public void setFlipX(double x0, double x1) {
		xx = -1;
		xy = 0;
		xd = x0 + x1;
		yx = 0;
		yy = 1;
		yd = 0;
	}
public void setFlipX ( double x0 , double x1 ) { xx = - 1 ; xy = 0 ; xd = x0 + x1 ; yx = 0 ; yy = 1 ; yd = 0 ; }
Sets the transformation to be a flip around the X axis. Flips the X
coordinates so that the x0 becomes x1 and vice verse.

@param x0
The X coordinate to flip.
@param x1
The X coordinate to flip to.