c++ - two way communication between unmanaged code and unity3d code -

i have 2 apps. 1 of them written in visual c++ , other unity app, both running on windows. in scenario, want call unity function , draw object whenever user presses on button in c++ app. far, have tried load unity executable same address space c++ app calling mono_domain_assembly_open. however, returns null , not able call mono_jit_exec run unity app. possible maintain 2 way communication between 2 applications using mono? in advance!

here old example have, based off of this post. want pass c# delegate c++ function pointer. can store function pointer use button, or whatever else you'd like.

c++ dll:

typedef int ( __stdcall *unitycallback )( int );  static unitycallback gcallback; extern "c" __declspec( dllexport ) inline int callbackexample( unitycallback unityfunctionpointer, int n ) {     gcallback = unityfunctionpointer;     if( gcallback )     {         return gcallback( n );     }     return 0; } 

c# caller:

using unityengine; using system; using system.runtime.interopservices;  public class callback : monobehaviour {     public delegate int callbackdelegate( int n );      [dllimport ("unityplugincallback")]     private static extern int callbackexample(callbackdelegate fp, int n);      void awake()     {         int result = callbackexample(new callbackdelegate(this.callbacktest), 42);         debug.log("result callback, should 43: " + result);     }       int callbacktest( int n )     {         debug.log("received: " + n + " c++ dll");         return n+1;     } } 

in example, c++ dll calls c# callback value of 42. c#'s callback increments value 1 , returns c++ in turn returns c# @ callbackexample call site.

unity doesn't when try access engine outside of main thread i'm not sure happens if c++ dll has asynchronous calls c#. in example calls starts in main unity thread there aren't issues. suggest not allow unity specific functionality in c# callback, instead use callback set boolean(or other mechanism) used update implement whatever want unity engine.