compas_rpc_example

compas_rpc_example: example scripts for calling cpython functions from Grasshopper/Rhino via compas_rpc and compas_xfunc.

Installation

Prerequisites

0. Operating System: Windows 10

1. Rhinoceros 3D 6.0

   We will use Rhino / Grasshopper as a frontend for inputting geometric and numeric paramters, and use various python packages as the computational backends. The tight integration between Grasshopper and python environments is made possible by the xfunc and rpc functions in COMPAS.

2. Git

   We need Git for fetching required packages from github.

3. Miniconda

   We will install all the required python packages using Miniconda (a light version of Anaconda). Miniconda uses environments to create isolated spaces for projects' depedencies.

Working in a conda environment

It is recommended to set up a conda environment to create a clean, isolated space for installing all the required python packages.

Have an existing conda environment with COMPAS (>=0.7.2)?

Activate your own conda environment and install the following depedencies:

pip install pycddlib

We use these external libraries to demonstrate our examples. Now jump to Package installaton & compas_rhino install to install compas_rpc_example to your environment and connnect it to GH/Rhino.

First time working with a conda environment?

Type in the following commands in your Anaconda terminal (search for Anaconda Prompt in the Windows search bar):

git clone https://github.com/yijiangh/compas_rpc_examples.git
cd compas_rpc_example/test_envs
conda env create -f rpc_example_ws.yml

Wait for the building process to finish, the command above will fetch and build all the required packages, which will take some time (1~2 mins).

Then, activate the newly created conda environment (with all the needed packages installed):

conda activate rpc_example_ws

Package installaton & compas_rhino install

Now, install compas_rpc_example to your conda environment by:

cd <path to where setup.py lives>
pip install -e .

(Go the Developing a package session to learn more about the difference between using with and without the -e flag here.)

Great - we are almost there! Now type python in your Anaconda Prompt, and test if the installation went well:

>>> import compas_rpc_example

If that doesn't fail, you're good to go! Exit the python interpreter (either typing exit() or pressing CTRL+Z followed by Enter).

Now let's make all the installed packages available inside Rhino. Still from the Anaconda Prompt, type the following:

In order to make compas_rpc_example accessible in Rhino/Grasshopper, we need the run the following commands in the Anaconda prompt first and then restart Rhino:

python -m compas_rhino.install
python -m compas_rhino.install -p compas_rpc_example

And you should be able to see outputs like:

Installing COMPAS packages to Rhino 6.0 IronPython lib:
IronPython location: C:\Users\<User Name>\AppData\Roaming\McNeel\Rhinoceros\6.0\Plug-ins\IronPython (814d908a-e25c-493d-97e9-ee3861957f49)\settings\lib

compas               OK
compas_rhino         OK
compas_ghpython      OK
compas_bootstrapper  OK
# second time when you type with -p compas_rpc_example
compas_rpc_example   OK

Completed.

Congrats! 🎉 You are all set!

Grasshopper examples can be found in gh_examples.

Developing a package

If you are developing the python package and want to test it in the GH/Rhino environment, you might want to avoid doing pip install . every time you make a change in the scripts.

In order to have this live editting - test workflow work, you have to do the following once:

1. Activate your conda environment (bad habit if you work in the base!)
2. cd to the folder of your package (where setup.py lives) and type in pip install -e .. This will install the package to your conda environment using the develop mode, which allows your change to be used immediately. Read more about -e flag in the editable install section in pip's doc.
3. Run python -m compas_rhino.install -p <package_name>

Restart Rhino, and you should be good to go!

Important:

The compas_rhino.install will try to find the package you specify in -p <package name> by looking at all installed packages in your python (conda) environment. So it is crucial to have a setup.py file in your python package, which makes your package pip-installable.

Also, the return data from compas_rpc call needs to be in a json serializable format (list, dictionary of primitive data types, etc), which means that you cannot return class or other composed data types. Read more in the compas_rpc_doc.

Troubleshooting

Sometimes things don't go as expected. Here are some of answers to the most common issues you might bump into:

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Q: When trying to install the framework in Rhino, it fails indicating the lib folder of IronPython does not exist.

Make sure you have opened Rhino 6 and Grasshopper at least once, so that it finishes setting up all its internal folder structure.

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Q: Windows error in the Grasshopper rpc call.

Make sure you enter the correct python path in the GH file. An easy way to obtain the path is to type where python in your conda prompt after you activate your conda environment.

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Q: Runtime error: Fault in the Grasshopper rpc call.

Try the following:

1. If you have V-Ray installed, uninstall V-Ray for Rhinoceros and restart your computer.

2. If the problem persists after retrying, first open your Task Manager and end all Python processes.

   Then in your activated conda environment, run:

   cd gh_examples
   python rpc_test.py
   

   It should print the following:

   Starting a new proxy server...
   New proxy server started.
   

   Then, retry opening the Grasshopper file.

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Q: In Xfunc call, error message "Cannot find DLL specified. (_Arpack ...)"

This happens because some previous calls blocked the scipy complied libraries. For a temporal fix, in your conda environment, uninstall pip install scipy and then pip install scipy=1.3.1 works.