Add ZnDraw visualizer

[phohenberger]

Description of changes:

• add support for the ZnDraw visualizer

[phohenberger]

Use the ZnDraw-Visualizer to live visualize ESPResSo simulations in Jupyter Notebooks.

First you need to install pip install zndraw==0.4.5

Then you can import the relevant classes from the /src/python/espressomd/zn.py file.

Example usage:

from espressomd.zn import Visualizer, LBField

color = {0: "red", 1: "#ff00ff"} # particle type mapping, there are some standard colors but you can also add hex
radii = {0: 0.2, 1: 0.5} # particle type mapping

LBField(system, step_x = 2, step_y=2,  step_z=2, scale=3.0)

vis = Visualizer(system=system, colors=color, radii=radii, vector_field = LBField, bonds=False, folded=False)

# Some integration loop
for i in range(1000):
    system.integrator.run(10)
    vis.update()

Of course stuff like bonds, vector_field are optional and can be left away.

This currently only works in jupyter as the server closes down if the script is finished running to ensure no runaway processes.

[phohenberger]

Some screenshots