I would like to know how can I do one way collision. It's the collision common in mario's games and many platforms. I try to do an code but I cannot post because it's part of a paid game.
Basically I have two rectangles like this:

```
struct Rect {
  int x, y; // positions in the world
  int w, h; // width and height
};

```

The rect A moves and the rect B is fixed with the world.
Someone has a idea of how to do this?