Collision problem


i just created an huge static mesh, which should be shown as an walk in top of an abyss.

so here is my first trial-workflow:
1- i made my uv´s and exported my mesh from maya as an fbx
2- i imported the fbx into ue4.4
3- i double-clicked the static mesh (fbx) in the content browser
4- i go to the popped up new menue bar and select “collision” / “box simplified collision”
5- i select the static mesh in the content browser and click on the right mouse button
6- i choose “create blueprint using…”
7- i drag my static mesh into the vieport and select it
8- i go to the details panel and select “collision”: “simulation hit events”, and “collision presets “block all””

after all i can walk over the static mesh in game modus.

but unfortunately i can´t walk correctly on this walk.
the walk is winding, so when i took the static mesh as one single collision-object (as i tried first) ,
i could walk in the winding areas “in the air”, without falling into the abyss.

so after this first trial i decided, to break up the static mesh into pieces, and give them all an seperate collision.
(here is an real good painter pic from an small part of this walk… the red stripes are the places, where i broke the static mesh into single parts):


unfortunately it doesn´t work right after all… i can “walk through the air” without falling into the abyss again…

**and finally here is my question:

what can i do, to make an collision, which fits the winding walk and having a good engine-performance…
(with falling into the abyss, when i leave the walk)?**

thank you very much for an answer!


An easy and effective way would be to create your collision in your 3d program -> (1st way) :slight_smile: (make sure to disable “one convex hull per…” in the import settings)

Btw, why do you convert it into a blueprint and is your mesh very complex (many tris) or a very simple one (like a cube)?

hi ,

thanks for your tipps!

first of all, i convert it into an blueprint, because someone has told me to do :slight_smile:
(you see, i do, what people are telling me to do .-))

and now the serious part:

  • my mesh is an very long walk with many winded sections (like shown in the picture), so it has 568 tris .
    i think it could be complicated to create an correct working collision in maya too?

  • otherwise i could “tell” the model to have per poly collision meaning that the mesh itself will be the collision… but this seems not so good for my performance (i´ve been told)…

or is this all an general point in ue4:

  • have i to forget winded areas in general and should i go better the way to make the geometry much more simpler (less than 563 tris) for an better performance?
  • maybe i should make this walk in general with the box-brush from ue4 (but i was told, that this way is not good for performance too) collision is included…

so, what way i should i go with my modeling in your opinion for an good working collison, which has a good performance also?


First of all I would recommend you to not convert it to a bp except you want something to happen (a door opens, interactive stuff with the player,…) I think before you converted it you had some lightmap problems? (overlapping UV’s) :wink:

For just 568 tris I would use the per poly collision, because you wont see a significant performance loss :slight_smile:
I always think like that: When I can save some tris, then I will do it :smiley:
Dont use the in-engine geometry tool, because you will have to convert it to a static mesh + create lightmaps in your 3d program.

hi ,

thanks a lot for your answer again!!

you´re right: less tris are good tris :wink:

but the last question:
when i got 4 static meshes with 568 tris is there an significant performance loss…
or at what tris-number the engine will slow down with per poly collision?

sorry for all my questions… but when i start, i won´t make major-errors :slight_smile:


You wont even realize the performance loss ^^ -> actually I cant answer your question at which tri count you will feel it (I hade some meshes with over 50.000 tris + the per poly collision and I havent realized anything)

that sounds beautiful to me :-))

have a nice week


thank you very much for your kind patience!!