[x3d-public] quaterntion lib., was: errors in convertJsonToStl.js

[Andreas Plesch]

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>
> To: X3D Graphics public mailing list <x3d-public at web3d.org>
> Subject: Re: [x3d-public] errors in convertJsonToStl.js
> Message-ID: <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
>
>
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> Message: 3
> Date: Mon, 4 Jun 2018 06:48:24 -0400
> From: John Carlson <yottzumm at gmail.com>
> To: X3D Graphics public mailing list <x3d-public at web3d.org>
> Subject: Re: [x3d-public] errors in convertJsonToStl.js
> Message-ID: <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/? (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
>
>
>
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-- 
Andreas Plesch
Waltham, MA 02453