Legacy Document

Inside Macintosh: QuickDraw GX Environment and Utilities /

Chapter 8 - QuickDraw GX Mathematics / Using QuickDraw GX Mathematics

Resetting a Mapping

You can use the ResetMapping function to reset a mapping. The following code example first uses the ResetMapping function to initialize the destination to the identity matrix, and then uses RotateMapping to calculate a resultant mapping that rotates by a given angle about a specified center.

gxMapping *RotationMap(gxMapping *dest, Fixed angle, 
                        gxPoint *center)
{
    return RotateMapping(ResetMapping(dest), angle, 
                           center->x,center->y);
}

The ResetMapping function is described on page 8-64.