How to draw two or multiple lines from one location to another without overlapping the lines?

Question

I want to draw two or many curved lines from fixed start point to another fixed end point on map. So, I started with geodesic but it draws overlapping lines. Then I tried to draw trajectory but not very useful as points could be any where in the world. How can I achieve this? I am using python and javascript. The below image is something I am aiming for (map is not added but imagine as if it is there :)). Also, is there any way to add directional arrow? Please help.

Answer 1

This could be done with Bézier curves. Here is the python library to create Bézier curves.

import bezier
import numpy
import matplotlib

x1 = [0.0, 1.0, 2.0]
y1 = [0.0, 1.0, 0.0]

x2 = [0.0, 1.0, 2.0]
y2 = [0.1, 2.0, 0.1]

nodes1 = numpy.asfortranarray([x1, y1])
nodes2 = numpy.asfortranarray([x2, y2])

curve1 = bezier.Curve(nodes1, degree=2)
ax = curve1.plot(100, color='r', alpha=None, ax=None)

curve2 = bezier.Curve(nodes2, degree=2)
curve2.plot(100, color='g', alpha=None, ax=ax)

number_of_point = 15
s_vals = numpy.linspace(0.0, 1.0, number_of_point)
[curve2_values_x, curve2_values_y] = curve2.evaluate_multi(s_vals)

print('curve2_values_x=', curve2_values_x, end='\n'*2)
print('curve2_values_y=', curve2_values_y)

matplotlib.pyplot.plot(x1, y1, 'ro')
matplotlib.pyplot.plot(x2, y2, 'go')
matplotlib.pyplot.plot(curve2_values_x, curve2_values_y, 'b+')
matplotlib.pyplot.show()