Optimising Voxel Meshes for Games Using Blender

Doug Binks - Juliette Foucaut - 18 Sep 2023

Reducing the number of polygons in 3D objects helps improve a game's performance. This tutorial explains step by step how to clean up the geometry of voxel models in Blender to prepare them for export to game engines like Unreal or Unity.

Note you may have encountered 'polygon reduction' techniques under other names such as 'vertex reduction', '3D model optimisation' or '3D model clean up'.

This post covers the following workflow:

How to use Avoyd Voxel Editor to convert your voxel model to mesh for Unreal or Unity.
How to use Blender to optimise the mesh.
How to use Blender to export to .fbx, and links to documentation for importing the optimised .fbx into Unreal and Unity.

Not covered in this post:

Export to Godot Engine: we haven't tested importing the materials into Godot. However you could try using the same methodology exporting the .gltf format from Blender.

Convert the Voxel Model to Mesh Using Avoyd

Use Avoyd Voxel Editor to export your voxel model to mesh (.obj) for games - together with its materials and their properties, such as metallic, transparent and emissive - as follows:

Open Avoyd. (You can use the free demo.)
Load the voxel model you want to optimise.
- If you need a model, you can use one of the following:
  - Open a .avwr Avoyd world file using File > Open. (Download Camper.avwr.)
  - Import a MagicaVoxel .vox file, a heightmap or a Minecraft file.
Export to Mesh:
1. Select File > Export > Mesh (.obj)
2. Enter the .obj file name and press Save.
3. Untick Optimise Mesh. (Because you will optimise in Blender.)
4. Choose the Target Application Preset: Unreal or Unity. (For Godot use the Unity preset.)
5. Press Export.

Optimise the Mesh Using Blender

Open the .obj file in Blender and clean up the geometry as follows:

Open Blender. (Using Blender version 3.6.2.)
Delete the following objects from the Scene Collection:
- Camera.
- Cube.
- Light.
Select File > Import > Wavefront (.obj).
Select the .obj file then click Import OBJ.
1. Select the object by either clicking on it in the viewport or on the object name.
2. Set the Viewport Shading to Material Preview (third sphere in the top-right corner).
3. Set the object Interaction Mode to Edit Mode (drop-down on the top left).
  1. Choose Select > All (button to the right of the interaction mode control)
  2. Choose Mesh > Merge > By Distance (button to the right of the select button).
4. Set the object Interaction Mode to Object Mode.
  1. Select the Modifiers (blue wrench on the right-hand side).
  2. Click Add Modifier
    1. Select Decimate in the Generate column.
    2. Open the Planar tab.
      1. Hold down the Shift key and click all the Delimit options to select them:
        
        Normal
        
        Material
        
        Seam
        
        Sharp
        
        UVs
      2. Leave All Boundaries unticked.
      3. Leave Angle Limit to 5 degrees.
    3. Click the down arrow button (next to decimate) and select Apply.
5. Set the object Interaction Mode to Edit Mode to see the result: the object is cleaned up, it has fewer polygons:

Export the Model to Game Engines

Export to FBX using Blender

In Blender export the mesh to .fbx for Unreal or Unity (.gltf for Godot) as follows:

Select File > Export > FBX (.fbx).
Name the file <filename>.fbx and click Export FBX.

Import and Configure in Unreal or Unity

Finally, follow the documentation to import the optimised .fbx into Unreal or Unity:

Import in Unreal Engine.
Import in Unity 3D. (Note you'll need to import the .fbx file instead of the .obj and .mtl referred to in the documentation.)

previous

Optimising Voxel Meshes for Games Using Blender

Convert the Voxel Model to Mesh Using Avoyd

Optimise the Mesh Using Blender

Export the Model to Game Engines

Export to FBX using Blender

Import and Configure in Unreal or Unity

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