Cesium for Unity(v1.15.3) – Developer Setup (Ubuntu 22.04, Unity 2022.3)

This guide documents how to clone and configure Cesium for Unity(v1.15.3) so that it builds correctly on Ubuntu 22.04 with Unity 2022.3 LTS. Some extra adjustments are needed for Reinterop and the CMake build files in order to compile the editor and runtime native libraries on Linux.

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System Environment

• OS: Ubuntu 22.04.5 LTS
  • Architecture: 64-bit
  • Windowing System: X11
  • GNOME Version: 42.9
• Unity Editor: 2022.3.55f1
• Unity Hub: 3.11.0
• .NET SDKs Installed: .NET 6.0 / .NET 8.0 (with the dotnet CLI)

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Original Documentation

The official starting point is the Cesium for Unity developer-setup.md, but we’ll override some steps for Linux compatibility and Reinterop adjustments.

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1. Clone the Repository

We typically place this in a Packages/ folder if you’re integrating into a Unity project.
For example:

cd /path/to/YourUnityProject/Packages
git clone --recurse-submodules -b v1.15.3 git@github.com:CesiumGS/cesium-unity.git com.cesium.unity

This clones the cesium-unity repo into a folder named com.cesium.unity, including its submodules.

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2. Adjust Reinterop.csproj in Reinterop~

By default, Reinterop.csproj might be targeting something newer than netstandard2.0 or have LangVersion=Preview, which Unity’s Roslyn won’t accept on Linux. Replace it.

cd com.cesium.unity
gedit Reinterop~/Reinterop.csproj

Replace by copy paste:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <LangVersion>latest</LangVersion>
    <IsRoslynComponent>true</IsRoslynComponent>
    <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
    <CompilerGeneratedFilesOutputPath>Generated</CompilerGeneratedFilesOutputPath>
  </PropertyGroup>

  <ItemGroup>
    <Compile Remove="RoslynIncrementalGenerator.cs" />
  </ItemGroup>
  
  <ItemGroup>
    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.8.0" PrivateAssets="all" />
  </ItemGroup>

  <!-- This ensures the library will be packaged as a source generator when we use `dotnet pack` -->
  <ItemGroup>
    <None Include="$(OutputPath)\$(AssemblyName).dll" Pack="true" PackagePath="analyzers/dotnet/cs" Visible="false" />
  </ItemGroup>

</Project>

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3. Change needed for allowing ceisum to be built for runtime unity build

open com.cesium.unity/Runtime/CesiumRuntime.asmdef

and add "LinuxStandalone64" in includePlatforms like

  {
      "name": "CesiumRuntime",
      "rootNamespace": "",
      "references": [
          "Unity.InputSystem",
          "Unity.Mathematics",
          "Unity.Splines"
      ],
      "includePlatforms": [
          "Android",
          "Editor",
          "iOS",
          "macOSStandalone",
          "WSA",
          "WindowsStandalone64",
          "LinuxStandalone64"
      ],
      "excludePlatforms": [],
      "allowUnsafeCode": true,
      "overrideReferences": false,
      "precompiledReferences": [],
      "autoReferenced": true,
      "defineConstraints": [],
      "versionDefines": [
          {
              "name": "com.unity.splines",
              "expression": "1.0.0",
              "define": "SUPPORTS_SPLINES"
          }
      ],
      "noEngineReferences": false
  }

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4. Publish Reinterop

From inside com.cesium.unity, do:

# Build/publish Reinterop to ensure we have the Reinterop.dll we want.
pwd # you should be in com.cesium.unity folder
dotnet publish Reinterop~ -o .
git restore Reinterop.dll.meta

This generates a Reinterop.dll in the com.cesium.unity/ folder (copied from Reinterop~/bin/Release/netstandard2.0/Reinterop.dll).

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5. Open the project in unity editor to compile and create DotNet folder.

Go to Unity Hub and open the project!.

• Unity might show DllNotFoundException for the native plugin until you build it, which is expected.

After it finishes compiling you can close it. Now back to the console, you should be able to see some DotNet folders generated if you enter in the console:

pwd # you should be in com.cesium.unity folder
find . -iname "*dotnet*"

you should get something like:

./native~/Runtime/generated-Editor/src/DotNet
./native~/Runtime/generated-Editor/include/DotNet
./native~/Editor/generated-Editor/src/DotNet
./native~/Editor/generated-Editor/include/DotNet

If you do see DotNet folders, you can move on to the next step, to build the cpp side of the cesium package.

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6. fix Cesium3DTilesSelection/src/TilesetJsonLoader.cpp

CesiumGS/cesium-unity#513 (comment)

pwd # you should be in com.cesium.unity folder
gedit native~/extern/cesium-native/Cesium3DTilesSelection/src/TilesetJsonLoader.cpp

Copy paste the following file's content:

TilesetJsonLoader.cpp

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7. create custom x64-linux-unity.cmake

CesiumGS/cesium-unity#513 (comment)

pwd # you should be in com.cesium.unity folder
gedit native~/vcpkg/triplets/x64-linux-unity.cmake

Copy paste:

include("${CMAKE_CURRENT_LIST_DIR}/shared/common.cmake")
# Custom triplet for x64-linux with Unity-specific settings.
set(VCPKG_TARGET_ARCHITECTURE x64)
set(VCPKG_CRT_LINKAGE static)
set(VCPKG_LIBRARY_LINKAGE static)
set(VCPKG_CMAKE_SYSTEM_NAME Linux)
set(VCPKG_LIBRARY_PREFIX "")

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8. Build using x64-linux-unity.cmake you created

1. Build the Native Editor Library

   • Close Unity.
   • In a terminal:

   pwd # you should be in com.cesium.unity/ folder
   cd native~
   cmake -B build-Standalone -S . -DCMAKE_BUILD_TYPE=RelWithDebInfo -DVCPKG_TRIPLET=x64-linux-unity -DVCPKG_OVERLAY_TRIPLETS=$(pwd)/vcpkg/triplets -DEDITOR=OFF
   cmake --build build-Standalone --target install --parallel $(nproc)
   
   • This produces CesiumForUnityNative-Editor.so (on Linux) and installs it to ../Editor by default.

2. Restart Unity

   • After installing the Editor library, reopen Unity.
   • Unity should now load CesiumForUnityNative-Editor.so without throwing DllNotFoundException.

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9. Done!

With these changes:

• Reinterop is recognized as a netstandard2.0 analyzer.
• The Editor code is compiled separately from runtime code to avoid partial-definition conflicts.
• Unity Editor can load CesiumForUnityNative-Editor.so.
• The runtime plugin is built only if needed, using -DEDITOR=OFF.

Now you can open scenes from Cesium for Unity, test your Ion integration, and avoid all the “No such file or directory: DotNet/…” or DllNotFoundException issues.