static extern void gimp_vector2_normalize(ref GimpVector2 vector);
static extern void gimp_vector2_mul(ref GimpVector2 vector, double factor);
static extern void gimp_vector2_neg(ref GimpVector2 vector);
static extern double gimp_vector2_inner_product(ref GimpVector2 vector1, ref GimpVector2 vector2);
static extern double gimp_vector2_length(ref GimpVector2 vector);
static extern void gimp_vector2_sub(ref GimpVector2 result, ref GimpVector2 vector1, ref GimpVector2 vector2);
static extern double gimp_vector2_cross_product(ref GimpVector2 vector1, ref GimpVector2 vector2);
static extern void gimp_vector2_rotate(ref GimpVector2 vector, double alpha);
public Vector2(double x = 0.0, double y = 0.0) { _vector = gimp_vector2_new(x, y); }
static extern void gimp_vector2_set(ref GimpVector2 vector, double x, double y);