Simplygon 10.4.117.0

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Unreal Engine 5 plugin ​

The Simplygon Unreal Engine 5 plugin exposes the following features.

For a complete list of supported Simplygon features, see the feature table.

Supported versions ​

Unreal Engine 5.4 & 5.5.

Generate Static- and Skeletal Mesh LODs ​

The plugin introduces a new asset type, the LOD Recipe, which makes generating good-looking LODs for Static- and Skeletal Meshes easy. A LOD Recipe can be used to run mesh reductions, simplify advanced meshes, bake materials and create impostors (which are particularly good for foliage assets). For Skeletal Mesh LODs it also offers the option to reduce bones and transfer morph targets.

Skeletal Mesh lod chain
Figure 1: Example Skeletal Mesh LOD chain.

Create replacement meshes ​

For workflows inside the level editor the plugin provides a special Actor type called a Stand-In. Using Stand-Ins it's possible to replace one or more meshes in the scene with a single (potentially simplifed) mesh, bake materials down to only one for all the objects as well as cull away triangles that are not visible.

Original vs Stand-In
Figure 2: Example Stand-In.

Hierarchical Level-of-Detail ​

The plugin exposes a new Remeshing HLOD builder which can be selected and configured in any HLOD layer. The builder is based on Simplygon's Remeshing pipeline which main task is to generate a faster approximation of all source meshes inside a World Partition cell. It does also support common features such as material baking and landscape culling. This HLOD builder replaces the previous ProxyLOD / standard interface implementation.

HLOD visualization mode
Figure 3: HLOD visualization.

Important

As Unreal Engine 5 is heading towards World Partition we've decided to follow in the same direction. The new HLOD builder exposes more functionality than the previous standard interface implementation and will offer users much more flexibility when generating HLODs. A limitation of this step is that non-World Partition world types are no longer supported. Moving away from the standard interface also means that generation of HLODs through the HLOD Outliner and the Simplification HLOD builder will no longer use Simplygon.

Automation using scripting and commandlet ​

The plugin provides a Blueprint Library which can be of great help when automating your optimization workflows. It's possible to create LOD Recipes and Stand-Ins, assign meshes to them, set desired settings and kick off builds.

python
## Pseudo code for creating and building a LOD Recipe

# Create new recipe
lod_recipe = unreal.AssetToolsHelpers.get_asset_tools().create_asset(asset_name = "LR_LargeProp", package_path = "/Game", asset_class = unreal.LODRecipe, factory = unreal.LODRecipeFactory())

... # Set settings

# Assign an asset with the recipe
asset = unreal.load_asset(...)
unreal.SimplygonBlueprintLibrary.assign_recipe_to_asset(lod_recipe, asset)

# Build the LODrecipe for the asset
unreal.SimplygonBlueprintLibrary.build_lod_recipe(asset)
python
## Pseudo code for creating and building a Stand-In

# Create Stand-In actor from a given list of static mesh actors.
actors = ... # list of actors to replace with a Stand-In
standin_actor = unreal.SimplygonBlueprintLibrary.create_standin_actor_from_actors(actors)

# Assign far pipeline to Stand-In
far_pipeline = unreal.StandinFarPipeline()
standin_actor.set_editor_property("pipeline", unreal.SimplygonStandinPipeline.cast(far_pipeline))

# Builds meshes for all Stand-In actors
unreal.SimplygonBlueprintLibrary.build_standin_meshes()

The plugin also offers the option to build LOD Recipes from outside the Unreal Editor using the LOD Recipe Commandlet.

shell
# LOD Recipe Commandlet example
UnrealEditor-Cmd.exe <ProjectPath> -AllowCommandletRendering -run=LODRecipeCommandlet -Save -NoSourceControl