"Installation" of compiled mitsuba (windows)

[ssh4net]

Sorry for pretty dumb request, but is it possible add "how to" install compiled Mitsuba to make it work as installed with pip?
For this moment it required always run setpath.bat before any works in Jupyter notebook.

[merlinND]

Hello @ssh4net,

I haven't personally tested this, but in principle it should be as easy as:

python3 ./setup.py install

Another way would be to keep everything in place inside of your mitsuba3/build folder, and then modify your system-wide environment variables to point to that directory (essentially doing the same as setpath.bat, but persistent and global).

[anderslanglands]

On this topic, the cmake install almost works. The following changes need to be made to make it work ootb. Assuming the following sequence of commands:

git clone <mitsuba repo> mitsuba3
cd mitsuba3
mkdir build
cd build
cmake .. -DCMAKE_INSTALL_PREFIX="../install"
cmake --build . --config Release --target install

This installs most of the pieces, but is missing drjit. To make it work I had to then:

cp -r ..\ext\drjit\drjit ../install
cp .\Release\python\drjit\drjit_ext.cp39-win_amd64.pyd ../install/drjit

And finally I needed to modify drjit's __init__.py to add the installed path to the DLLS:

if os.name == 'nt':
    os.add_dll_directory(os.path.join(os.getenv("MITSUBA_DIR"), "bin"))

This still isn't quite enough to build against the installed mitsuba distribution: the drjit headers are also missing but I haven't needed or had time to look into that yet.

[njroussel]

For completeness, let me add the following:

As a general word of precaution, uninstall any drjit or mitsuba package you have downloaded through PyPi before using and installing your own builds.

If you're simply looking to apply some modifications to mitsuba and then have it accessible through Python without any PATH or PYTONPATH modifications. You can simple do this:
pip install /some/path/to/mitsuba

This will also download any requirement from PyPi, including DrJit. If you want to roll your own version of Drjit, you must first (before installing mitsuba) run:
pip install /some/path/to/drjit

Both of these commands will place the packages in the appropriate site-packages folder of your Python environment. These commands should also, in most cases, create the proper folder hierarchy for mitsuba to find drjit's libraries.
If you're installing your builds directly through cmake, you will need to carefully select your install paths to handle this. @anderslanglands's answer has an example of a small fix needed with his specific setup.

[ommaury]

Hi @njroussel, I'm not quite sure how to read your last sentence about @anderslanglands comment: I'm finding I have to do the same (i.e. manual copy after cmake install) or use the compilation output directly as my working dir (which contains drjit). Is that to be expected?

This is really not a high priority btw, I'm just curious if there's another way to configure cmake that would make the install work. Thanks!

[njroussel]

@ommaury I wanted to point out that there are a few extra (undocumented) steps, like the copying.

Honestly, I don't see any reason to install mitsuba/drjit through CMake. If you're just running the code, using pip is much more reliable.

If you want to build againt mitsuba, I'm pretty sure you can also use the pip install and change your build system to pickup the pip install directories. The advantage is that the pip installations have all the headers and have the correct folder structure.
This was our initial intention: packaging mitsuba as a Python package which people would also be able to build against. Unfortunately, we never really tested it thoroughly. I'd be very happy if you could report back any issues or unexpected extra steps you had to take to make this work if you decide to go down this route 😄

[ommaury]

Thanks @njroussel, I understand.