OK I have a D3DMATRIX: D3DMATRIX spinmat; spinmat = { 11 21 31 41 12 22 32 42 13 23 33 43 14 24 34 44 } (Pseudo code for my example) ok I then make it an identy matrix by: 11 = 22 = 33 = 44 = 1.0f; And then to setup the matrx to spin by setting this: 11=cos(ftimekey) 33=cos(ftimekey) 13=sin(ftimekey) 31=sin(ftimekey) My question is why do I set 11,33,13,31 different. Why those vaules? Why does this cause my triangle to spin? Thanks for any info. I'm using the DX7 sdk doc tutorials (Triangle) for study.. if anyone can shed any light on any of this please let me know. Thanks again, Chris Edited by - Viri- on April 27, 2001 12:14:10 PM