[x3d-public] Q. should TriangleStripSet smooth? was Towards an ACID-like test for X3D

[Holger Seelig]

The specification is quite clear at this point:11.4.14 TriangleStripSetIf the normal field is not provided, for each strip, the normal shall be generated as follows: if normalPerVertex isTRUE, the normal shall be the average of all triangles within that strip sharing that vertex. IfnormalPerVertex is FALSE, the normal shall be generated for the triangle based on the ccwfield.
Holger

-------- Ursprüngliche Nachricht --------
Von: doug sanden <highaspirations at hotmail.com> 
Datum: 12.08.2016  18:22  (GMT+01:00) 
An: x3d-public at web3d.org 
Betreff: Re: [x3d-public] Q. should TriangleStripSet smooth? was Towards an
  ACID-like test for X3D 

Submitted.
-Doug
________________________________________
From: Don Brutzman <brutzman at nps.edu>
Sent: August 12, 2016 9:58 AM
To: doug sanden
Cc: x3d-public at web3d.org
Subject: Re: [x3d-public] Q. should TriangleStripSet smooth? was Towards an ACID-like test for X3D

thanks for flagging this issue Doug.

if the specification is unclear or ambiguous, then someone should please submit specification feedback describing both the problem and possible solutions.  That way we can link in this email thread and the deficiency can go on the list of mantis issues for working-group resolution.  Then the specification gets fixed - for everyone.  8)

        web3d.org > STANDARDS > SEND A COMMENT

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On 8/12/2016 8:21 AM, doug sanden wrote:
> TriangleStripSet has no creaseAngle field.
> Should browsers smooth the normals, or not smooth, or something in-between ie with an intermediate creaseAngle default?
> TriangleStripSet: triangles share vertexes along the strip.
> TriangleSet: each triangle has separate vertices/no shared vertices, so no smoothing by any browser
>> You can see the scene at http://www.jishop.com/temp/x3d/#Castle (click Download to get the X3D file).
> See the middle triangles at the top of Castle which are TriangleStripSet (end ones are TriangleSet)
> octaga - smooths
> vivaty - smooths
> instantReality - smooths
> freewrl - smooths
>
>
> On 8/9/2016 1:23 PM, Alekseyev, Vsevolod (NIH/NIAID) [E] wrote:
>> For my latest X3D implementation, I've put together a scene that deliberately contains all the geometries under Geometry3D and Rendering modules. You can see the scene at http://www.jishop.com/temp/x3d/#Castle (click Download to get the X3D file).
>>
>> It demonstrates the following geometry nodes:
>>  - Box
>>  - Cone
>>  - Cylinder
>>  - Sphere
>>  - ElevationGrid
>>  - Extrusion
>>  - IndexedFaceSet
>>  - IndexedTriangleFanSet (x2)
>>  - IndexedTriangleSet  (x2)
>>  - IndexedTriangleStripSet  (x2)
>>  - TriangleFanSet  (x2)
>>  - TriangleSet  (x2)
>>  - TriangleStripSet (x2)
>>
>> The only widely available browser that renders it as intended is Cobweb, with InstantPlayer as a close second, some shading looking weird. X3DOM misses half the merlons, and misshades the CW ones. Xj3D badly misrenders the balcony extrusion (which is *not* pathological). Meshlab skips all primitives but Cylinder.
>>
>> Triangle set geometries are present twice, once as CCW and once as CW, to test the correctness of vertex flipping.
>>
>> The following polygonal geometries are *not* present in the file:
>>
>>  - Disk2D
>>  - Rectangle2D
>>  - TriangleSet2D
>>  - Text
>>  - GeoElevationGrid
>>  - NurbsPatchSurface
>>  - NurbsSweptSurface
>>  - NurbsSwungSurface
>>  - NurbsTrimmedSurface
>>  - IndexedQuadSet
>>  - QuadSet
>>
>> Neither are the point/line ones.
>>
>> Enjoy.

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

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