[x3d-public] Specification editors mantis issues: PBR review

[Don Brutzman]

1. Meeting planning: we again reviewed our schedules.

- we can meeting this Friday 8-10 pacific as part of regular X3D Working Group call

- we can meet next week, Monday or Tuesday, at same time planned today for spec editors.

Please let us know what you think, thanks Michalis.

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2. Spec questions.

a. see new inquiries today regarding PointProperties from Andreas and Holger.  Let's continue/contribute on that thread please.

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b. 12.2.2 Appearance characteristics

Seems like we can remove the sentences starting with "This set of nodes may be extended by creating new nodes derived from..."

If so, we can likely merge the two corresponding bullet lists.

We might also remove the sentence "This set may be extended by creating new nodes derived from the abstract X3DTextureNode base class as defined in 18.3.2 X3DTextureNode."

We don't have to give guidance about extending.  (Prototypes are based on the first node within ProtoBody so those rules are separately defined.)

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c. 12.2.3 Two-sided materials

- small wording changes in first section.

- Can't a model Appearance without a material field still have a backMaterial field?

- If Appearance material has TwoSidedMaterial and backMaterial has another node, can't backMaterial take precedence?

- Appearance only has one texture field.  Why are you talking about DEF/USE?

We need to discuss the various cases, seems like the allowed combinations might be stated more simply.

I suspect that if we primarily define material and backMaterial, then note how TwoSidedMaterial can be used, that best sets us up for long term (when TwoSidedMaterial is no longer supported).

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12.2.4 Texture mapping specified in material nodes

- This section doesn't make much sense, especially the "xxxTexture" phrasing (I think you mean "emissiveTexture and normalTexture" in X3DOneSidedMaterialNode).  Let's discuss please.

Striving for simplification and clarity as best way to achieve correctness.

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12.2.5 Coexistence of textures specified in material nodes with the "Appearance.texture" field

This might be greatly simplified and merged if we get prior simplifications done well.

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12.3.4 X3DOneSidedMaterialNode

- Your "Editorial note: We consider merging this abstract node with X3DMaterialNode."

Am thinking we should keep both of these in order to support Material (which won't change) and X3D3 versus X3D4 PBR rendering.

- "tangent space" discussion can be simplified.

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12.4.5 Material

- You have a number of textures (seven total!) but only two are listed in X3DOneSidedMaterialNode.  Shouldn't they be in the abstract node type also?

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All of the changes need to have a Mantis issue as title (reference).

We probably should review that also.

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Looks like we have a lot to discuss!  We not sensing any significant disagreements at all, just keen to get precise phrasing of specification prose.  This may take a few sessions to accomplish.

Having others implement these changes will certainly help us achieve clarity as well.

Thanks for your review and continuing efforts.

v/r Don and Dick


On 8/24/2020 8:29 AM, Brutzman, Donald (Don) (CIV) wrote:
> Thanks for letting us know, No problems. I can meet three hours later than scheduled time today, noon Pacific. Teaching before then. Thank you Michalis.
> 
> v/r Don
> 
> Sent from my handheld device
> 
>> On Aug 24, 2020, at 08:22, Michalis Kamburelis <michalis.kambi at gmail.com> wrote:
>>
>> 
>>
>> NPS WARNING: *external sender* verify before acting.
>>
>> I am sorry, I am stuck travelling with an unscheduled errand. I will not be able to join in 45 mins.
>>
>> Can we move our meeting to tomorrow (Tuesday)? Or make it 2 hours later today than we planned?
>>
>> (My Wednesday is mostly booked now, and Thursday and Friday will be crazy:) )
>>
>> Regards,
>> Michalis

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