DisplayInfo

class DisplayInfo
    {
    public:
        DisplayInfo() : _varsSet(0) {}
        enum
        {
            kChange_x               = (1 << 0),
            kChange_y               = (1 << 1),
            kChange_rotation        = (1 << 2),
            kChange_xscale          = (1 << 3),
            kChange_yscale          = (1 << 4),
            kChange_alpha           = (1 << 5),
            kChange_visible         = (1 << 6),
            kChange_z               = (1 << 7),
            kChange_xrotation       = (1 << 8),
            kChange_yrotation       = (1 << 9),
            kChange_zscale          = (1 << 10),
            kChange_FOV             = (1 << 11),
            kChange_projMatrix3D    = (1 << 12),
            kChange_viewMatrix3D    = (1 << 13)
        };

        double      _x;
        double      _y;
        double      _rotation;
        double      _xScale;
        double      _yScale;
        double      _alpha;
        UInt32      _visible;
        double      _z;
        double      _xRotation;
        double      _yRotation;
        double      _zScale;
        double      _perspFOV;
        GMatrix3D   _viewMatrix3D;
        GMatrix3D   _perspectiveMatrix3D;
        UInt32      _varsSet;

        void SetX(double x)                 { SetFlags(kChange_x); _x = x; }
        void SetY(double y)                 { SetFlags(kChange_y); _y = y; }
        void SetRotation(double degrees)    { SetFlags(kChange_rotation); _rotation = degrees; }
        void SetXScale(double xscale)       { SetFlags(kChange_xscale); _xScale = xscale; }
        void SetYScale(double yscale)       { SetFlags(kChange_yscale); _yScale = yscale; }
        void SetAlpha(double alpha)         { SetFlags(kChange_alpha); _alpha = alpha; }
        void SetVisible(bool visible)       { SetFlags(kChange_visible); _visible = visible; }
        void SetZ(double z)                 { SetFlags(kChange_z); _z = z; }
        void SetXRotation(double degrees)   { SetFlags(kChange_xrotation); _xRotation = degrees; }
        void SetYRotation(double degrees)   { SetFlags(kChange_yrotation); _yRotation = degrees; }
        void SetZScale(double zscale)       { SetFlags(kChange_zscale); _zScale = zscale; }
        void SetFOV(double fov)             { SetFlags(kChange_FOV); _perspFOV = fov; }
        void SetProjectionMatrix3D(const GMatrix3D *pmat)
        {
            if (pmat) {
                SetFlags(kChange_projMatrix3D);
                _perspectiveMatrix3D = *pmat;
            } else
                ClearFlags(kChange_projMatrix3D);
        }
        void SetViewMatrix3D(const GMatrix3D *pmat)
        {
            if (pmat) {
                SetFlags(kChange_viewMatrix3D);
                _viewMatrix3D = *pmat;
            } else
                ClearFlags(kChange_viewMatrix3D);
        }

        // Convenience functions
        void SetPosition(double x, double y) { SetFlags(kChange_x | kChange_y); _x = x; _y = y; }
        void SetScale(double xscale, double yscale)  { SetFlags(kChange_xscale | kChange_yscale); _xScale = xscale; _yScale = yscale; }

        void SetFlags(UInt32 flags) { _varsSet |= flags; }
        void ClearFlags(UInt32 flags) { _varsSet &= ~flags; }
    };