quat, matrix, camera oh my!

#1 Read this article? I'm not sure what you're trying to do, but it might help.

http://www.gamasutra.com/features/19980703/quaternions_01.htm

#2 I am trying to position the camera at a specified location and rotation.

I am attempting to do the rotation first, then the positioning. I am not sure if this is correct etc, have yet to find a newbie type 3D math resource..

mCameraMatrix.identity();			
/*  
  X Y Z
X 1 0 0 
Y 0 1 0
Z 0 0 1 
*/

// set the X axis rotation in deg's
mCameraRot.set( mDegToRad(90.0f), 0, 0 );	

// rotate CameraMatrix around the CameraRot
mCameraMatrix.mul(mCameraRot);

// set postion in deg's
mCameraPos.set( 0, mDegToRad(-200.0f), mDegToRad(500.0f) );

// position CameraMatrix based on CameraPos
mCameraMatrix.mul(mCameraPos);

#3 Ron,

I wish I could help, but best I can offer is 'I know the feeling'! If you find a good text or resource that explains this stuff in baby steps please post it :)

James

#4 this should work, you dont set position in radians ..

mCameraRot.set(EulerF(mDegToRad(90), 0, 0)); // Initialize rotation matrix using euler
mCameraMatrix.mul(mCameraRot); // mult in rotation
mCameraPos.set( 0, -200.0f, 500.0f); // setup position Point
mCameraMatrix.setColumn(3, &mCameraPos); // set matrix position

#5 @Badguy - Can you or anyone explain why column 3 is used to set position? Haven't found a good answer for that one. Do the other columns have similiar uses?

mCameraMatrix.setColumn(3, &mCameraPos); // set matrix position

#6 Wendell, That's just the way that the math works out. If you take a matrix and multiply it by a vector, the 4th column (Remember, C/C++ is zero based!) will end up being added to the components of the vector. The other columns are mostly components of the rotation matrix.

You can get some decent information about the components of the rotation matrix at http://www.makegames.com/3drotation/

Just be sure to ignore Gruber's somewhat goofy opinions on quaternions found at the end of the article.

#7 Wendell, maybe this helps, also:
(Torque-)Matrix:
1) x-axis position
2) y-axis position
3) z-axis position

4) x-axis rotation
5) y-axis rotation
6) z-axis rotation

These rotation numbers make up the axis of rotation of the object,
and the 7th and final number is the ...

7) rotation about that axis in radians