How to have 3ds Max recognize my custom file type?

[martim.grosner]

I'm using the image plugin samples as an example to make a plugin for my custom file type. The plugin works and I can load it to 3ds Max with no errors. But when I open a file dialog, through bitmap selection, I don't see my custom file type extension under the file type selection. What virtual functions of BitmapIO class should I be overriding? What other functionality from BitmapIO is essential? Maybe that's what I am missing. I have already overridden Ext() and ExtCount().

[klvnk]

think its probably Ext() and ExtCount()

[martim.grosner]

Then why isn't it working? It doesn't add the custom file type to the file type selection list on the dialog. Should I expect this to happen?

[klvnk]

have you implemented 

int Capability ( )

?

to honest without any code it's just pure guess work.

[martim.grosner]

Here is the source and header file. I haven't implemented "int Capability()". How should I do it, what should be on it's body?

Let me know if you need something like the DllEntry.cpp or a resource file.

[klvnk]

Capability() is implemented

nothing jumps out what does your .def file look like ?

also not sure why CanAutoDefer() isnt in Dllentry.cpp

ClassDesc2* GetFDRSImageIODesc()
{
	static FDRSImageIOClassDesc FDRSImageIOClassDesc;
	return &FDRSImageIOClassDesc;
}

this is wrong you can't use a class name as a Variable name.... would have thought the compiler would have complained 🙁

try something like....

ClassDesc2* GetFDRSImageIODesc()
{
	static FDRSImageIOClassDesc FDRSImageDesc;
	return &FDRSImageDesc;
}

[martim.grosner]

I corrected the variable's name, thanks for pointing it out.

.def looks like this: 

LIBRARY FDRSImageIO.bmi
EXPORTS
   LibDescription       @1       PRIVATE
   LibNumberClasses     @2       PRIVATE
   LibClassDesc         @3       PRIVATE
   LibVersion           @4       PRIVATE
   LibInitialize        @6       PRIVATE
   LibShutdown          @7       PRIVATE
SECTIONS
   .data READ WRITE

DllEntry.cpp is automatically generated by the Wizard so I couldn't know either, am I supposed to include CanAutoDefer() manually?

[klvnk]

move CanAutoDefer() to dllentry.cpp

and add

CanAutoDefer          @5       PRIVATE

to your def file

also you could remove LibInitialize & LibShutdown  and delete the functions from dllentry.cpp if they exist.

[martim.grosner]

Deleted those two without issues, but adding CanAutoDefer() gave me the link error LNK2005 saying that CanAutoDefer() is already defined in .obj.

[klvnk]

you need to delete the one in FDRSImageIO.cpp

[martim.grosner]

Oh yes of course, I should've just ctrl F from the start.

It builds fine, but I still don't get the file type in the drop list.

[klvnk]

is your plugin listed in the plugin manager ?

if it is, you could try running under the debugger with a breakpoint in Ext() or something

[martim.grosner]

Yes, it is. It is also loaded by default. I'm gonna try that.

[klvnk · Accepted solution]

try changing Capability()

to

        int            Capability         ( )       { return BMMIO_READER    | 
                                                             BMMIO_WRITER    |
                                                             BMMIO_INFODLG   |
                                                             BMMIO_EXTENSION |
                                                             BMMIO_CONTROLWRITE; }

think you may need the extension flag set, delete the BMMIO_CONTROLWRITE flag if you don't have a custom control panel for write ops

[martim.grosner]

I get this when I use a breakpoint in Ext(): the breakpoint will not currently be hit no symbols have been loaded for this document. 

Is this normal? Does the breakpoint hit if I try to select a bitmap?

Edit: It doesn't hit when I select a bitmap, I'm not sure what's wrong here.

[klvnk]

have you fixed the Capability yet adding  | BMMIO_EXTENSION ?

[martim.grosner]

My bad, I was confused, give me a second.

Edit: Well that did it, thank you so much. How can I find more information about this?

[klvnk]

glad we got there in the end 😁

3ds Max 2022 Developer Help | 3ds Max C++ API Reference: BitmapIO Capability Flags | Autodesk

having the flag and ExtCount() function is kind of belt and braces programming 😏

[martim.grosner]

Thanks a lot!