Making a map in blender. Odd collisions

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#1

I’m making a map in blender, and when i import the file in roblox studio, the collisions are terrible. I think roblox just makes a large box of collision around the mesh.

Anyone had the same problem or has a fix ?

Here’s what i mean (i’m standing on top of the cave entrance, where i should fall) :

Capture d’écran, le 2020-05-24 à 15.43.42
Capture d’écran, le 2020-05-24 à 15.43.42946×660 194 KB

The cave :

Capture d’écran, le 2020-05-24 à 17.18.31
Capture d’écran, le 2020-05-24 à 17.18.311818×1046 1.19 MB

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#2

Roblox has a hard time calculating hitbox geometry for meshes with concave shapes (like the opening in your mesh). There’s really not much you can do about it, but you can try these things:

  • Go to File > Settings > Physics > Show Decomposition Geometry then restart Studio to see the hitbox for yourself (this won’t help anything, it just allows you to visualize the hitbox)

  • Split the mesh up into smaller parts. This isn’t a guaranteed fix but it’s worth a try and fixes this problem most of the time

  • Change the CollisionFidelity of the mesh to something else. You can try Default or PreciseConvexDecomposition.

Edit I meant to say PreciseConvexDecomposition

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#3

Change CollisionFidelity to PreciseConvexDecomposition in the Properties tab.

This may not fix the problem you are experiencing though. You included the floor of your cave inside your mesh as well, which is unnecessary. The geometry of the cave’s floor is not complicated enough to include that in your mesh, doing that will only add an additional complexity to your collisions.

I would suggest to remove the floor of your cave from the mesh and switch it out for a Part.

If you at some point in the future do require a more complicated floor, split the cave and the floor up into two seperate meshes or use a terrain plugin that uses WedgeParts.

https://www.roblox.com/library/1083345917/Atrazines-Terrain-Plugin-V2

Good luck.

2 Likes
#4

Crashes roblox studio when i change CollisionFidelity to PreciseConvexDecomposition in the Properties tab.

#5

As a modeler myself, I wouldn’t recommend anyone to make the whole map in blender and here are a few reasons why:

  1. It messes up your collissions
  2. You can’t use multiple materials on your mesh
  3. The limit for each mesh is 10k, which limits your map detail closely to 0.
    I’d recommend using Roblox terrain, but if you’re enjoying making assets in blender that much, I’d suggest making multiple hill meshes, rocks and other cool yet smaller stuff.
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#6

Oh, man, this is giving me Stackoverflow flashbacks.

“How do i do x using y ?”

“Nobody uses y for that, use this very different thing that was not asked for”

2 Likes
#8

Using PreciseConvexDecomposition May or may not work, but you can always import each part separate to make sure it works, or if you want to go probably the best route in terms of performance is to make your own hitboxes using invisible parts and the mesh being false colliding.

1 Like