Modeling Mode Overview

Learn the basics of the Modeling editor mode.

The Modeling editor mode, refered to as Modeling Mode, provides a toolset for creating, sculpting, and editing meshes directly in Unreal Engine. You can use it to create new meshes, rapidly prototype level geometry, and edit existing models to add variety to your world. This overview outlines the core concepts behind these tools and their workflow, how to access them, and the basics of working with them.

Accessing the Modeling Editor

To use the Modeling Mode, click the Select Mode dropdown, then select Modeling. Alternatively, press SHIFT+5 to immediately switch to this mode.

The Mode Toolbar (1) and the Modeling panel (2) will appear.

Mode Toolbar and Modeling panel in Modeling Mode

If you select a tool from the Mode Toolbar, its properties will appear in the Modeling panel. You can use this panel to configure your tool's output before you commit to creating a mesh or making changes.

Understanding Key Concepts

Although many tools in Modeling Mode are similar to their counterparts in other modeling software, there are a few important key differences in how Modeling Mode structures mesh editing that you should know before you begin working with it.

Terminology

The modeling tools are usable when you are working on various types of Actors in Unreal Engine, for example, a Static Mesh, a Dynamic Mesh, or a Volume. These are collectively referred to as "a mesh" or "meshes", except for occasions where a tool is only usable for a specific Actor type.

Triangles and PolyGroups

Unreal Engine renders all models as triangulated meshes. In other words, when you import or create a mesh, its surface is automatically broken up into triangles (tris) regardless of whether they were already defined in a different environment. This conversion to triangles provides several guarantees:

  • UE can't import or create a model that it can't render.

  • UE's rendering is portable across all platforms, as all graphics drivers universally recognize triangles.

  • UE does not need to spend time and resources resolving quadrilateral (quad) polygons and n-gons (polygon with more than 4 sides) into triangles at runtime.

In the Modeling editor, you can edit the triangles of your model using the tools in the TriModel category. These are the most low-level editing tools, based entirely around selecting and editing tris and vertices directly.

Although Unreal Engine does not natively recognize quads or n-gons, it does support PolyGroups, which can mimic those features. PolyGroups are arbitrary collections of triangles that various tools in the Modeling editor can define. You can then manipulate these groupings using the PolyModel tools.

When creating a mesh using the Shapes category, you can configure the PolyGroups of your new mesh using the Polygroup Mode setting.

Additionally, you can use the TriSel (Triangle Selection), GrpGen (PolyGroup Generation), and GrpPnt (PolyGroup Paint) tools to assign PolyGroups.

You can then use PolyGroups for traditional modeling using the PolyEd tool and to create UV islands using the UV tools.

To learn more about creating and using PolyGroups, refer to the Understanding PolyGroups documentation.

Tools, Undo History, and Accepting Changes

Most mesh editing tools in the Modeling editor mode will not apply changes to meshes immediately. Instead, the tool shows a preview of the mesh with your changes in place, and a prompt will display the Cancel and Accept buttons.

Accept and Cancel Buttons

If you exit Modeling Mode or press Cancel, the changes are discarded, and the mesh will revert to what it looked like before you started editing it. If you press Accept, the Modeling editor applies the changes. It will also apply the changes from a tool if you select a different modeling tool while in the middle of the same editing session.

Unreal Editor keeps an undo history of each operation a tool performs when using the mesh editing tools. For example, if you do several extrude operations using TriEd or PolyEd, using Undo will undo the most recent one first, stepping back through the history of each of your edits.

All tools have an On Tool Accept category in their settings to configure what happens to modeling operations in your undo history. By default, the Handle Inputs setting is set to Delete Inputs. This means after you press Accept, Unreal Editor will treat your mesh editing session as a single operation, and using Undo will revert all the changes you made since the last time you pressed Accept. You can change Handle Inputs to keep some or all of your individual changes.

Meshes, Assets, and Project Settings

The type of Actor you choose to represent your mesh determines how Modeling Mode handles the creation and editing process. When creating a new mesh using the Shapes or Create category, you use Output Type to select the desired Actor. You can choose between the following Actors as your target mesh:

  • Static Mesh

    • Represents your model and is saved in the Content Browser. An instance of the mesh is placed in the Level.

  • Dynamic Mesh

    • Represents your model and is saved in the Level only.

  • Volume

    • Represents an area that triggers a behavior and is saved in the Level only.

These types have various use cases and benefits. You can change the Actor type of the current mesh using editing tools such as Convert and Transfer. Using Project Settings, you can configure the creation and selection of meshes, as well as the saving of Assets.

Refer to the Working with Meshes documentation to continue learning about how output types are handled and how to adjust settings for your workflow.

Using the Modeling Mode

Creating a Mesh

To create a new mesh, click any of the tools in the Shapes category and move your mouse cursor into the Viewport. A template of the shape you selected will follow your cursor and snap to the Level grid. Click where you want to add the mesh in your game's world and the editor will create the shape with the parameters you configured in the Modeling panel.

Shape Tools in Modeling Mode

You can also create meshes using tools in the Create category. For example, the PolyExt tool can draw a footprint for a mesh, then extrude it to create a custom 3D shape.

Creating A Mesh In Modeling Mode

Editing a Mesh

Most of the other tools in Modeling Mode are built around editing an existing mesh in your game's world. For example, if you select TriEd or PolyEd, then click a mesh, you can select its individual components and perform modeling operations on them. Individual operations in the TriEd and PolyEd tools, such as Extrude, Push Pull, or Cut Faces, appear in the Modeling panel. After you make your edits, click the Accept button at the bottom of the viewport to finalize your changes or click Cancel to discard them.

Editing A Mesh in Modeling Mode

You can select any mesh in your world and edit it using these tools, including meshes that were not created with the Modeling editor. For example, you can use the Lattice tool on a high-quality Static Mesh to quickly reshape it.

If you are going to edit a high-quality model, it is highly recommended that you duplicate the asset using the MshDup tool to preserve the original mesh.

Tool Categories

Category

Description

Shapes

Creates a new mesh using a selection of predefined primitives.

Create

Build meshes from paths or existing geometry.

PolyModel

Perform granular editing using a mesh's PolyGroups. Only useable if the model has more than one polygroup.

TriModel

Perform granular editing using a mesh's triangles.

Deform

Alter or distort a mesh as a whole or in specific areas.

Transform

Adjust the placement or representation of a mesh.

MeshOps

Optimize a mesh's geometry.

VoxOps

Convert a mesh into voxels to perform volumetric operations before converting it back into a mesh.

Attributes

Inspect and adjust the secondary properties of a mesh.

UVs

Edit the UV coordinates of a mesh, changing how textures are mapped to the surface.

Baking

Generate textures and vertex color data for meshes.

Volumes

Convert between volume, mesh, Binary Space Partitioning (BSP), and Simple Collision representations. You can also inspect the collision and physics properties of the selected mesh.

LODs

Edit and manage the levels of detail (LODs) for a mesh.

To learn more about these tools, refer to the Modeling Tools documentation.

Geometry Script

Geometry Script is an Unreal Engine plugin containing a set of Function Libraries that provide the ability to generate and edit mesh geometry via Blueprints and Python. Geometry Script UFunctions and Blueprint Nodes operate on UDynamicMesh objects, which are objects created using the FDynamicMesh3 C++ triangle mesh data structure. This is the same data structure used by the Geometry Processing plugin and Modeling Editor Mode.

Geometry Script can be used in Editor Utility Widgets and Asset Actions to create custom mesh analysis / processing / editing tools. It can also be used in Actor Blueprints to create "procedural objects" and implement complex geometric queries.

For more information on using Geometry Scripting, refer to the Geometry Script Users Guide.