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[QUATERNION] right handed to left handed


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#1 Alundra   Members   -  Reputation: 927

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Posted 07 July 2013 - 07:13 AM

Hi all,

I convert my quaternion to a matrix using left handed coord system.

I have an input who is right handed, so the rotation needs to be inverted on each axis.

When I input my quaternion, if I change w to -w it's ok, inverted axis works too.

What is the more correct, invert the w or invert (x,y,z) ?

 

Thanks


Edited by Alundra, 07 July 2013 - 07:15 AM.


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#2 Paradigm Shifter   Crossbones+   -  Reputation: 5436

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Posted 07 July 2013 - 07:47 AM

It's the same. q and -q both represent the same rotation (although if you interpolate you need to make sure the [4d] dot-product of the quaternions you interpolate between dot(q0, q1) is > 0 to go the short way round (i.e. less than 180 degrees)).


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#3 Alundra   Members   -  Reputation: 927

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Posted 07 July 2013 - 12:15 PM

-q = ( -x, -y; -z; -w )

all components of the quaternion are inverted.
I was talking about just changing the real or the imaginary part of the quaternion.


#4 Paradigm Shifter   Crossbones+   -  Reputation: 5436

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Posted 07 July 2013 - 12:25 PM

No, you were asking whether

 

q = (x, y, z, -w)

 

was more correct than

 

-q = (-x, -y, -z, w)

 

the answer is neither: they both represent the same rotation/orientation.


Edited by Paradigm Shifter, 07 July 2013 - 12:33 PM.

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