I am making a side scrolling SHMUP with 3d objects, was using 3d physics but ran into odd spikes during parenting so am switching to 2d physics with much faster results but I can’t get around to how colliders editing works… and I wonder if it’s sprite only…
I add a circle2d and can size it fine but any value in x offset does nothing, y does move it up.
I add a box2d and it doesn’t show up, gives me a warning about shape verification
Capsule2d… work on some objects but not on others, seem it needs to be placed on a mesh not a gameobject… wat!? switching direction acts out: size 10 10 in vertical does show a vertical capsule but in horizontal i get a circle so I shrink down size y to 1 and get a … vertical capsule
So I try polygon collider but am only getting a vertical line in the 2d scene mode, when I switch to 3d view and orbit to face the zy plane then i see a pentagon! Isn’t 2d physics supposed to be in the XY plane?!
edit collider button does nothing in all cases - does it even work for anything 2D physics?
So yeah, what’s the trick?
Not a single thing of what you wrote happens here (Unity 5.6). If it was just one, I’d say editor glitch, but it’s literally nothing. 
Maybe you’re working on an unusable scale (way too small or too big). Capsule colliders are components, components are placed on GameObjects, not meshes. It works on all objects. A size of X=10, Y=1 with a horizontal direction gives a horizontal capsule:
If you use X=1, Y=10 with vertical then you get a vertical capsule. A polygon collider will be in the shape of any sprite it’s attached to; if you attach it to a non-sprite object then it’s a basic pentagon to start with (yes, in 2D scene view mode):
And yes, physics is in the XY plane. The polygon colliders are drawn in 3D, like every single object in Unity, but that doesn’t change how physics works. If you click the edit collider button, you can edit it as described in the docs.
–Eric
I found out why the colliders were acting weird: I build all my 3d objects facing z so when I rotate them to face x, I get a y rotation of 90 which give me the slice of the 2d colliders. the only one that maintains its profile regardless of 3d orientation is the circle so I made composite colliders out of them. Now everything works - at first I thought they didn’t but that’s because I forgot to tick is trigger in the bullets 
Editing polygon collider still doesn’t do a thing for me, following the docu I hover above a vertex and nothing happen wether I click it or not, shift+clicking on an edge is the same. In fact I tried editing even lights and handles do not appear. 5.6f3, driver bug maybe?
