Getting Started With Geometry Mode

Document Summary: This is an introduction on how to use the geometry mode within UnrealEd to manipulate your BSP.

Document Changelog: Created by Warren Marshall.

Introduction

Geometry mode gives the level designer much greater control over their BSP geometry than was ever possible with vertex editing. Vertex editing is still supported, of course, but you can now also manipulate entire polygons and the edges between them as separate entities.

The best part is that you can do all of this without worrying about the integrity of your BSP data. The editor will keep track of what you're doing and will handle most situations automatically. Collapsing a polygon will see it silently removed from the brush, moving a vertex off of a polygons plane will see that polygon automatically triangulated to compensate, etc. Geometry Mode gives you a lot of power but also offers a safety net.

This document will give you the basic information you need to start using geometry mode.

Entering

To enter geometry mode, select some brushes in your level and click the Geometry Mode button.

When you do this, you'll be in geometry mode with the default selection type, which is "Object" (more on these below). You should see the following:

Selection Modes

You have your choice of which level you want to work on your brushes at. These are selected by clicking the toolbar at the top left of the editors main window:

The base entities are drawn using their usual wire frame colors and anything selected is drawn in a light orange color.

The icons are, from left to right:

Object

Works with the entire object.

Note: dragging an object will appear to be dragging the entire brush but what is -really- happening is that all the vertices are being moved at once but the origin of the brush is staying where it was originally. This seems confusing, but there are valid reasons for it.

Polygon

Works with individual polygons.

Edge

Works with individual edges. Edges are treated as single objects, so manipulating an edge will affect all polygons touching it.

Vertex

Works with individual vertices. Vertices are treated as single objects, so manipulating a vertex will affect all edges touching it.

Options

There are also a few other controls on the toolbar. They are as follows:

Show Normals?

Shows the normal vector of items you can select. They will show up as little red lines. This is useful for knowing exactly which direction something will move if you drag it in local coordinate space.

Affect Widget Only?

This will let you move the widget around and not affect anything you have selected. This is useful, for example, for setting up the origin in exactly the right spot before doing a rotation. Sometimes you need that extra bit of finesse, and this checkbox gives it to you.

Use Soft Selection?

If this is checked, geometry mode will use soft selection when you are working with vertices. What this means is that when you select a vertex, all vertices within a certain range of that vertex will be selected and assigned a falloff value - meaning that the vertices further away from the selected vertex will be affected less than the ones closer to it.

This allows you to modify geometry in a way that makes it feel more organic.

The picture below shows a typical selection when using soft selection. The vertex in the middle was selected and every vertex in a 500 unit radius (the default) has been selected and assigned a falloff value. The falloff is visually represented by darkening the color of the selected vertex (the darker a vertex is, the less influence will be applied to it).

You can now move/rotate/scale these vertices and they will respect the soft selection strengths assigned to them. For example, dragging the selected vertex upwards will result in this:

As you can see, soft selection can be a powerful tool. It's not something you'll use every day, but it's there for when you need it.

Radius

This is the radius of the soft selection influence. As you type into this field, your soft selection data will change in the viewports dynamically. This way you can get the proper radius set up before trying to move/rotate/scale anything.

Modifiers

When you are in Geometry Mode, the modifier window appears. This floating toolbox contains all of the modifiers that you can use on your selected items. It will look something like this:

Something to note is that certain modifiers only work with certain selection types. For example, the "extrude" modifier doesn't work with edges, so if you go into edge selection mode the "extrude" modifier will disable itself. This is automatic so you don't need to really think about it - just be aware that if a modifier you want to use is disabled, it's because it doesn't support the selection mode that you're in.

The window is broken up into two sections, upper and lower. This is because there are two kinds of modifiers and they are used slightly different from each other.

Passive Modifiers

The modifiers at the top of the window are passive - meaning that they require your input to do anything. Selecting "extrude" for example, turns on that radio button and also fills in the property window in the middle of the toolbox. Not all modifiers have properties like this for you to enter, but some will.

You can click on the widget and start moving it around to cause the modifier to take effect or, if the modifier has properties in the property window, you can enter values by hand and click the "Apply" button. This gives you more direct control over what happens rather than relying on your mouse dragging skills.

Active Modifiers

The modifiers at the bottom of the window are active - meaning that they are simple push buttons. You push them and they take effect immediately.

Modifiers : In Detail

What follows is a list of the modifiers and a basic description of what they do.

Edit (passive)

Allows dragging, rotating and scaling of items within the selected brushes.

Extrude (passive)

Moves the select item forward, along its normal, creating new geometry behind it if necessary.

Example

1) Select the item that you want to extrude.

2) Pull the widget. Notice that the selected polygon has moved and new polygons were created behind it to fill in the newly created gap.

Keyboard Input

Length

Sets the length of each extrusion segment.

Segments

Sets the number of segments that you want to create when you click "Apply".

Delete (active)

Removes whatever you have selected from the source brush. Note that if you delete something that multiple items depend on, the geometry will be collapsed to reflect this.

Example

1) Select the item that you want to delete.

2) Click the delete button. As you can see, that vertex was shared by multiple polgons and they have now been reduced to triangles to compensate for the lost vertex.

Create (active)

You can create new geometry by selecting vertices and using this modifier.

Example

1) Select the vertices that we want to create a new polygon from. Bear in mind that these need to be selected in the order you want the polygon created with. Selecting them at random will lead to an invalid polygon that the engine just doesn't deal with.

2) Click the create button. If we flip into polygon selection mode you can see that a new polygon has been created from the vertices we selected earlier.

Flip (active)

Flips the selected items across their normal plane. This is most handy if you use the "create" modifier but select the vertices in counter-clockwise order. This will create a polygon that faces the wrong direction. Using this modifier, you can flip it back without having to delete and create it all over again.

Split (active)

This modifier can be used to break up polygons and edges. If you select 2 edges, you will split the polygon they belong to across the midpoints of those edges. If you select any other number of edges, the edges will split in half where they sit.

Example

1) Select the 2 edges that you want to split across.

2) Click the "split" button.

Triangulate (active)

This modifier can be used to triangulate selection polygons. This is useful if you want to eventually turn edges and/or have more control over the final geometry.

Example

1) Select the polygon you want to triangulate.

2) Click the "triangulate" button.

Turn (active)

This modifier can be used to turn edges. This modifier has a restriction that the polygons on either side of the the selected edge must be triangles since that's the only way that turning an edge makes logical sense. You can turn multiple edges at one time but be careful as this can sometimes lead to confusing results.

Example

1) Select the edge you want to turn.

2) Click the "turn" button.

Weld (active)

This modifier can be used to weld vertices together. The same effect can be had by dragging vertices on top of each other, but this allows you to weld them quickly without worrying about trying to get them all lined up manually.

Example

1) Select the vertices you want to weld.

2) Click the "weld" button.

Summary

As you can see, geometry mode gives you more power over your BSP brushes than vertex editing could have ever hoped to. New modifiers will be added over time as the need arises for them, and they will be added to this document when that happens.

Have fun!