How would one go about doing this?

  LMkbxfD.jpg

I’m trying to make an arcade basketball game like the image above. I’m just wondering how would the gravity work? As you can see the sides of the cage gets more narrow as it gets closer to the basket. So I wouldn’t be able to draw a line to act as a wall. It almost seems as though I will need to update the boundaries as the ball is moving. Can anyone come up with a better idea?

This may be something more easily done in Graphics 2.0/2.5D physics.  The artwork is using perspective to simulate depth.  This is one of the things if I understand correctly is coming with the new graphics/physics engine.  

Could you make several collision versions for the walls and then group them to z values. You could probably get away with 5 and snap to nearest z when it hits wall?

This may be something more easily done in Graphics 2.0/2.5D physics.  The artwork is using perspective to simulate depth.  This is one of the things if I understand correctly is coming with the new graphics/physics engine.  

Could you make several collision versions for the walls and then group them to z values. You could probably get away with 5 and snap to nearest z when it hits wall?