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Collisions on imported model with holes

Development Discussion Content Creation
#1

Hello,

I am new to Unreal Engine 4 and new to modeling in general. I’ve made a simple model which is basically 4 walls, but collision does not seem to work properly. It seems to create a box around the entire model and treats it as one. When I import it to Unity it works correctly (after inserting mesh colliders.)

Also in Unreal it seems to treat everything as one object, while in Unity it correctly imports all the pieces involved in the model. Example of how it is unity.

vs

All 4 walls are grouped under one element instead of being separate.

Also, unrelated but something I would like to know, is how to rotate models properly using the Rotation Tool. Example:

Start :

After Rotate :

It seems to rotate in a spherical arc, while in unity using the Rotation Tool also affected the translation so it is more intuitive.

Start:

After Rotate:

I don’t know if you can tell but it stayed in the same position.

Any help on doing what I’m asking would be really appreciated, thanks!

#2

A few things–What happens in Unity is that it creates a Prefab object if you have multiple objects that are in a file that you import. UE4 doesn’t have prefabs, so the only option is to import the objects as separate meshes, or combine them into a single mesh.
For something like that, you would want it as a single mesh, because each object you place is a draw call so it slows things down the more objects you have. As far as collision goes, it can automatically try to create collision shapes for your object, but usually you have to create a collision mesh to import with your object. The collision mesh must be convex shapes, so in that situation you’d have to build the collision mesh out of multiple boxes.

As for the other thing, that’s due to the pivot point, the pivot point is always going to be placed at 0,0,0 so if your object isn’t placed there then it won’t be in the same place that you had it in your 3D program.

#3

Or if you’re feeling super lazy, in the mesh properties window, select ‘Use Complex collision as Simple’ as a workaround. Bear in mind there’s a performance impact with doing this - on one mesh you probably shouldn’t notice much difference, but it all adds up.