Wandering Simulator
In 1986, Craig Reynolds developed an algorithm aiming to model the flocking behavior of birds, which remains a cult method used in flock simulations today. In my initial study, the bird-oids (boids) have no rules or limitations, just chilling randomly on the screen. I call this initial version Wandering Simulator. There are several reasons why this fundamental simulation is difficult in Grasshopper and Python, our parametric design interface. In Grasshopper (data flow modeling), pushing the back doors a bit is necessary to run an interactive and flowing simulation that needs loops. Firstly, I have to ensure that the GhPython component updates certain variables with a trigger inside a loop. This is something painful in a dataflow environment.
I have not yet been able to reach Reynolds’ algorithm or another intelligent flocking algorithm. However, this is a beginning and I think it’s promising. With only 25 lines of code, I managed to produce small creatures moving on the screen. In the future, I will add functions for detecting and reacting to each other and the obstacles. This can evolve into many interesting studies. This Grasshopper definition includes the first version of my flocking simulation study inside Rhinoceros CAD. It uses native Grasshopper components and one GhPython component. So, no add-ons are required to use it.
import Rhino
import rhinoscriptsyntax as rs
from random import *
class Boid:
def __init__(self, pos, dir):
self.obj = Rhino.Geometry.Point3d(pos)
self.dir = dir
def update(self):
self.dir.Rotate((random() - 0.5) / 10, rs.CreateVector(0, 0, 1))
rs.MoveObject(self.obj, self.dir / (10 - S))
if "ready" not in globals() or Reset:
ready = True
flock = []
output = []
vectors = []
for i in range(N):
boid = Boid(
rs.CreateVector((random() - 0.5) * 100, (random() - 0.5) * 100, 0),
rs.CreateVector((random() - 0.5), (random() - 0.5), 0),
)
flock.append(boid)
output.append(boid.obj)
vectors.append(boid.dir)
if ready and Run:
for boid in flock:
boid.update()
boids = output
vects = vectors
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