Hi,

I’m trying to implement a basic trackball navigation based on quaternions, i’ve found the new orientation but im not sure how to plug it in, I would like to set it to my basic camera, which I have as vectors cameraPos, cameraView and cameraUp that I use with the glulookat() function.

If I assign the quaternion rotation to the vectors I get a trackball rotation, but it gets wrong after a couple of rotations. I guess I need to keep track of the rotation in some way, by setting up a own lookat view matrix and get the rotation matrix from that or save the old orientation? Is it even possible to use the glulookat for this, or need I glMultMatrix(…)/glLoadMatrix(…)?

This is how I setup the rendering

```
glViewport(0, 0, width, height);
glClearColor(0.f, 0.f, 0.f, 0.f);
// Enable Z-buffer read and write
glEnable(GL_DEPTH_TEST);
// Setup a perspective projection
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.f, (GLfloat)width/(GLfloat)height, 1.0f, 100.0f );
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// Camera position, view target, up vector.
gluLookAt( m_cameraPos.x() , m_cameraPos.y() , m_cameraPos.z() ,
m_cameraView.x(), m_cameraView.y(), m_cameraView.z(),
m_cameraUp.x() , m_cameraUp.y() , m_cameraUp.z() );
```

Here I get the point coords and assign the rotation

```
Vec3<double> p1 = MapToSphere(oldPoint);
Vec3<double> p2 = MapToSphere(currPoint);
Vec3<double> axis = p2.cross(p1);
double angle = asin(axis.length());
Quaternion<double> rot(axis,angle);
rot.normalize();
m_cameraPos = rotate(m_cameraPos, rot)*5;
m_cameraView = rotate(m_cameraView, rot);
m_cameraUp = rotate(m_cameraUp, rot);
```

Here is the rotate() function

```
Quaternion<double> rotconj = rot;
rotconj.conjugate();
Quaternion<double> qTarget(vec.x(),
vec.y(),
vec.z(),
0);
Quaternion<double> qResult = (rot * qTarget) * rotconj;
Vec3<double> vecRes(qResult.x(),qResult.y(),qResult.z());
vecRes.normalize();
return vecRes;
```

Thanks for your help!