Date: Feb 20, 2012 8:56 AM
Author: giuseppe
Subject: rotation arownd an axis ,Euler?
My problem is that I must find from a 3d matrix(that is an input from a .ifc file bim) the rotation component around the axis of extrusion vector (that i have).

If you multiply all the 2d profile points for the rotation matrix or if i find the angle with Eulers , is correct only for a beam or column oriented in x/y plane

If i change the extruding direction i change the x,y,z of the multiplied 2d points(the profile of the section)

for example a point is 122,122,0 for the z direction :

0, 122 ,122

or for a y direction:

122, 0 , 122

or x

122,122,0 ecc.......

in the rotation matrix there is the rotation of the profile(around the z axis) and the rotation of the beam profile.

How i can extract only the section rotation angle?

I see that is sufficient get the correct pair of coords , but how i can create an algorithm in c++ that select the correct coordinates pairs?

x,y

x,z

or

y,z?

thanks