Unrealistic Style Guide

A practical set of style conventions for assets, code, and other things in Unreal Engine 4.

Preface

In the developer universe, there is an oft-cited mantra that there is no such thing as "good" or "bad" style. Instead, it has been said:

"Arguments over style are pointless. There should be a style guide, and you should follow it."

Rebecca Murphey

I disagree. Having come from a legal background, I can say with certainty that there is such a thing as good and bad style, just as there is good and bad writing. Indeed, quality lawyers spend their working lives trying to become better writers (until they become judges, at which point all writing skill and common sense goes out the window).

There are sentences, words, and formats that convey meaning well, and then there are sentences, words, and formats that obfuscate, confuse, and mislead. The same can be said for software development. After all, the end user is the same in each domain: human. As humans building for other humans (including ourselves), the empathetic thing to do is to maintain good style to the extent we can.

With that said, the following style rules are designed as a lowest common denominator. Each project, like each essay or brief, will have its own unique classes and logical structure that defy one-size-fits-all classification. However, each project should strive to follow these basic guidelines. (Thanks are due to Michael Allar for creating the Gamemakin UE4 Style Guide, which served as the inspiration for this style guide.)

Linter

There is an Editor plugin available on the Marketplace that allows you to easily enforce the asset styling conventions in this guide (or to edit those conventions to fit your needs).

Discussion

To discuss this style guide, add a comment to the dedicated page on Unrealistic.dev.

Structure

There are three main buckets that Unreal Engine 4 content falls into:

1. Assets - Anything that has a .uasset extension.
2. Code - Anything that has a .cpp, .h, or .cs extension.
3. Projects - Everything else.

This guide will approach styling using this basic structure.

Assets

An 'asset' can mean many things in many contexts. In Unreal Engine 4, and for purposes of this guide, an asset means any file that has a .uasset extension.

1.1 A Rule for Every Asset, and Every Asset Following Its Rule

This guide provides rules for many of the standard asset types. However, there is no way it can account for game- or project-specific assets (e.g. projectiles, quests, etc.). This does not mean that you should not establish rules for those assets yourself.

As new asset types get added to your project, define corresponding naming conventions for those asset types and enforce them.

1.2 Naming Format

The name of an asset is made up of four elements:

1. Prefix
2. Base
3. Variant
4. Suffix

A prefix is typically a combination of letters that hints at the asset type. For example, SM_ is used for StaticMesh. With the exception of Blueprint Enumerations and Structures, every prefix should include an underscore (_). Every asset should have a prefix.

The base is the locus of the asset. For example, assets related to the character Amena would have the base Amena (e.g. P_Amena_Explosion, T_Amena_Eyes, etc.).

A variant is used to identify a subset of a base. For example, skeletal mesh skins of the character Amena might be SKM_Amena_Summer, SKM_Amena_Sand, SKM_Amena_BeachParty, etc. Generic variants should be named using two digits. For example, SM_Tree_01, SM_Tree_02, SM_Tree_03, etc.

A suffix is used to identify a subset of an asset type. Certain assets, such as Textures, will have various sub-types (e.g. diffuse, normal, alpha) which are not reflected in the prefix and which cannot otherwise be determined without opening up the asset itself. In these limited circumstances, a suffix can help to provide further context in a consistent way. A suffix is not a substitute for a prefix. Most assets will not have a suffix.

1.2.1 Spacing and Casing

Asset names should not have spaces. Asset names should not have underscores, except for prefixes and suffixes. Bases and variants should be in PascalCase.

1.3 Naming Conventions

Pair the base and variant of your asset with the following modifiers to calculate the final name for your asset.

1.3.1 Blueprints

Asset Type	Prefix	Suffix	Notes
Blueprint (Objects)	BP_
Blueprint Interface	BPI_
Blueprint Function Library	BPFL_
Blueprint Macro Library	BPML_
Enumeration	E
Structure	F

Many assets come with Blueprint scripting - Objects, Actors, Widgets, etc. This has led to the unfortunate practice of using the BP_ prefix with anything that incorporates Blueprint scripting. In turn, this results in a Content directory full of BP_ prefixed assets, with no way to tell what each one is without looking at the thumbnail or opening the asset.

We can do better than that. Only apply the BP_ prefix to Object Blueprints. Do not apply the prefix to:

• Actors or Actor subclasses
• Widget Blueprints
• Animation Blueprints
• Anything else

1.3.2 Gameplay Core

Asset Type	Prefix	Suffix	Notes
Component (Actor)	ACOMP_
Component (Scene)	SCOMP_
Actor	ACT_
Pawn	PWN_
Character	CH_
PlayerController	PC_
PlayerState	PS_
GameModeBase	GM_
GameStateBase	GS_
GameInstance	GI_

1.3.3 Animations

Asset Type	Prefix	Suffix	Notes
Animation Sequence	A_
Animation Composite	AC_
Animation Montage	AM_
Animation Blueprint	ABP_
Aim Offset 1D	AO1_
Aim Offset (2D)	AO2_
Blend Space 1D	BS1_
Blend Space (2D)	BS2_

1.3.3.1 Skeletons

Asset Type	Prefix	Suffix	Notes
Rig	RIG_
Skeleton	SK_
Skeletal Mesh	SKM_
(Skeletal) Pose Asset	SKP_
(Skeletal) Physics Asset	SKPH_

1.3.4 Artificial Intelligence

Asset Type	Prefix	Suffix	Notes
AI Controller	AIC_
Behavior Tree	BT_
Blackboard	BB_
Decorator	BTDecorator_
Service	BTService_
Task	BTTask_

1.3.5 Materials

Asset Type	Prefix	Suffix	Notes
Material	M_
Material (Decal)	M_	_Decal
Material (Post Process)	M_	_PP
Material (UI)	M_	_UI
Material Function	MF_
Material Instance (Constant)	MI_	_C
Material Instance (Dynamic)	MI_	_D
Material Parameter Collection	MPC_

1.3.6 Textures

Asset Type	Prefix	Suffix	Notes
Texture	T_
Texture (Diffuse/Albedo/Base)	T_	_D
Texture (Normal)	T_	_N
Texture (Roughness)	T_	_R
Texture (Alpha/Opacity)	T_	_A
Texture (Ambient Occlusion)	T_	_O
Texture (Bump)	T_	_B
Texture (Emissive)	T_	_E
Texture (Mask)	T_	_M
Texture (Specular)	T_	_S
Texture Cube	TC_
Media Texture	MT_
Render Target	RT_
Cube Render Target	CRT_
Texture Light Profile	TLP_

1.3.6.1 Texture Packing

From the Gamemakin LLC style guide:

It is common practice to pack multiple layers of texture data into one texture. An example of this is packing Emissive, Roughness, Ambient Occlusion together as the Red, Green, and Blue channels of a texture respectively. To determine the suffix, simply stack the given suffix letters from above together, e.g. _ERO.

It is generally acceptable to include an Alpha/Opacity layer in your Diffuse/Albedo's alpha channel and as this is common practice, adding A to the _D suffix is optional.

Packing 4 channels of data into a texture (RGBA) is not recommended except for an Alpha/Opacity mask in the Diffuse/Albedo's alpha channel as a texture with an alpha channel incurs more overhead than one without.

1.3.7 Meshes

Asset Type	Prefix	Suffix	Notes
StaticMesh	SM_

1.3.8 Particles

Asset Type	Prefix	Suffix	Notes
Particle System	P_
Niagara System	NFX_
Niagara Emitter	NFXE_
Niagara Effect Type	NFXET_
Niagara Dynamic Input Script (General)	NFXS_
Niagara Dynamic Input Script (Function)	NFXS_	_FN
Niagara Dynamic Input Script (Module)	NFXS_	_MOD
Niagara Parameter Collection	NFXP_
Niagara Parameter Collection Instance	NFXPI_

1.3.9 Physics

Asset Type	Prefix	Suffix	Notes
Physical Material	PHYSM_
Physical Material Mask	PHYSMM_

1.3.10 Sounds

Asset Type	Prefix	Suffix	Notes
Sound Cue	S_
Sound Wave	SW_
Sound Attenuation	SATT_
Sound Mix	SMIX_
Sound Class	SCL_
Sound Concurrency	SCN_		Should be named after corresponding Sound Class

1.3.11 User Interface

Asset Type	Prefix	Suffix	Notes
Widget Blueprint	W_
Widget Blueprint (Used In World)	W_	_World
Font	FONT_
Slate Brush	SBR_
Slate Widget Style	SWS_

Code

Epic recently put a C++ style guide. It covers most use cases and should be followed absent a compelling countervailing reason.