[X3D-Public] JavaScript: Question to SFMatrix3f.set/getTransform

[doug sanden]

My guess/hypothesis: Matrix3 2D rotation SFVec3f = (x,y,angle)
- where x,y is the 2D point about which the rotation occurs(?)
(don't compute rotation from xy)
I base that on my hypothesis the designers were attempting to make Matrix3 analogous to Matrix4.
See also the documentation on Transform node for how to apply scaleOrientation for 3D, which takes a series of steps.

________________________________
> Date: Mon, 20 Oct 2014 19:05:15 +0200 
> Subject: AW: Re: [X3D-Public] JavaScript: Question to 
> SFMatrix3f.set/getTransform 
> From: holger.seelig at yahoo.de 
> To: highaspirations at hotmail.com; x3d-public at web3d.org 
> 
> A matrix3 is coordinate system in 2d space, that has a origin (the 
> translation) and a rotation and a scale and scaleOrientation. You Doug 
> says, the first two values of the SFVec3f should be the complex number 
> of the rotation, from that complex number I can calculate an angle. 
> Should this be the third value? 
> 
> 
> Von Samsung Mobile gesendet 
> 
> 
> -------- Ursprüngliche Nachricht -------- 
> Von: doug sanden 
> Datum:20.10.2014 18:49 (GMT+01:00) 
> An: x3d-public at web3d.org 
> Betreff: Re: [X3D-Public] JavaScript: Question to SFMatrix3f.set/getTransform 
> 
> I think matrix3 is a 2D homogenous transform, much like matrix4 is a 3D 
> homogenous transform. For 3D a rotation has 4 values: a 3D direction 
> vector for the axis of rotation, and 4th value for the rotation angle 
> about that axis. 
> For matrix3 (2D), there would be something analogous, but with one less 
> dimension. Likely 2 values xy for a point of rotation, and a 3rd value 
> for the angle of rotation about that point. scale orientation in 2D 
> would need a point and rotation. 
> -Doug 
> 
> 
> ---------------------------------------- 
>> Date: Mon, 20 Oct 2014 18:34:28 +0200 
>> From: holger.seelig at yahoo.de 
>> To: x3d-public at web3d.org 
>> Subject: [X3D-Public] JavaScript: Question to SFMatrix3f.set/getTransform 
>> 
>> I cannot figure out what are the second and fourth argument of 
>> SFMatrix.getTransform are, the spec says: 
>> 
>> SFMatrix3f .setTransform setTransform (SFVec2f translation, 
>> SFVec3f rotation, 
>> SFVec2f scale, 
>> SFVec3f scaleOrientation, 
>> SFVec2f center) 
>> 
>> I can see that a SFVec3f should be used for the rotation arguments, but 
>> I don't know what the three values (x,y,z) stand for. To my 
>> understanding like the TexureTransform node a matrix3 rotation is only a 
>> simple float. I know that simple numbers cannot be passed by value to a 
>> JavaScript function. 
>> 
>> 
>> -- 
>> Holger Seelig 
>> Mediengestalter Digital – Digital Media Designer 
>> 
>> Scheffelstraße 31a 
>> 04277 Leipzig 
>> 
>> Telefon: 01577 147 26 11 
>> E-Mail: holger.seelig at yahoo.de 
>> 
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