I want to define my transformation directly by the matrix and not by translate and rotate. I want to do this because I know my eigenvectors and not my angles of rotation. Thk

sorry buddy, but you are SOL.
since multiplying by a matrix is a linear transfrom, that means:

A(0) = 0

where 0 is the zero vector, and A is the matrix. a translation would violate this. this is why you need to explicitely do the translation, instead of putting it all into one big matrix.

also, it seems to me that you can reconstruct your rotation matrix from your eigenvectors/eigenvalues....

I may be misunderstanding, but I think glLoadMatrix{df} is what you are looking for?

I haven't got a clue what the AP is on about.

Enigma

Well, glMultMatrix{f,d} probably.

I to am a little confuzzled about what you're asking... Do you want to know how to setup the matrix, or just how to multiply or load it?

AP definately doesn't know what homogeneous coordinates are.

aurelien: if you've got the center of your world and the direction vectors of the X, Y and Z axis (sometimes called i, j and k), you can use the following matrix :

[ ix  jx  kx  Ox ][ iy  jy  ky  Oy ][ iz  jz  kz  Oz ][  0   0   0   1 ]ix being the x component of the i vector, iy being the y component, etc, and O being the center of your world.

DOH

my apologies.... quite right vincoof.