Writing .Net Action plug-ins using MaxCustomControll.dll

In order to write .NET Action plug-ins using MaxCustomControll.dll your plug-in class should implement the CuiActionCommandAdapter. Using C# in Visual Studio, you will have the option to right click on the interface name and select "Implement Abstract Class" for the list of functions and properties in the base class to be automatically populated. Doing so for CuiActionCommandAdapterThe will populate four properties and one function for you. The properties provide basic information about your CUI action plug-in. The only function is named Execute() and implements the actual functionality of your plug-in.

Any plug-in class extended from CuiActionCommandAdapter can be independantly compiled and loaded in 3ds Max. We will see later that it is not the case for plug-ins implementing the interfaces from Autodesk.Max.dll. This code provides an example of a simple .Net Action plug-in that prompts a message in a pop up window.

Writing .Net plug-ins using Autodesk.max.dll

Plug-in developers can use a complete list of interfaces defined in Autodesk.max.dll to implement any type of plug-in they need. This is similar to extending from a 3ds Max base class for a C++ plug-in. There is almost a 1 to 1 mapping between 3ds Max SDK plug-ins and the interfaces available in Autodesk.Max.dll. We will create a utility plug-in as a basic example. At the beginning, your code will look like this:

using System;
using Autodesk.Max;

namespace firstDotNet
{
    public class utilityDotNet : Autodesk.Max.Plugins.UtilityObj
    {        
    }
}

Using visual studio's "Implement Abstract Class" option for this class that implements Autodesk.Max.Plugins.UtilityObj will populate two functions for you to override, BeginEditParams() and EndEditParams(). These two functions are explained in the lesson 1 of the 3ds Max SDK learning path. Similar to the example there, we just get this utility plug-in to prompt some text to the prompt area of 3ds Max. The following code shows how your code will look like after this step:

using System;
using Autodesk.Max;

namespace firstDotNet
{
    public class utilityDotNet : Autodesk.Max.Plugins.UtilityObj
    {
        public override void BeginEditParams(IInterface ip, IIUtil iu)
        {
            ip.PushPrompt("Hello Dot Net!");
        }
        public override void EndEditParams(IInterface ip, IIUtil iu)
        {
            ip.PopPrompt();
        }
    }
}

.Net Plug-ins still need class descriptors similar to the unmanaged (C++) plug-ins. Class descriptors are explained in Getting Started Writing Plug-ins. You can define your own class descriptor that extends from Autodesk.Max.Plugins.ClassDesc2. The descriptor class returns an object of your plug-in class in its Create() function. You can right click on the class descriptor declaration name and select Implement Abstract Class so the list of the function you have to implement gets populated. Project Lesson1b.net contains a .NET utility plug-in that uses the Autodesk.max.dll assembly to prompt a message in a pop up window.

You do not need to explicitly define a constructor for your plug-in class since your call in Descriptor::Create() does not use any argument. Your plug-in project can be compiled at this point but 3ds Max still cannot recognize it even after placing the .dll file in [3ds max installation folder]\bin\assemblies and starting 3ds Max. As explained in .NET Assembly Loader you will need to register your plug-in in 3ds Max by exposing a public static function named AssemblyMain(). You can implement this function in any public class in your plug-in's namespace, including the main plug-in class and the class descriptor. We create a new public class to implement this and other assembly functions for more clarity. Similar to AssemblyMain(), the public static function AssemblyShutdown() is used to perform the required tasks (if any) when your plug-in is being terminated. Adding the following public class to the namespace will make your plug-in be loaded by the .NET Assembly Loader when 3ds Max is starting up:

public static class AssemblyFunctions
    {
        public static void AssemblyMain()
        {
            var g = Autodesk.Max.GlobalInterface.Instance;
            var i = g.COREInterface13;
            i.AddClass(new Descriptor(g));
        }

        public static void AssemblyShutdown()
        {
        }
    }

The .NET project Lesson7.zip provides different examples to use the Autodesk.Max.dll assembly along with CUI action items to create .NET plug-ins.

IGlobal global = Autodesk.Max.GlobalInterface.Instance;
Interface13 Interface = global.COREInterface13;
global.PushPrompt("...");

Interface* ip = GetCOREInterface();
ip->PushPrompt("...");