Hey guys! My physics engine is coming along quite nicely (thanks for asking!) and I'm ready to start working on some even more advanced junk. Case in point, I'm trying to set up my collision engine so that an arbitrary delegate can be notified when a collision occurs. Let me set up a scenario for you:
Say we have object A, object B, and object C in the physics simulation. I want to be able to inform a delegate about a collision between A and B, AND inform a potentially DIFFERENT delegate about a collision between A and C.
A little background information: I have a known interface for the delegate, I have the potential of storing state for my collision detector (but don't atm), and have the ability to store state in the objects themselves. Similarly, I use this delegate model to handle collision resolution, simply setting the physics engine as the delegate for all objects by default, allowing the user to change the delegate if desired.
Now, I already tried having each object store it's own collision delegate that would be informed when a collision occurred. This didn't work because when the objects had the same collision delegate, the same collision was handled twice. When I switched to only using the delegate of the first object (however that was decided), the order of simulation became an issue. I want to use a dictionary, but that introduces a significant amount of overhead. However, that seems like the direction I need to be heading.
So here's the question: fight to the death over a suitable solution. How would YOU solve this problem?