Circle as custom style for a sensor

[BastelBaus]

Anyone has a hint on how to achieve this? I managed Solenoids and other 3D models but not a path. Maybe due to the SensorStyle type style attribute?
Thanks
BastelBaus

[OrtnerMichael]

hi @BastelBaus

sorry for the late reply ... busy times here.

Question: What do you mean by Circle as custom style? Do you want to have a circle in the x-y plane ? or do you want to have a circle that is always visible as a circle from the viewpoint - i.e. like a plot marker ?

br michael

[BastelBaus]

Thanks Michael for your efforts I am also so happy that such free communities exist!

This works

class CoilSensor(magpy.Sensor):
    def __init__(self, r=None, position=(0, 0, 0),orientation=None,pixel=None,
                handedness="right",style=None,**kwargs,):

        self._update()        
        super().__init__(position,orientation,pixel,handedness,style,**kwargs)
        trace = magpy.graphics.model3d.make_CylinderSegment(
            dimension=(19/20*r, 21/20*r,r/10, 0, 360),
            vert=150)
        self.style.model3d.add_trace(trace) # Hand trace over as callable

But this not

class CoilSensor(magpy.Sensor):
    def __init__(self, r=None, position=(0, 0, 0),orientation=None,pixel=None,
                handedness="right",style=None,**kwargs,):

        self._update()        
        super().__init__(position,orientation,pixel,handedness,style,**kwargs)
        trace = magpy._src.display.traces_core.make_Circle(self)
        self.style.model3d.add_trace(trace) # Hand trace over as callable

it gives me the following error

  File " xxxx Python39\site-packages\magpylib\_src\display\traces_core.py", line 114, in make_Circle
    kind_style = getattr(style, kind)

AttributeError: 'SensorStyle' object has no attribute 'arrow'

Which I understood from debugging a bit, since the properties of SensorStyle and Style does somehow not match and the decoding is somehow "hard coded" (as far as i think I understood ...)

BR,
BastelBaus

[Alexboiboi]

Hi @BastelBaus,

Thanks for your interest in Magpylib ;)

As you pointed out, there are only 3D models available in the public API as helper functions. In your code you are using the private API which is not meant to be used that way. There is in fact a rather complex machinery to make this work internally.
There is however a simple way to achieve what you want by defining a custom trace as a dictionary (see also the example in the docs here).

import magpylib as magpy
import numpy as np


class CoilSensor(magpy.Sensor):
    def __init__(
        self,
        r,
        mode="2D",
        position=(0, 0, 0),
        orientation=None,
        pixel=None,
        handedness="right",
        style=None,
        **kwargs,
    ):
        # using keyword arguments since positionals have changed
        # from Magpylib v4 to v5. This makes it compatible for both versions.
        super().__init__(
            position=position,
            orientation=orientation,
            pixel=pixel,
            handedness=handedness,
            style=style,
            **kwargs,
        )
        vert = 100
        if mode == "3D":
            rth = r / 10  # relative thickness
            trace = magpy.graphics.model3d.make_CylinderSegment(
                dimension=(r - rth / 2, r + rth / 2, rth, 0, 360),
                vert=vert,
            )
        elif mode == "2D":
            ts = np.linspace(0, 2 * np.pi, vert)
            trace = {
                "backend": "generic",
                "constructor": "Scatter3d",
                "kwargs": {
                    "x": r * np.cos(ts),
                    "y": r * np.sin(ts),
                    "z": np.zeros(vert),
                    "mode": "lines",
                },
            }
        else:
            raise ValueError("Invalid mode, must be either 2D or 3D")
        self.style.model3d.add_trace(trace)  # trace is not a callable

# Example of usage
cs2D = CoilSensor(r=1, mode="2D", style_label="CoilSensor2D")
cs3D = CoilSensor(r=2, mode="3D", style_label="CoilSensor3D")
coll = magpy.Collection(cs2D, cs3D)
coll.rotate_from_angax([0, 20, 40, 60], "x")
magpy.show(*coll, style_path_frames=1)

Note that the code example above does not make use of "trace as callable", and therefore does not allow to simply edit the radius after object instantiation. If you need this feature have a look here