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Actor Merging

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The Merge Actors tool enables the user to combine multiple Static Meshes into a single new Actor. Materials can also be baked together into a single Material with a series of custom textures using a new UV layout, and the original Static Meshes used can even be completely replaced by the newly merged asset.

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Actor Merging Workflow

Merging Static Meshes in your scene is handled like so:

  1. From the main menu choose Window > Developer Tools > Merge Actors.

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  2. Select a number of Static Meshes in your level that your would like to merge.

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  3. Choose the appropriate options for merging the selected Actors.

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    Use the reference tables below to learn about each of the settings in this window and the actions they perform.

  4. Click the Merge Actors button and give your new merged Actor a name, then click Save.

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    You can then open the merged Actor as it's own asset from your Content Browser.

Merge Actors Tool Options

At the top of the Merge Actors window is a list of all the Static Meshes selected in the viewport. Here you can check which meshes will be included in the final merge.

If you have one or fewer meshes selected, you will see a yellow warning near the bottom of the window stating that you have insufficient mesh components for merging.

Mesh Components List

In the Mesh Components List you'll find the selected actors that will be used when merging them together.

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Option

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Description

Mesh Components List

This area contains a checklist where you can choose which of the selected meshes will be included in the merge.

Mesh Settings

In the Mesh Settings section, you'll find the mesh properties that pertain to the meshes that will be merged.

MeshSettings.png

Option

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Description

Pivot Point at Zero

If set to true, the pivot point of the final merged actor will be set to the scene's origin [0,0,0]. If set to false, the pivot will be located at the pivot location of the first Static Mesh Actor selected for the merge.

Merge Physics Data

If true, this will merge together all of the physics primitives into a single physics object.

Bake Vertex Data

Bakes vertex data including vertex color and normals into the new resulting mesh.

LOD Selection Type

Use this to control which LODs are added to the merged object.

Selection

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Description

Use All LODs

If selected, this use all available LOD levels when merging the actors.

Use Specific LOD Level

If selected, this will use only the selected LOD level when merging the actors.

Calculate Correct LOD level

If selected, this will calculate the appropriate LOD model for the given screen size.

Advanced Options

Generate Lightmap UVs

Creates a new lightmap UV layout for the merged mesh, using the existing UV islands. This new layout will be placed in the Target Light Map UVChannel.

Target Light Map Resolution

Specifies the resolution for the new lightmap UVs, which controls the distance calculated between each island within the layout. Higher resolutions will yield tighter spacing between each island.

Material Settings

In the Material Settings section, you'll find the texture and material properties that pertain to the meshes that will be merged.

MaterialSettings.png

Option

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Description

Merge Materials

If checked, the Materials of all the merged assets will be combined into a single Material with new UV layout. The following subsettings apply only if Merge Materials is checked.

Texture Size

This provides access to the X and Y pixel dimensions (resolution) for the final merged Material's textures.

Texture Sizing Type

The selection options available when choosing how you want the size of your texture to be calculated.

Type

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Description

Use TextureSize for all material properties

This will use the value entered into Texture Size for sizing.

Use automatically biased texture sizes based on TextureSize

This creates a biased set of {normal:diffuse:otherproperties} textures using the ratio of {1:0.5:0.25} so if the texture size is set to 512 it will output a 512 normal map, 256 diffuse map and 128 map for roughness specular etc (diffuse is clamped to 32x32 and roughness specular etc to 16x16)

Use per property manually overridden texture sizes

Enables the per texture overrides, and uses those values instead of Texture Size.

Use Simplygon’s automatic texture sizing

Uses Simplygon's algorithm for texture sizing based on its decimation settings. This should only be used if you are already using Simplygon.

Normal Map

If checked, a Normal map will be baked out for the resulting merged Actor.

Metallic Map

If checked, a Metallic map will be baked out for the resulting merged Actor. This nullifies the Metallic Constant property.

Metallic Constant

Only enabled if Metallic Map is unchecked, this sets a constant value for the Metallic property of the resulting merged Actor's Material.

Roughness Map

If checked, a Roughness map will be baked out for the resulting merged Actor. This nullifies the Roughness Constant property.

Roughness Constant

Only enabled if Roughness Map is unchecked, this sets a constant value for the Roughness property of the resulting merged Actor's Material.

Specular Map

If checked, a Specular map will be baked out for the resulting merged Actor. This nullifies the Specular Constant property.

Specular Constant

Only enabled if Specular Map is unchecked, this sets a constant value for the Specular property of the resulting merged Actor's Material.

Emissive Map

If checked, an Emissive map will be baked out for the resulting merged Actor.

Opacity Map

If checked, an Opacity map will be baked out for the resulting merged Actor. This nullifies the Opacity Constant property. Must also use the Blend Mode for Translucent to show correctly in the generated instances.

Opacity Constant

Only enabled if Opacity Map is unchecked, this sets a constant value for the Opacity property of the resulting merged Actor's Material.

Opacity Mask Map

If checked, an Opacity Mask map will be baked out for the resulting merged Actor. This nullifies the Opacity Mask Constant property. Must also use the Blend Mode for Masked to show correctly in the generated instances.

Opacity Mask Constant

Only enabled if Opacity Mask Map is unchecked, this sets a constant value for the Opacity Mask property of the resulting merged Actor's Material.

Diffuse Texture Size

Override for the Diffuse Texture Size. Enabled when Texture Sizing Type is set to Use per property manually overriden texture sizes.

Normal Texture Size

Override for the Normal Texture Size. Enabled when Texture Sizing Type is set to Use per property manually overriden texture sizes.

Metallic Texture Size

Override for the Metallic Texture Size. Enabled when Texture Sizing Type is set to Use per property manually overriden texture sizes.

Roughness Texture Size

Override for the Roughness Texture Size. Enabled when Texture Sizing Type is set to Use per property manually overriden texture sizes.

Specular Texture Size

Override for the Specular Texture Size. Enabled when Texture Sizing Type is set to Use per property manually overriden texture sizes.

Emissive Texture Size

Override for the Emissive Texture Size. Enabled when Texture Sizing Type is set to Use per property manually overriden texture sizes.

Opacity Texture Size

Override for the Opacity Texture Size. Enabled when Texture Sizing Type is set to Use per property manually overriden texture sizes.

Opacity Mask Texture Size

Override for the Opacity Mask Texture Size. Enabled when Texture Sizing Type is set to Use per property manually overriden texture sizes.

Blend Mode

This determines how the material's color is blended with background colors.

Selection

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Description

Opaque

This blend mode defines a surface through which light neither passes nor penetrates.

Masked

This blend mode defines the visibility in a binary (on/off) fashion by marking whether areas of the Material should be visible or not.

Translucent

This blend mode defines the visibility of a Material by using an Opacity value.

Additive

This blend mode takes the pixels of the Material and adds them to the pixels of the background.

Modulate

This blend mode multiplies the value of the Material against the pixels of the background.

Alpha Composite (Premultiplied Alpha)

This blend mode is used with textures that already have a pre-multiplied alpha.

Use Vertex Data for Baking Material

Whether or not to use vertex data such as vertex color to bake Material result. Useful if you have a Material that is being controlled in some way by vertex color.

Use Texture Binning

This will calculate the varying output texture sizes according to their importance when packing the final atlas texture.

Landscape Culling Settings

In the Landscape Culling section, you'll find properties that use the Landscape to cull parts of the mesh while merging them.

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Option

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Description

Use Landscape Culling

If checked, existing landscape geometry will be used to cull fully occluded triangles. For example, if you had a tree mesh that was planted such that the bottommost triangles were well below the surface of a landscape, then those occluded triangles would be removed upon merge.

Standard Options

In this section, you'll find properties that do not fit categorically in other sections, like being able to replace the actors in the viewport with the merged one.

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Option

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Description

Replace Source Actors

If checked, the Actors selected in the viewport will be removed and replaced with the new merged version. This will not affect the the original objects in the Content Browser.