Need collision detection and response system

[davexunit]

Need collision detection and response system

[davexunit]

I have some ideas for a collision detection system. I want to write a quadtree data type for the spatial partitioning that will allow for fast collision detection. I'm glad you noticed the rect module. That's the first step towards this.

As far as collision response handlers and stuff, I think that is best left to the person writing the game. Giving the necessary primitives (rect and quadtree) will give users the means to do what they please. I don't want to embed a collision system deep into the game/scene part of the API.

So, as far as what could use work: a quadtree module would be awesome.

[zan-xhipe]

ok, I can work on a quadtree module.

[Halfwake]

EDIT: Oh right, you moved. Let me try there.

If it helps, I have a quad tree module written in Common Lisp. I can port it over, but I need to setup my guile environment and find some time first. https://github.com/Halfwake/cl-quad

[davexunit]

Thanks for sharing the code. That makes 2 CL quadtree implementations that I know of. From what I can see, this implementation uses a mutable quadtree. In Sly (the new name for guile-2d), the quadtree must use a purely functional data structure. I've been meaning to look into how to implement a persistent quad tree, but haven't gotten around to it.

[Halfwake]

Are you sure my implementation isn't purely functional? There is no use of assignment operators. Methods return new quad trees instead of changing an existing tree. The slots for all classes are read only. It might even be a persistent tree. When a method creates a new tree, it uses references to the last tree without making copies.

[davexunit]

In that case I didn't read the code carefully enough! Thanks for explaining. I would love to see it implemented in Guile.

I'd be curious about the performance profile of it as well. I imagine the time complexity for read/write are different than a mutable quad tree.