To enable interoperability between managed .NET code and native unmanaged C++ code, Microsoft created the C++/CLI language as a superset of native C++. The C++/CLI compiler is available in Visual Studio 2008, and is enabled by using the command-line option /clr. The C++/CLI Language Specification is published by ECMA International as Standard ECMA-372 and is available for download at the following link:
http://www.ecma-international.org/publications/standards/Ecma-372.htm.
Section 8. Language Overview (of ECMA specification) provides a useful introduction to the language. The remainder of the specification is useful as a reference.
Developers must use C++/CLI to make calls into the native 3ds Max SDK from a managed project. Developers can also use C++/CLI to wrap native types in managed objects and export these managed wrapper classes outside their assembly. Such exported types may be called from any .NET language: C#, C++/CLI, Visual Basic, etc.
The .NET Framework classes can be used from C++/CLI similar to how they are used in C#. Developers familiar with native C++ and C# will find that their C# experience carries over easily to C++/CLI. Any good documentation on the .NET platform will be useful for C++/CLI work.
To create a C++/CLI plug-in, we generally follow the same procedure as for a native plug-in documented elsewhere in the SDK documentation. The major difference is that the CLR language extensions must be turned on in the project settings using the /clr option.
Additionally to refer to the .NET 3ds Max SDK components, a \#using reference path must be configured in the project settings. These components are in the maxsdk\assemblies and maxsdk\x64\assemblies folders. This setting for the sample C++ / CLI project can be found in: Project Properties > Configuration Properties > C/C++ > General > Resolve #using References: ..\..\assemblies
The 3ds Max SDK installation includes a sample how-to plug-in demonstrating some of the fundamental issues involved in creating a .NET plug-in for 3ds Max. The plug-in project file and code is in howto\\SceneExplorerExtension under your 3ds Max SDK installation folder. This sample plug-in is loaded by the managed plugin loader. This plugin then makes calls into managed code to add a new "Hit Points" property column to the Scene Explorer.