Sweep Angle in Python API

[jeme95]

Is there a way to get the sweep- or dihedral angle between two sections using python interface?

[AntonReiswich]

I tried to get these angles using a simple example, but ran into an error. Let me get back to you in the beginning of next month with a suggestion. I hope it is ok for you.

[jeme95]

My approach was to calculate the angles using the x, y and z coordinates of the sections, but was wondering if there is a built-in method in TiGL that does this.
The angles are actually in the CPACS file in the positioning element, but I haven't found a way to access them using Python-API.

[AntonReiswich]

Yes, I was also trying to take a CPACS example and extract the angles directly from there, as you mentioned. Unfortunately this hasn't worked yet. I will try to figure this out and get back to you right after. I have to discuss this with a coleague of mine, who I will be able to speak to in the beginning of January. I hope this is not too late for you!

[jeme95]

waiting for your answer, thanks for the effort.

[joergbrech]

If the wing has positionings defined, you can get them using TiXI:

# Create a handle to the tixi document
tixi_handle = tixi3wrapper.Tixi3()
tixi_handle.open("simpletest.cpacs.xml")

# get dihedral using TiXI
xpath = '/cpacs/vehicles/aircraft/model/wings/wing[1]/positionings/positioning[1]/dihedralAngle'
print(tixi_handle.getDoubleElement(xpath))

Without a positionings definition, you would have to calculate the angles from cartesian coordinates as you mentioned in your question.

In theory, you should be able to get the angles using TiGLs internal Python API instead of TiXI, but as of now, the class CCPACSPositioning is not exposed via swig: #936

[jeme95]

Thanks for opening a ticket for this, I actually wanted to work mainly with TiGL because I am unsure if it makes sense to use TiGL and TiXI (and thus two handlers on the same file) at the same time

[joergbrech]

Working with TiGL and TiXI at the same time is absolutely no problem. It is actually the usual way to do it: When you use the Python API of TiGL, you also need a TiXI handle to the CPACS file.

In fact, you could say that - eventhough in many cases it can be done - using the TiGL Python API for simple xpath queries is a bit overcomplicated. The TiGL Python API is intended for more high level functions, such as geometry modifications etcetera.