[x3d-public] getContainerField() [was cobweb DOM integration]

[Roy Walmsley]

Hi,

 

I don’t know the origin of the term “containerField” within X3D. However, I now that Coin3D has a class structure as follows: SoBase -> SoFieldContainer -> SoNode. This is the same as in VSG. It originated with implementation of SGIs Open Inventor. The SoFieldContainer class was described as an “abstract base class for objects that contain fields” (in particular, nodes or engines). Whether that is relevant, though, I have to leave to those with a long history of X3D development.

 

Roy

 

From: Andreas Plesch [mailto:andreasplesch at gmail.com] 
Sent: 11 October 2016 16:56
To: Joe D Williams <joedwil at earthlink.net>
Cc: Roy Walmsley <roy.walmsley at ntlworld.com>; X3D Graphics public mailing list <x3d-public at web3d.org>
Subject: Re: [x3d-public] getContainerField() [was cobweb DOM integration]

 

On Mon, Oct 10, 2016 at 7:17 PM, Joe D Williams <joedwil at earthlink.net <mailto:joedwil at earthlink.net> > wrote:

But containerField is also a rather unintuitive concept, requiring to think 'backwards', eg. up the hierarchy.


It really helps to look at the X3D Classic and VRML encodings. Not really up the hierarchy except to verify that the parent can contain the following node. 

 

I agree, it really helps to understand the VRML encoding although I am not sure it is a good sign that one should do so to understand the XML encoding.

When I first looked at X3D, I remember that I decided to ignore the containerField attribute due its apparent strangeness. It took to me some time to understand that it has to do with the parent node (after some more time understanding that child nodes are field values, eg. fields are not necessarily attributes). Perhaps "parentField" would have been a more straightforward name for this attribute.

-Andreas



-- 

Andreas Plesch
39 Barbara Rd.
Waltham, MA 02453

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