Blender to Unity 01 – Scale, UV’s and Import

This post forms part of a likely ongoing series of notes related to using Blender with Unity.

Scale and Dimensions

Any initial Blender scene will present with a unit scale cube that has dimensions of 2x2x2. To get set with a unit cube that can be later exported and imported into Unity without scaling concerns, any scaling or rotation operations MUST BE APPLIED:

This process is important for maintaining consistency across platforms.

If 1 Blender Unit = 1 Unity Unit = 1 metre issues of weird scaling and sizes when switching platforms can be minimised. This concept is also valuable when building assets in Blender that can successfully translate to real world values/dimensions in Unity.

UV Problems

When using Blender to unwrap objects  – a better approach when building more complex assets – make sure to recalculate the mesh normals so that the Unity import has no ‘missing’ faces:

Recalculate normals on unwrapped mesh

Using .blend files in Unity:

.blend files can be imported directly by dragging and dropping into Unity.

In a blender scene with multiple meshes/objects, the whole collection can be dragged into the Unity scene or each individual mesh can be selected and dragged out – but will have a rotation on x of -90. 

This issue can be solved by using this approach from this forum post:

’In object mode, set the X rotation of your model to -90. Press Ctrl + A and apply rotation, X rotation appears to be 0 now in Blender, set it to 90 and save/export it. You’ll see that it will appear both correct and at 0 rotations now.’

This approach has the advantage of being able to use an ‘open’ blender file as opposed to a ‘closed’ FBX file:

Using .fbx Files

.fbx files can be easily exported from Blender and used in Unity. Once the Blender model is complete – unwrapped etc. – select the mesh/meshes/objects/collections needed in the model for Unity and use File–> Export–>FBX:

Use the Presets shown on the right – make sure to check Apply Unit and Apply Transform

The exported FBX file can now be imported to Unity. Select the mesh and look at the following settings in the Inspector:

  • In the ‘Model’ tab all ‘Scene’ checks can be turned off except ‘Convert Units’
  • Use ‘Swap UVs’ if the blender model has its own UV map(s).
  • Click ‘Apply’ to reimport the mesh with these settings.

At this time ‘Material Creation Mode’ drop down in the ‘Materials’ tab is set to ‘None’.

Materials and Textures will be exported from Blender as image files .

This process to be covered at a later date.