Difference between revisions of "X3D v4.0 CAD Improvements"

Revision as of 14:24, 17 August 2012

These are proposed changes for a future X3D v3.4 Specification under consideration by the X3D CAD Working Group.

Many parent-child node relationships are vague, leading to difficulty deciding which children are allowed. For example, X3DGroupingNode is implemented by many candidate nodes.
These relationships are strictly captured in the X3D DTD and X3D Schema, with further support in X3D Schematron
In order to best support model export and interoperability, the child nodes are limited to those listed in the CADInterchange Profile

Proposed specification prose: needed.

Exporters can significantly reduce file size using primitive-geometry nodes (e.g. Cylinder, Disk2D, etc.)
Tesselation quality is not strictly defined in X3D
In order to match polygonal tessellation strictly and avoid "cracks" between adjactent geometry, some form of association is needed (similar to the NURBSet node)
CADPart semantics can be improved to include this constraint

Proposed specification prose: needed.

Nodes to add:

Anchor
- Needed for description and Viewpoint selection (level 1)
- Also needed for linking to other networked resources (level 2)

Concern: possibility of short-circuiting CAD product structure within an extended file. Related future specification change:

- Any node children created by Inline, ProtoInstance or Script (via a createX3D method )

need to follow the CAD product structure defined by their parent nodes.

FillProperties
- Definitely needed for proper display to distinguish different parts or selected parts. Related to definition of component levels in the profile.

OrthoViewpoint
- The primary purpose of OrthoViewpoint is to support common use cases for CAD model viewing. (This node was probably added after the initial CAD profile.)

ViewpointGroup
- Allows nesting of Viewpoints within models without exploding or overloading the Viewpoint list, which is an essential tool for user navigation.

Nodes to remove:

Extensive changes to this profile may make backwards compatibility difficult. X3D profiles do not support a concept of level as components do.

Should the profile be renamed for clarity, maintaining the old profile separately?
Alternatively should the old profile be deprecated?
Is there a better way to express this evolution, simply noting that the v3.4 profile is different?

@@ Line 26: / Line 26: @@
 * Existing specification:  [http://www.web3d.org/files/specifications/19775-1/V3.3/Part01/CADInterchange.html X3D v3.3 CADInterchange profile]
+* Primary discussion: [http://web3d.org/mailman/private/cad_web3d.org/2012-August/000191.html revising CADInterchange profile] email thread
 === Improved nodeset ===
 Nodes to add:
+* Anchor
+** Needed for description and Viewpoint selection (level 1)
+** Also needed for linking to other networked resources (level 2)
+* Inline
+** Needed for modular re-use of CAD-model files
+Concern:  possibility of short-circuiting CAD product structure within an extended file.  Related future specification change:
+** Any node children created by Inline, ProtoInstance or Script (via a createX3D method )
+need to follow the CAD product structure defined by their parent nodes.
+* FillProperties
+** Definitely needed for proper display to distinguish different parts or selected parts.  Related to definition of component levels in the profile.
+* OrthoViewpoint
+** The primary purpose of OrthoViewpoint is to support common use cases for CAD model viewing.  (This node was probably added after the initial CAD profile.)
+* ViewpointGroup
+** Allows nesting of Viewpoints within models without exploding or overloading the Viewpoint list, which is an essential tool for user navigation.
 Nodes to remove: