How to find the angle betwen two vectors

Become a member of the CGSociety

Connect, Share, and Learn with our Large Growing CG Art Community. It's Free!

Thread Tools Display Modes
  07 July 2004
How to find the angle betwen two vectors

I got two vectors A and B as Point3, how could I find the 3 eulerangles between them, I look in the manual but I can't find a "simple" method to do it.
What I wan't to do is to copy the result rotation on to other object rotations.

Thank you in advance.
Mathematics, rightly viewed, possesses not only truth, but supreme beauty - a beauty cold and austere, like that of sculpture.
  07 July 2004
I think you can use quats. Here's my idea: calculate cross product of A and B. Put its x,y,z into quat's x,y,z. Thats your rotation vector, now you need angle. Equation is very simple:
ang = acos((A.x*B.x+A.y*B.y+A.z*B.z) / ((length A)*(length B))). ang is w part of quat. Now simply convert quat to eulerangles using "as eulerangles". I think it should work but never tried that.
  07 July 2004
Look up "Dot Product" in the MS reference manual.
  08 August 2004
There is actually only one angle between two vectors (in relation to eachother). You can get that value like this:

ang = acos (dot vec1 vec2)

Note that the vectors must be normalized.

To get the angle of a vector in worldspace you're gonna hafta use some trig.
  01 January 2006
Thread automatically closed

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.
CGTalk Policy/Legalities
Note that as CGTalk Members, you agree to the terms and conditions of using this website.
Thread Closed share thread

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Society of Digital Artists

Powered by vBulletin
Copyright ©2000 - 2006,
Jelsoft Enterprises Ltd.
Minimize Ads
Forum Jump

All times are GMT. The time now is 10:28 AM.

Powered by vBulletin
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.