[x3d-public] Should Material.diffuseColor be updated to 1.0 1.0 1.0? & Should normalTexture be removed from UnlitMaterial?

[Michalis Kamburelis]

> No no, if you look at the origingal VRML97 spec eg. at
> https://www.bitmanagement.com/developer/spec/vrml97specification.pdf
> Material diffuseColor is ignored (i.e. white) for texture types RGB RGBA
> See table 4.6. ODrgb = ITrgb, so diffuseColor in this case is ignored !

Yes indeed -- I mean my intention was to write exactly this :) Sorry
if my previous message was not clear. It is exactly as you write, and
my previous message (esp. AD 2) there is aligned with what you say
(except I talked about X3D 3.x, and didn't remember to mention that
VRML 97 == X3D 3.x equations in this matter).

With RGB textures, in X3D 3.x (and VRML 97), the diffuseColor was
ignored. But with grayscale textures, it was used for multiplication.
At least, that was a theory -- my tests on
https://castle-engine.io/x3d_multi_texturing.php#section_Material_color_mixed_with_texture_color
show how it was inconsistently applied in practice.

In X3D 4.x, diffuseColor multiplies the texture, always (regardless if
it is RGB or grayscale). I think that's better and more universally
supported now.

As for AdvanceMaterial, we thought about this, just like we considered
CommonSurfaceShader. But the issue would be then that it introduces
complexity (of the spec, implementations) so it would introduce
confusion even more. If browsers already implement RGB/grayscale
inconsistently, and we (at least I) think that X3D 3.x approach
(behave differently for RGB vs grayscale texture) is not very useful,
then we'd have a complicated situation having in spec something like
"basic Material" and "AdvancedMaterial" and explaining to people that
AdvancedMaterial has somewhat different equations and actually
everyone is recommended to upgrade to AdvancedMaterial.

In the end, it is easier to just make "Material in X3D 4.x" extended
and as good as we can. Easier for spec and for implementors and for
model authors, hopefully :)

Regards,
Michalis

pt., 26 wrz 2025 o 13:01 Holger Grahn <hg at snafu.de> napisał(a):
>
>
> Hi Michalis,
>
> > As for diffuseColor making texture darker: this is indeed the case (by
> > default, texture gets multiplied by 0.8), but this is equal in X3D 3.x
> > and 4.x. *For grayscale textures*. For RGB textures, we did one other
> > change, that may cause darkening -- see below.
>
> No no, if you look at the origingal VRML97 spec eg. at
> https://www.bitmanagement.com/developer/spec/vrml97specification.pdf
> Material diffuseColor is ignored (i.e. white) for texture types RGB RGBA
> See table 4.6. ODrgb = ITrgb, so diffuseColor in this case is ignored !
> diffuseColor is still useful in this case to modualate with
> GRAY/Intensity textures.
>
> In general I am glad about the new features of Material and
> PhysicalMaterial in X3D 4
> My concern would be to have the new Material texture fields as a derived
> node (AdvanceMaterial) from the classical Material, for many scenes with
> simple Materials X3D 4.0 Material implementation needs much more memory
> and code, even for simple shapes.
>
> Many Greetings
> Holger
>
>
>
>
>
> --
> Diese E-Mail wurde von Avast-Antivirussoftware auf Viren geprüft.
> www.avast.com