Describes a matrix.
typedef struct _D3DMATRIX { union { struct { float _11, _12, _13, _14; float _21, _22, _23, _24; float _31, _32, _33, _34; float _41, _42, _43, _44; }; float m[4][4]; }; } D3DMATRIX;
In Direct3D, the _34 element of a projection matrix cannot be a negative number. If your application needs to use a negative value in this location, it should scale the entire projection matrix by -1 instead.
IDirect3DDevice9::GetTransform, IDirect3DDevice9::MultiplyTransform, IDirect3DDevice9::SetTransform, IDirect3DDevice9::SetTransform, D3DXMATRIX, Transforms