Install OpenSim and Bpy on an older Blender version

[ChristianJovenGarcia]

I tried to follow the full installation steps, but the nature of the error thrown leads me to the assumption that I did something incorrectly.

The Steps I Took

I will list the steps and what I did on each, as the operations I performed may differ from the intended ones.

OS: Windows 11 23H2, 64-bit
Blender 3.6 LTS, Miniconda 3, .zip downloaded from link in instructions

'3.10.13 (main, Oct 10 2023, 08:34:31) [MSC v.1928 64 bit (AMD64)]'

'C:\Users\my_name\miniconda3\envs\Pose2Sim_Blender'
attempting to install packages again yielded "# All requested packages already installed."
"conda list | grep opensim" doesn't run, so I used numpy 1.23 as in the example text
"pip install bpy toml vtk anytree" yielded "no matching distribution found for bpy", so ran "pip install toml vtk anytree" instead

from innit
Line 4: curFolder = os.path.dirname(os.path.realpath(r"C:\OpenSim 4.5\bin"))
I have the OpenSim4.5 app installed, so this is correct

This one was a little complicated because the UNIX commands didn't work in my Win11 cmd, but I think I did this right
Renamed …\Blender3.6\3.6\python to python_old
Linked …\miniconda\envs\Pose2Sim_Blender into …\Blender3.6\3.6\ under the name "python", and it works properly

Within …\miniconda\envs\Pose2Sim_Blender,
DLLs is linked to Blender 3.6's python_old DLLs folder
bin is linked to Blender 3.6's python_old bin folder

I don't know if this is important to note, but I loaded the addon into Blender 3.6 prior to following the steps detailed above.

The Error Thrown

Loading my .osim file works file
The following error throws upon loading .mot IK results

Python: Traceback (most recent call last):
File "C:\Users\my_name\AppData\Roaming\Blender Foundation\Blender\3.6\scripts\addons\Pose2Sim_Blender\Pose2Sim_Blender\motion.py", line 85, in apply_mot_to_model
import opensim as osim
File "C:\Program Files\Blender Foundation\Blender 3.6\3.6\python\lib\opensim_init_.py", line 19, in
from .simbody import *
File "C:\Program Files\Blender Foundation\Blender 3.6\3.6\python\lib\opensim\simbody.py", line 10, in
from . import _simbody
ImportError: DLL load failed while importing _simbody: The specified module could not be found.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\Users\my_name\AppData\Roaming\Blender Foundation\Blender\3.6\scripts\addons\Pose2Sim_Blender_init_.py", line 338, in execute
motion.apply_mot_to_model(mot_path, osim_path, direction='zup', target_framerate=self.target_framerate)
File "C:\Users\my_name\AppData\Roaming\Blender Foundation\Blender\3.6\scripts\addons\Pose2Sim_Blender\Pose2Sim_Blender\motion.py", line 88, in apply_mot_to_model
raise('OpenSim API required: Please proceed to Pose2Sim_Blender full install.')
TypeError: exceptions must derive from BaseException

[davidpagnon]

Okay, so the underlying issue is that OpenSim was not correctly installed. Thanks for letting me know, I'll have a look over the weekend !

[davidpagnon]

Hi again,

Let's start from the beginning:

• sys.version gives: 3.10.13, right?
• then, you did create a conda environment with the same python version?
• and the first stage that did not work was the OpenSim installation? What did conda install -c opensim-org opensim -y yield?
  It should have given something like opensim 4.5.1 py311np123 opensim-org
  Probably not the same since you installed a different version. Looking at that, you're likely to get opensim 4.5.2 py310np125 opensim-org, so you should install numpy==1.25

[davidpagnon]

The next problem is the installation of bpy, which is important.

I might have just found where the issue comes from. Basically, it stems from the fact that you are using an old Blender version: https://pypi.org/project/bpy/

Blender versions outside the current LTS window are removed from PyPI but are available at: https://download.blender.org/pypi/bpy/.

You can install it with pip install bpy==3.6.0 --extra-index-url https://download.blender.org/pypi/

I'm pretty sure it will work; if not, you can find the right version there. Check the Blender and Python version, in your case it is likely to be: bpy-3.6.0-cp310-cp310-win_amd64.whl, that you can install this way:
pip install https://download.blender.org/pypi/bpy/bpy-3.6.0-cp310-cp310-win_amd64.whl.

[ChristianJovenGarcia]

Hi David,
Thanks for the swift reply!
I'll update you with the results from these fixes when I get into my lab tomorrow.

[ChristianJovenGarcia]

Hi again,

Let's start from the beginning:

* `sys.version` gives: 3.10.13, right?

* then, you did create a conda environment with the same python version?

Yes, sys.version gave 3.10.13, and I created an environment in that version

* and the first stage that did not work was the OpenSim installation? What did `conda install -c opensim-org opensim -y` yield?
  It should have given something like `opensim                   4.5.1                py311np123    opensim-org`

Running conda isntall-c... gave
3 channel Terms of Service accepted
Retrieving notices: done
Channels:

• opensim-org
• defaults
  Platform: win-64
  Collecting package metadata (repodata.json): done
  Solving environment: done

#All requested packages already installed.

conda list | grep opensim does not run

  Probably not the same since you installed a different version. Looking at [that](https://anaconda.org/opensim-org/opensim/files/manage), you're likely to get `opensim   4.5.2   py310np125 opensim-org`, so you should install numpy==1.25

I've uninstalled numpy 1.23 and installed 1.25 as requested

You can install it with pip install bpy==3.6.0 --extra-index-url https://download.blender.org/pypi/

This ran properly

Now that I've done all this, Blender takes a while to start up and doesn't respond upon clicking buttons in the Pose2Sim plugin

Would you recommend that I switch my opensim and blender version? I'm not terribly attached to the version I have currently installed.
If reinstalling all my software means that the plugin works, I'm all for it.

[ChristianJovenGarcia]

I just tried to load an IK.mot file, and the issue persists. All that's changed is that the plugin now runs slower.

Python: Traceback (most recent call last):
File "C:\Users\ninja\AppData\Roaming\Blender Foundation\Blender\3.6\scripts\addons\Pose2Sim_Blender\Pose2Sim_Blender\motion.py", line 85, in apply_mot_to_model
import opensim as osim
File "C:\Program Files\Blender Foundation\Blender 3.6\3.6\python\lib\opensim_init_.py", line 19, in
from .simbody import *
File "C:\Program Files\Blender Foundation\Blender 3.6\3.6\python\lib\opensim\simbody.py", line 10, in
from . import _simbody
ImportError: DLL load failed while importing _simbody: The specified module could not be found.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\Users\ninja\AppData\Roaming\Blender Foundation\Blender\3.6\scripts\addons\Pose2Sim_Blender_init_.py", line 338, in execute
motion.apply_mot_to_model(mot_path, osim_path, direction='zup', target_framerate=self.target_framerate)
File "C:\Users\ninja\AppData\Roaming\Blender Foundation\Blender\3.6\scripts\addons\Pose2Sim_Blender\Pose2Sim_Blender\motion.py", line 88, in apply_mot_to_model
raise('OpenSim API required: Please proceed to Pose2Sim_Blender full install.')
TypeError: exceptions must derive from BaseException
bpy.ops.mesh.add_osim_motion(filepath="C:\Users\ninja\UFL Dropbox\Christian Joven Garcia\Garcia_Christian\OSIM Source Data\NEW GG26 Source Data\GG26_11_MJG_IK_Results.mot")

[davidpagnon]

It's a bit hard to debug at a distance, and I've never had buttons that would not respond, nor the plug-in running slower. In any case, it seems like OpenSim was not properly installed.

It used to run without any problem on Blender 3.6, but I now use Blender 4.2, and I edited a few things on the plugin since then. Itt is not completely impossible that this would break things on 3.6. So if as you say, you are not particularly attached to this Blender version, you might want to try 4.2?

Also, did you do that? It seems like your error is the one that was corrected by this:

OpenSim installation needs to be fixed. Run the following command and write down the location of your Pose2Sim_Blender environment (typically C:\Users<USERNAME>\miniconda3\envs\Pose2Sim_Blender):
conda env list
Open <LOCATION_OF_POSE2SIM_BLENDER_ENV>\Lib\opensim_init_.py with any text editor:
comment out the line # from .moco import *
line 4, insert the path to your OpenSim bin folder: os.add_dll_directory(r"C:/OpenSim 4.5/bin").
Replace 4.5 with the OpenSim version you installed