[GRASS-dev] symbol rotation is go

[Hamish]

Glynn Clements wrote:
> > I have just added a new libgis function: G_rotate_around_pt() in
> > 6.3cvs.
> >  (make distclean, yet again)
> > 
> > It rotates a point around a given center coord by a given angle.
> 
> I would suggest an alternate version:
> 
> void G_rotate_around_point(double X0, double Y0, double *X1, double *Y1, double angle) {
> 	double dx = *X1 - X0;
> 	double dy = *X1 - X0;
> 	double c = cos(D2R(angle));
> 	double s = sin(D2R(angle));
> 	double dx1 = dx * c - dy * s;
> 	double dy1 = dx * s + dy * c;
> 
> 	*X1 = X0 + dx1;
> 	*Y1 = Y0 + dy1;
> }


Hi,

committed, with a minor fix:
 -double dy = *X1 - X0;
 +double dy = *Y1 - Y0;


thanks,
Hamish