[x3d-public] Sphere subdivision in to X3DV4 standard

[John Carlson]

X3DOM has primitiveQuality:

https://doc.x3dom.org/tutorials/basics/runtimeConfiguration/index.html

John

On Sun, May 31, 2020 at 4:55 PM John Carlson <yottzumm at gmail.com> wrote:

> I believe there are now "tesselation" or "geometry" shaders now. Do the
> browsers support them?
>
> Thanks,
>
> John
>
> On Sun, May 31, 2020 at 10:54 AM Don Brutzman <brutzman at nps.edu> wrote:
>
>> 1, Well said Joe, also thanks to John and Mufti for sharing.
>>
>> Following that sense of things, I refined the warnings/hints for geometry
>> fields in X3D Tooltips.  For example:
>>
>> ==================================
>> * X3D 4.0 Tooltips, Sphere, radius
>>    https://www.web3d.org/x3d/content/X3dTooltips.html#Sphere.radius
>>
>> [radius accessType initializeOnly, type SFFloat CDATA "1"] (0,+∞)
>>
>> Size in meters.
>>
>> Warning: simple-geometry dimensions are initializeOnly and cannot be
>> changed after initial creation, avoiding the need for potentially expensive
>> tessellation at run time.
>>
>> Hint: for size animation, modify the scale of a parent/ancestor Transform
>> node instead.
>> ==================================
>>
>> Questions/improvements/suggestions always welcome.  In some sense this
>> file is a kind of context-sensitive FAQ for X3D scene graph.
>>
>> ----
>>
>> 2. Meanwhile, there is a relevant Mantis issue pending for X3D 4.0:
>>
>> * Mantis 1280: Add quality parameter for Geometry3D primitives
>>    https://www.web3d.org/member-only/mantis/view.php?id=1280
>>
>> PDF attached for those without direct access.
>>
>> Previous thread:
>>
>> * [x3d-public] Add quality parameter to Geometry3D primitives
>>
>> https://web3d.org/pipermail/x3d-public_web3d.org/2020-February/011748.html
>>
>> Defining something like "subdivision" field as mentioned there does not
>> pass common-sense test.  Any mechanism must be sensible to new authors,
>> since primitive nodes are typically what they learn first.
>>
>> Of note is that browsers are welcome to substitute any geometry they wish
>> at run time, including parametric surfaces (as long as geometric results
>> are a Sphere with correct radius, for example).
>>
>> Suggested approach, if included:
>> ================================
>> [initializeOnly] SFString primitiveQuality "MEDIUM" ["LOW", "MEDIUM",
>> "HIGH"]
>>
>> The /primitiveQuality/ field is an authoring hint regarding tessellation
>> resolution expected for this geometry.  Browser implementations may vary.
>> ================================
>>
>> All feedback welcome.  Will put this on next Friday's agenda for X3D
>> Working Group resolution, either reject or accept with modifications.
>>
>>
>> On 5/30/2020 7:33 PM, Joseph D Williams wrote:
>> >   * … during models lifetime
>> >
>> > So much is true, please notice the access type of the field.
>> >
>> > If it is initialize only, then it is set when the node is initialized
>> or replaced.
>> >
>> > This has been used as a clue that the browser has to completely redraw
>> the node if the field is changed.
>> >
>> > Of course the sphere’s shape can be altered by xyz scaling in the
>> parent transform so you can change the shape to most anything without a
>> hole but not the initialized radius in parent space or the number of points
>> in the shape without redrawing it.
>> >
>> > Thanks,
>> >
>> > Joe
>> >
>> > *From: *John Carlson <mailto:yottzumm at gmail.com>
>> > *Sent: *Saturday, May 30, 2020 3:47 PM
>> > *To: *J. Scheurich <mailto:mufti11 at web.de>
>> > *Cc: *X3D Graphics public mailing list <mailto:x3d-public at web3d.org>
>> > *Subject: *Re: [x3d-public] Sphere subdivision in to X3DV4 standard
>> >
>> > Surely you can apply transforms such that the radius changes?
>> >
>> >> But according to the X3D standards, a sphere may not change its single
>> >> parameter (radius)
>> >> during models lifetime.
>>
>>
>> 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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