[x3d-public] IndexedTriangleSet defaults

[Joe D Williams]

> I found X3DOM’s Sphere very useful for creating texture and geometry 
> coordinates.   X3D needs an upgrade!

> John

What is the upgrade? Usually the 'default' texcoords re created simply 
by using the x andy coords of the shape.
Joe

----- Original Message ----- 
From: "John Carlson" <yottzumm at gmail.com>
To: "Joe D Williams" <joedwil at earthlink.net>
Cc: "Andreas Plesch" <andreasplesch at gmail.com>; "Roy Walmsley" 
<roy.walmsley at ntlworld.com>; "X3D Graphics public mailing list" 
<x3d-public at web3d.org>
Sent: Sunday, May 01, 2016 9:29 PM
Subject: Re: [x3d-public] IndexedTriangleSet defaults




> On May 1, 2016, at 10:28 PM, Joe D Williams <joedwil at earthlink.net> 
> wrote:
>
> I think it was a simple convenience for the author of an 
> indexedfaceset to automatically produce a default texcoord array, 
> mainly by a simple copy of the x and y coords (by not z) of the 
> shape. This should work in all cases even if the ifs is skin of 
> hanim. I think historically, it should be ok if no automated 
> texcoord generation is offered for other shapes than ifs.
> Thanks,
> Joe
> .
> ----- Original Message ----- From: "Andreas Plesch" 
> <andreasplesch at gmail.com>
> To: "Roy Walmsley" <roy.walmsley at ntlworld.com>
> Cc: "X3D Graphics public mailing list" <x3d-public at web3d.org>
> Sent: Monday, April 11, 2016 10:03 AM
> Subject: Re: [x3d-public] IndexedTriangleSet defaults
>
>
> Apologies, I took a short cut in the hope to get to the question 
> directly
> but ended up with producing a surprise.
>
> Not sure how useful the default implementation behaviour for texture
> coordinates of IndexedFaceSets is. Although I can see that there are 
> use
> cases with overall planar geometries and exactly matching map 
> textures.
>
> Could this implementation behaviour be a candidate for deprecation ? 
> In
> contrast, default texture coordinates for the various convenience
> geometries (box, plane, sphere, elevationgrid ..) are very useful.
>
> I was coming across this when I looked at three.js and its 
> constructors for
> geometry on which in turn aframe's geometric primitives are based. 
> Three.js
> does not have IndexedFaceSet but it has IndexedTriangleSet without 
> default
> texture coordinates (UV).
>
> It might be good to harmonize where possible.
>
> Since aframe is designed to be very extensible and has concepts 
> similar to
> x3d, it may be actually possible to implement a (limited) x3d 
> browser using
> aframe as the underlying framework, with x3d nodes and fields 
> corresponding
> to aframe components. A thought for another time.
>
> Andreas
>
>
>
>
>
>
>
>
> On Mon, Apr 11, 2016 at 10:21 AM, Roy Walmsley 
> <roy.walmsley at ntlworld.com>
> wrote:
>
>> Hi Andreas,
>>
>>
>>
>> Initially I was surprised by your comment below. As you say, the 
>> default
>> value of the *texCoord* field is NULL for the IndexedTriangleSet 
>> node.
>> But when I looked at the IndexedFaceSet node, I found that it too 
>> has a
>> default value of NULL for the *texCoord* field (see
>> http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/geometry3D.html#IndexedFaceSet).
>> So both are in agreement there.
>>
>>
>>
>> However, I assume you are referring to the text in the penultimate
>> paragraph for the IndexedFaceSet, which commences “If the 
>> *texCoord*
>> field is NULL, ….”. Here an implementation behaviour is detailed 
>> for when
>> the default value is NULL. In comparison, the IndexedTriangleSet 
>> node has
>> no such behaviour defined.
>>
>>
>>
>> I don’t know why the two instances are different. It is an 
>> interesting
>> observation., which is also worthy of a specification comment.
>>
>>
>>
>> Regards,
>>
>>
>>
>> Roy
>>
>>
>>
>> *From:* x3d-public [mailto:x3d-public-bounces at web3d.org] *On Behalf 
>> Of *Andreas
>> Plesch
>> *Sent:* 11 April 2016 14:34
>> *To:* X3D Graphics public mailing list
>> *Subject:* [x3d-public] IndexedTriangleSet defaults
>>
>>
>>
>> For IndexedTriangleSet the default value for texCoord is NULL.
>>
>>
>> http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/rendering.html#IndexedTriangleSet
>>
>> On the other hand the texCoord default value for IndexedFaceSet is 
>> a
>> reasonable map which tries to fit a texture on the mesh.
>>
>> Is there a reason for this divergence ?
>>
>> Andreas
>>
>
>
>
> -- 
> Andreas Plesch
> 39 Barbara Rd.
> Waltham, MA 02453
>
>
>
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