Re: Global to Body Coord Conversions

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Brian Furtaw (brian++at++hotsauce.clubfed.sgi.com)
Wed, 6 Aug 1997 11:43:07 -0400


Would this help you,

     void pfMatrix::makeVecRotVec(const pfVec3& v1,
                      const pfVec3& v2);

     pfMatrix::makeVecRotVec sets the pfMatrix to the rotation matrix which
     rotates the vector v1 onto v2, i.e. v2 = v1 * dst. v2 must be
     normalized. The rotation axis is always chosen to be perpendicular to
     both v0 and v1 so that the rotation angle is as small as possible. Note
     that the result is ambiguous only when v0 == -v1; in this case the
     rotation axis is chosen to be an arbitrary vector perpendicular to v0 and
     v1.

Brian

On Aug 5, 2:08pm, Charlie Jones wrote:
> Subject: Global to Body Coord Conversions
> I have a humans finger (DCS DOF node which has local coords) and I want
> to point at an object in the scene (DCS node which could have local or
> world coords). I can get the world coord of the finger and draw a
> vector from finger to object using pfMakePtsSeg which gives me a
> direction but in a world unit vector. Graphics 101 Question: How can I
> get the appropriate matrix to rotate my finger to point at the
> object.(Assume the hand is always pointing in the general direction of
> the object)?
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>-- End of excerpt from Charlie Jones

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Brian Furtaw (brian++at++sgi.com) VisSim Technical Consultant 12200-G Plum Orchard Drive Office:(301)572-3293 Fax: (301)872-3293 Silver Spring, Maryland 20904 OpenGL/ImageVision/OpenInventor/Performer ======================================================================= List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/ Submissions: info-performer++at++sgi.com Admin. requests: info-performer-request++at++sgi.com


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