#include "vector2d.h" bool vector2d_equals(Vector2d v1, Vector2d v2) { return v1.x == v2.x && v1.y == v2.y; } bool vector2d_is_opposite(Vector2d v1, Vector2d v2) { return (v1.x > 0 && v2.x < 0) ^ (v1.y > 0 && v2.y < 0); }