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Unreal Journal
Strings and Other Things

Strings and Other Things

We untangle the Unreal string types, and outline how to choose the one you need!
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A Collection of Little Fixes

A Collection of Little Fixes

Using static code analysis, we look at some of the easy-to-miss, tiny little bugs/mistakes in Unreal Engine's codebase.
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The Consequence of the Missing References

The Consequence of the Missing References

We delve into Sequencer, looking for optimization opportunities using PVS Studio, a static code analysis tool... with some interesting findings.
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Slate 101 – Building a Leaderboard

Slate 101 – Building a Leaderboard

Figuring out the basics of UE4's Slate syntax is sometimes daunting for programmers when they first use it. In this post we discuss some core concepts in order to help out new Slate users, and possibly refresh the memories of those who don't use it all that often!
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Getting Into Games Dev – Part 2

Getting Into Games Dev – Part 2

So, yeah, I started writing this story in July 2017 with Part 1 ... and intended to finish it a month later. It's now March 2020 ... nearly 3 years have passed ... and the world has most definitely moved on from wondering what happened next in my route to the games industry! So, yeah, let's pick right up where we left off...
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The Curious Incident of the Archive Corruption

The Curious Incident of the Archive Corruption

During an optimisation pass on an internal project we spotted a few areas in UE4 deserialization code that could be hardened up. This post presents those fixes.
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Blueprint Extension: Hide Unrelated Nodes

Blueprint Extension: Hide Unrelated Nodes

This is a new feature for both the blueprint editor and the material editor. When selecting regular nodes (except comment nodes, document nodes and the material output node) in the editor, this feature will fade out nodes which don't affect the selected nodes and nodes which are not affected by the selected nodes to make sure that users can focus on the nodes which are related to the selected nodes.
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Loops and Bubbles

Loops and Bubbles

Some quick fixes for mini bugs. A superfluous for loop, and some visual tweaks to comment bubbles!
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Be Vewwwy Vewwwy Quiet, We’re Hunting UObjects

Be Vewwwy Vewwwy Quiet, We’re Hunting UObjects

While hunting down some mysteriously vanishing UObjects we stumbled across a more fundamental problem in the garbage collector.
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Trash Compactor

Trash Compactor

We recently found a huge leak in the UE4 garbage collector, particularly rearing its head on dedicated servers for large open-world games. Servers for arena type games with short play times (<1 hour) seem to be little affected, and clients don’t see the problem much either. “Huge” is not hyperbole here – we’re talking the garbage collector alone using up to 10 GB of ram in under 24 hours of server operation!
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Placating The Natives

Placating The Natives

In this article we delve into Blueprint Nativization, a relatively new feature of UE4 that offers significant performance improvements for many projects. Sadly, it often doesn't work out of the box - we've spent some time fixing and improving it for a particular project that we were working on. We have a LOT of changes to present here - some of which have already been implemented into UE4.
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PhysX: The Case Of The Leaky Cloth

PhysX: The Case Of The Leaky Cloth

We found quite a large leak within Apex 3.4 (currently used in Unreal Engine 4, amongst others) - in a relatively short run of the title that we were working on, we saw over 150mb of leaked memory. Here, we present some changes that will fix this
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Getting Into Games Development (Part 1)

Getting Into Games Development (Part 1)

In this post our MD, Robert Troughton, starts his story about how he got into the games industry
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So Long MAX_PATH… And Thanks For All The Fish!

So Long MAX_PATH… And Thanks For All The Fish!

Almost every developer that we've spoken to seems to have, at some point, encountered the MAX_PATH limit problem... this post talks about how to PROPERLY fix it
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Is It A Drive? Is It A Directory? No, It’s…

Is It A Drive? Is It A Directory? No, It’s…

In this post, we look into why IPlatformFileCreateDirectory() was responsible for nearly 1 million allocations during a full cook of KiteDemo and why FPaths::IsDrive(), a huge 100-line function, is being used just to determine whether a filepath begins with a drive mapping... all for the purpose of further speeding up Unreal's cook process just a little bit more
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Cache-ing Up, Cache-ing In

Cache-ing Up, Cache-ing In

As part of modifying the file profiler we looked at the file IO activity on starting the UE4 editor with one of the lightweight sample projects, noticing that certain files were being read multiple times. Each was being read in their entirety up to 200 times simply opening the editor. In this post we show you why this was happening and how it can be fixed
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The Quickening Of The Light Map UV Generation

The Quickening Of The Light Map UV Generation

Lightmap UV generation in UE4 can take a considerable amount of time. Here, we take a look at it and present some optimisations that can yield 5x faster performance
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The Improvement of the File Profiler

The Improvement of the File Profiler

UE4 has a little-known profiler for analysing file operations (with the intention that this information can then be used to make optimisations). In this post we take a look at that - and we make some improvements to make it (even more) useful
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The Case of the Locked File

The Case of the Locked File

We were seeing frequent file IO errors in relation to temporary files created during cooking (particularly when compiling shaders). Our findings for why this were happening were surprising. Here we present a clean way to fix the issues
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The Long and Winding Path of the Cook

The Long and Winding Path of the Cook

Long file path problems are commonplace when cooking with UE4. We took a look at it - and found that the engine was being too aggressive with its checks for whether or not a path really was too long
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It’s A Size, Jim, But Not As We Know It, Not As We Know It…

It’s A Size, Jim, But Not As We Know It, Not As We Know It…

A really small bug fix is presented here - with a lot of Trekkie banter to fluff the piece out... and why not?
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Static Code Analysis With PVS-Studio (Part 6)

Static Code Analysis With PVS-Studio (Part 6)

The sixth part in our series looking at coding errors found by using the static code analysis tool PVS-Studio
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Sign Of The Times

Sign Of The Times

PVS-Studio pointed us toward some code with suspiciously mixed signed/unsigned math. This was actually causing some issues - and here we tell you how to fix them
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Clear And Reset Danger

Clear And Reset Danger

A common programming mistake is fixed here, this time in the FBX importer
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Static Code Analysis With PVS-Studio (Part 5)

Static Code Analysis With PVS-Studio (Part 5)

The fifth part in our series looking at coding errors found by using the static code analysis tool PVS-Studio
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The Sadness of the Ignored Null Pointer

The Sadness of the Ignored Null Pointer

In this post we present an optimization coming from removing some pointless null pointer checks. The way that we found this was quite interesting
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Speeding Up The Time Limit Controls

Speeding Up The Time Limit Controls

When a process takes a long time to complete, it makes absolute sense to put some time limit checks in so that you're not starving other work. What you don't want to do, of course, is to have those checks slow your original task down further by any considerable amount - here, we found that exactly this was happening .. so we present a solution
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The Battle of the Lean and the Inlined Bone Functions

The Battle of the Lean and the Inlined Bone Functions

We took a look at the inlining of a certain part of the codebase and were shocked with what we found... we then went about improving it
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ToString() Or Not ToString()… Wait, What’s The Question?

ToString() Or Not ToString()… Wait, What’s The Question?

ToString() is one of the most commonly called functions in UE4 - certainly across the editor, the content cooker and such. Here we take a look at it and make it over twice as fast
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Tiny Code Fixes – Part 1

Tiny Code Fixes – Part 1

Here we present several small code fixes and improvements in a nice little package
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Package Versioning… How It Works… And An Optimization

Package Versioning… How It Works… And An Optimization

UE4's Package Versioning is a bit of a dark art for most.. here we try to remove some of the confusion around it - while, again, offering some improvements through optimization
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Portrait Of A Serialize Perf Killer

Portrait Of A Serialize Perf Killer

With performance critical editor and cooker code, it's well advised to consider performance when adding tests for rare errors. Here we take a look at this and show by, by considering the CPU pipeline and code cache, a simple change can yield a significant performance improvement without reducing stability
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Sweeping Up And Disassembling A Physics Macro

Sweeping Up And Disassembling A Physics Macro

Macros can often be useful to make certain programming tasks simpler - but they can also cause hidden performance headaches that might otherwise be avoided. Here we look at one of those - and how to improve it
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Static Code Analysis With PVS-Studio (Part 4)

Static Code Analysis With PVS-Studio (Part 4)

The fourth part in our series looking at coding errors found by using the static code analysis tool PVS-Studio
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When Are Shopping Lists A Waste of Time?

When Are Shopping Lists A Waste of Time?

We take a look at some list generating code with UE4 - and why it was completely pointless
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Using The Disassembler To Highlight Optimization Targets

Using The Disassembler To Highlight Optimization Targets

We use the debugger's disassembly view to look at FPaths::IsRelative() after it shows up in our profiling tests. Then we optimize it
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Static Code Analysis With PVS-Studio (Part 3)

Static Code Analysis With PVS-Studio (Part 3)

The third part in our series looking at coding errors found by using the static code analysis tool PVS-Studio
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The Cook, The Resave, His Garbage And Her Optimization

The Cook, The Resave, His Garbage And Her Optimization

We present here a way to improve cook times by reducing the frequency of garbage collection
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The Case Of The ExportHash String Monster

The Case Of The ExportHash String Monster

We found CreateExportHash() was showing up in profiling the cooker - so we optimized it. Our findings and changes are presented here
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Static Code Analysis With PVS-Studio (Part 2)

Static Code Analysis With PVS-Studio (Part 2)

The second part in our series looking at coding errors found by using the static code analysis tool PVS-Studio
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Patch Content Early – NOT At Runtime

Patch Content Early – NOT At Runtime

We present an optimization that removes a significant amount of memory churn from the animation code
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Static Code Analysis With PVS-Studio (Part 1)

The first part in our series looking at coding errors found by using the static code analysis tool PVS-Studio
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A Huge PhysX Memory Churn Reduction

A Huge PhysX Memory Churn Reduction

Here we implement a scratch buffer to reduce temporary memory churn passing through PhysX
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The Smallest, Coolest Optimization

The Smallest, Coolest Optimization

While profiling a game's runtime, we found that 40% of memory allocations were coming from a single function. The fix/optimization involves adding a single character
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The Clue In The Code Comments

The Clue In The Code Comments

We present a tiny little fix for a simple - but serious - coding error in the UE4 codebase
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