basic doubt in 3d

Make the shift to Euler Angles, Spherical coordinates or Quaternions. They each have their pros and cons.

Euler angles are rectilinear angular coordinates representing rotations about each of the three Cartesian axes. Each coordinate is 2p-periodic, which is handy, but representation of an orientation isn't unique and suffers from Gimbal lock. Alternative terminology for the three coordinates is 'Yaw, Pitch, Roll', and D3DX offers a helper function as such: D3DXMatrixYawPitchRoll.

(Unit) Spherical coordinates are simpler than Euler angles. Only two coordinates are required to represent an arbitrary orientation, corresponding to the two degrees of freedom on the sphere surface, providing uniqueness. However, the range of the two coordinates isn't equal (0-2p, 0-p) and periodicity is difficult to emulate. You are probably already familiar with spherical coordinates in the form of geocentric coordinates (longitude, latitude). The unit-spherical-to-Cartesian conversion goes like:

x = sin(q)cos(f)
y = sin(q)sin(f)
z = cos(q)

(0 < q < 2p, 0 < f < p)

Finally, quaternions are a three-dimensional complex representation of rotations. They are slightly tricker to get your head around, but offer the best performance and don't suffer from aperiodicity or Gimbal lock. I suggest you take a look at GameDev's Articles section for information on quaternions.

Admiral

Yes.I have shifted to quaternions.

To a Quaternion I have assigned an axis and an angle.

D3DXQUATERNION qt1;
qt1.w=25*0.0174;
qt1.x=0.0f;
qt1.y=1.0f;
qt1.z=0.0f;

I construct a rotation matrix out of the quaternion.

D3DXMatrixRotationQuaternion(&matRotate,&qt1);

Then I construct a look at matrix.

D3DXMatrixLookAtLH( &matView, &Right, &Look, &Up );

Then I multiply the rotation matrix to the view matrix.

g_pd3dDevice->SetTransform( D3DTS_VIEW, &(matView*matRotate));

This causes the rotation of the camera.
What should I do (to get the effect of orbiting around the object )to the quaternion.

[Edited by - tinu on March 29, 2007 11:08:19 PM]

To achieve rotation with (linear) respect to time, you'd need to periodically increment the angle in your render loop. Something like this:



Note that this will rotate the world about the origin, not the camera about the viewing point. I'm not sure if this is what you intended.
I don't think it's necessarily a good idea to separate the view matrix from the rotation in the way you are. Not least, at the end of the calculation, your view matrix won't contain the actual D3DTS_VIEW matrix.

Admiral