[x3d-public] colorMode of PointProperties

[Holger Seelig]

Specification says still something different:

https://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/geometry3D.html#IndexedFaceSet
There shall be at least as many indices in the /colorIndex/ field as 
there are faces in the IndexedFaceSet. If the greatest index in the 
/colorIndex/ field is N, there shall be N+1 colours in the /X3DColorNode/

To use the last color value if there are less values could be possible, 
but what is with TextureCoordinate? X3Dom uses modulo if there are less 
indices:
texCoords.push( texCoords[ i % lastTexCoord ] );
This behavior is used in 
https://www.web3d.org/x3d/content/examples/Basic/HumanoidAnimation/JoeSkinTexcoordDisplacerKickIndex.html

But spec say that there should be as many tex coords as indices, nothing 
about a special behaviour.

But there are also FogCoordinate, Normal, X3DVertexAttributeNode. What 
special behavior should these nodes follow, more like Color or more like 
texCoord, or something very different? Confusing. Spec is quite clear in 
that point, the behavior is undefined if there are to less values.

Best regards,
Holger


On 27.11.19 02:37, Joseph D Williams wrote:
>
>   * should the color node be allowed to have less entries
>
> than the total number of points, with points lacking a corresponding
>
> color getting assigned the last color in the color node list of colors
>
> ?
>
> Thanks,
>
> Yes, that’s the way color per vertex should also work
>
> Joe
>
> *From: *Andreas Plesch <mailto:andreasplesch at gmail.com>
> *Sent: *Sunday, November 24, 2019 12:30 PM
> *To: *X3D Graphics public mailing list <mailto:x3d-public at web3d.org>
> *Subject: *Re: [x3d-public] colorMode of PointProperties
>
> It looks like the PointProperties colorMode is a way to deal with
>
> 11.4.11 PointSet which says
>
> "PointSet nodes are not lit, not texture-mapped, .."
>
> although in fact points can now be texture-mapped.
>
> Since this is a change for PointSet is might be necessary to correct
>
> 11.4.11 instead of introducing a workaround with colorMode.
>
> "PointSet nodes are not lit. Textures are applied to the full size of
>
> each point after blending as defined in Table 17.2."
>
> in 11.4.11 PointSet may suffice to address all colorMode options.
>
> On another note, should the color node be allowed to have less entries
>
> than the total number of points, with points lacking a corresponding
>
> color getting assigned the last color in the color node list of colors
>
> ? This makes sense for the common scenario that there a lot of points
>
> of the same color.
>
> -Andreas
>
> On Fri, Nov 22, 2019 at 7:44 AM Andreas Plesch 
> <andreasplesch at gmail.com> wrote:
>
> >
>
> > I am looking at colorMode field of the new PointProperties which has 
> these options:
>
> >
>
> > POINT_COLOR shall display the RGB channels of the color instance 
> defined in X3DMaterialNode or X3DColorNode, and the A channel of the 
> texture if any. If no color is
>
> > associated to the point, the default RGB color (0, 0, 0) shall be used.
>
> >
>
> > TEXTURE_COLOR shall display the original texture with its RGBA 
> channels and regardless
>
> > to the X3DMaterialNode or X3DColorNode which might be associated to 
> the point set.
>
> >
>
> > TEXTURE_AND_POINT_COLOR shall display the RGBA channels of a texture 
> added to the
>
> > RGB channels of the color defined in X3DMaterialNode or X3DColorNode 
> node, and the A
>
> > channel of the texture if any. If no color is associated to the 
> point, the result shall be exactly
>
> > the same as TEXTURE_COLOR.
>
> >
>
> > What is the motivation, eg. what is the value over standard blending 
> behaviour, multiplying color and texture if both are given ?
>
> >
>
> > Also, I do not understand how summing RGBA channels of texture and 
> color could be useful, as required by the TEXTURE_AND_POINT_COLOR option.
>
> >
>
> > At this point, I would be in favour of removing the field. Instead, 
> standard lighting behaviour would apply. Other than color blending, 
> this may also include shading if normals are provided per point.
>
> >
>
> > Andreas
>
> >
>
> -- 
>
> Andreas Plesch
>
> Waltham, MA 02453
>
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-- 
Holger Seelig
Digital Media Designer

Scheffelstraße 31a
04277 Leipzig
Germany

Cellular: +49 176 420 479 37
E-Mail:   holger.seelig at create3000.de
Web:      http://create3000.de

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