpoint) control point, it needs to
used for points on the Nurbs surface close to that control point.

-Andreas

On Wed, Apr 22, 2020 at 12:25 PM Michail Vidiassov <master at iaas.msu.ru> wrote:
>
> Dear Andreas,
>
> you wrote:
> - Not sure if x3dom deals well with RGBA vertex colors
> - Viewer capabilities and conformance are important but secondary to
> design and spec. decisions.
>
> Unless you know another magic trick to fix the RGB part or I have
> missed something,
> in x3dom vertex colors even on a simple Quad work differently,
> depending from what corner point the quad starts:
>
> http://media.iaas.msu.ru/x3d_RGB_test.htm
>
> Other browsers (x_ite, Instant player, view3dscene) showed similar results.
> "Somehow" looks to be the practical answer to the question of how
> colors should vary across a vertex-colored square.
> So worries about the way color should vary on a NURBS patch look
> divorced from the current state of affairs.
>
> Sincerely, Michail



-- 
Andreas Plesch
Waltham, MA 02453

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