Many CAD applications provide features that rotate objects which were drawn in the client area. If your application requires rotation capabilities, you can use the SetWorldTransform function to set the appropriate world-space to page-space transformation. This function receives a pointer to an XFORM data structure which contains the appropriate values. The member eM11 specifies the cosine of the angle of rotation, the member eM12 specifies the sine of the angle of rotation, the member eM21 specifies the negative sine of the angle of rotation, and the member eM22 specifies the cosine of the angle of rotation.
The following illustration shows a rendering of the house after it was rotated 30 in the counter-clockwise direction:
Rotated Front-View of House