[x3d-public] Minutes of Schema/DTD Review Meeting 17th August 2015

[Roy Walmsley]

Minutes of X3D Schema and DTD Review, Refactoring meeting held 3rd August
2015 at 0800 PDT (1500 UTC).

 

Attendees: Roy Walmsley, Don Brutzman

 

1. Siggraph review

 

Don gave a summary review of the Siggraph conference, covering the following
topic areas: X3DOM, high performance rendering, profiles, CAD, 3D printing,
examples, Schema analysis work by Marc Petit, glTF and binary glTF, shaders
and their usage.

 

2. ComposedCubeMapTexture

http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components
/env_texture.html#ComposedCubeMapTexture

 

It was noted that Don had already agreed and implemented the suggested
change, i.e. the failure of the DTD to permit prototypes. Furthermore, he
had also fixed similar issues with TextureBackground and ComposedTexture3D.
For full details see:

http://web3d.org/mailman/private/x3d_web3d.org/2015-August/003467.html

 

3. ComposedShader

http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components
/shaders.html#ComposedShader

 

For full details of comment see:

http://web3d.org/mailman/private/x3d_web3d.org/2015-August/003465.html

 

It was agreed that there was a lack of examples to understand the usage of
the ComposedShader node, particularly with respect as to how any user
defined fields are accessed by child ShaderPart nodes.

 

There was also some discussion as to the usage of shader nodes in general.
Suggestions arose during Siggraph that shader nodes might be more browser
based rather than appearance based. Roy commented that he had used shader
nodes in VRML, where shader nodes were inserted into the scene graph before
and other geometry or material nodes and then applied to all subsequent
geometry. He agreed to post an example to the lists.

 

Don noted that the ComposedShader node had a language field which would
apply to all child ShaderPart nodes. He updated the tooltips to clarify
this.

http://www.web3d.org/x3d/content/X3dTooltips.html#ComposedShader

http://www.web3d.org/x3d/content/X3dTooltips.html#ShaderPart

 

It was also noted that the node names were confusing, and some of the text
in the specifications not entirely clear. Don raised a specification comment
for text in the ShaderPart node, for which Mantis issue 842 was raised.

http://web3d.org/mailman/private/x3d_web3d.org/2015-August/003469.html

http://www.web3d.org/member-only/mantis/view.php?id=842

 

It was agreed that the definition of the ComposedShader node in the Schema
is missing field in the child content model.

 

It was agreed that in each of the three cases where user defined fields were
permitted, i.e. ComposedShader, PackagedShader and ShaderProgram, the field
children must come before the standard IS and ChildContentModelCore defined
for X3DNode.

http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components
/shaders.html#PackagedShader

http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components
/shaders.html#ShaderProgram

 

The question arose whether these three nodes should be mixed content or not.

ComposedShader definitely is not as it does not have a url field.

PackagedShader has a url field but, in the Schema, is stated to not allow
mixed content (i.e. source code instead of a URL).

ProgramShader has a url field, and the Schema states it is allowed mixed
content (i.e. source code instead of a URL).

 

The specification does not comment on this.

 

It was agreed that further review was required on this topic. Don added a
TODO comment to the Schema for each of these three nodes.

 

Next meeting: No meeting next week due to attendance at ISO SC24 meeting.
Next meeting 7th September 2015 at 0800 PDT (1500 UTC).

 

The meeting closed at 1030 PDT (1730 UTC).

 

Roy

 

PS Subsequent to the meeting it was noted that there is a relevant Mantis
issue 432.

http://www.web3d.org/member-only/mantis/view.php?id=432

 

 

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