Best way to handle collision for mesh?

[caleb68]

Most the meshes i’ve been making for building a level are pretty basic, and can use simple collision for them, which is easy enough to export with the model (UCX_ addition) but I’m wondering for more complex models what would be the best way to handle the collision for it, simular to the model attached to the post. I’m thinking simple collsion in this case just won’t do, and i tried making planar collision to export using UXC_ but the engine is converting it to simple collision and causing major issues.

Any suggestions are greatly appreciated, I’m trying to make a bunch of reusable assets for my project, but some like this one have a specific purpose.

[MostHost_LA]

Use UBX liberally and disable the option to generate collision on import.

This model should probably be modular, but if you don’t want to waste time cutting it up then sprinkling UCB around it will be just fine.
you’ll have something close to 30 collision boxes to cover the model.
if the arches are important, then UCX for the arched aperture and UBX for the column.

That should should much sort it.

[caleb68]

I’ve got it turned into a smaller segment mesh as shown below, most segment meshes are 320x320x320 cm max in size but this because of what it is 320x800x800, the center section in the other picture is just the arch and floor, and the pillar bases are separate. The back wall i could turn into its own mesh as well. All the meshes are setup with a central snap location so they can be easily combined, similar to how Bethesda does the mesh snapping for their engine.

the main issue however is on forming the collision for the objects, planar seems to convert to box shapes even when telling the importer to leave the collision alone. So say if I were to basically make a ‘simplified’ version of the mesh for collision, the engine is turning it into a simple collision box that encompasses the entire model.

[DarkS474]

[You could try using lower LODs for collision

https://docs.unrealengine.com/en-US/...ion/index.html](Creating and Using LODs in Unreal Engine | Unreal Engine 5.3 Documentation)

Setting up Collisions with Static Meshes in Blueprints and Python

Using an LOD for Collisions

If you have already set up Levels of Detail (LODs) for your Static Mesh, you can use one of the less-detailed LODs as the Collision Mesh.

Call the set_editor_property() function on the unreal.StaticMesh object to set the lod_for_collision property to the index of the LOD you want to use. For example:

import unreal asset_path = “/Game/ArchVis/Mesh” def use_lod_for_collisions (static_mesh): static_mesh.set_editor_property(“lod_for_collision”, 3) unreal.EditorAssetLibrary.save_loaded_asset(static_mesh) # get a list of all Assets in the path. all_assets = unreal.EditorAssetLibrary.list_assets(asset_path) # load them all into memory. all_assets_loaded = [unreal.EditorAssetLibrary.load_asset(a) for a in all_assets] # filter the list to include only Static Meshes. static_mesh_assets = unreal.EditorFilterLibrary.by_class(all_assets_loaded, unreal.StaticMesh) # run the function above on each Static Mesh in the list. map(use_lod_for_collision, static_mesh_assets)

[MostHost_LA]

You can delete the hull the engine generates. Just select and delete from the editor.
You should be using boxes, not sheets. Because just about any collision only actually works with thickness to stop intergenerational at speeds.

[caleb68]

@MostHost_LA

You can delete the hull the engine generates. Just select and delete from the editor.
You should be using boxes, not sheets. Because just about any collision only actually works with thickness to stop intergenerational at speeds.

so if im reading what you wrote here right, your saying planar/sheet collision in Unreal engine tends to fail for things like bullet projectiles?

[caleb68]

with box collision… im having a hard time visualizing the best method for doing it, for example this tunnel segment, Convex collision can’t have any open holes in it, and for base doorways I ended up having to use 3 convex objects to make the box collision for them, I’m thinking something like this for example would use alot more, lowering performance over sheet collision.

[MostHost_LA]

you xan do that model with 9 collisions. 2 convex, 6 Boxes.