Optimising Voxel Meshes for Games Using Blender

Doug Binks - Juliette Foucaut - 18 Sep 2023 - edited 14 May 2025      # Game Technology

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, Godot 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:

1. How to use Avoyd Voxel Editor to convert your voxel model to mesh for Unreal, Godot or Unity.
2. How to use Blender to optimise the mesh.
3. How to use Blender to export to glTF for Unreal 5 and Godot, and to FBX for Unreal 4 and Unity, and Links to guides for importing and configuring the model in each engine.

☛   Update to Avoyd version 0.26 or above:

• You can now export to .obj with Best optimisation to skip the manual optimisation in Blender.
• If you own Avoyd we recommend you export your voxel model to glTF Binary Mesh .glb instead of .obj. This both optimises your mesh better and simplifies your workflow. You can then directly import your .glb mesh into your game engine.

Convert the Voxel Model to Mesh Using Avoyd

Use Avoyd (1*) to export your voxel model to mesh .obj - together with its materials and their properties, such as metallic, transparent and emissive - for games as follows:

1. Open Avoyd Voxel Editor. (You can use the free version.)
2. Load the voxel model you want to optimise. You have several options:
   • Open a .avwr Avoyd world file using File > Open. (You can download Camper.avwr.)
   • Import a MagicaVoxel .vox file, a heightmap or a Minecraft file.
3. Export to Mesh:
   1. Select File > Export > Mesh (.obj)
   2. Enter the .obj file name and press Save.
   3. ☛  With Avoyd 0.26+ you can set Mesh Optimisation to Best and skip the manual optimisation in Blender.
   4. Choose the Material Export option according to the game engine you want to use your model in.
   5. Press Export.

(1* Note you can also use MagicaVoxel to export .vox to .obj. However it exports all the materials as diffuse, thus losing the metallic, transparency and emissive properties.)

Optimise the Mesh Using Blender

☛  You can skip this section if you used Avoyd 0.26+ with Best optimisation on export.

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

1. Open Blender. (Using Blender version 3.6.2.)
2. Delete the following objects from the Scene Collection:
   • Camera.
   • Cube.
   • Light.
3. Select File > Import > Wavefront (.obj).
4. 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. Deselect Realtime (small monitor icon next to the word 'Decimate') for better performance.
         3. 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.
         4. 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 or glTF Using Blender

In Blender, export to glTF or FBX depending on the destination game engine.

• Unreal 5 and Godot - export to glTF as follows:
  1. Select File > Export > glTF 2.0 (.glb/.gltf).
  2. Name the file filename.glb and click Export glTF 2.0.
• Unreal 4 and Unity - export to FBX as follows:
  1. Select File > Export > FBX (.fbx).
  2. Name the file filename.fbx and click Export FBX.

Import and Configure in Unreal, Unity or Godot

Finally, follow the relevant guide to import the optimised mesh into your game engine:

• Import .obj into Unreal Engine via glTF for UE5 and via FBX for UE4.
• Import .obj into Godot Engine via glTF.
• Import .obj into Unity 3D via FBX.

[ Edit 03 Oct 2023 - Added Godot and Unreal 5 export to glTF.]
[ Edit 16 Jan 2025 - Added step 4.4.2.2 to deselect Realtime.]
[ Edit 14 Mar 2025 - Added Avoyd 0.26 'Best' obj optimisation that replaces the manual optimisation in Blender. - Added link to export to glTF, a better workflow for games.]
[ Edit 12 Apr 2025 - Clarified Avoyd 0.26+ workflows.]
[ Edit 14 May 2025 - Added information about import guides for game engines.]