[X3D-Public] conversion of example scenes for Follower (Chaser and Damper) nodes

Don Brutzman brutzman at nps.edu
Mon Dec 5 07:25:51 PST 2011

Hi Herbert.  I have updated X3D-Edit implementations of the Follower
(Chaser and Damper) nodes, and have at long last worked to translate
your original .wrl examples into X3D.  This required several days of
dedicated work but worthwhile.

Only some of these examples seem to be working, further work is needed.
Of note is that some node definitions changed from your original
paper.  Here are my comments on the translation process.  I welcome
feedback by you and others to help complete the demonstration of
these excellent capabilities.


Player support for X3D components

- BS Contact apparently not supporting most nodes
- instant Reality apparently supporting most nodes
- Xj3D not supporting any of the follower nodes
- X3D-Edit validation and panels for editing are working, now available
- Have added X3D Schematron quality-assurance rules for checking chasers
	and dampers in .x3d scenes

Important issues:

- Why is there no ScalarDamper node (similar to ScalarChaser) in the
	final specification, as your original examples recommended?
	This inconsistency might be a specification erratum, since
	SFFloat scalar animation is a very commonplace technique.
	Of interest:  instantReality already implemented it.

- Updated examples and originals from your site are now available online.

- Your examples are both interesting and complex, it looks like I need
	help to finish debugging some of the translations.  Status for
	each scene is found in the <meta name='warning' ... /> elements.

Translation notes:

- Changed your ProtoDeclare/ExternProtoDeclare/ProtoInstance constructs
	to X3D v3.2 native nodes (PositionChaser PositionChaser2D et al.)
	Some of the final node names are different than your prototypes.

- Found and fixed a few idiosyncrasies/bugs in the X3DtoVrml97Nist converter,
	 which is also used by X3D-Edit.  Checked into sourceforge, published links.

- Fixed duplicate DEF names, added new note to X3D Scene Authoring Hints:
Avoid duplicate DEF names for nodes inside multiple prototype declarations contained in a single file. Although the DEF namespaces contained inside each independent ProtoBody declaration are logically independent from an X3D perspective, duplicate DEF names will provoke XML validation errors regarding duplicate ID names.

- Added tooltips http://www.web3d.org/x3d/content/X3dTooltips.html

Looking forward to further progress in broadening proper support for
these valuable nodes.  Thanks in advance for advice and contributions.

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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