I'm writing a small game in DirectX 9.0c and Visual C++. I'm having my artist lay out the level in 3d studio max and export it as an ASE file. Originally I was using the *TM_POS attribute to position my objects. But of course this doesn't take rotation into account. So, I changed to use the *TM_ROW0 - *TM_ROW3 attributes to get a nice transformation matrix. So, from what I'm reading in now versus what my old transformation matrix (for a simple unrotated object) was has a slight discrepency, as follows: Old TM_POS matrix ============= 1 0 0 0 0 1 0 0 0 0 1 0 x y z 1 New TM_ROWx matrix ================= 1 0 0 0 0 1 0 0 0 0 -1 0 x y z 1 This makes my objects light funny (very dark), and I'm guessing that maybe I'm looking at the backs of the triangles (forgive me if I just don't know what I'm talking about). Can someone tell me what this -1 in the 3,3 position of the matrix is doing to my object and what kind of transformation I could do to undo it? I tried multiplying the x,3 positions by -1 and it turned the lighting back to normal, but made my rotation backwards on my objects that were actually rotated. Thanks for all your help.

I figured it out. This page about coordinate systems on MSDN gave me the plan. I needed to not only swap y and z, but negate the 3rd row of the transformation matrix.

http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/directx9_c_Summer_04/directx/graphics/programmingguide/GettingStarted/3DCoordinateSystems/coordinatesystems.asp