FBX Settings Actors tab - Lumberyard User Guide

FBX Settings Actors tab

This feature is in preview release and is subject to change.
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Actors are assets with at least one bone and can contain one or more skinned meshes. By default, all actors in the .fbx file are processed. However, you can manually exclude individual actors within your .fbx file. You can also process multiple actors from a single .fbx file. Each Actor group produces its own .actor file. The processed runtime assets appear in Asset Browser as children of the .fbx file.

Actors tab properties

                The FBX Settings Actors tab.
Add another actor

Add an Actor group to process. Each Actor group produces a .actor file.

Name actor

Enter a name for the Actor. This is the name of the .actor file that appears in Asset Browser as a child of the .fbx file.

Select root bone

Select the root bone of the skeleton hierarchy. The top parent bone of the skeleton is automatically selected as the default bone. All descendant bones of the root bone are processed.

Select base meshes

Specify the meshes to process from the .fbx file for this Actor group. Choose the Hierarchy icon to see a list of meshes found in the .fbx file. Select meshes from the list to include them in the Actor group and process as visible render meshes. If the .fbx contains meshes that are intended to be used as PhysX collider meshes, or meshes that are not skinned to the skeleton hierarchy being processed, you should exclude them from the Actor group by deselecting them in this list.


If you have defined level of detail meshes for your actor by appending _lod0 through _lod5 to meshes in the .fbx file, the _lod0 meshes are automatically selected for the Select base meshes property.

Add Modifier

Modifiers add additional specialized options for processing assets. Choose the Add Modifier button to see a list of available modifiers:

  • Cloth

  • Comment

  • Coordinate system change

  • Material

  • Mesh

  • Scale actor

  • Skeleton optimization

  • Skin

  • Tangents


Some modifiers are not be available unless the gem that provides the modifier is enabled in your project.

Cloth modifier

                The FBX Settings Actors tab Cloth modifier.

Add NVIDIA Cloth data to a selected mesh to simulate cloth physics.


Each mesh in the Actor group to simulate as cloth requires its own Cloth modifier.

For more information, see Simulate cloth with NVIDIA Cloth.

Select Cloth Mesh

Select the mesh to have cloth data applied and simulate as a cloth object.


For information on the Inverse Masses, Motion Constraints, and Backstop properties below see Per vertex properties for cloth.

Inverse Masses

Select a vertex color stream to apply per vertex inverse mass data for cloth simulation. If no vertex color stream is selected, an inverse mass value of 1.0 is assigned to all vertices in the cloth mesh.

Inverse Masses Channel

Select the channel in the vertex color stream that contains inverse mass data.

Motion Constraints

Select a vertex color stream to apply per vertex motion constraints data for cloth simulation. If no vertex color stream is selected, a motion constraint value of 1.0 is assigned to all vertices in the cloth mesh.

Motion Constraints Channel

Select the channel in the vertex color stream that contains motion constraints data.


Select a vertex color stream to apply per vertex backstop data for cloth simulation. If no vertex color stream is selected, backstop will be disabled for the cloth mesh.

Backstop Offset Channel

Select the channel in the vertex color stream that contains backstop offset data.

Backstop Radius Channel

Select the channel in the vertex color stream that contains backstop radius data.

Comment modifier

                The FBX Settings Actors tab Comment modifier.

Add a comment to the file. You can add a comment about changes made to the .fbx file for tracking purposes or notes on export options, for example. Comments don't affect how files are processed and multiple comment modifiers can be added to a mesh group.

Coordinate system change modifier

                The FBX Settings Actors tab Coordinate system change

Modify the coordinate system of the actor. Third-party content creation applications use varying coordinate systems with content applications often rotating the direction of the forward axis. The Facing direction property can be set to rotate the actor 180 degrees around its up axis to account for this difference. The rotation is applied when the asset is processed and the .fbx file remains unchanged.

Level of Detail modifier

                The FBX Settings Actor tab Level of Detail modifier.

The Level of detail (LoD) modifier is added to the Actor group automatically when LoDs are found in the .fbx file. Choose the Hierarchy button to verify or modify the meshes and bones assigned to each LoD. Actors support up to 5 levels of detail in additon to the base mesh(es).


The Level of detail modifier for Actor groups cannot be added or removed manually and does not appear in the modifier list. The Level of detail modifier is automatically added and configured when actor LoDs are found in an .fbx file.

LoDs are optimized assets with progressively lower polygon counts, fewer and smaller textures, and simplified materials. An Actor LoD can also have a simplified skeleton where some leaf bones have been removed from the skeleton. The farther an entity is from the camera, the less detail is required from the actor contained in the entity. As the entity moves farther from the camera, it swaps to a lower actor LoD.

In addition to the base actor mesh, You can create up to five LoDs for actors which are numbered [1] to [5], with [1] being the highest level of detail. As the actor moves away from the camera, it will transition from the base mesh to LoD 1, and then progressively through the LoDs the further it moves from the camera. LoDs are not required. Creating LoDs, however, is recommended because they help get the best performance and visual fidelity across a range of platforms with different hardware capabilities.


When you author the actor in your 3D application, you must add _lod1, _lod2, _lod3, _lod4, _lod5 as suffixes to your mesh names to automatically add a Level of Detail modifier and assign the meshes to appropriate LoDs. _lod1 is mapped to LOD 1, _lod2 is mapped to LOD 2, and so on.


The meshes for the base mesh, and the corresponding skeleton are assigned in the Select base meshes and Select root bone properties of the Actor group automatically. Meshes labeled _lod1 through _lod5 and their skeleton hierarchies are assigned to corresponding LoDs in the Level of Detail modifier.

For more information, see Using Actor LODs to Optimize Game Performance.

Material modifier

                The FBX Settings Actors tab Material modifier.

The Material modifier helps automatically manage the contents of the .mtl file that corresponds to the Actor group when actor assets are updated.

A material is a combination of shaders and properties that define the surface of a mesh. Materials contain shader and texture assignments, settings for shader properties such as smoothness, opacity, emissive color, etc., and if necessary, a physics material assignment that defines physical properties such as friction. An Actor group processed with a file named myfile.actor has a corresponding material file named myfile.mtl.

When an Actor group is processed, Asset Browser generates a material file (.mtl) containing a list of materials and their property settings for the mesh group. A mesh can have multiple materials, and an Actor group can have multiple meshes, so the .mtl file might contain several materials even if the asset seems simplistic visually.

Update materials

When enabled, updates the texture map file names in the .mtl file to match the texture map names in defined in the .fbx file.

Remove unused materials

When enabled, removes materials that are present in the .mtl file that are not defined in the .fbx file.

Mesh modifier

                The FBX Settings Actors tab Mesh modifier.

Set a vertex color stream and its precision for the Actor's visible render mesh.

Vertex color stream

If the mesh for this Actor group contains a vertex color stream, it can be selected from this list to be processed.

Vertex color streams contain per vertex color data that can be referenced by materials. Vertex color streams are also often used for tagging meshes with arbitrary data such as the inverse mass value used in cloth simulation. Because of this, a mesh might have multiple vertex color streams. Be sure to select a vertex color stream intended to be referenced by materials if multiple streams exist.

Vertex color mode

Set the vertex color precision to either 32 bit (8 bits per channel) or 128 bit (32 bits per channel).

Vertex color streams contain four channels: red, green, blue, and alpha. Setting the mode to 32 bit vertex color precision saves significant memory over 128 bit vertex color precision at a loss of dynamic range. If you are targeting a platform with memory constraints, using 32 bit precision is a very useful optimization. If you are targeting a platform that supports high dynamic range (HDR) display, 128 bit precision offers much greater color fidelity.

Scale actor modifier

                The FBX Settings Actors tab Scale actor modifier.

The Scale factor modifier sets a uniform scale for the Actor group. This setting is useful if your assets are created in an application that uses a different base standard unit of measurement than Lumberyard.

Skeleton optimization modifier

                The FBX Settings Actors tab Skeleton optimization

The Skeleton optimization modifier automatically optimizes Actor skeletons for client and server scenarios.

Auto Skeleton LoD

When enabled, unskinned bones (bones not weighted to any vertices), are optimized out of the client side skeleton hierarchy.

Server Skeleton Optimize

When enabled, bones that do not have colliders attached are optimized out of the server side skeleton hierarchy.

Critical bones

Choose the Hierarchy button to select bones that should not be optimized out of the hierarchy. Your actor might have bones that have no skin weights such as attachment bones for weapons and accessories, for example, that you do not want optimized out of the hierarchy.

Skin modifier

                The FBX Settings Actors tab Skin modifier.

The Skin modifier sets the maximum bones and minimum weight per vertex.

Max weights per vertex

The maximum number of bones that can influence a vertex. Values range from a minimum of 1 to a maximum of 4.

Weight threshold

The minimum bone weight per vertex. Weight values beneath this threshold are ignored during export. Values range from a minimum of 0 to a maximum of 0.01.

Tangents modifier

                The FBX Settings Actors tab Tangents modifier.

The Tangents modifier generates or exports tangents and bitangents from your .fbx file. You should use the same tangent space you use to generate normal maps to achieve the desired appearance in Lumberyard.

Normal maps can make a surface appear as though it has more geometric surface detail than exists in the mesh. The normals in the map are in tangent space which points in the positive Z direction. Tangent space is local to the surface and is used to transform the normals in the normal map into world space so the material can be lit and rendered correctly on a deforming surface such as a character mesh. You can create tangents and bitangents in your third-party content application and save them as vertex attributes, then export the tangents with the Tangents modifier, or use the Tangents modifier to generate tangents when the mesh for this Actor group is processed.

Tangent space

Defines the tangent space that Lumberyard uses for an actor. Choose from the following options:

  • MikkT – Uses MikkT to generate the tangents. MikkT is a widely used solution for generating tangent space that strives for consistency regardless of changes and optimizations to the source mesh. This is the default setting.

  • From FBX – Export the tangents from the FBX file.

  • EMotion FX – Use EMotion FX to calculate the tangents.


    The EMotion FX option is for backward compatibility only and is not recommended.


Defines how to generate or read the bitangents.

  • Use from source – Use the bitangents from the FBX file or the output from the tangent generator used (MikkT).

  • Orthogonal – Generates the bitangents orthogonal to the tangent and normal. This is the default setting.


When enabled, tangents and bitangents are normalized. Normalize is enabled by default.

UV set

The index of the UV set to generate tangents from. The default setting is 0, the first UV set.