Attention: Here be dragons (unstable version)

This is the latest (unstable) version of this documentation, which may document features not available in or compatible with released stable versions of Redot.

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Frequently asked questions

What can I do with Redot? How much does it cost? What are the license terms?

Redot is Free and open source Software available under the OSI-approved MIT license. This means it is free as in "free speech" as well as in "free beer."

In short:

You are free to download and use Redot for any purpose: personal, non-profit, commercial, or otherwise.
You are free to modify, distribute, redistribute, and remix Redot to your heart's content, for any reason, both non-commercially and commercially.

All the contents of this accompanying documentation are published under the permissive Creative Commons Attribution 3.0 (CC BY 3.0) license, with attribution to "Juan Linietsky, Ariel Manzur and the Redot Engine community."

Logos and icons are generally under the same Creative Commons license. Note that some third-party libraries included with Redot's source code may have different licenses.

For full details, look at the COPYRIGHT.txt as well as the LICENSE.txt and LOGO_LICENSE.txt files in the Redot repository.

Also, see the license page on the Redot website.

Which platforms are supported by Redot?

For the editor:

Windows
macOS
Linux, *BSD
Android (experimental)
Web (experimental)

For exporting your games:

Windows
macOS
Linux, *BSD
Android
iOS
Web

Both 32- and 64-bit binaries are supported where it makes sense, with 64 being the default. Official macOS builds support Apple Silicon natively as well as x86_64.

Some users also report building and using Redot successfully on ARM-based systems with Linux, like the Raspberry Pi.

The Redot team can't provide an open source console export due to the licensing terms imposed by console manufacturers. Regardless of the engine you use, though, releasing games on consoles is always a lot of work. You can read more about Console support in Redot.

For more on this, see the sections on exporting and compiling Redot yourself.

Note

Redot 3 also had support for Universal Windows Platform (UWP). This platform port was removed in Redot 4 due to lack of maintenance, and it being deprecated by Microsoft. It is still available in the current stable release of Redot 3 for interested users.

Which programming languages are supported in Redot?

The officially supported languages for Redot are GDScript, C#, and C++. See the subcategories for each language in the scripting section.

If you are just starting out with either Redot or game development in general, GDScript is the recommended language to learn and use since it is native to Redot. While scripting languages tend to be less performant than lower-level languages in the long run, for prototyping, developing Minimum Viable Products (MVPs), and focusing on Time-To-Market (TTM), GDScript will provide a fast, friendly, and capable way of developing your games.

Note that C# support is still relatively new, and as such, you may encounter some issues along the way. C# support is also currently missing on the web platform. Our friendly and hard-working development community is always ready to tackle new problems as they arise, but since this is an open source project, we recommend that you first do some due diligence yourself. Searching through discussions on open issues is a great way to start your troubleshooting.

As for new languages, support is possible via third parties with GDExtensions. (See the question about plugins below). Work is currently underway, for example, on unofficial bindings for Redot to Python and Nim.

What is GDScript and why should I use it?

GDScript is Redot's integrated scripting language. It was built from the ground up to maximize Redot's potential in the least amount of code, affording both novice and expert developers alike to capitalize on Redot's strengths as fast as possible. If you've ever written anything in a language like Python before, then you'll feel right at home. For examples and a complete overview of the power GDScript offers you, check out the GDScript scripting guide.

There are several reasons to use GDScript, but the most salient reason is the overall reduction of complexity.

The original intent of creating a tightly integrated, custom scripting language for Redot was two-fold: first, it reduces the amount of time necessary to get up and running with Redot, giving developers a rapid way of exposing themselves to the engine with a focus on productivity; second, it reduces the overall burden of maintenance, attenuates the dimensionality of issues, and allows the developers of the engine to focus on squashing bugs and improving features related to the engine core, rather than spending a lot of time trying to get a small set of incremental features working across a large set of languages.

Since Redot is an open source project, it was imperative from the start to prioritize a more integrated and seamless experience over attracting additional users by supporting more familiar programming languages, especially when supporting those more familiar languages would result in a worse experience. We understand if you would rather use another language in Redot (see the list of supported options above). That being said, if you haven't given GDScript a try, try it for three days. Just like Redot, once you see how powerful it is and how rapid your development becomes, we think GDScript will grow on you.

More information about getting comfortable with GDScript or dynamically typed languages can be found in the GDScript: An introduction to dynamic languages tutorial.

What were the motivations behind creating GDScript?

In the early days, the engine used the Lua scripting language. Lua can be fast thanks to LuaJIT, but creating bindings to an object-oriented system (by using fallbacks) was complex and slow and took an enormous amount of code. After some experiments with Python, that also proved difficult to embed.

The main reasons for creating a custom scripting language for Redot were:

Poor threading support in most script VMs, and Redot uses threads (Lua, Python, Squirrel, JavaScript, ActionScript, etc.).
Poor class-extending support in most script VMs, and adapting to the way Redot works is highly inefficient (Lua, Python, JavaScript).
Many existing languages have horrible interfaces for binding to C++, resulting in a large amount of code, bugs, bottlenecks, and general inefficiency (Lua, Python, Squirrel, JavaScript, etc.). We wanted to focus on a great engine, not a great number of integrations.
No native vector types (Vector3, Transform3D, etc.), resulting in highly reduced performance when using custom types (Lua, Python, Squirrel, JavaScript, ActionScript, etc.).
Garbage collector results in stalls or unnecessarily large memory usage (Lua, Python, JavaScript, ActionScript, etc.).
Difficulty integrating with the code editor for providing code completion, live editing, etc. (all of them).

GDScript was designed to curtail the issues above, and more.

What 3D model formats does Redot support?

You can find detailed information on supported formats, how to export them from your 3D modeling software, and how to import them for Redot in the Importing 3D scenes documentation.

Will [insert closed SDK such as FMOD, GameWorks, etc.] be supported in Redot?

The aim of Redot is to create a free and open source MIT-licensed engine that is modular and extendable. There are no plans for the core engine development community to support any third-party, closed-source/proprietary SDKs, as integrating with these would go against Redot's ethos.

That said, because Redot is open source and modular, nothing prevents you or anyone else interested in adding those libraries as a module and shipping your game with them, as either open- or closed-source.

To see how support for your SDK of choice could still be provided, look at the Plugins question below.

If you know of a third-party SDK that is not supported by Redot but that offers free and open source integration, consider starting the integration work yourself. Redot is not owned by one person; it belongs to the community, and it grows along with ambitious community contributors like you.

How can I extend Redot?

For extending Redot, like creating Redot Editor plugins or adding support for additional languages, take a look at EditorPlugins and tool scripts.

Also, see the official blog post on GDExtension, a way to develop native extensions for Redot:

Introducing GDNative's successor, GDExtension

You can also take a look at the GDScript implementation, the Redot modules, as well as the Jolt physics engine integration for Redot. This would be a good starting point to see how another third-party library integrates with Redot.

How do I install the Redot editor on my system (for desktop integration)?

Since you don't need to actually install Redot on your system to run it, this means desktop integration is not performed automatically. There are two ways to overcome this. You can install Redot from Steam (all platforms), Scoop (Windows), Homebrew (macOS) or Flathub (Linux). This will automatically perform the required steps for desktop integration.

Alternatively, you can manually perform the steps that an installer would do for you:

Windows

Move the Redot executable to a stable location (i.e. outside of your Downloads folder), so you don't accidentally move it and break the shortcut in the future.
Right-click the Redot executable and choose Create Shortcut.
Move the created shortcut to %APPDATA%\Microsoft\Windows\Start Menu\Programs. This is the user-wide location for shortcuts that will appear in the Start menu. You can also pin Redot in the task bar by right-clicking the executable and choosing Pin to Task Bar.

macOS

Drag the extracted Redot application to /Applications/Redot.app, then drag it to the Dock if desired. Spotlight will be able to find Redot as long as it's in /Applications or ~/Applications.

Linux

Move the Redot binary to a stable location (i.e. outside of your Downloads folder), so you don't accidentally move it and break the shortcut in the future.
Rename and move the Redot binary to a location present in your PATH environment variable. This is typically /usr/local/bin/redot or /usr/bin/redot. Doing this requires administrator privileges, but this also allows you to run the Redot editor from a terminal by entering redot.
- If you cannot move the Redot editor binary to a protected location, you can keep the binary somewhere in your home directory, and modify the Path= line in the .desktop file linked below to contain the full absolute path to the Redot binary.
Save this .desktop file to $HOME/.local/share/applications/. If you have administrator privileges, you can also save the .desktop file to /usr/local/share/applications to make the shortcut available for all users.

Is the Redot editor a portable application?

In its default configuration, Redot is semi-portable. Its executable can run from any location (including non-writable locations) and never requires administrator privileges.

However, configuration files will be written to the user-wide configuration or data directory. This is usually a good approach, but this means configuration files will not carry across machines if you copy the folder containing the Redot executable. See File paths in Redot projects for more information.

If true portable operation is desired (e.g. for use on a USB stick), follow the steps in Self-contained mode.

Why does Redot prioritize Vulkan and OpenGL over Direct3D?

Redot aims for cross-platform compatibility and open standards first and foremost. OpenGL and Vulkan are the technologies that are both open and available on (nearly) all platforms. Thanks to this design decision, a project developed with Redot on Windows will run out of the box on Linux, macOS, and more.

While Vulkan and OpenGL remain our primary focus for their open standard and cross-platform benefits, Redot 4.3 introduced experimental support for Direct3D 12. This addition aims to enhance performance and compatibility on platforms where Direct3D 12 is prevalent, such as Windows and Xbox. However, Vulkan and OpenGL will continue as the default rendering backends on all platforms, including Windows.

Why does Redot aim to keep its core feature set small?

Redot intentionally does not include features that can be implemented by add-ons unless they are used very often. One example of something not used often is advanced artificial intelligence functionality.

There are several reasons for this:

Code maintenance and surface for bugs. Every time we accept new code in the Redot repository, existing contributors often take the responsibility of maintaining it. Some contributors don't always stick around after getting their code merged, which can make it difficult for us to maintain the code in question. This can lead to poorly maintained features with bugs that are never fixed. On top of that, the "API surface" that needs to be tested and checked for regressions keeps increasing over time.
Ease of contribution. By keeping the codebase small and tidy, it can remain fast and easy to compile from source. This makes it easier for new contributors to get started with Redot, without requiring them to purchase high-end hardware.
Keeping the binary size small for the editor. Not everyone has a fast Internet connection. Ensuring that everyone can download the Redot editor, extract it and run it in less than 5 minutes makes Redot more accessible to developers in all countries.
Keeping the binary size small for export templates. This directly impacts the size of projects exported with Redot. On mobile and web platforms, keeping file sizes low is important to ensure fast installation and loading on underpowered devices. Again, there are many countries where high-speed Internet is not readily available. To add to this, strict data usage caps are often in effect in those countries.

For all the reasons above, we have to be selective of what we can accept as core functionality in Redot. This is why we are aiming to move some core functionality to officially supported add-ons in future versions of Redot. In terms of binary size, this also has the advantage of making you pay only for what you actually use in your project. (In the meantime, you can compile custom export templates with unused features disabled to optimize the distribution size of your project.)

How should assets be created to handle multiple resolutions and aspect ratios?

This question pops up often and it's probably thanks to the misunderstanding created by Apple when they originally doubled the resolution of their devices. It made people think that having the same assets in different resolutions was a good idea, so many continued towards that path. That originally worked to a point and only for Apple devices, but then several Android and Apple devices with different resolutions and aspect ratios were created, with a very wide range of sizes and DPIs.

The most common and proper way to achieve this is to, instead, use a single base resolution for the game and only handle different screen aspect ratios. This is mostly needed for 2D, as in 3D, it's just a matter of camera vertical or horizontal FOV.

Choose a single base resolution for your game. Even if there are devices that go up to 1440p and devices that go down to 400p, regular hardware scaling in your device will take care of this at little or no performance cost. The most common choices are either near 1080p (1920x1080) or 720p (1280x720). Keep in mind the higher the resolution, the larger your assets, the more memory they will take and the longer the time it will take for loading.
Use the stretch options in Redot; canvas items stretching while keeping aspect ratios works best. Check the Multiple resolutions tutorial on how to achieve this.
Determine a minimum resolution and then decide if you want your game to stretch vertically or horizontally for different aspect ratios, or if there is one aspect ratio and you want black bars to appear instead. This is also explained in Multiple resolutions.
For user interfaces, use the anchoring to determine where controls should stay and move. If UIs are more complex, consider learning about Containers.

And that's it! Your game should work in multiple resolutions.

When is the next release of Redot out?

When it's ready! See When is the next release out? for more information.

Which Redot version should I use for a new project?

We recommend using Redot 4.x for new projects, but depending on the feature set you need, it may be better to use 3.x instead. See Which version should I use for a new project? for more information.

Should I upgrade my project to use new Redot versions?

Some new versions are safer to upgrade to than others. In general, whether you should upgrade depends on your project's circumstances. See Should I upgrade my project to use new engine versions? for more information.

Should I use the Forward+, Mobile, or Compatibility renderer?

You can find a detailed comparison of the renderers in Renderers.

I would like to contribute! How can I get started?

Awesome! As an open source project, Redot thrives off of the innovation and the ambition of developers like you.

The best way to start contributing to Redot is by using it and reporting any issues that you might experience. A good bug report with clear reproduction steps helps your fellow contributors fix bugs quickly and efficiently. You can also report issues you find in the online documentation.

If you feel ready to submit your first PR, pick any issue that resonates with you from one of the links above and try your hand at fixing it. You will need to learn how to compile the engine from sources, or how to build the documentation. You also need to get familiar with Git, a version control system that Redot developers use.

We explain how to work with the engine source, how to edit the documentation, and what other ways to contribute are there in our documentation for contributors.

Is it possible to use Redot to create non-game applications?

Yes! Redot features an extensive built-in UI system, and its small distribution size can make it a suitable alternative to frameworks like Electron or Qt.

When creating a non-game application, make sure to enable low-processor mode in the Project Settings to decrease CPU and GPU usage.

Check out Material Maker and Pixelorama for examples of open source applications made with Redot.

Is it possible to use Redot as a library?

Redot is meant to be used with its editor. We recommend you give it a try, as it will most likely save you time in the long term. There are no plans to make Redot usable as a library, as it would make the rest of the engine more convoluted and difficult to use for casual users.

If you want to use a rendering library, look into using an established rendering engine instead. Keep in mind rendering engines usually have smaller communities compared to Redot. This will make it more difficult to find answers to your questions.

What user interface toolkit does Redot use?

Redot does not use a standard GUI toolkit like GTK, Qt or wxWidgets. Instead, Redot uses its own user interface toolkit, rendered using OpenGL ES or Vulkan. This toolkit is exposed in the form of Control nodes, which are used to render the editor (which is written in C++). These Control nodes can also be used in projects from any scripting language supported by Redot.

This custom toolkit makes it possible to benefit from hardware acceleration and have a consistent appearance across all platforms. On top of that, it doesn't have to deal with the LGPL licensing caveats that come with GTK or Qt. Lastly, this means Redot is "eating its own dog food" since the editor itself is one of the most complex users of Redot's UI system.

This custom UI toolkit can't be used as a library, but you can still use Redot to create non-game applications by using the editor.

Why does Redot use the SCons build system?

Redot uses the SCons build system. There are no plans to switch to a different build system in the near future. There are many reasons why we have chosen SCons over other alternatives. For example:

Redot can be compiled for a dozen different platforms: all PC platforms, all mobile platforms, many consoles, and WebAssembly.
Developers often need to compile for several of the platforms at the same time, or even different targets of the same platform. They can't afford reconfiguring and rebuilding the project each time. SCons can do this with no sweat, without breaking the builds.
SCons will never break a build no matter how many changes, configurations, additions, removals etc.
Redot's build process is not simple. Several files are generated by code (binders), others are parsed (shaders), and others need to offer customization (modules). This requires complex logic which is easier to write in an actual programming language (like Python) rather than using a mostly macro-based language only meant for building.
Redot's build process makes heavy use of cross-compiling tools. Each platform has a specific detection process, and all these must be handled as specific cases with special code written for each.

Please try to keep an open mind and get at least a little familiar with SCons if you are planning to build Redot yourself.

Why does Redot not use STL (Standard Template Library)?

Like many other libraries (Qt as an example), Redot does not make use of STL (with a few exceptions such as threading primitives). We believe STL is a great general-purpose library, but we had special requirements for Redot.

STL templates create very large symbols, which results in huge debug binaries. We use few templates with very short names instead.
Most of our containers cater to special needs, like Vector, which uses copy on write and we use to pass data around, or the RID system, which requires O(1) access time for performance. Likewise, our hash map implementations are designed to integrate seamlessly with internal engine types.
Our containers have memory tracking built-in, which helps better track memory usage.
For large arrays, we use pooled memory, which can be mapped to either a preallocated buffer or virtual memory.
We use our custom String type, as the one provided by STL is too basic and lacks proper internationalization support.

Why does Redot not use exceptions?

We believe games should not crash, no matter what. If an unexpected situation happens, Redot will print an error (which can be traced even to script), but then it will try to recover as gracefully as possible and keep going.

Additionally, exceptions significantly increase the binary size for the executable and result in increased compile times.

Does Redot use an ECS (Entity Component System)?

Redot does not use an ECS and relies on inheritance instead. While there is no universally better approach, we found that using an inheritance-based approach resulted in better usability while still being fast enough for most use cases.

That said, nothing prevents you from making use of composition in your project by creating child Nodes with individual scripts. These nodes can then be added and removed at runtime to dynamically add and remove behaviors.

More information about Redot's design choices can be found in this article.

Why does Redot not force users to implement DOD (Data-Oriented Design)?

While Redot internally attempts to use cache coherency as much as possible, we believe users don't need to be forced to use DOD practices.

DOD is mostly a cache coherency optimization that can only provide significant performance improvements when dealing with dozens of thousands of objects which are processed every frame with little modification. That is, if you are moving a few hundred sprites or enemies per frame, DOD won't result in a meaningful improvement in performance. In such a case, you should consider a different approach to optimization.

The vast majority of games do not need this and Redot provides handy helpers to do the job for most cases when you do.

If a game needs to process such a large amount of objects, our recommendation is to use C++ and GDExtensions for performance-heavy tasks and GDScript (or C#) for the rest of the game.

How can I support Redot development or contribute?

See How to contribute.

Who is working on Redot? How can I contact you?

See the corresponding page on the Redot website.