Edit Wrapping Surface Proprties API

[Bryce Killen]

Hi All,

I am trying to find replacements for functions that existed in the OpenSim 3.3 API but are now no longer in the OpenSim API guide ( to my knowledge).

I am specificlaly trying to automatically update wrapping surface (ellipsoidsand spheres) properties such as transaltion, radius etc.

In OpenSim 4.0 I have only been able to update the translation and rotations when querying the Wrapping surface as a WrapObject type, i.e,,

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Model.getBodySet().get(bod).getWrapObjectSet().get(wrapName).set_translation(newLoc)
Model.getBodySet().get(bod).getWrapObjectSet().get(wrapName).set_xyz_body_rotation(newRot)

I have not been able to update the size of a wrapping sphere for example using the PropertyHelper class (see below) which has been removed

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radProp = wrapObject.getPropertyByName('radius')
osim.PropertyHelper.setValueDouble( newRad , radProp , 0)

Is there any work around (no matter how ugly) I can use to edit these properties using the OpenSim API in python ?

Thank you in advance for any ideas

Bryce

[Ayman Habib]

Hi Bryce,

Not sure what version of OpenSim 4.0+ you're using but PropertyHelper is available in version 4.1 and later, and the reason it's back is that there's no workaround in cases where classes are not exposed in their native API where normally setters and getters give access to properties. This is problematic for scripting languages that do not have access to the templated C++ accessor methods.

Please type:

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import org.opensim.modeling as osim
methodsview(osim.PropertyHelper)

at the scripting shell of the OpenSim application you installed to confirm if PropertyHelper is available and what methods it exposes.

Hope this helps,
-Ayman

[Bryce Killen]

Hi Ayman,

Thank you for your reply. I am using just OpenSim 4.0 so not 4.1 or higher. I'm happy to hear that it has been added back to the API for these versions.
I will try and upgrade my current version to one of these more recent versions and translate the rest of my code.

Thanks for the help.

Bryce

[Bryce Killen]

Hi Ayman,

I just did a quick check, when I open the OpenSim 4.1 GUI , and type the code you suggested, it does indeed return the different methods of PropertyHelper I was looking for. While this is useful, I want to be able to access these functions OUTSIDE of the GUI , i.e., through the Python API.

When I have mapped the OpenSim API to my Python version and import the opensim module - I cannot access these same functions. When I try to run a small sample code, it states

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AttributeError: module 'opensim' has no attribute 'PropertyHelper'

Should this be the case or I have something wrong with my OpenSim + Python interaction ?

Thanks
Bryce

[Najoua Assila]

Hi Bryce,

I am not sure what changes were included in the 4.1 version, but I had a compiled version from the gihub repo somewhere between the 4.0 and 4.1 Opensim releases. I was able then to modify the properties of the wrapping objects via pyhton by safe downcasting the functions from the class corresponding to the wrapping type (WrapEllipsoid, WrapTorus, ...).

Hope it helps,

Najoua

[Bryce Killen]

HI Najoua,

Thank you for the reply. Are you able to share a small snippet of the code you used to edit, for example, the wraping surface radius , in the case of a sphere. I am assuming you were still reliant on the PropertyHelper function ?

Thanks in advance for any help you can provide.

Best
Bryce

[Bryce Killen]

[SOLVED] ** to some degree

I managed to get around this by calculating a scale factor and scaling the wrapping surface object (after safeDownCast) , then resetting the translations to what they were previously.

[Najoua Assila]

Hi Bryce,

Here is a code snippet for an ellipsoid wrapping object

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ellipsoid = osim_model.getBodySet().get(0).getWrapObjectSet().get(4)
wrap_ellip = osim.WrapEllipsoid.safeDownCast(ellipsoid)
initial_dim = wrap_ellip.getRadii() # value: [0.1,0.135,0.08]
wrap_ellip.set_dimensions(osim.Vec3(0.1, 0.235, 0.08))
wrap_ellip.getRadii().toString() #output: '~[0.1,0.235,0.08]'

Hope it helps,

Najoua