Axis rotation, Blender vs Unity

I'm wondering what the recommended workflow is between Blender and Unity. In Blender, the Z axis is pointing up, while in Unity, the Z axis is pointing forward. So Y and Z are swapped.

So now when I construct something in Blender and import that into Unity, the thing will lay on its side. I can either rotate the object in Unity, or rotate it beforehand in Blender. I don't really want to rotate it in Unity to keep things clean, so it looks to me like pre-rotating it in Blender is the way to go. Of course this gets a bit tedious the more objects you have.

Is there any other recommended option? Perhaps an editor script that can massage the mesh vertices after importing so that the object is upright again without rotating the object in Unity?

Partial solution: Turns out this was rather simple. See this Gist for a script and instructions.
This MAY mess up UV mappings. I haven't tested that yet.

 

I always set X rotation -90 in Blender, use Ctrol + A and apply the rotation. Then, I export it to Unity, place the object on the scene, it will have X rotation -90, change it to 0 and do a prefab. You are good to go.

 

Actually I'd like to minimize work on this. Ideally it would be possible to just leave everything as is in Blender (no rotating), then import into Unity, create an object in the scene (which will be flat on its side), and then just press a button somewhere that uprights the object.

I think I'll mess with a custom editor that shuffles around the vertices in the mesh. Should be fun!

 

I've managed to come up with a script that does exactly what I need. I've updated the OP with a link to the script.

 

Btw. how to set proper scale in Unity5, when importing from blender? I am really annoyed by it. In unity 4 I had NO problems. In unity5 I have no idea why the scale is wrong.

 

Hmm, my script does not seem to be a final solution, I'm afraid. A simple restart of Unity reverts all the meshes back to their original state. Which kind of makes sense since I don't think it imports the mesh from the Blender file and then copies it somewhere else. Need to dig some more.

 

The best solution is to make sure the models are properly rotated in blender before exporting.
Max artists have to do this as well.
It gets a lot more complicated when dealing with characters, bones and skin.
Best to orient the mesh before going into Unity, and before setting up animation rigs.

 

Yes, but then you constantly rotate back and forth if you plan to iterate on the models.

 

No - you make sure the model is facing the correct direction and the axis is right upon creation. So then everything you do after that in the modeling application is oriented correctly.

You probably thought I meant the last thing you do before exporting is rotate to conform in Unity. On the contrary the first thing you do after creating the object is orient it correctly and make sure the axis is correct.
Iterate 100 times after that. The characters orientation in 3D software and Unity will match.

 

Exprort FBX > Z forward > Check box "Apply transform"

 

That sounds interesting. I'll try that.

 

One wonders why would blender do it this way?

 

Because world coordinate systems are arbitrary. Unity picked one way, Blender another. Neither option is wrong. Neither option is "more correct".

https://twitter.com/freyaholmer/status/1325556229410861056

 

Excluding factors like preference and familiarity with one system, software that deals with geolocated data tends to use a Right Handed Z up coordinate system, just like AutoCAD in the picture above. Other examples are QGIS and Pix4D.

Without being 100% certain on this and from what I remember, whether it's Projected Coordinates(meters) or Geographic(lat/long) usually get displayed in flat maps, so using Cartesian coordinates becomes intuitive, therefore Y+ points to North while X+ points to East and the origin is at the intersection of the Prime Meridian and the Equator.

 

For a few years I'm thinking if it would be possible to have FUR (forward up right) coordinate system where math would be hidden behind and all software would be compatible.
I wonder if it is just to hairy to implement.

 

Unity chose another option, that is definitely "the least correct".
Left-handed for graphics and right handed inherited from physx for physics.