[osg-users] Getting model's direction vector from MatrixTransform?

Paul Martz pmartz at skew-matrix.com
Sun Mar 29 16:35:52 PDT 2009

The upper left 3x3 of the local to world matrix is the orthonormal basis for
the current orientation of the car. If the car is modeled so that the front
of the car is positive X, then the current direction vector is just the
first three elements of the local to world matrix. You can get the local to
world matrix from the MatrixTransform.
Paul Martz
Skew Matrix Software LLC
http://www.skew-matrix.com <http://www.skew-matrix.com/> 
+1 303 859 9466


From: osg-users-bounces at lists.openscenegraph.org
[mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of Ümit Uzun
Sent: Sunday, March 29, 2009 3:45 PM
To: OpenSceneGraph Users
Subject: [osg-users] Getting model's direction vector from MatrixTransform?

Hi All,

I have an simple math question which I had resolved before but now I can't
figure out what would be the problem. I have car model which's direction is
x coordinate. I want to translate it by using it's current direction. So I
need to know it's next visit coordinate while it is rotating to left or
right. So this is my math;

osg::Vec3d carDirection = quad * osg::Vec3d(1.0, 0.0, 0.0); // getting car's
x direction vector.

Then using carDirection, I calculate each next related coordinates
respectively by using iterator.

osg::Vec3d DestinationPos, SourcePos;
DestinationPos = SourcePos + carDirection * iterator; (iterator >= 0)

Do you think it is wrong?

Best Regards.

Ümit Uzun

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