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Collision Detection & Response: Together or Seperate?

leiavoia · 2004-06-05T04:27:16

let''s say i do something like so: // returns true if collision happens bool CollideObjects( Object* A, Object* B ); Now in that function i find out of two objects collide. The question is: Should the collision response be in the same function as the collision detection? problem: My system has multiple collision geometries. Different types are inherited from the basic CollisionObject. I have a sphere, polygon, line, and all geometries have a box as well. In my current system, my objects also have an object "Type" such as Player, Enemy, Weapon, World, etc.. So when i do a collision check, i currently check to see if they collide, then i do the resolution action for those objects. The difficulty here is that the two things are disassociated and some object types need to knwo about the collision geometry as well. A bouncing ball type of enemy for instance, needs to know how to bounce off other objects. It can''t do that unless it knows the other object''s collision geoetry. So basically, my problem is that some objects need to know not only if they collided, but need to know how they collided. If i seperate the detection from the response, it''s difficult and i end up with many switch statements and repetetive code. If i merge the two operations together, my cleanly partitioned and Object Oriented system gets real messy. If you have already come across this issue, which route did you go and how did you go about it? Thanks for your input.

General and Gameplay Programming Programming

Started by leiavoia June 03, 2004 09:28 PM

11 comments, last by leiavoia 19 years, 10 months ago

Ravyne

14,306

June 05, 2004 12:56 AM

Really this is a design issue. You can just as easily go either way, its up to you. Decide what fits best, implanting the response within the detection function may be easier to follow and save some typing. On the other hand, seperating the response provides a more flexible approach, sometimes you may simply want to detect a collision and not respond, or respond in a special way.

Personally I prefur to seperate detection from response as it provides more flexibility and, in my mind, provides a better seperation of code. The detection function ONLY detects and the response function ONLY responds, rather than muddling the two together.

I strongly recommend seperation, but you may have an arguement for the opposite approach, the decision is yours. Just my two cents.

Ravyne, NYN Interactive Entertainment
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leiavoia

960

Author

June 05, 2004 01:29 AM

My (rather complicated) system is already very cleanly seperated. I did this for flexability and future expansion. However, no design is perfect. Since i seperated the two functions, there is this sticky issue of needing geometry info in the response code. It also may (or may not) require recalculating a lot of the things the detection function already went through.