emaame / assimp_utf8

An exmaple for AssimpNet Issue #86

Motivation

Handle a filepath string as UTF-8.

.NET use Unicode as default, but Assimp expects UTF-8.

• OriginalAssimpNetTests : use an original Assimp.AssimpContext (failure)
• Utf8AssimpDllImportTests : use a modified AssimpContext_ImportFile_MarshalAs_LPUTF8Str (a cutout code of ImportFile)

In AssimpContext_ImportFile_MarshalAs_LPUTF8Str, use the same dll, but it specifies UnmanagedType.LPUTF8Str instead of UnmanagedType.LP8Str (passing string as UTF-8 to a DLL).

There are more I/O functions to fix and test.

Although what I need is that ImportWorks_For_Filename_Includes_Multibyte_MarshalAs_LPUTF8Str works fine.

Memo

This project is .NET6 (I'm sorry, this is for my environment circumstances).

Just 'OBJ' is test. I use Visual Studio 2022.

About TestFiles

TestFiles includes some OBJ model copied from assimp/test/models/OBJ/, and they are renamed with emoji. I choose emoji as a popular multibyte character for English people.

why 📁\Spider🕸️.obj is?

We usually aviod to use multibyte characters to filenames, but it is slipped in to folder names unintentionally (or as copied filename's postfix at local language).

A filename with emoji is a terrible one. I use it as a description.

Details of Tests

OriginalAssimpNetTests fails to handle a filename with multibyte characters

• AssimpContextCouldNotImportFileWithMultibyteCharacters : a simple failure test.
• ImportFileFromStreamIsNotAlsoAbleToHandleMultibyteCharacters : this shows ImportFileFromStream helps to import an OBJ file, but it could not help to import a MTL file inside a DLL.

Utf8AssimpDllImportTests

They mostly succeed.

One tes shows that could not handle Material name Terraindæk (æ was troubled). It's not my concern at present, but I keep it FYI, don't care it seriously (THIS_TEST_IS_CURRENTLY_FAILURE_because_MaterialName_is_incorrect_even_if_It_uses_MarshalAs_LPUTF8Str_FYI).

It might be including another problem about code pages (A Field Guide to Japanese Mojibake).

Screenshot: Expected Test Results in Test Explorer