Real-Time Physics Simulation Forum 2013-11-18T11:44:51+00:00 https://pybullet.org/Bullet/phpBB3/app.php/feed/topic/9555 2013-11-18T11:44:51+00:00 2013-11-18T11:44:51+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=32184#p32184 <![CDATA[get direction vector from btScalar matrix]]>

I can obtain the turret transform and opengl matrix like this:

Code: 

    // get chassis and turret transformsbtTransform chassisTransform = m_vehicle->getChassisWorldTransform();btTransform turretTransform = compound->getChildTransform(1);// multiply transforms to get updated turret transformturretTransform *= chassisTransform;// get turret matrixbtScalar turretMatrix[16];turretTransform.getOpenGLMatrix(turretMatrix);
I am trying to get the turret forward/direction vector from this matrix. I need this so that I will have the camera fixed to the turret's position and direction.

What I have tried is this:

Code: 

btVector3 turretForwardVector = btVector3(turretMatrix[2], turretMatrix[6], turretMatrix[9]);
But this doesn't give me the right vector.
Could someone please point out where exactly do I have to look for the vector in this matrix?


EDIT:

I managed to find this [link](http://www.opengl.org/discussion_boards ... ix-or-Quat). It explained where I would find the direction vector in the matrix (3rd column).

So I got the 8th, 9th and 10th matrix elemets and created the turretForwardMatrix from that like this:

Code: 

btVector3 turretForwardVector = btVector3(turretMatrix[8], turretMatrix[9], turretMatrix[10]);

Statistics: Posted by b0gd4n — Mon Nov 18, 2013 11:44 am

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