Join Craig Barr for an in-depth discussion in this video Overview of geometry brushes, part of Unreal Essential Training (2016).
- When designing your game project in Unreal Engine 4, it's important to think of basic conceptual level design. Now, Unreal actually has some very valuable tools to help you with this idea of blocking out a level. And that's what we want to look at here is a quick understanding of what geometry brushes are. Now, within the Unreal Engine editor environment, geometry brushes can be found over in the modes panel down under BSP. Now what is BSP? Well, BSP stands for binary space partitioning and binary space partitioning or BSP is what this toolset has been referred to in the legacy versions of Unreal.
So it's been around for quite some time, and this used to be actually, back in the original day of the Unreal editor, the primary way to build or construct your level. The best way to think of these geometry brushes, which they're referred to for the most part, today with Unreal Engine 4 is a way to quickly carve out or block out your level. These are not just simple pieces of geometry here, the box, the cone, the cylinder, et cetera.
These are dynamic shapes and what they allow you to do is essentially carve out or add pieces of geometry that are going to represent the overall space or volume of your level. Now before we dive into how these tools work and what you can do with them, let's take a quick look at an overview of what BSP or geometry brushes is all about in Unreal Engine 4 So geometry brushes, let's take a look at some of the quick benefits here. So these are the most basic tools for level construction and level layout within the Unreal Engine 4 environment.
Conceptually, I guess, the best way to think of this, it's a quick way to fill a scene or to carve out pieces of geometry that can represent shapes or structures that you will use for your level. Now why would you want to use geometry brushes? What are the benefits? Well, let's take a look at a few here. First one is that it's a very quick and easy way to block out a level. So this is an excellent way to start thinking about how your level may work. Now, the idea here is that you have two directions you can go in.
One is that you can actually effectively create your level using geometry brushes. They aren't just simple proxy pieces of geometry. You could get away with building an entire level with geometry brushes. That is possible. We'll look at the pros and cons of that here in a moment. Now as well with using geometry brushes to rapidly block out a level, it's an excellent way of addressing things like scale and size issues. So, for an example, in our level here, we have a base island that we've used the landscape creation tools here in Unreal.
Now we want to place some simple items to represent where our objects should be or where we like them to be on the island. For example, the lighthouse. We have a car that we want to eventually model and build and be able to put in place here, and we have other things like log piles, a tool shed, other objects that are going to populate the scene. Another thing that's excellent with using geometry brushes to rapidly block out your level or address scale issues is that these scale issues are going to help you compose your overall scene.
That is, perhaps how you're going to line up cameras, for example, for our cinematic that we're going to create with this scene as well. Now, the ideal of rapidly blocking out a level with geometry brushes, it's an excellent way to playtest an overall concept of a level, and that is that you could put these pieces in place very quickly, and be able to run a camera through from a first person perspective or a third person, whatever concept or perspective you're going with with your game. You can try out a volume to scale to see how it's going to work with your overall game idea and how that level fits into that overall project idea.
And lastly here, for a benefit, this is actually a way that you can use just to fill in gaps between game assets. Now, it sounds simple but here's the overall idea. Once you've populated your scene, you blocked it out, and then you maybe replaced the blocked out areas that you've used geometry brushes for, with your actual final game assets, that is your final models, your final texture maps on those models with all their custom UV layouts, all the nice things that make the game assets look great, you may find that there are little places that there are some gaps showing.
For example, where corners aren't maybe lining up properly or a piece in the background that is a bit of gap once you get in there and look, and you look at it and it simply could be filled in with just a simple piece of geometry from this BSP or geometry brush system. And this is where you could rapidly just place that object and have it textured with whatever in the background to fill it in. It does actually help and once the final assets are in there, just to close up any gaps or issues within your scene. Now we looked at some quick benefits here of using geometry brushes for blocking out a level in Unreal Engine 4.
What are some caveats or some of the gotchas? Well, there are a couple of them here and the first one to keep in mind is that it can get very expensive if BSP or geometry brushes are overused. The reason why can be computational or very expensive to calculate all of these objects. Because of what's going on, these objects you're kind of carving out volumes, that is, they almost work like boolean operators and the meshes can get quite expensive. They can get more dense than they may need to be, as compared to a static mesh that would represent that volume for a final game asset.
As well, you are getting into limited ways that you can work with it, and the first kind of limitation here is that you are dealing mainly with kind of linear sharpened, flat-edged, non-organic structures. So you're certainly not going to dive into this to build maybe something very organic like a tree, not to say you couldn't build something in here with those tools but it would be definitely more effort as compared to something that has a really robust modelling toolset. For example, Autodesk Maya, or 3ds Max, or Cinema 4D, or Blender, whatever it is you prefer to use, those toolsets have a very robust 3D modelling toolset in there, as compared to what geometry brushes would offer.
And lastly, you really are limited to your capability in modelling it. It doesn't have that full robust toolset in there and that's not the point of geometry brushes. It is to rapidly lay out almost a prototype of your project, and to be able to rapidly test the scene, and then eventually replace those with static meshes but as I pointed out, you can use these objects as final game assets in there. They have basic texture capabilities but certainly, not the custom UV coordinate layout that you typically would have with your final game assets or for that matter, static meshes that you would bring into your project.
So that's just a quick overview of how geometry brushes can be used to quickly populate, construct, and conceptualize your level for your project to be able to see how it's going to work when you're composing a scene or how it's going to actually play when you get to the point of playtesting your project.
- Customizing the Unreal UI
- Creating a new project
- Creating landscapes
- Blocking out levels
- Assembling a scene
- Working with materials and lights
- Adding post-processing effects
- Defining bodies of water
- Adding atmospherics, foliage, and wind
- Working with the Blueprint editor
- Creating cinematics
- Monitoring performance
- Packaging a game for distribution