Arma3Ext_CSharpFeatureFlagsSample

Provides a working example of adding Feature Flags to a C# DLL Extension for Arma 3

The goal of this repository is simply to provide a working example of one of the many ways to include RVExtFeatureFlags directly into a C# DLL. It uses the minimal setup simply to demonstrate the process. Since C# cannot provide a global variable for Arma 3 to hook into for Feature Flags, we are basically providing that access through some other language binary which is embedded directly into the C# dll. And optionally, providing a getter/setter for C# to manipulate the field. This is a working Visual Studio solution example to demonstrate one of the ways it can be done.

What this is not:

• A Feature-Complete example of a C# Extension
• The only way to accomplish this

For this example, we assume use of Visual Studio and it's associated tools and compilers. It is not required. Simply adjust the steps as needed to use your preferred environment.

The Process

In this example, we use C++ to provide the necessary external field to manipulate the RVExtFeatureFlags but other languages can be useed.

The .cpp file is located in the same directory as the C# project files but, it can be placed anywhere.

See Arma3ExtFeatureFlags.cpp for an example of such a file

Step 1 - Compile the .cpp file into a .obj file

The goal is to compile and place an .obj file into the Intermediary Folder so we can link into the final C# DLL.

The intermediary directory is typically 'obj\ (build) \ (target) \ (runtime)' or in this case 'obj\Release\net8.0\win-x64'

e.g. cl /c /EHsc Arma3ExtFeatureFlags.cpp /Fo:obj\Release\net8.0\win-x64\Arma3ExtFeatureFlags.obj

This only has to happen once unless you need to modify the cpp file in which case recompilation is required.

WARNING : For this to be x64 compatible, you have to use the 64-bit cl.exe or the 'x64 Native Tools Command Prompt' If the compilation results in an x86 .obj file as the normal Command Prompt would typically result in, the final compilation will fail.

Step 2 - Opional : Make sure you use LibraryImportAttribute (or DLLImport) in your .cs file for the getter/setter we added in the .cpp file

LibraryImport is technically slightly faster and newer but, DLLImport is still supported and works

• For LibraryImport - use partial classes and methods for the source generator to work.
• For DLLImport - just use extern as normal

WARNING: The DLLImport or LibraryImportAttribute MUST reference your final DLL filename. If "__Internal" is used, it will crash Arma. The reason is because __Internal references the Arma assembly instead of the DLL itself once Arma has loaded the extension into memory.

See Main.cs for an example.

Step 3 - Make sure your .csproj file includes an ItemGroup item to include the .obj file

• For net8.0 - NativeLibrary can be used
• For net10.0 - LinkerArgs must be used

See SampleExt.csproj for an example

Step 4 - Compile the C# library

e.g. dotnet publish -c Release -r win-x64

Step 5 - Verify all symbols are in the DLL using dumpbin or something equivalent

e.g. dumpbin /exports SampleExt_x64.dll

should result in something like this:

  Section contains the following exports for SampleExt_x64.dll

    00000000 characteristics
    FFFFFFFF time date stamp
        0.00 version
           1 ordinal base
           6 number of functions
           6 number of names

    ordinal hint RVA      name

          1    0 0019FB10 DotNetRuntimeDebugHeader = DotNetRuntimeDebugHeader
          2    1 00002190 GetRVExtensionFeatureFlags = GetRVExtensionFeatureFlags
          3    2 00071E40 RVExtension = RVExtension
          4    3 00071F20 RVExtensionArgs = RVExtensionArgs
          5    4 0019F9F0 RVExtensionFeatureFlags = RVExtensionFeatureFlags
          6    5 00002170 SetRVExtensionFeatureFlags = SetRVExtensionFeatureFlags

  Summary

        E000 .data
       79000 .managed
        D000 .pdata
       79000 .rdata
        1000 .reloc
        1000 .rsrc
       70000 .text
       3C000 hydrated