Raylib-cs VS ImGui.NET

Glad I could help! Just one more disambiguation -- it's not built in. raylib is created by Ray/raysan5,and the C# bindings are created primarily by Chris Dill. Dill has packaged the bindings as a NuGet package, which you can add using the command line. The command downloads the package from the online repository and installs it.

Generally the respective Github pages for the binding would be a good starting point so for C# go here if you have not already https://github.com/ChrisDill/Raylib-cs

I'm converting rlImGui from C++ to C# so I can use it with ImGui.NET and Raylib-cs but I'm getting stuck at a couple places. I don't know how to convert line 331 to C# since in ImGui.NET cmd.UserCallback is an IntPtr and not something I can call. I did a quick google search and you can use the Marshal library to convert it to a callable delegate but I think you need to also have the delegate known to do that. There's also line 82 but that is specific to Raylib. The function it calls does not seem to be included in Raylib-cs. Also, rlImGui keeps using a Texture type but that is not defined in Raylib-cs or ImGui.NET. I assume I can substitute it with Texture2D from Raylib-cs but I'm not to the point in porting to see if Texture2D has the necessary fields/properties/methods.

You can go with raylib: https://github.com/ChrisDill/Raylib-cs

I've been using raylib-cs C# wrapper for raylib and have been quite happy with both. raylib is a relatively thin layer on top of OpenGL, especially if you use the rlgl functions.

Not sure about "official", but I use raylib-cs and it works perfectly for me.

Raylib-cs is very easy to use: https://www.raylib.com/ https://github.com/ChrisDill/Raylib-cs It's a binding to the Raylib C library.

If you're looking to make simple games with C#, consider looking into MonoGame or Raylib-cs. OP's use of Windows Forms could prove hard to manage with a larger game project, but it is a pretty novel approach!

If you find the structure of MonoGame too opaque or technical -- totally reasonable given that you're learning your way around -- check out Raylib-cs, a C# wrapper for the C games programming library raylib. It doesn't get much simpler.

Now I'm trying to integrate ImGui into the engine. One solution I found was using this but as far as I can tell it locks you into using OpenGL which is something I would like to avoid as one of the main selling points of SDL2 for me is it's abstraction over the rendering backend.

In additiona to imgui wrapper which works great with NativeAOT, only slight nudge and you have 10Mb executable. With all deps it's 13Mb. Also there Avalonia mentioned in sibling message which work great and in 11.0-preview5 probably would not need any additional configuraiton. In case if OP is have soft spot for web tech, he can use photino.Blazor which also with slight modifications would simply works and produce 27Mb executable.

Imgui gets rendered using ImguiRenderer provided here in the example: https://github.com/mellinoe/ImGui.NET/tree/master/src/ImGui.NET.SampleProgram.XNA

I'm converting rlImGui from C++ to C# so I can use it with ImGui.NET and Raylib-cs but I'm getting stuck at a couple places. I don't know how to convert line 331 to C# since in ImGui.NET cmd.UserCallback is an IntPtr and not something I can call. I did a quick google search and you can use the Marshal library to convert it to a callable delegate but I think you need to also have the delegate known to do that. There's also line 82 but that is specific to Raylib. The function it calls does not seem to be included in Raylib-cs. Also, rlImGui keeps using a Texture type but that is not defined in Raylib-cs or ImGui.NET. I assume I can substitute it with Texture2D from Raylib-cs but I'm not to the point in porting to see if Texture2D has the necessary fields/properties/methods.

ImGui.NET 1.87.3 (using the example implementation)

If you use this example implementation for XNA/MonoGame, you can just use ImGuiRenderer.BindTexture() which returns an IntPtr.

The only thing I could really think of is something like ImGui for C# (https://github.com/mellinoe/ImGui.NET) but I've never used it. It's going to give you some simple wrappers around ImGui (https://github.com/ocornut/imgui) but even this is going to lock you into the UI framework -- you can't just "draw a rectangle" per se and use it as a "control." Do note however this is an "immediate mode" GUI which is different from how most general desktop windowing systems work in "retained mode" (which are typically event driven, which saves on computing power to not draw the same stuff over and over).