[x3d-public] Nurbs patch coloring

[Andreas Plesch]

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