Notes

This is where I keep notes for things I keep revisiting throughout my work. Entries are sorted alphabetically.

Unity game dev

Analyzers

As of 2023-10-06, and since a new Unity extension for VSCode has been released, there is no official way to support adding Roslyn analyzers for C# code (perhaps other than reverting to using Omnisharp).

There should be an official way of adding these directly in the Unity editor, but I was unsuccessful in doing so.

I may revisit this later, but at this point it might be wiser to wait for the VSCode extension to become more mature.

Animations

Importing

  • “bake into pose” root transform changes that shouldn’t be applied to the gameobject on each animation.

Mixamo

Downloading animations “without skin” prevents wasting memory with unnecessary models. However, the avatar generated by Unity for these won’t work properly. That can be fixed by downloading the default Mixamo character (Y Bot) in T-pose and generating an avatar from it, which can then be used with “without skin” Mixamo animations.

Movement without foot sliding

See How to avoid foot sliding.

Blender

Settings

  • Disable saving .blend1 files

Unity interop

  • Store .blend files directly inside the Unity project’s “Assets” folder
  • There doesn’t seem to be a way to store textures in .blend file, so keep them in “Assets” folder and use them in both Blender and Unity

Inspector

Textures

It is often useful to generate textures for debugging code visually through the inspector.

To view a texture through the inspector, assign it to a public or [SerializeField] field.

Then generate the texture with the following logic.

var tex = new Texture2D(width, width, TextureFormat.RGBA32, mipChain: false);

for (int i = 0; i < width; i++)
{
    for (int j = 0; j < width; j++)
    {
        tex.SetPixel(
            i,
            j,
            Color.Lerp(Color.black, Color.white, VoronoiNoise.Get(i, j, 30f, 1234L))
        );
    }
}

tex.Apply();

Calling Apply() is required for the texture to appear right away, otherwise an update has to be triggered by changing something on the inspector (such as its anisotropic filtering level).

LODs

  • Only the last LOD matters
  • Impostors > LOD meshes
  • Advancements like Nanite can change 3D lore fast

Based on https://medium.com/@jasonbooth_86226/when-to-make-lods-c3109c35b802

Math

Floating point

Key Insights On IEEE 754 Floating Point Numbers

Error accumulation

Avoid updating decimal numbers iteratively, which can accumulate errors. Instead, prefer to calculate values from the underlying constants each time.

This is one of the main concerns of the field of numerical analysis.

Frame rate independence

Everything that runs in Update() (as opposed to FixedUpdate()) should be carefully designed to ensure independence from variations in frame rate.

For example, there is a specific formula for a frame rate independent version of calling lerp (linear interpolation) iteratively.

There is an extensive post about this here.

Ready to use code should be available in the Unity utilities repo.

Mathf vs MathF

UnityEngine.Mathf relies on System.Math, which runs computations on the double type.

System.MathF does computations on the single/float32 type.

The difference may be small however since CPUs generally handle 64bit math better than GPUs.

Optimizations

Comparing distances

The expensive square root operation can be avoided by comparing squared distances.

Exponentiation

When raising a number to an integer exponent, direct multiplication (x * x) is more efficient than calling a function such as MathF.Pow() which accepts any real number as exponent.

Multithreading

Awaitable vs Task

Unity introduced Awaitable in version 2023.1, which essentially is a modernization of the Coroutine API (which handles things like waiting for the next frame) to make it compatible with async/await in C#.

The new Awaitable can also handle multithreading with explicit switching between main and background threads using await Awaitable.MainThreadAsync() and await Awaitable.BackgroundThreadAsync().

However, BackgroundThreadAsync appears to be a mere wrapper around Task.Run(), thus with no advantages when it comes to allocating Task objects.

In addition to this, a previously existing issue where pending tasks continue running even after exiting/entering play mode in the Unity editor remains:

Unity doesn’t automatically stop code running in the background when you exit Play mode.

To get around this, I had implemented a SafeTask wrapper as a replacement for Task.Run() (no other Task API functionality is replaced), which still makes sense to continue using:

Relevant links:

General tips

  • Use Tasks over manually creating Threads except for long lived tasks, to avoid hoarding a thread from .NET’s thread pool.
  • Always use concurrency management mechanisms when sharing data across threads. Even when there is only a single writer thread, memory caching mechanisms can interfere with synchronization.

Order of preference for concurrency management mechanisms:

  1. Task model
  2. Concurrent (thread safe) collections
  3. Interlocked
  4. lock
  5. volatile (avoid this for being more obscure and harder to reason about than the Interlocked class)
  6. Lower level synchronization primitives (Mutex, Semaphore, …)

Optimization tips:

  • Use static lambdas (introduced in C# 9) with Task.Run() to avoid capturing scope, which requires heap allocations for the underlying class.
  • Prefer long-running tasks to starting new tasks frequently, which avoids Task object allocations and context switching overhead

NuGet dependencies

With no official NuGet support in Unity at time of writing, one can set up NuGet dependencies through a separate C# project.

There are two other options worth mentioning:

  • NuGet for Unity (too heavy handed/complex solution that runs the risk of going unmaintained)
  • Downloading packages manually and copying .dlls to the Unity project (troublesome not just for the extra manual work but also because one has to manually go through dependencies and download each, with no simple way of keeping track of everything over time)

These are the steps to set up dependencies through a standalone C# project:

  1. Run dotnet new classlib --framework netstandard2.1 -o NuGetDependencies.

    We target .NET Standard 2.1 according to Unity compatibility.

    Also feel free to delete any .cs files created by default, as we won’t need to write any code.

  2. cd NuGetDependencies
  3. dotnet new gitignore
  4. Add dependencies with dotnet add package <package name> --version <version> (can be copied from NuGet website directly)
  5. Build with dotnet publish (debug configuration is the default). Note we don’t use dotnet build, which doesn’t include dependency .dlls in build files.
  6. Copy the files in ./bin/Debug/netstandard2.1/publish/ to somewhere in the Unity project’s Assets folder, such as Assets/NuGetDependencies/

General optimization

The points below have more importance in the context of frequently run code, such as that in Update().

  • Avoid generating garbage (allocating heap memory for short-lived objects). One way to do this is to reuse objects, by storing them in class fields instead of instantiating locally. Object pooling is a similar and popular strategy.
  • Use fixed size over dynamically sized collections (such as arrays over lists) whenever possible, for the reduced overhead.
  • Use static lambda expressions (introduced in C# 9) over non-static to avoid capturing scope.

Microsoft’s recommendations

See Microsoft’s mixed reality performance recommendations for Unity.

Procedural mesh generation

Call MarkDynamic on meshes that are updated frequently at runtime.

Project set up

These are things to think about when starting a new project, which can also be worth revisiting once in a while. Generally high-leverage settings with poor defaults or quick fixes for common issues.

Color banding

Fix color banding by checking “enable dithering” in the camera inspector. I only tested this in URP.

Mono vs IL2CPP

Decide between Mono or IL2CPP.

Generally, IL2CPP should be better as it can have better performance than Mono, although it may complicate mod creation (although hacking would also become more difficult accordingly).

IL2CPP can improve performance across a variety of platforms, but the need to include machine code in built applications increases both the build time and the size of the final built application.

Shaders

Shader Graph

Hiding properties from inspector

Before version 2023.3.0a11, Shader Graph properties not marked as “Exposed” simply don’t work unless initialized in code. The expected behavior would be to simply hide the property from the material inspector.

There is more info about this issue in this thread.

Utilities repo

https://github.com/marcospgp/unity-utilities

Web

CSS

px vs rem

Generally, rem and em should be used for font size related styles and px for everything else, such as margins or padding.

There’s no consensus on whether to use rem for everything or only for font size related styles (using mainly px otherwise).

Browsers zoom by increasing the size of px, so this decision should only affect users who manually configure a different browser default font size.

For those, it may be better to scale fonts only and keep spacing the same, as otherwise they could simply use the zoom feature.

Email

When setting up email make sure to enable SPF, DKIM, and DMARC to properly authenticate messages. Use https://www.dmarctester.com to test this.

If unable to send email through a third party client for a Google Workspace account, try enabling “Allow per-user outbound gateways” in the admin panel.

Git

Commit without a message

git add -A && git commit --allow-empty-message -m '' && git push

Submodules

Git submodules are a nice way of setting up project dependencies.

Adding

You can add a dependency into a repo by running:

git submodule add --name steamworksnt https://github.com/marcospgp/steamworksnt.git <target-folder>

Including the --name prevents the destination path from being used as the name by default, which can be confusing if the module is moved with git mv later.

If submodules will be used in-editor as part of a Unity project, they should be placed in the Assets folder.

Updating

To update dependencies or download them after a fresh git clone, use:

git submodule update --init --recursive --merge --remote

Removing

To remove a submodule, use git rm <submodule path> (and not git submodule deinit) in accordance with the docs.

However, also note that:

the Git directory is kept around as it to make it possible to checkout past commits without requiring fetching from another repository. To completely remove a submodule, manually delete $GIT_DIR/modules/<name>/.

$GIT_DIR will usually be the .git folder.