Using any C++ library in Godot

(blog.conan.io)

152 points | by czoido 13 hours ago ago

52 comments

  • voodooEntity 12 hours ago

    Was playing arround recently building an RTS with godot until i just hit the ceilling of what i could handle with gdscript performance wise.

    Than started to move alot of heavy logic to c++ simulation : tedious indeed but the results speak for themself.

    Basically allows me to use godot for things like menus dialogues and similar stuff while running the true heavy work in a c++ simulation.

    • 8-prime 10 hours ago

      What motivated you to use c++ rather than C#? Especially when you mention the usage of c++ being tedious, when I would argue using C# is equally straight forward as gdscript is.

      • voodooEntity 8 hours ago

        A combination of two factors that are rather specific to myself. One being that even tho its quite some time ago i have a bit of c++ experience, while i never tried to code C#. So when i got the idea to try to run the heavy simulation in an "extension" it was just a language i was a bit familiar with. Maybe C# would have been the "smarter" choice, i just never digged into it yet.

        The other reason is that in my well closer circle i got quite some people that code c++ on a daily basis and i don't know (at least i think so) anyone doin C# actively, so i thought if i would get stuck i have people i can easily ask about my c++ problems.

        So it wasn't a "i think c++ is better than c#" decision rather a what do i know and what resources i have available easily.

        • jdw64 8 hours ago

          C# is mostly in the Unity community. I agree that GDScript performance isn't good.

          • KronisLV 7 hours ago

            Godot, Unity, Stride, Flax and even jank niche engines like NeoAxis generally have pretty good C# integration!

            If you look more at Stride, you’ll see that even their physics engine is C# which is insane in the best possible way: https://doc.stride3d.net/4.3/en/Manual/physics/index.html and https://github.com/bepu/bepuphysics2

            Very cool language and as much of a mainstay in gamedev like something like Lua.

            It surprises me that Java never got similarly big despite their GC improvements, though jMonkeyEngine was a nice project last I looked.

            • torginus 6 hours ago

              Yeah there are some gamedev treasures in C#, owning to the fact that Microsoft created the Xbox Live Indie Games program back in the X360 era, which meant you could ship games to customers with generally little oversight and meddling - this was WAY before Steam did something similar, and even before the iPhone app store.

              The catch was that you had to use C# and XNA (which was a wrapper for gaming related APIs like DirectX, XAudio and XInput, generally considered to be very good). This meant there were a lot of hardcore libs made for C# gamedev (BEPU physics is from that era, and there were things like very good UI frameworks).

              Tons of games were made with XNA, and its open source ofshoots, MonoGame and FNA power some of the greatest indie hits (Stardew Valley, Celeste, Bastion and other Supergiant titles, Terraria come to mind).

              Imo this is one of the main reasons Unity went with C# in the first place.

              • pjmlp 5 hours ago

                Historical note that Arena Wars, released in the .NET 1.0 days, with thin bindings to OpenGL, was the very first .NET game, years before XNA.

                https://en.wikipedia.org/wiki/Arena_Wars

                C# being closer to C++, and .NET having direct support for C++ helped quite a bit regarding adoption among game studios.

                Unity started on Mac, and they only adopted .NET when doing the cross platform rewrite.

                I also don't remember if there wasn't some Mono advocacy at the time, as they became customers in the process.

                Ironically Mono/Xamarin is almost gone from official .NET, all these years after the acquisition, with every modern .NET release, another bit falls off.

                We are already on the phase that CoreCLR might take the remaining bits.

      • windsurfer 9 hours ago

        C# is a "first class" language in Godot and doesn't need a GDExtension, but it's not compatible with web builds yet. There is a draft PR that includes C# support but it adds about +50 MB to a web export and is also missing a few features.

        • 8-prime 7 hours ago

          I did not know that. Thanks for the info. I always use C# with Godot, but never had a use-case where i needed a web build.

        • pjmlp 5 hours ago

          And even that doesn't add consoles support, is W4 that far?

      • pier25 6 hours ago

        Not sure how relevant this is for this simulation use case but IIRC C# has a bigger overhead when communicating with the core engine compared to GDScript or C++.

    • momocowcow 11 hours ago

      gdscript is incredibly slow, worst than something like lua, maybe only good for handling the UI events

      the hierarchy and physics api isn’t great either, it’s easy to hit heap allocs even from a gdextension

      a lot of things wrong with this generic engine, but at least it’s lightweight

      • Fraterkes 11 hours ago

        Lots of things right too, thankfully

      • tancop 8 hours ago

        Godot is only the best open source engine because Bevy is not ready for production, Lumberyard/O3DE is hard to set up and everything else is ancient or 2D only. one eyed man among the blind type shit

        • pier25 6 hours ago

          > Godot is only the best open source engine because Bevy is not ready for production

          I would argue that even if Bevy was ready for production it would not really compete with Godot.

          Godot's performance is plenty for the vast majority of small to medium games. Plus they're starting to work on features like texture streaming for bigger games. It also has an editor which is a big plus for most teams.

          Bevy would be objectively better for expensive CPU simulation stuff but realistically what percentage of games need that? Maybe 1%?

          For Bevy to catch up on the indie game scene it needs an editor plus a scripting language and/or something like Unreal Blueprints. If it only wants to target the hardcore Rust dev that does everything by code it will never go mainstream.

        • tapoxi 5 hours ago

          Godot is the best open source engine because it is dead simple to use, comes bundled with its own IDE and documentation, the editor runs on any platform that Godot runs (including the web) and the performance benefits for something like Bevy only apply to a handful of games that really need it.

          Godot gives GDScript simplicity for the vast majority of use cases which is that iteration boon, provides C# for games that need the additional guardrails. For performance critical game scripts you can just jump to C++, Rust, Swift, etc.

          But most game scripts are not performance critical. Clair Obscur: Expedition 33 swept the game awards last year as an Unreal Engine game made using almost entirely visual scripting (blueprints).

          • pjmlp 5 hours ago

            Also Unreal C++ has a GC, exactly to have easy interoperability between engine code and C++ components exposed to Blueprints.

        • subhero 2 hours ago

          I always do not understand why defold is never put into the fold [sic!] of those sentiments/discussions. You can learn a clean & fun language (lua) and its JIT is maybe/probably running laps around something like GDScript, which in itself is proprietary and has no other uses for you than, ehh, Godot?? You can integrate C/C++ extensions natively, neatly exposing them through lua APIs. Its mobile and web target footprint is unbeatably (?) small, desktop at least 10x smaller than Godot or Unity. It is Open Source.

          Maybe it's the "ancient" part, because more recent is always better ;)

          • Supermancho 43 minutes ago

            > I always do not understand why defold

            Starting with absolutely nothing but a compiler is always going to be a worse experience (and less likely to result in anything released) than a GUI-driven and aided solution. If Defold developers had produced a fraction of the libraries that Godot has, it might have had a chance. As of now, it's worse than other abandoned engines like Solar2D (was CoronaSDK) for people entering the space. As most people know, the vast majority of games are net-losses, so engines live and die by the ease of adoption by newcomers.

          • valorzard 2 hours ago

            defold is really cool, the only downside is its really weird build system for native extensions

        • jdw64 5 hours ago

          No. If you try Bevy, it feels different from ECS and ordinary OOP. So it's hard to get used to. But Godot, although GDScript has performance issues, if you use GDScript it's easy to port to mobile and web games, and the syntax itself is OOP, so it's easy to adapt to.

          A lot of people complain about OOP, but it's a paradigm very well suited for rapid development.

          • pjmlp 5 hours ago

            Lots of people complain, yet nothing else has won over in GUI development tooling.

        • stackghost 6 hours ago

          I miss Torque

    • droptablemain 5 hours ago

      Assuming it's a 2D game, why not just use something like SFML to build your own simple RTS engine at that point?

      Seems like carrying a lot of Godot baggage around for nothing.

      • omoikane 5 hours ago

        Godot comes with a lot of tools in addition to the runtime. Maybe they are using the IDE to do layouts for the menu dialogues, for example.

        Also, I am not sure about how easy it is to build binaries using SFML for various platforms (such as WASM), but with Godot you just have to download the right template.

  • valorzard 13 hours ago

    If you know rust, the Godot rust bindings for GDExtension are also really good and let you use any Rust library in Godot (including tokio and async rust if you really want) https://godot-rust.github.io/

  • fwsgonzo 13 hours ago

    Just don't forget the versioning script needed on at least Linux. It's either that or build with the same older distro Godot uses, so you have a matching libstdc++ version. You can link with a newer stdlibc++ but you will need a linker versioning script that hides your impl from the dynamic linker so you don't get random ghosts in your machine.

    • czoido 12 hours ago

      Hi! Yes, you are right, thanks for pointing this out. It's something to keep in mind when distributing an extension for Linux. I have just updated the post with a note about it.

  • MeteorMarc 12 hours ago

    So, what profiling support is available to find the critical parts of your GDscript or C# code. Before needlessly jumping into c++ hassle for performance reasons? Tfa addresses functional reasons, which is ok.

    • Fraterkes 11 hours ago

      For C# there’s basically nothing in engine, so you’d use Rider or Superluminal. Which is fine, Godot can have a bit too much nih imo

    • pjmlp 11 hours ago

      I don't follow it that much, but I think there are no plans to improve GDscript performance other than maybe the interpreter itself, nothing with JIT or AOT in mind.

      Also .NET integration has the issue it doesn't work in all target platforms, that is why Capcom and Unity have their own compilers to native code. Even when Unity finally adopts modern .NET, Native AOT naturally doesn't cover game consoles.

      • Rohansi 7 hours ago

        It's too bad .NET AOT wouldn't support consoles. They use x86 and ARM processors that it already supports.

        • MindSpunk 5 hours ago

          It's not up to .NET AOT, it's up to Xbox and Sony.

          .NET can generate the code, but your game won't pass certification if it runs machine code generated by something other than the officially provided C/C++ tool chain.

          • Rohansi 3 hours ago

            I know. That's why it's too bad! It would probably (almost) just work if only it used the console's toolchain, which requires signing NDAs to even look at.

          • pjmlp 5 hours ago

            Devil May Cry on PlayStation 5 uses .NET, as do many other games from Capcom.

            They have their own in-house fork of modern .NET, integrated into RE:Engine.

        • pjmlp 7 hours ago

          There is more to it than just a CPU ISA.

    • irskep 5 hours ago

      Coming from Instruments (Apple) and Chrome Dev Tools, I found the Godot profiler to be hilariously hard to get useful results out of because of its simplistic presentation of information that you can't drill down into.

  • jokoon 12 hours ago

    So it requires writing a CMake script, some python, and some weird C++ code.

    A bit tedious but that's how it goes.

    • OsrsNeedsf2P 12 hours ago

      The point is that it's compatible, not that it's the recommended way of doing things.

  • Asmod4n 11 hours ago

    I am building something similar, with c++26 reflection. So any language can use c++ libs with only a few lines of boilerplate in a lifetime and memory safe way where possible. And where it’s not possible to infer the safe lifetime of an object i got a small .toml file which tells the lib how to safely use those functions.

  • zerr 13 hours ago

    > // Copy the position of every entity into the MultiMesh buffer

    So, is a zero-copy impossible due to world (C++ vs Godot) boundaries?

    • czoido 12 hours ago

      Hi! I don't think the boundary itself is the issue, although I'm not an expert on that part of Godot. My understanding is that the copy in this example comes from converting data from flecs into the layout MultiMesh expects. A different layout might reduce that work, but I haven't explored if fully zero-copy is possible.

  • TedDallas 5 hours ago

    I’m using CPP with Godot for runtime procedural mesh generation. Works like a charm. It’s nice to have this option when you need it.

  • le-mark 11 hours ago

    > Engine modules are compiled into the engine itself. They have full access to the internals, but you need to build and ship your own copy of Godot, including the editor and export templates for every platform.

    I’m not familiar with distributing godot games. If I build a game to distribute on steam (for example) would this be an option? Or is a GDExtension (runtime loaded .so) the standard way to go?

    • warent 11 hours ago

      It depends on what your use case is. GDExtension is the standard way to go, unless its API is too limited and you have to access/modify engine internals not otherwise exposed.

      That being said, this has no impact on distribution either way as far as I know.

    • eole666 11 hours ago

      GDExtension is the standard way. But building a custom version of Godot is common and won't be a problem for distributing the game on steam or any platform. It's necessary to build your own godot version and export templates to produce an encrypted build not too easily hackable for example.

  • hnacobsxph 12 hours ago

    Static linking libstdc++ with -fvisibility=hidden saved me on Linux, though it bit me the day I needed exceptions to cross the boundary.

  • sylware 11 hours ago

    c++ is sorta private to the application.

    If the API is c++ based you have to statically link it to the engine since the chosen c++ runtime is statically linked to the engine binaries.

    You cannot ship as a shared c++ runtime since it would conflict with a possible version installed on the user distro (version of the gcc libstdc++, version of the clang runtime, intel?, or none see below).

    To avoid c++ ABI issues, distros may statically link their c++ runtimes (clang[c++ and compiler versions]/gcc[c++ and compiler and versions]/intel[c++ and compiler versions]/etc)... if they need any (and the new c++ to C transpiler may have some significant impact in the near future).

    (BTW, is the c++ intel compiler still shipping??)

    If the API is "C" based (aka core platform ABI), no issue, just statically load only the common glibc libs (ELF DT_NEED entries) and dynamically load (libdl/dlopen/dlsym/dlclose) everything else (private libs, or system interface shared libs), and you are good to ship. A word though: wayland code with its libxkbcommon are statically linked, do not reproduce the same mistakes than with x11).

    This is required for broad distro support [and long term support].

    Basically, game binaries should be "-static-libgcc -static-libstdc++ --enable-new-dtags" everywhere, statically load _ONLY_ common glibc libs (and with "old" symbol versions, see binutils ld documentation, the 2nd part of the VERSION documentation page), and dynamically load everything else.

    I have been inspecting many recent godot4 games on steam: all had "correct" binaries to maximize broad distro loading support on the long run.

    The current issues: some games are written in microsoft rust which toolchain is still unable to statically link libgcc (see tinyglade game). Or some unity versions which "forgot" the '-static-libgcc' compiling/linking options, and even forgot to statically link their libz Oo.

    If valve could do just that with the binaries of their client and their games... They can keep their 'runtimes' for old broken games but should have 'correct' binaries for everything else on their side (and valve still has to port the final 32bits reaper command to 64bits for clean 64bits support, hopefully I did not miss other 32bits binaries). Forcing distros to compile that user namespace in their linux kernel is quite "inappropriate", better keep that optional for those broken games only.

    • ape4 9 hours ago

      A big issue. If you can't ship a library its basically useless.

      • sylware 5 hours ago

        If your API is c++ based, you ship a static lib. If the game engine is "closed" source, you also a have static lib (or a set of) for the game engine too, and "exporting" is actually linking (basically a binutils ld invokation). Ofc, you better use the same c++ compiler _VERSION_ than the game engine devs did use, or you are good for c++ hell.

        If your API is C based (or core platform ABI), and you should design such API for interop with any framework anyway, you can ship a shared lib (but it has to statically load only the common glibc libs, and that with "old" symbol versions, and the other things too, see my previous post).