[x3d-public] multiple texture fields - why in Material rather than Appearance?

[Don Brutzman]

Michalis, we were looking at draft X3D4 Shape component and updated support table today.  Here are some questions that likely hold general interest.

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1. Hoping you can tell us more (perhaps again) about design rationale for integration of texture-related fields within Shape component nodes.

[1] X3D4 Working Draft 2, Shape Component
     https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-WD2/Part01/components/shape.html

Interestingly
- Appearance has the same fields as before including texture (adding backMaterial and pointProperties),
- PhysicallyBasedMaterial has a number of new fields including various textures (seems sensible),
- Material has the same fields as before, plus a set of textures fields similar to PhysicallyBasedMaterial,
- UnlitMaterial has two texture fields (curious since it is unlit).

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2. Wondering, why were a number of texture fields added to Material instead of Appearance?

- presumably so that Material has a similar design to PhysicallyBasedMaterial...


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3. Wondering, what is the similarity/difference/interaction between
(a) Appearance texture field and
(b) Material ambientTexture field?

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4. Why does UnlitMaterial have emissiveTexture and normalTexture fields?

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Thanks for helping us all understand plus steady efforts together to achieve good scene-graph structure overall.

all the best, Don
-- 
Don Brutzman  Naval Postgraduate School, Code USW/Br       brutzman at nps.edu
Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA   +1.831.656.2149
X3D graphics, virtual worlds, navy robotics http://faculty.nps.edu/brutzman