FBX Mesh Pipeline
After preparing your geometry assets, you need to export them to FBX. This format has a long, history that eventually led to its being one of the most common interchange formats available for 3D data.
UE4 uses FBX extensively for both Mesh and animation data so knowing what Unreal Engine 4 expects from your exported geometry is important.
Be sure to select Smoothing Groups and Tangents and Binormals and to Triangulate your Mesh in your export options, if available (see Figure 3.5). These options ensure that your Mesh is triangulated and shaded exactly the same way in both your 3D package and UE4.
Figure 3.5 Suggested FBX export settings for static meshes (3D Studio Max)
If your scene is in a scale other than centimeters, you can easily rescale all of your assets as you export by explicitly setting Scene units to converted to: to Centimeters.
Exporting Multiple Meshes
You can employ several workflows to export multiple Meshes. Each has drawbacks and advantages.
Single FBX File
You can include multiple Meshes in a single FBX file. When you import into UE4, you are offered an option to combine those Meshes into a single Mesh or to import those Meshes as individual Meshes.
I’m not a huge fan of this method. Several issues can make this workflow clunky and sometimes unstable.
A common issue is that you need to export the exact same set of Meshes each time you update any single one. This task is very hard to maintain, and failing to so can cause crashes and other issues.
Later versions of UE4 have additional workflows to help alleviate the aforementioned issue. Scene Import takes a single FBX file, imports all the Meshes, and places them into a Level. This promising feature can also import cameras, lights, and animation; however, it needs to mature some to become a solid workflow.
Keep an eye on this feature as the engine improves over time. Try to apply it to your data. It could make exchanging data between your 3D application and UE4 much easier.
Multiple FBX Files
Exporting multiple FBX files is my favorite option. Although most 3D applications don’t natively support exporting in this manner, several scripts and tools are available that enable you to batch the export process. You can find a selection of these scripts at www.TomShannon3D.com/UnrealForViz.
UE4 can quickly import entire folder structures of FBX files. With this workflow, if you need to update a single asset or a group of assets, you can easily and reliably replace their FBX files and reimport into UE4. This fine-grained approach gives you a great deal of control, and it is the least risky and least technically complicated of the options.
An easy iterative workflow is to simply overwrite your existing, exported FBX with the updated geometry. This allows you to select the file in the Content Browser and reimport it, updating the asset in UE4.
I frequently use the auto reimport feature in UE4. It enables you to define a directory and, any time you update or create a new, importable file, the Editor detects the change and automatically updates existing assets or imports and creates new ones.
To enable this feature, open Editor Preferences, and define a folder to watch and a corresponding folder in your Content folder (see Figure 3.6).
Figure 3.6 Setting up Auto Import in the Editor Preferences
Where to Put Your FBX Files
Typically, you do not need to maintain your exported FBX files, and can be considered temporary. You can save them wherever is most convenient for you. Being consistent is important so you can use reimporting features.