[x3d-public] X3DParticleEmitter node inherit fromX3DChildNode(rather than X3DNode)
Andreas Plesch
andreasplesch at gmail.com
Thu Mar 10 20:01:19 PST 2022
Correct. bufferViews has a buffer key which holds the index to a specific
buffer in the buffers array. Typically there is only one buffer which has
all the data but there could be multiple. So "buffer" is not a misspelling
but the well defined name of a key (field). In that sense it is a reserved
word just like the names of all other keys which all have a specified
meaning.
Most plurals (scenes, buffers, bufferViews, nodes ..) are arrays which have
corresponding keys with names in the singular.
On Thu, Mar 10, 2022 at 10:19 PM John Carlson <yottzumm at gmail.com> wrote:
> From what hat I recall, buffers is a grouping node for buffer’s
>
> On Thu, Mar 10, 2022 at 8:41 PM Brutzman, Donald (Don) (CIV) <
> brutzman at nps.edu> wrote:
>
>> Sorry I thought we were talking about Metadata examples, not DEF/USE
>> id/idref identifier/copy-by-reference kinds of reuse.
>>
>>
>>
>> BTW am puzzled by glTF example, it looks like “bufferViews” is intended
>> to point to “buffers” but actually points at something called “buffer”
>> which does not appear to be defined. Is “buffer” a reserved term for a
>> different data structure, or a misspelling?
>>
>>
>>
>> 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 https://
>> faculty.nps.edu/brutzman
>>
>>
>>
>> *From:* Andreas Plesch <andreasplesch at gmail.com>
>> *Sent:* Thursday, March 10, 2022 2:29 PM
>> *To:* Brutzman, Donald (Don) (CIV) <brutzman at nps.edu>
>> *Cc:* Joseph D Williams <joedwil at earthlink.net>; X3D Graphics public
>> mailing list <x3d-public at web3d.org>; Jakub Flotyński <
>> flotynski at kti.ue.poznan.pl>
>> *Subject:* Re: [x3d-public] X3DParticleEmitter node inherit
>> fromX3DChildNode(rather than X3DNode)
>>
>>
>>
>> NPS WARNING: *external sender* verify before acting.
>>
>>
>>
>>
>>
>> Likely we should create a set of examples from each of the languages
>> you’ve listed (and more) to show how to do it.
>>
>>
>>
>> Here is a start:
>>
>>
>>
>> - svg
>>
>>
>>
>> https://developer.mozilla.org/en-US/docs/Web/SVG/Element/defs
>> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdeveloper.mozilla.org%2Fen-US%2Fdocs%2FWeb%2FSVG%2FElement%2Fdefs&data=04%7C01%7Cbrutzman%40nps.edu%7C71b726f7803c4453578608da02e56444%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637825481566341786%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=SnVCDx91lJdcpdtElaeY7q8EuqvklS1%2FtJHE%2BY%2F3IEo%3D&reserved=0>
>>
>> https://www.w3.org/html/wiki/SVGElements/defs
>> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.w3.org%2Fhtml%2Fwiki%2FSVGElements%2Fdefs&data=04%7C01%7Cbrutzman%40nps.edu%7C71b726f7803c4453578608da02e56444%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637825481566341786%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=aUiYIRLUZnwwEQokDtQBjCRKLP0P7tpeqGpnBEfbqX0%3D&reserved=0>
>>
>>
>>
>> - glTF
>>
>>
>>
>>
>> https://www.khronos.org/registry/glTF/specs/2.0/glTF-2.0.html#indices-and-names
>> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.khronos.org%2Fregistry%2FglTF%2Fspecs%2F2.0%2FglTF-2.0.html%23indices-and-names&data=04%7C01%7Cbrutzman%40nps.edu%7C71b726f7803c4453578608da02e56444%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637825481566341786%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=WXsL2sAj5x5O0qXplpV7fsRW6aR0an0r4X4jKvSmiEw%3D&reserved=0>
>>
>> by index into a library array
>>
>>
>>
>> - a-frame
>>
>>
>>
>> https://aframe.io/docs/1.3.0/core/asset-management-system.html
>> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Faframe.io%2Fdocs%2F1.3.0%2Fcore%2Fasset-management-system.html&data=04%7C01%7Cbrutzman%40nps.edu%7C71b726f7803c4453578608da02e56444%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637825481566341786%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=ZSoNXKKQcGNEoMoE%2FQPJZOY3b2kH%2B4Q2ySULFfyzJ6k%3D&reserved=0>
>>
>> https://aframe.io/docs/1.3.0/core/mixins.html
>> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Faframe.io%2Fdocs%2F1.3.0%2Fcore%2Fmixins.html&data=04%7C01%7Cbrutzman%40nps.edu%7C71b726f7803c4453578608da02e56444%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637825481566341786%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=27kABl7V5hTwUd9IjVHXH3zqIsFMfWFveJettlVdPuo%3D&reserved=0>
>>
>>
>>
>> - collada
>>
>>
>>
>> https://www.khronos.org/files/collada_reference_card_1_4.pdf
>> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.khronos.org%2Ffiles%2Fcollada_reference_card_1_4.pdf&data=04%7C01%7Cbrutzman%40nps.edu%7C71b726f7803c4453578608da02e56444%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637825481566341786%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=vwKXCN5ZEmHLt6mImNrcCvkoAh0ibEoBgSyhx%2BflXKM%3D&reserved=0>
>> : The library_* elements (modules)
>>
>>
>>
>> All of those have examples, except for collada. Perhaps I can collect the
>> examples and put them onto a wiki page.
>>
>>
>>
>> Cheers, Andreas
>>
>>
>>
>> PS: Here is a collada conversion of the simple gltf box at
>> https://github.com/KhronosGroup/glTF-Sample-Models/blob/master/2.0/Box/glTF/Box.gltf
>> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FKhronosGroup%2FglTF-Sample-Models%2Fblob%2Fmaster%2F2.0%2FBox%2FglTF%2FBox.gltf&data=04%7C01%7Cbrutzman%40nps.edu%7C71b726f7803c4453578608da02e56444%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637825481566341786%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=QpxauQKjQWMX6h8gkImVz3bBwgWPwIUaSDGglygdFiA%3D&reserved=0>
>>
>>
>>
>> <?xml version="1.0" encoding="utf-8"?>
>> <COLLADA version="1.5.0" xmlns="
>> http://www.collada.org/2008/03/COLLADASchema
>> <https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.collada.org%2F2008%2F03%2FCOLLADASchema&data=04%7C01%7Cbrutzman%40nps.edu%7C71b726f7803c4453578608da02e56444%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637825481566341786%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=Qva0eEoVLsNK7oSp6aq51cMcKFG%2By7XklLsyYY3PW94%3D&reserved=0>
>> ">
>> <asset>
>> <contributor />
>> <unit meter="1" />
>> </asset>
>> <library_lights />
>> <library_materials>
>> <material id="Red" name="Red">
>> <instance_effect url="#effect-Red" />
>> </material>
>> </library_materials>
>> <library_effects>
>> <effect id="effect-Red" />
>> </library_effects>
>> <library_cameras />
>> <library_geometries>
>> <geometry id="mesh_1">
>> <mesh>
>> <source id="mesh_1-position" name="position">
>> <float_array id="mesh_1-position-array" count="72">-0.5 -0.5
>> 0.5 0.5 -0.5 0.5 -0.5 0.5 0.5 0.5 0.5 0.5 0.5 -0.5 0.5 -0.5 -0.5 0.5 0.5
>> -0.5 -0.5 -0.5 -0.5 -0.5 0.5 0.5 0.5 0.5 -0.5 0.5 0.5 0.5 -0.5 0.5 -0.5
>> -0.5 -0.5 0.5 0.5 0.5 0.5 0.5 -0.5 0.5 -0.5 0.5 0.5 -0.5 -0.5 -0.5 0.5 -0.5
>> 0.5 0.5 -0.5 -0.5 -0.5 -0.5 0.5 -0.5 -0.5 -0.5 -0.5 -0.5 0.5 -0.5 0.5 -0.5
>> -0.5 0.5 0.5 -0.5 </float_array>
>> <technique_common>
>> <accessor source="#mesh_1-position-array" count="24"
>> stride="3">
>> <param name="X" type="float" />
>> <param name="Y" type="float" />
>> <param name="Z" type="float" />
>> </accessor>
>> </technique_common>
>> </source>
>> <source id="mesh_1-normal" name="normal">
>> <float_array id="mesh_1-normal-array" count="72">0 0 1 0 0 1 0
>> 0 1 0 0 1 0 -1 0 0 -1 0 0 -1 0 0 -1 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 1 0 0
>> 1 0 0 1 0 -1 0 0 -1 0 0 -1 0 0 -1 0 0 0 0 -1 0 0 -1 0 0 -1 0 0 -1
>> </float_array>
>> <technique_common>
>> <accessor source="#mesh_1-normal-array" count="24" stride="3">
>> <param name="X" type="float" />
>> <param name="Y" type="float" />
>> <param name="Z" type="float" />
>> </accessor>
>> </technique_common>
>> </source>
>> <vertices id="mesh_1-vertices">
>> <input semantic="POSITION" source="#mesh_1-position" />
>> </vertices>
>> <triangles material="default" count="12">
>> <input semantic="VERTEX" source="#mesh_1-vertices" offset="0" />
>> <input semantic="NORMAL" source="#mesh_1-normal" offset="1" />
>> <p>0 0 1 1 2 2 3 3 2 2 1 1 4 4 5 5 6 6 7 7 6 6 5 5 8 8 9 9 10
>> 10 11 11 10 10 9 9 12 12 13 13 14 14 15 15 14 14 13 13 16 16 17 17 18 18 19
>> 19 18 18 17 17 20 20 21 21 22 22 23 23 22 22 21 21</p>
>> </triangles>
>> </mesh>
>> </geometry>
>> </library_geometries>
>> <library_images />
>> <library_visual_scenes>
>> <visual_scene id="Scene">
>> <node id="Node--0" sid="Node--0" name="Node #0" type="NODE">
>> <matrix>1 0 0 0 0 0 1 0 0 -1 0 0 0 0 0 1</matrix>
>> <node id="Node--1" sid="Node--1" name="Node #1" type="NODE">
>> <matrix>1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1</matrix>
>> <instance_geometry url="#mesh_1">
>> <bind_material>
>> <technique_common>
>> <instance_material symbol="mat0" target="#Red" />
>> </technique_common>
>> </bind_material>
>> </instance_geometry>
>> </node>
>> </node>
>> </visual_scene>
>> </library_visual_scenes>
>> <library_animations />
>> <scene>
>> <instance_visual_scene url="#Scene" />
>> </scene>
>> </COLLADA>
>>
>>
>>
>> Test cases welcome.
>>
>>
>>
>> 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 https://
>> faculty.nps.edu/brutzman
>>
>>
>>
>> *From:* Andreas Plesch <andreasplesch at gmail.com>
>> *Sent:* Thursday, March 10, 2022 1:08 PM
>> *To:* Joseph D Williams <joedwil at earthlink.net>
>> *Cc:* Brutzman, Donald (Don) (CIV) <brutzman at nps.edu>; X3D Graphics
>> public mailing list <x3d-public at web3d.org>
>> *Subject:* Re: [x3d-public] X3DParticleEmitter node inherit
>> fromX3DChildNode(rather than X3DNode)
>>
>>
>>
>> Good comments.
>>
>>
>> - MetadataSet to have X3DNode nodes
>>
>> If I understand it, the idea of ending meta to include actual user code
>> for the scenegraph is exactly the sort of extension wanting to be
>> “worthwhile to deviate a bit and be more permissive than the spec” that
>> dooms the long-term validation operation. Maybe good for something with
>> simple structure that looks convenient and logical and seemingly convenient
>> to implement at first thought and elementary usage, then ends up making
>> something definitely not to be best practice. Please delineate the
>> “worthwhile” parts that make a case.
>>
>>
>>
>> I only know that this construction shows up in most of x-ite examples,
>> and is how the Titania editor saves a scene, simple or complex. I can only
>> deduce that this decision was deliberate but cannot speak to the specific
>> motivation by the author. Speculating, the feature seems to be valuable for
>> authoring. It should be possible to convert to standard x3d automatically
>> by moving the DEF node from the MetadataSet to the first USE node, perhaps
>> by xslt.
>>
>>
>>
>> Not quite sure how validation would be affected.
>>
>>
>>
>> I agree that Metadata nodes should be limited to actual metadata but a
>> library node seems sensible.
>>
>>
>>
>> Here is a list of other, well established scene graph systems which do
>> have a concept of a non-renderable library which is separate and can then
>> be referenced as needed:
>>
>>
>>
>> - svg
>>
>> - glTF
>>
>> - a-frame
>>
>> - collada (I believe)
>>
>>
>>
>> it is a natural concept and perhaps allows for cleaner user code
>> organization. Having two alternative ways to define a DEF node (in a
>> library, and as a first scene graph node) does seem to invite friction, and
>> would need to be carefully considered.
>>
>>
>>
>> Andreas
>>
>>
>>
>>
>>
>> *From: *Andreas Plesch <andreasplesch at gmail.com>
>> *Sent: *Tuesday, March 8, 2022 11:39 AM
>> *To: *Brutzman, Donald (Don) (CIV) <brutzman at nps.edu>
>> *Cc: *X3D Graphics public mailing list <x3d-public at web3d.org>
>> *Subject: *Re: [x3d-public] X3DParticleEmitter node inherit
>> fromX3DChildNode(rather than X3DNode)
>>
>>
>>
>> Yes, I am pretty sure Holger is aware. I only brought it up because
>> Titania/x-ite typically stays very close to the spec. But this is a
>> capability where Titania/x-ite found it worthwhile to deviate a bit and be
>> more permissive than the spec. This decision may point to the value of
>> having a way to DEF any X3DNode (not just child nodes) outside of the scene
>> graph, outweighing strict compliance.
>>
>>
>>
>> All the best, Andreas
>>
>>
>>
>> On Tue, Mar 8, 2022 at 2:22 PM Brutzman, Donald (Don) (CIV) <
>> brutzman at nps.edu> wrote:
>>
>> MetadataSet is only allowed to contain other Metadata* nodes or
>> comments. Other content will fail validation (and will not load or import
>> in the X3DJSAIL Java and X3DPSAIL Python libraries).
>>
>>
>>
>> The right way to cache non-rendered content for DEF/USE libraries is to
>> put them as children nodes within a Switch node with whichChoice=’-1’.
>>
>>
>>
>> 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 https://
>> faculty.nps.edu/brutzman
>>
>>
>>
>> *From:* x3d-public <x3d-public-bounces at web3d.org> *On Behalf Of *Andreas
>> Plesch
>> *Sent:* Tuesday, March 8, 2022 10:11 AM
>> *To:* X3D Graphics public mailing list <x3d-public at web3d.org>
>> *Subject:* Re: [x3d-public] X3DParticleEmitter node inherit from
>> X3DChildNode(rather than X3DNode)
>>
>>
>>
>> Of note is that Titania and x-ite allow MetadataSet to have X3DNode
>> nodes, eg. any node, in the value field, not just X3DMetadataObject nodes.
>>
>>
>>
>> This allows MetadataSet to be used as a NodesLibrary for DEF/USE
>> purposes. In fact, this kind of redirection is the default setup for scenes
>> created in Titania.
>>
>>
>>
>> SVG also has a NodesLibrary equivalent, the <defs> element:
>>
>>
>>
>> https://developer.mozilla.org/en-US/docs/Web/SVG/Element/defs
>> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdeveloper.mozilla.org%2Fen-US%2Fdocs%2FWeb%2FSVG%2FElement%2Fdefs&data=04%7C01%7Cbrutzman%40nps.edu%7C71b726f7803c4453578608da02e56444%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637825481566498003%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=fWfdIffjmDjNN%2FLZkZKXD6XecQj%2BHBAlDBeNhIWI%2BjI%3D&reserved=0>
>>
>>
>>
>> -Andreas
>>
>>
>>
>> Date: Mon, 7 Mar 2022 21:29:41 +0100
>> From: Michalis Kamburelis <michalis.kambi at gmail.com>
>> To: Joseph D Williams <joedwil at earthlink.net>
>> Cc: GPU Group <gpugroup at gmail.com>, "X3D Public Mailing List
>> (x3d-public at web3d.org)" <x3d-public at web3d.org>
>> Subject: Re: [x3d-public] X3DParticleEmitter node inherit from
>> X3DChildNode(rather than X3DNode)
>> Message-ID:
>> <
>> CAKzBGZNToR-7CmaUzRxBE3xx9J6j2mPgmvKAjQKpGQxjdY_0hA at mail.gmail.com>
>> Content-Type: text/plain; charset="UTF-8"
>>
>> Perhaps I should have written
>>
>> """
>> The nodes within NodesLibrary don't make any effect, they are not
>> traversed. They are only to be reUSEd (referenced) by other parts of
>> the graph."
>> """
>>
>> This makes the wording consistent with how e.g. Switch is described.
>> Sure you have all the nodes in memory, you just don't traverse to
>> inactive parts of Switch, LOD, NodesLibrary etc.
>>
>> Regards,
>> Michalis
>>
>>
>>
>>
>> --
>>
>> Andreas Plesch
>> Waltham, MA 02453
>>
>>
>>
>>
>>
>>
>> --
>>
>> Andreas Plesch
>> Waltham, MA 02453
>>
>>
>>
>>
>> --
>>
>> Andreas Plesch
>> Waltham, MA 02453
>> _______________________________________________
>> x3d-public mailing list
>> x3d-public at web3d.org
>> http://web3d.org/mailman/listinfo/x3d-public_web3d.org
>>
>
--
Andreas Plesch
Waltham, MA 02453
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