in Debug_demo/Collisions.cpp [3:9]
CollisionType getCollisionWithWalls(const Ball& b, const QRectF& bounding) {
auto ballBB = b.aabb();
if (ballBB.right() > bounding.right()) return Right;
if (ballBB.left() < bounding.left()) return Left;
if (ballBB.top() < bounding.top()) return Top;
return None;
}