just released Bonk, an open source collision detection library for MonoGame Core. this is the tool we are using for collision detection on Samurai Gunn 2
- extremely modular design
- implements line, circle, rectangle, and convex polygons
- spatial hash for broad phase
- GJK for narrow phase
- EPA for separating vector
- 0 heap allocations (no garbage collection)
licensed under LGPL 3
i am going on vacation tomorrow so i dont have time to release docs for this but i will do so right when i get back. in the meantime there is a link to the source.
but essentially the way it is structured is that for each collision check you have a separate Shape and Transform (position, rotation, scale) that modifies the Shape vertices. that way you can easily use collision shapes in conjunction with a transform without needing to constantly update the Shape itself.
another choice i made was to use integer positions for Transforms. the way this works is that Position2D stores carryover. when positions are added, the carryovers are added too. this way no information is lost but you still have the convenience of actual pixel-perfect collision so you dont get discrepancies in 2D rendering.
also shout out to @takaeri for the great name.
Bonk docs are now available here:
@dankwraith ooooooooo no heap?? thats nice
can it do convex shapes?
@dankwraith ohhh sorry I meant concave. I get those mixed up
@popefucker ahhh no, concave is tricky to support and it is almost never needed in practice because you can just compose multiple shapes
@dankwraith yeah thats what I thought but it would be cool to make that automatic or something, idk
@dankwraith anyway, mega sweet lib my dude
@dankwraith yay! i'm glad you picked it! congrats on the release :)
@dankwraith I might actually unironically be interested in this, thanks!
@dankwraith no heap allocations? in .Net?? how???
@hirojin the power of structs. also technically the spatial hash uses a Dictionary but you will never remove a spatial hash during gameplay so GC is negligible. narrow phase detection and separating vector calculation have absolutely no heap allocations at all
@dankwraith C# has become a very different language since i left (gave up) school
@hirojin it is a very very good language
@dankwraith you know what i don't get about programming languages anymore?
why people say Lisp is unreadable, but this is somehow okay
@dankwraith (the easiest way i have found so far to avoid these, is to write Erlang 🤷♀️)
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