Setup

VIDEO GUIDE

Please watch the whole video BEFORE following the steps below.
The setup process is complex and things are easy to miss!

Watch Getting Started Video

Setup will go through the following

1. Enable the plugin
2. Update DefaultEngine.ini
3. Patch engine shaders
4. Add MeshBlend Activator Actor to level
5. Update Materials
6. Blend meshes

Each step is required to setup the plugin.
Make sure you follow the setup guide word for word. Some things are easy to miss.

1. Enable plugin

• Enable MeshBlend plugin for project
• Restart editor

Editor Toolbar

You should see a B in the editor toolbar after restart.

2. Update DefaultEngine.ini

• Open <project>/Config/DefaultEngine.ini
• Find the [/Script/Engine.RendererSettings] section
• Add the following console variables

r.AllowStaticLighting=False
r.Lumen.ScreenProbeGather.MaterialAO=0

NOTE

These changes are needed so that the plugin doesn't make meshes darker, since it's using the AO channel for data.

3. Patch engine shaders

Use the shader patcher tool to make sure the material Ambient Occlusion channel doesn't affect Unreals lighting while using MeshBlend.

• Open the MeshBlend toolbar and Readme
• Click Open Shader Patcher Tool in the bottom left corner
• Click Apply All
• Click Restart Editor

4. Add MeshBlend Activator Actor to level

The Activator ensures each mesh is assign a correct blend ID. There should be one, and only one of this actor in your level at any time.

• Add the /Plugins/MeshBlend Content/BP_MeshBlend_Activator blueprint to your level.

NOTE

If you can't find it, make sure Plugin Content is checked in the Content Browser Filter.

5. Update Materials

Example using a normal material

Example using a material that uses material attributes

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Each master material needs to be updated for a mesh to blend.

1. Add the MeshBlend_Activator [Index X] material function to your material and hook it up to the correct output channel. (Default is Ambient Occlusion)
2. Disconnect anything going to the AO in materials that are not blending (characters, items, etc). If not, they will show up in the MeshBlend debug view.

NOTE

Make sure you connect the function to the final output channel of the material.

Custom Primitive Data

The index on the material function corresponds to the Custom Primitive Data index it is supposed to use. If your material is already using CPDs you need to duplicate the material function and modify it to use an available index.

6. Blend meshes

Now that the project is setup you can make a mesh blend. There are multiple ways to achieve this.

For most meshes you want to use either the Mesh Assets or Mesh Actors approach. For landscape actor you need to use Static ID.

NOTE

If changing the blend has no effect, try clicking Refresh Actors in the toolbar.
If it's still not working, double check the following:

• The material is updated with the material function
• The BP_MeshBlend_Activator is in the level
• The earlier setup steps have been followed (r.AllowStaticLighting is 0)

A - Mesh Assets

VIDEO GUIDE

Shown at 2:32 in the Getting started video.

• Go to the mesh in your content browser that you want to blend
• Right click and choose Scripted Asset Actions -> MeshBlend and choose a size
• Any affected meshes in your level will automatically refresh

Asset User Data

This helper function stores the size on the mesh asset as a Asset User Data. You can also edit it manually in the asset.

B - Mesh Actors

VIDEO GUIDE

Shown at 4:12 in the Getting started video.

• Find the mesh in your level you want to blend
• Right click and choose Scripted Actor Actions -> MeshBlend and choose a size

Actor Tag

This helper function stores the size on the mesh asset as a Tag on the actor.

You can also set these directly in the Actor or Component Tags
Tag names are:

AutoBlend_Small
AutoBlend_Medium
AutoBlend_Large
AutoBlend_ExtraLarge
AutoBlend_Disabled

C - Static blend ID on material

VIDEO GUIDE

Shown at 1:01 in the Getting started video.

NOTE

Only use this approach when you need to. In most cases it's usually better to set it on the mesh asset or actor directly.

You can set a static blend ID on a material. This is required by some meshes like landscapes and landscape grass. It can also be used to make multiple meshes appear like one mesh to the plugin, causing them to not blend between each other.

The static values are values not used by the activator.

NOTE

Meshes with the same static ID will never blend with each other.

So use this feature for stuff that either need a static ID (like landscape), or when you don't need the mesh to blend with other meshes of the same type. (like foliage where you want it to blend with the ground, but don't need each flower to blend with each other.)

• Open the material instance
• Set MeshBlend / Use Static Value to true
  When toggling Use Static Value off you need to click Refresh Actors after saving the material instance
• Set MeshBlend / StaticAutoBlendID to a corresponding value.

Static blend ID

Static blend IDs for landscape, foliage & special cases (Remember to divide by 255 in parameter input)
Examples: 2/255 or 5/255 give a small blend, 67/255 gives a medium blend, etc.

Small:       2-6
Medium:      65-69
Large:       128-132
Extra Large: 191-195

ALWAYS REMEMBER TO DIVIDE THIS NUMBER BY 255 WHEN INPUTTING IT

Blend ID

At it's core the MeshBlend shader works on a grayscale mask where each mesh has a value (0 - 255) that holds the blend size and unique ID.

The activator blueprint ensures each mesh gets a value that is not overlapping with any intersecting meshes, since we only have a limited number of values to choose from.

Read more about this in Rules of Blending.

Static/Dynamic activation

Landscape and Landscape Grass are not dynamically activated and need to have a static ID set
It's also advised to use static IDs on foliage to improve performance.