I have a solid black bar moving to the right, and the player (the blue box) is stationary. When they collide, the blue box is pushed to the right AND upwards, instead of just to the right.
http://imgur.com/a/WptOe
The collision points on both objects are simple rectangles / squares, why does this happen when collisions occur when 2 objects with flat surfaces are parallel?
The blue box has 8 directional movement, so I can't restrict the vector Y to prevent this.