Subject:
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3D geometry question
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Newsgroups:
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lugnet.cad
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Date:
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Wed, 13 Oct 1999 09:46:22 GMT
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Viewed:
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565 times
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Hi, I have this problem I hope someone may solve.
Say I have a vector v with length normalized to 1. For simplicity,
picture this vector as starting in the origin. Now, I need a
rotation matrix M with the following properties:
o If I rotate a part with one edge going from (0,0,0) to (0,-1,0)
(i.e., pointing upwards), this edge should coincide with the vector v
after the transformation
o M should be a proper transformation, i.e., no scaling or shearing.
Thanks for any help!
Fredrik
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Message has 2 Replies:
 | | Re: 3D geometry question
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| Fredrik Glöckner: (...) Vectors don't start anywhere. A vector is just a direction and a length. (...) Lets call the vector along the edge e. (...) There are infinitely many solutions to the problem. When you have one solution, any rotation around v (...) (25 years ago, 13-Oct-99, to lugnet.cad)
| | | Re: 3D geometry question
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| Fredrik Glöckner skrev i meddelandet ... (...) What about: Assume V = (Vx, Vy, Vz) B = arctan(Vx/Vz) (Better with arctan2(Vz, Vx) if available, otherwise you have to adjust to the right quadrant manually) Matrix for rotation around Y: ( cos(B) 0 (...) (25 years ago, 13-Oct-99, to lugnet.cad)
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