Mitsuba Package Installation: Failed to load Mitsuba Module (Blender 4.5)

[Microno95]

Issue Title
Failure to load Mitsuba module despite successful pip install due to changing search paths in Blender 4.5.

Bug Description
Mitsuba-Blender add-on fails to find Mitsuba module when running in Blender 4.5 on Windows as the mitsuba (and drjit) python packages are installed in the user-specific site-packages folder (%APPDATA%\Python\Python311\site-packages), but this folder is no longer included in the search path for Python packages as of (as far as I can tell) Blender 4.2.

To Reproduce
Steps to reproduce the behavior:

1. Install add-on in Blender 4.5 on Windows
2. Enable add-on and run Install Dependencies
3. Failed to load mitsuba module error ensues despite successful installation pip log in Blender console.

Expected behavior
No error on failing to load the module.

Environment (please complete the following information):

• OS: Windows
• Blender Version: 4.5.0
• Add-on Version: 0.4.0 (the add-on version shows up as 0.1 inside Blender btw)

Additional context
This can be fixed, following this thread on the Blender Stack-Exchange by additionally importing site as a module and adding the lines

user_site_pkgs = site.getusersitepackages()
if user_site_pkgs not in sys.path:
    sys.path.append(user_site_pkgs)

to the init_mitsuba function which ensures that the user-site packages path is automatically included in the search path for import mitsuba.

This is the simplest solution, but modifies the package search path globally so an alternative could be to only invoke this if/when Mitsuba fails to load and then remove the path from sys.path after Mitsuba is successfully imported - might break things with dynamic reloading of packages as Mitsuba does with switching variants.

[bathal1]

Thank you for bringing this up.

We are currently working on adding support for Blender 4.5, and a release should come out soon. Until then, we unfortunately do not support it so we kindly ask you to downgrade your Blender version to the previous LTS version (4.2).

Keeping this open until we can fix it for 4.5

[Microno95]

Thanks! I have manually patched the add-on so it works and am looking forward to the next release that will officially support 4.5.