[x3d-public] quaterntion lib., was: errors in convertJsonToStl.js
Leonard Daly
Leonard.Daly at realism.com
Mon Jun 4 07:05:58 PDT 2018
John & Andreas,
I think what John is stating is that STL needs world coordinates for
everything. That means transforming every coordinate to world space
prior to conversion. Since X3D supports skewing (non-uniform and
non-axial scaling), you will need to use 4x4 matrices. I have seen math
libraries in X3DOM as Andreas has pointed out. THREE.js also deals with
quaternions (see https://threejs.org/docs/index.html#api/math/Quaternion
-- link at bottom to code). It also has methods to return the world
transform (see https://threejs.org/docs/index.html#api/core/Object3D for
.matrixWorld and related methods).
Leonard Daly
> What I need for STL is to unwind all the transforms into actual
> coordinates. STL has no concept of transforms.
>
> John
>
> On Mon, Jun 4, 2018, 8:47 AM Andreas Plesch <andreasplesch at gmail.com
> <mailto:andreasplesch at gmail.com>> wrote:
>
> x3dom has a pretty complete matrix et al. math library which includes
> quaternions:
>
> https://github.com/x3dom/x3dom/blob/master/src/fields.js#L1754
>
> Its invert methods looks the same as yours.
>
> I am not sure if inverting a quaternions is identical to inverting the
> 4x4 rotation matrix derived from a quaternion, or if that is what you
> need for stl.
>
> -Andreas
>
> > Date: Mon, 4 Jun 2018 03:18:40 -0400
> > From: John Carlson <yottzumm at gmail.com <mailto:yottzumm at gmail.com>>
> > To: X3D Graphics public mailing list <x3d-public at web3d.org
> <mailto:x3d-public at web3d.org>>
> > Subject: Re: [x3d-public] errors in convertJsonToStl.js
> > Message-ID: <5b14e7cf.1c69fb81.b0537.d319 at mx.google.com
> <mailto:5b14e7cf.1c69fb81.b0537.d319 at mx.google.com>>
> > Content-Type: text/plain; charset="utf-8"
> >
> > I looked at my quaternion code today, and at quaternions and
> rotations on the web. I am not quite sure how I came up with the
> code I did (I saw some video). I think I watched the wrong video,
> or I was smoking anxiety that day. Currently, my converter
> converts lots of stuff to a plane, it looks like (see SuperCobra).
> >
> > Can anyone point me to a reasonable open source implementation
> of quaternion rotations in JavaScript, Java, C or C++? X_ITE or
> X3DOM? Ideally, the quaternions would fit into a 4x4 matrix stack,
> which is how I learned how to do transforms (I am not doing a
> perspective transform that I know of, so perhaps 3x3 is good
> enough). Yes, I know that other implementations are probably more
> efficient. I?d like to try to get 4x4 transforms working first
> before optimizing. 4x4 transforms are NOT a requirement, however,
> just a nice to have.
> >
> > John
> >
> >
> > Sent from Mail for Windows 10
> >
> > From: John Carlson
> > Sent: Saturday, May 20, 2017 2:20 AM
> > To: Don Brutzman; X3D Graphics public mailing list
> > Subject: RE: errors in convertJsonToStl.js
> >
> > New versions of X3D JSON, STL and PLY interoperability are here:
> >
> >
> https://github.com/coderextreme/X3DJSONLD/blob/master/src/main/node/convertJsonToStl.js
> >
> https://github.com/coderextreme/X3DJSONLD/blob/master/src/main/node/convertPlyToJson.js
> >
> https://github.com/coderextreme/X3DJSONLD/blob/master/src/main/node/convertStlToJson.js
> >
> > This mostly works with Indexed geometry.? I don?t handle PLY
> texture coordinates yet.
> >
> > Contributions are welcome, particularly JSON to PLY?
> >
> > John
> >
> >
> > -------------- next part --------------
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> >
> > ------------------------------
> >
> > Message: 3
> > Date: Mon, 4 Jun 2018 06:48:24 -0400
> > From: John Carlson <yottzumm at gmail.com <mailto:yottzumm at gmail.com>>
> > To: X3D Graphics public mailing list <x3d-public at web3d.org
> <mailto:x3d-public at web3d.org>>
> > Subject: Re: [x3d-public] errors in convertJsonToStl.js
> > Message-ID: <5b1518f7.1c69fb81.ed8cb.38a4 at mx.google.com
> <mailto:5b1518f7.1c69fb81.ed8cb.38a4 at mx.google.com>>
> > Content-Type: text/plain; charset="utf-8"
> >
> > Well, I ?fixed? my code, but would appreciate a second pair of
> eyes looking at it. Essentially, I added an inverse quaternion to
> the transform ?stack? (now not quite a stack).
> >
> >
> https://github.com/coderextreme/X3DJSONLD/blob/master/src/main/node/matrix.js
> >
> https://github.com/coderextreme/X3DJSONLD/blob/master/src/main/node/convertJsonToStl.js
> >
> > search for quaternion.
> >
> > If you hook up the X3DJSONLD web server, you can search for
> ?LightsOn? in X3DJSONLD and look at the JSON file at
> /c/x3d-code/www.web3d.org/x3d/content/examples/Savage/
> <http://www.web3d.org/x3d/content/examples/Savage/>? (set up
> Cygwin/MingW, node.js etc, create symbolic link).
> >
> > It should convert to STL automatically I think. To convert back
> to JSON (and display as a green surface), press the here above the
> STL output pane.
> >
> > But really, just a review of the quaternion code should be
> sufficient. There?s probably an issue with the viewpoint in the
> example (STL doesn?t have viewpoints, and I don?t think I?ve taken
> the time to introduce the necessary transforms).
> >
> > Thanks,
> >
> > John
> >
> >
> > Sent from Mail for Windows 10
> >
> > From: John Carlson
> > Sent: Monday, June 4, 2018 3:18 AM
> > To: X3D Graphics public mailing list
> > Subject: RE: errors in convertJsonToStl.js
> >
> > I looked at my quaternion code today, and at quaternions and
> rotations on the web.? I am not quite sure how I came up with the
> code I did (I saw some video). I think I watched the wrong video,
> or I was smoking anxiety that day. ?Currently, my converter
> converts lots of stuff to a plane, it looks like (see SuperCobra).
> >
> > Can anyone point me to a reasonable open source implementation
> of quaternion rotations in JavaScript, Java, C or C++?? X_ITE or
> X3DOM? Ideally, the quaternions would fit into a 4x4 matrix stack,
> which is how I learned how to do transforms (I am not doing a
> perspective transform that I know of, so perhaps 3x3 is good
> enough).? Yes, I know that other implementations are probably more
> efficient. I?d like to try to get 4x4 transforms working first
> before optimizing.? 4x4 transforms are NOT a requirement, however,
> just a nice to have.
> >
> > John
> >
> >
> > Sent from Mail for Windows 10
> >
> > From: John Carlson
> > Sent: Saturday, May 20, 2017 2:20 AM
> > To: Don Brutzman; X3D Graphics public mailing list
> > Subject: RE: errors in convertJsonToStl.js
> >
> > New versions of X3D JSON, STL and PLY interoperability are here:
> >
> >
> https://github.com/coderextreme/X3DJSONLD/blob/master/src/main/node/convertJsonToStl.js
> >
> https://github.com/coderextreme/X3DJSONLD/blob/master/src/main/node/convertPlyToJson.js
> >
> https://github.com/coderextreme/X3DJSONLD/blob/master/src/main/node/convertStlToJson.js
> >
> > This mostly works with Indexed geometry.? I don?t handle PLY
> texture coordinates yet.
> >
> > Contributions are welcome, particularly JSON to PLY?
> >
> > John
> >
> >
> >
> > -------------- next part --------------
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> >
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> >
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> >
> > End of x3d-public Digest, Vol 111, Issue 6
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>
>
>
> --
> Andreas Plesch
> Waltham, MA 02453
>
>
>
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--
*Leonard Daly*
3D Systems & Cloud Consultant
LA ACM SIGGRAPH Past Chair
President, Daly Realism - /Creating the Future/
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