How to get GL api from other library who create gl context?

[CeSun]

My program is a game written in c++, but I inherited clr, I want to develop some rendering work in c# through silk.net, I don't want to pass gl function pointer from c++ to c#, can silk.net help Do I do this? I know this is theoretically possible.

[aquagoose]

All that is needed is that you are able to get the GL proc address. If you can, you can pass that into the GL.GetApi() function, there's an overload that contains a Func<string, nint> that you link to the available proc address function. As long as the returned value can be cast to nint then it should work.

[CeSun]

First of all, thanks for your answer.
Should I pass the GetProcAddress function pointer to Silk.Net so that Silk.net can get the Opengl function?

[UnmanagedCallersOnly(CallConvs = new[] { typeof(CallConvCdecl) })]
public unsafe static void CSharpInitOpenGL(nint ptrGetProcAddress)
{
     GetProcAdressPtr = (delegate* unmanaged[Stdcall]<byte*, nint>)ptrGetProcAddress;
     var gl = GL.GetApi(new Func<string, nint>(GetProcAddress));
}

public static unsafe nint GetProcAddress(string name)
{

     var bytes = new byte[name.Length + 1];
     Encoding.ASCII.GetBytes(name, bytes);
     bytes[bytes.Length - 1] = 0;
     fixed(byte* ptr = bytes)
     {
         return GetProcAdressPtr(ptr);
     }
}

[CeSun]

it worked. Thank you again.

public static void CSharpInitOpenGL()
{
    GlMoudle = LoadLibrary("opengl32.dll");
    gl = GL.GetApi(new Func<string, nint>(GetProcAddress));
}

public static unsafe nint GetProcAddress(string name)
{

    var fun = GetProcAddress(GlMoudle, name);
    return fun;
}


[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern IntPtr LoadLibrary(string libname);

[DllImport("kernel32.dll", CharSet = CharSet.Ansi)]
public static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);