Fix Unwanted Bézier Curves and Improve Path Connections

[napakalas]

#172

• Fixes path rendering issues where Bézier smoothing caused wavy lines and small loops at node connections.
• Adds a --bezier-smoothing option (angle tolerance 0.1)
• Introduces connect_centre() for use by draw_line() to improve path continuity and visual clarity.

[napakalas]

Before and after update:

Rendering on vagus nerve (the busiest nerve):

[dbrnz]

generation_options.add_argument('--bezier-smoothing', dest='bezierSmoothing', action='store_true',
     help="Render bezier paths with angle tolerance set to 0.1")

It's not too clear what the --bezier-smoothing option is about. Where does the 0.1 come from? Looking at the code, the default is to have a tolerance of 0 -- this should be mentioned in the help text.

Which of the above pictures have the option turned on?

What value is intended to be the default when generating maps?

[napakalas]

Thanks for the questions! Not sure why this ended up in my promotional folder 🙂

The --bezier-smoothing option exists to reproduce the previous rendering behavior used in earlier map generations. When enabled, it applies a non-zero angle tolerance to Bezier path rendering.

The value 0.1 comes from the draw_line implementation, where tolerance defaults to 0.1 (see the definition here):

flatmap-maker/mapmaker/routing/routedpath.py

Line 430 in ac474e5

def draw_line(node_0, node_1, tolerance=0.1, separation=2000):

In the current code path:

• Without --bezier-smoothing, the tolerance is explicitly set to 0 (no smoothing).
• With --bezier-smoothing, the tolerance is set to 0.1, matching the previous behavior.
  In the figures referenced above, the top-left image was generated with --bezier-smoothing enabled.

The intended default for new map generation is tolerance = 0. The --bezier-smoothing flag is therefore optional and only needed to reproduce legacy outputs.

[napakalas]

Hi @dbrnz
I have updated the help message for --bezier-smoothing; it now mentions its purpose: to enable Bezier path smoothing to match legacy map rendering.

[dbrnz]

The help message now looks fine, thanks.

These details, and what they mean, is good material to include in a "Map Maker User Guide". Does such a document exist? 🤞 If not, is there a place to start accumulating useful bits and pieces with the aim of creating a Guide?