I've been stuck with this problem for awhile... Ok I have my billboarding matrix set this way (using D3D): getRightVec().x, getUpVector().x, getForwardVec().x, 0, getRightVec().y, getUpVector().y, getForwardVec().y, 0, getRightVec().z, getUpVector().z, getForwardVec().z, 0, getPosition().x, getPosition().y, getPosition().z, 1 (and it works, it rotates to face the viewer around the y axis) UpVector is always (0,1,0), because I want my billboard to turn around the Y axis. All vectors are normalized and orthogonal. Now using this matrix, how can I rotate the billboard around the Z axis and/or X axis ? I just need a simple extra X or Z rotation on the aldready billboarded quad and don't know how to do it without screwing the billboarding. thanks.