add_vertex
void vcgen_bspline::add_vertex(double x, double y, unsigned cmd)
void vcgen_contour::add_vertex(double x, double y, unsigned cmd)
void vcgen_dash::add_vertex(double x, double y, unsigned cmd)
void vcgen_markers_term::add_vertex(double x, double y, unsigned cmd)
void vcgen_smooth_poly1::add_vertex(double x, double y, unsigned cmd)
void vcgen_stroke::add_vertex(double x, double y, unsigned cmd)