[Blender] How do modifiers work with Unreal?

I have a character created in Blender and am at a point where I would like to start using shape keys to position things like the eyelids and mouth. After shape keys are applied, modifiers can no longer be applied and I wanted to make sure the following modifiers would import into Unreal with no unexpected results.

Armature.

Subdivision Surface.

Lattice - Cartoon eyes.

Shrinkwrap - Eyelids.

I had a similar issue once and found a Blender script that was a lifesaver. The script is called ApplyModifierForObjectWithShapeKeys . py and allows you to apply modifiers on objects with shape keys.

Blender thread: http://blenderartists.org/forum/showthread.php?331724-Mirror-Modifier-with-Shape-Keys&s=722f2c1cf7798923412b93ed3bfed5eb

Script link (from the thread): GitHub - przemir/ApplyModifierForObjectWithShapeKeys: Blender script

In my experience the script works well for most cases although there are certain setups where results might be unpredictable.

Worth noting that once you export your model into a format like FBX, all Blender specific artifacts like modifiers are no longer present so Unreal will not directly see them unless the effects of these modifiers are represented in the resultant FBX. That depends on Blender’s FBX export script and which features the script can successfully export so far (you may have already read elsewhere about the difficulties that Blender faces in developing an FBX exporter because they don’t have access to the proprietary format among other issues).

HTH.

Thanks for the detailed reply! How would I go about modeling something that would “break” if the modifier is applied? Example, my eyes are spheres with a lattice modifier so that they stay in the sockets when rotating, if this were applied the eyes would clip through the sockets. Additionally, If this is not a great place to ask these questions where would you ask? Thanks for your help!

AFAIK, any modifier that “breaks when applied” can’t be brought into the engine because it’s behavior won’t be included in the FBX unless the modifier is applied. However if you can bake the effect into an animation then the keyframes/bone transforms will be represented in the FBX and so you can bring the animation into the engine.

I haven’t used the lattice modifier I’m afraid so I’m not sure what the best workaround in your situation would be, perhaps other Blender users can point out something that I’ve missed.

PS: I didn’t mean to imply this wasn’t the place for Blender-UE4 integration issues! I’ve now modified my previous post for clarity. Just saying that modifiers are a Blender workflow artifact that Unreal’s importer code will not even be able to see because everything comes in through FBX right now.

I have a character with lattice on her eye’s and they seem to work fine. You’ll need to experiment with the import/compute normals and tangents setting but I haven’t seen any problems, make sure all your transforms are applied. I also have questions about which modifiers I can and can’t use and will need to experiment a lot to find out.