Known issues and limitations ​

Unreal 5 Launcher version ​

The plugin is not installed to the engine folder for the installer version of UE5. You need to copy the plugin into your project manually. This is mainly due to how dependencies for the launcher version of the engine are coupled into the UE5ModuleRules assembly.

DDC related issues ​

We recommend that you flush your DDC (Derived Data Cache) when you've switched over to using Simplygon's LOD interfaces after having used Epic's built-in version. This is to make sure that no cached LOD data from before will override or interfere with Simplygon generated LODs. Once you are using Simplygon we recommend that you use LODRecipes to generate your LODs.

Loss in texture resolution ​

Simplygon currently relies on material flattening to pre-bake the Unreal Engine material into an intermediate material. This is done using the material flattening process. This results in a new set of textures that are then used by Simplygon during its baking process. Since both material flattening and Simplygon using the same output resolution, which is usually lower than the source textures combined, this can results in slightly fuzzy looking textures if viewed at close distance. Ideally, material baking should be used for far away meshes.

Exporting scene and pipeline ​

If you are experiencing issues, you can enable debug settings in the project settings to help you (and us) to figure out the underlying problem. You go to Project Settings->Plugins->Simplygon plugin and enable Debug checkbox and Export pipeline and scene. This will allow you to export the scene and pipeline in the different Simplygon tools. The export path is ProjectDir/Intermediate/Simplygon by default but can be set in the project settings under Debug Path.

Distributed processing progress ​

When using distributed asset building there is unfortunately no support for getting progress from FastBuild or Incredibuild. However, for Incredibuild builds you can use the monitoring application provided as part of the package.

New UV generation limitation when separating trunk and foliage ​

Currently, when using the Billboard Cloud Foliage Pipeline with the setting Separate Trunk and Foliage checked, the number of UV's on the source asset has to be less than MAX_STATIC_TEXCOORDS (where MAX_STATIC_TEXCOORDS is an engine constant, default set to 8). The reason for this is that these settings requires us to keep both the source UV's (for the kept trunk geometry) and generate a new set of UV's for the foliage part. These combined can't be larger than the maximum set of UV's allowed.

LODGroup to LODRecipe Conversion ​

LODGroup to LODRecipe conversion is not currently provided. However with python scripting available technical artist should have tools available to easily write a script to map LODGroups to LODRecipes.

Limited support in Flipbook material shader ​

There is currently an issue with the normals generated by the flipbook material shader for pipelines that use a non-perpendicular view direction and up-vector. We are looking into this issue and it will be fixed in an upcoming release. For now, please only use a view direction and an up-vector that is perpendicular to each other if you want your flipbook to include normals.