A Simple Game Editor in C# - Game Coding Complete - page 764

int nCmdShow, int screenWidth, int screenHeight);
extern “ C ” DllExport void RenderFrame();

extern “ C ” DllExport int Shutdown();

extern “ C ” DllExport void OpenLevel( BSTR lFileName );

// Actor accessor functions
extern “ C ” DllExport int GetNumActors();

extern “ C ” DllExport void GetActorList(int *actorIdArrayPtr, int size);

extern “ C ” DllExport int PickActor(int *hWndPtrAddress);

extern “ C ” DllExport int GetActorXmlSize ( ActorId actorId );

extern DllExport void GetActorXml ( int *actorXmlPtrAddress,

ActorId actorId );

“ C ”

// Actor XML functions
extern “ C ” DllExport void RemoveActor( ActorId actorId );

extern “ C ” DllExport void CreateActor( BSTR bstrActorResource );

extern DllExport void ModifyActor ( BSTR bstrActorModificationXML );

Each exported function must have extern “C” _declspec(DLLexport) before
the declaration. The macro at the top of the last code segment helps keep the code
looking cleaner. As you read the remainder of this chapter, more C functions will be
added to this list as the C# editor side is explored.
The editor project settings are exactly the same as those set for the project that cre-
ated Teapot Wars, with one exception. Under Configuration Properties->General, the
Configuration Type should be set to

“ C ”

“ Dynamic Library (.dll) ” instead of “ Application

(.exe). ”

Wrapping Up the Editor Architecture
The editor application, logic, and view classes are thin extensions of the base classes
you

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ve seen in earlier chapters. They can add actors to a scene, render them, and
receive events on how to modify the actors, either by moving them around or delet-
ing them. The editor doesn t need too much more than that, at least from the game

engine itself. It does, however, need a fairly complicated user interface, a way to load
and save levels, create and modify actor properties, and package everything to be
used by the game engine. For that, we need to wrap the C++ editor implementation
with C#.
Getting that to work means the C# application needs to send information to and
retrieve information from the C++ code. This gets a little tricky, and for context, we
need to go over differences between managed and unmanaged code.

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