[Noob] Why does collision HAVE to be convex?

Ooms_dvc

Title.

I searched high and low, only found out HOW people do it, but not WHY people do it.

i use blender, i have an open topped box (manifold ofcourse), 14 polygons or something, duping it and slapping ucx on the copy and then importing as fbx works fine. i dont see a problem with it, even if i walk my character over it it functions as i would expect...

So someone please explain to me why our collision meshes need to be convex? i dont look forward to having 10 different collision meshes for 1 object.

poopipe

if an object is convex it is much simpler to work out whether a point is inside it than it is with a concave object.

this is a 2d version of the basic principle

https://www.geeksforgeeks.org/how-to-check-if-a-given-point-lies-inside-a-polygon/#:~:text=1)%20Draw%20a%20horizontal%20line,true%2C%20then%20point%20lies%20outside.

with a convex shape you only ever need to make one check against an edge (triangle when transposed to 3 dimensions) , with a concave shape you could (in theory) need to make infinite checks