ghPython stop update function

Scripting
, ,
1

Hi all!

I have a surface and multiple points that goes down by a move function.
I want to stop them whenever the subtraction of the last two points reaches a value of 0.005.
How to stop the move and update each of the points in the list individually?

surface
surface1615×341 62.6 KB

Code here 
import Rhino.Geometry as rg
import ghpythonlib.treehelpers as th
import random

# CREATING A CLASS CALLED PARTICLE
class Particle:

    def __init__(self, point, surface):

        self.pt = point
        self.srf = surface

        self.vec = rg.Vector3d.Unset
        self.plane = rg.Plane.Unset

        # A LIST CALLED HISTORY (starts with point self.pt)
        self.history = [self.pt]

    # A METHOD CALLED UPDATE (updates the position of the particle)
    def update(self):
        
        self.move()
        self.history.append(self.pt)

    # A NEW METHOD CALLED MOVE
    def move(self):

        #unpacking the returning values from the function
        success, U, V = self.srf.ClosestPoint(self.pt)

        if success:
            self.pt = self.srf.PointAt(U, V)
            self.plane = self.srf.FrameAt(U, V)[1]

            worldZ = rg.Vector3d.ZAxis
            localZ = self.plane.ZAxis

            vec1 = rg.Vector3d.CrossProduct( worldZ, localZ)
            vec2 = rg.Vector3d.CrossProduct( vec1, localZ)

            self.vec = vec2
            self.vec.Unitize()

            self.vec *= step

     self.pt += self.vec

allParticles = []
for pt in pts:

    p = Particle(pt, srf)
    allParticles.append(p)

allHistory = []
for i in range(count):
    for p in allParticles:
        p.update()
        allHistory.append(p.history)

a = th.list_to_tree(allHistory)

lastpointsZ = []
for p in allParticles:
    lastpointsZ.append(p.history[-1].Z)

secondlastpointsZ = []
for p in allParticles:
    secondlastpointsZ.append(p.history[-2].Z)

# SUBTRACT THE SECOND TO LAST POINT FROM THE LAST POINT
resultingZ = []
for i in range(len(lastpointsZ)):
    resultingZ.append(abs(secondlastpointsZ[i]) - abs(lastpointsZ[i]))
    
print lastpointsZ
print secondlastpointsZ

print resultingZ

Thanks!

2

extend your class a little

class Particle:
    @property
    def prev(self):
        if len(self.history) == 1:
            return None
        return self.history[-2]

then you can replace your main body with:

for p in allParticles:
    while p.prev is none or abs(p.pt.Z - p.prev.Z) > 0.005:
        p.update()
        allHistory.append(p.history)

lastpointsZ = [p.pt.Z for p in allParticles]
secondlastpointsZ = [p.prev.Z for p in allParticles]
resultingZ = [abs(prev) - abs(last) for prev, last in zip(secondlastpointsZ, lastpointsZ)]
3

@James_Parrott Thanks for your reply. But the while loop is freezing GH. Maybe is causing an infinite loop?

4

Ah sorry. While loops are always susceptible to that, even when they do converge.

Add a simple counter variable and an iterations limit condition, or make it a for loop instead and use the negation of the while loop condition to break it.