L-System for Primary Veins

Starting with the relatively simple Orthoptera rear wing. Pasted image 20240821153801 http://www.metafysica.nl/wings/wings_5.html

The rear wing has a little bit of branching at the leading edge but mostly lines spreading outward. It also has thicker lines alternating with thinner ones, so thin they’re the same thickness as the cross veins.

I could structure the model so there’s a list of all Segments or I could maintain the structure of the tree by storing a list of child Segments on each Segment. The latter would allow me to increase the length of the segment without having to recalculate positions of its descendants, which is something I think I might want to do.

Oops. I used pygame.key.get_pressed() to take a screenshot but got two screenshots for the price of one. Need to handle the keydown event, not check whether the key is pressed. I’m lucky I got only two screenshots. (-;

lsys_000 1

Here’s the first strand of output.

I guess a lot of this is going to be tuning the parameters to get the shape I want. Adding the ability to save to a file will be very helpful.

anim 1

Added a reference image so I can see just how bad my output is.

lsys_000 2

As per a few lines ago, I added loading and saving parameters from/to a JSON file. Right now I set it up to re-animate on load but what I really want is for everything to be calculated on the fly from the parameters object.

Also, I tried using Python’s dataclass to represent the parameters since it lets me define types and defaults in a very concise way. Unfortunately, serialization is a problem but I found I can use a TypedDict instead. It takes double the number of lines if I want to define defaults but I might not need those if I automatically load from the parameter file on initialization anyway.

from typing import TypedDict

class Parameters(TypedDict):
  num_root_segments: int
  root_segment_len: float
  root_segment_dir_x: float
  root_segment_dir_y: float
parameters = Parameters(
  num_root_segments=12,
  root_segment_len=100,
  root_segment_dir_x=1,
  root_segment_dir_y=-0.1,
)

vs.

@dataclass
class Parameters:
  num_root_segments: int = 12
  root_segment_len:float = 100
  root_segment_dir_x:float = 1
  root_segment_dir_y:float = -0.1

Can I serialize a pygame.Vector2d?

Following a blog post that uses jetblack-serialization library with TypedDict. Blog post. Library.

pip install jetblack-serialization
error: externally-managed-environment

× This environment is externally managed
╰─> To install Python packages system-wide, try apt install
    python3-xyz, where xyz is the package you are trying to
    install.
    
    If you wish to install a non-Debian-packaged Python package,
    create a virtual environment using python3 -m venv path/to/venv.
    Then use path/to/venv/bin/python and path/to/venv/bin/pip. Make
    sure you have python3-full installed.
    
    If you wish to install a non-Debian packaged Python application,
    it may be easiest to use pipx install xyz, which will manage a
    virtual environment for you. Make sure you have pipx installed.
    
    See /usr/share/doc/python3.12/README.venv for more information.

note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
hint: See PEP 668 for the detailed specification.

I tried pipx but apparently that’s not for libraries, only for applications. So instead I did:

python3 -m venv ./.venv
./.venv/bin/pip install jetblack-serialization

I wonder how many of the libraries I installed globally using plz apt install python3-pygame, for example, should have been done this way.

…

Okay, there were a couple. The globally-installed packages don’t get picked up from the virtual environment which in hindsight makes a lot of sense. I installed a few packages. There’s gotta be a way to use the virtual environment without having to type ./.venv/bin/python3 every time, though.

source .venv/bin/activate

Also, looks like people put it in ./venv and not /.venv so switching it up.

$ source venv/bin/activate
$ ...
$ deactivate

That’s not too bad.

Prompt kinda ugly tho. Pasted image 20240822161247

Also, looks like it remembered the name of the virtual environment even though I renamed the directory. Recreating the virtual environment…

Reflection
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Worked at a coffee shop and at a library today instead of at home. What a difference it makes for concentration.

Also, I just read up again on L-systems and this is definitely not that. Lindenmayer Systems are a grammar where words can be replaced recursively and is good for modeling fractals.

I’ll rename stuff tomorrow. 😅

Reflection #

Reflection
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