BlenderConversionIssues.txt                                     1 November 2017

https://www.web3d.org/x3d/content/examples/X3dForAdvancedModeling/ToolConversions/BlenderConversionIssues.txt

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Castle Game Engine (view3dscene) documentation provides excellent
detail on how to effectively convert from Blender to X3D on
https://github.com/castle-engine/castle-engine/wiki/Blender
along with a Blender export plugin at
https://castle-engine.sourceforge.io/creating_data_blender.php

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1. NavigationInfo headlight="off"/> means model is invisible.

Can either turn on, or simply leave out NavigationInfo which will have correct
values by default.

2. Updated X3D from version 3.0 to version 3.3.

3. Illegal and default/verbose Transform and Viewpoint values.

a. SFRotation values are a normal vector followed by a radians angle.
   A zero-magnitude vector is illegal.  Default value is 0 0 1 0.
   If a zero rotation was intended, it is best omitted.
   rotation='0.000000 0.000000 -0.000000 0.000000'

b. scale has default 1 1 1, translation has default 0 0 0, the following are
   both too long (due to trailing zeroes) and unnecessary.

   scale='1.000000 1.000000 1.000000'
   translation='0.000000 0.000000 0.000000'

c. Viewpoint default-valued attributes can similarly be omitted:
   centerOfRotation='0 0 0'  orientation='1.00 0.00 0.00 0.00' position='-0.00 -0.00 0.00'
   illegal rotation value:   orientation='0.00 0.00 0.00 0.00'

d. PointLight default-valued attributes can similarly be omitted:
   ambientIntensity='0.0000' color='1.0000 1.0000 1.0000' location='-0.0000 -0.0000 0.0000'

e. DirectionalLight direction='-0.0000 0.0000 -1.0000' matches default value 0 0 -1
   and can be omitted.

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f. The viewpoints themselves do not permit model viewing or navigation.  Any
   attempt to look at the model immediately spins it off and away into hyperspace.
   This is probably because the Viewpoints (and also PointLight definitions)
   are wrapped inside of Transform nodes, even though they are at scene root.

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g. Viewpoint description fields are ignored on import and thus omitted on export.
   This omission means that the five existing Viewpoints are not listed in the
   X3D browser's Viewpoint menu, again preventing/confounding user navigation.

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4. Original X3D Validator reports:

<X3D profile='Immersive'> is defined, but nodes in scene have actual profile='Interactive' [/X3D, info]
Missing X3D filename in meta tag, should appear as <meta name='title' content='FileName.x3d'/> [/X3D/head, warning]
<Viewpoint DEF='CA_Viewpoint_003'/> is missing description which is important for accessibility and usability.  Example: description='default view, rotate to examine object' [/X3D/Scene/Transform[164]/Viewpoint, warning]
<Viewpoint DEF='CA_Viewpoint_002'/> is missing description which is important for accessibility and usability.  Example: description='default view, rotate to examine object' [/X3D/Scene/Transform[165]/Viewpoint, warning]
<Viewpoint DEF='CA_Viewpoint_001'/> is missing description which is important for accessibility and usability.  Example: description='default view, rotate to examine object' [/X3D/Scene/Transform[166]/Viewpoint, warning]
<Viewpoint DEF='CA_Viewpoint'/> is missing description which is important for accessibility and usability.  Example: description='default view, rotate to examine object' [/X3D/Scene/Transform[167]/Viewpoint, warning]
<Viewpoint DEF='CA_Camera'/> is missing description which is important for accessibility and usability.  Example: description='default view, rotate to examine object' [/X3D/Scene/Transform[171]/Viewpoint, warning]

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5. Fixed meta tag:

	<meta content='BlenderFishHead.x3d' name='filename'/>
to
	<meta content='BlenderFishHead.x3d' name='title'/>

Also added further meta tags.

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6. Changed <X3D profile='Interactive'> as prompted by X3D Validator.
(Immersive is satisfactory, just tuning to best match.)

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7. Note that Viewpoint descriptions are present in original model, apparently
they were dropped during import since they do not appear in subsequent export.

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8. CAD structure nodes are lost: CADAssembly, CADPart, CADFace.

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9. Metadata nodes and values are lost on import.  This removes critical and
   required information in a scene.

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10. A small extraneous Box was added.  Inspection revealed that a small center
   Cube_TRANSFORM was inserted without user knowledge.  That should be an
   explicit decision by author, rather than having a Cube_Transform appear
   in any scene using Blender.

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Tool resources for conversion developers:

a. X3D Specifications, especially X3D Abstract Specification.
   http://www.web3d.org/standards
   http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/X3D.html
b. X3D Scene Authoring Hints
   http://www.web3d.org/x3d/content/examples/X3dSceneAuthoringHints.html
c. X3D Tooltips
   http://www.web3d.org/x3d/content/X3dTooltips.html
b. X3D Resources
   http://www.web3d.org/x3d/content/examples/X3dResources.html

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