<div align="center">
<h1> PyElastica to Rhino </h1>
<h2> The package is in alpha-phase dev-stage. </h2>
<img src="https://img.shields.io/badge/Python-3776AB?style=flat&logo=Python&logoColor=white"/>
<img src="https://img.shields.io/badge/Rhino-801010?style=flat&logo=rhinoceros&logoColor=white"/>
</div>
PyElastica extension and Rhino plugin for Cosserat Rod (+ Rigid Body) visualization.
## Requirements
The Grasshopper plugin does not have any additional requirement, but we recommend using [`anemone`](https://www.food4rhino.com/en/app/anemone) together. This plugin provide loop function that can be used to generate animated video.
## Grasshopper Plugin
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- PyElastica exports `npz` file which can directly be imported using `NpzImport` module.
- For now, `NpzImport(Legacy)` is used. More generalized version is still under development.
- Provides `CosseratRod` and `CosseratRodPeriodic` that constructs rods directly.
- Shape of position: `(num_rod, timesteps, 3, num_nodes)`
- Shape of radius: `(num_rod, timesteps, 3, num_elements)`
- If `periodic` is set to true, the trapazoidal averaging step is skipped for the radius.
- All modules include `C (switch)` input. The purpose is to serialize the execution.
- All modules include `D (debug)` output which returns the debugging text to inform progression or runtime error.
### Legacy Import Mode
The grasshopper module import `npz` file. In the legacy import module, we expect the `npz` file to have the key `<group>_position_history` and `<group>_radius_history` for each group.
- `<group>_position_history` should have the shape `<number of rod, timesteps, 3 (dimension), number of nodes>`.
- `<group>_radius_history` should have the shape `<number of rod, timesteps, number of elements>`.
>The `number of nodes` is expected to be one more than the `number of elements`. If the periodic is set to `True`, the `number of nodes` can be equal to the `number of elements`.
> For sphere, the `number of elements` and the `number of nodes` are both `1`. In such case, a `sphere module` must be used in grasshopper.
## PyElastica Extension
We provide a data collector extension to PyElastica to easily collect the batch of data.
```sh
pip install elastica-rhino
```
### Example Usage
```py
import elastica
import elastica_rhino as er
... <simulation setup>
data_collector = er.RhinoExportCollector(
save_path="data",
step_skip=int((1/fps)/dt) # Collect data every 'step_skip' iteration
)
for arm in arm_list:
simulation.collect_diagnostics(arm).using(
er.ExportGeometry,
data_collector,
group="arm"
)
for muscle in muscle_list:
simulation.collect_diagnostics(muscle).using(
er.ExportGeometry,
data_collector,
group="muscle"
)
... <simulation setup>
simulation.finalize()
... <simulation run>
data_collector.save()
```
In Rhino, objects in the same group will be collected by layers. We recommend setting the parameter `group` for the same material or color of the rods.
### Included Callbacks
- ExportGeometry
- ExportStrain (work in progress)
- ExportInternalStress (work in progress)
- ExportExternalStress (work in progress)
