Blend My Bot

🐍 Requirements

• python3
• Blender 4
• iDynTree
• numpy
• bpy 4

[!NOTE] You should use a Python version that matches the one supported by the Blender version. For example, Blender 4 supports Python 3.10

[!NOTE] This library does not define the rig of the robot. For this, you can use a library such as blender-robotics-utils.

💾 Installation

Create a conda environment and install the dependencies:

Use the setup_conda_blender.sh script

You can use the setup_conda_blender.sh script to create a conda environment having the same python version as the one used by the Blender version you are using. This script will also create a symbolic link to the conda environment in the Blender python folder. Run the script from the root of the repository:

```bash bash setupcondablender.sh folder/to/blender/executable conda activate blenderenvversion pip install blend-my-bot

or pip install -e .

```

Manually

If you prefer to do it manually, you can follow these steps:

bash conda create -n blender_env python=3.10 conda activate blender_env

Create a backup of the python folder in the blender folder:

bash mv blender_folder/version/python blender_folder/version/python_backup

Run the command below in the blender python folder to create a symbolic link to the conda environment in the blender python folder:

bash sudo ln -s ~/mambaforge/envs/blender_env blender_folder/version/python

From the root of the repository install the package:

bash pip install blend-my-bot

If you want to run the scripts from Visual Studio Code, you need to install the vscode python extension and set the python interpreter to the already created conda environment.

You need an additional vscode extension: Blender Development which can be found here.

Once installed, you can run Blender by typing Ctrl+Shift+P and then Blender: Start. It will ask you to select the blender executable: select the one in the folder where you extracted the blender archive (or the installed version if you installed it). Once Blender is running, you can run the script by typing Ctrl+Shift+P and then Blender: Run Script.

You can add objects, lights, and cameras as well as play with render parameters directly in Blender. If you prefer, you can save the Blender project. Everything will be there, including the robot and its motion, so that it does not need to run your script again.

Note that you could also write a script directly in the Scripting tab of Blender and run it from there.

For possible issues when running the script see the Troubleshooting section.

🚀 Usage

```python

import the library

from blendmybot import ModelImporter

import the blender python API

import bpy

ModelImporter needs 3 arguments:

- the name you want to give to your robot

- the path to the urdf file

- the list of the joints you want to move in the animation

urdfpath = "path/to/urdf" robotname = "myrobot" jointslist = ["joint1", "joint2", "joint3", "etc"]

build the blender robot model

model = ModelImporter.buildmodel(robotname, urdfpath, jointslist)

you need to set the frame rate and the number of frames of the animation

length of the animation in seconds

bpy.context.scene.render.fpsbase = timelength

number of frames

bpy.context.scene.render.fps = numberofframes

when the animation starts

bpy.context.scene.frame_start = 0

when the animation ends

bpy.context.scene.frameend = numberof_frames

in Blender the effective frame rate is fps / fps_base

you can now move the base and the joints of the robot

for k in range(numberofframes): # jet the joint trajectory at time k s = jointtrajectory[k] # get the base pose described by a 4x4 homogeneous matrix at time k wHb = basetrajectory[k] # update the robot model model.update(wHb, s) # set the frame bpy.context.scene.frame_set(k) ```

Have a look at the examples folder for more examples.

In the examples/jumping folder you can find a script that generates a jumping animation of the iCub robot. Here the meshes are in a gray, stl format.

Having the meshes in an obj format, instead, will give a nicer and more colorful render! See the Readme of the following repository, for example!

Whole-Body Trajectory Optimization for Robot Multimodal Locomotion

🦿 Troubleshooting

FileNotFoundError when running the script

If you install a new package in the conda environment but it is not working as you expect when you run the script, try to activate it in a terminal before and then open Visual Studio Code from the terminal:

bash conda activate blender_env code .

For example, when using resolve_robotics_uri_py an error like the following one appears:

FileNotFoundError: resolve-robotics-uri-py: No file corresponding to uri "package://iCub/robots/iCubGazeboV2_7/model.urdf" found

This is due to the fact that environmental variables are not sourced. Activating the conda environment before opening vscode solves this issue!

Crush when running the script

If Blender crashes when running the script from Visual Studio Code, try to run the script from the Scripting tab of Blender.

🦸‍♂️ Contributing

blend-my-bot is an open-source project. Contributions are very welcome!

Open an issue with your feature request or if you spot a bug. Then, you can also proceed with a Pull-requests! 🚀

📝 Tips

Some tips to speed up your Cycle render: https://www.youtube.com/watch?v=FNiobzflmpA

Feel free to add your own tips here!