gistfile1.txt

# Lineweld.py
from matplotlib import pyplot
from random import random
import math

# Stuff
def Dot(x1, y1, x2, y2):
    return x1 * x2 + y1 * y2

def Mag(x1, y1):
    return math.sqrt(x1 ** 2.0 + y1 ** 2.0)

def GregsResaw(listoftuple):
    return [p[0] for p in listoftuple], [p[1] for p in listoftuple]

# Example points
density = 20
ex = [i / density for i in range(density * 200)]
ey = [i * math.sin(i / 10) for i in ex]

# Squiggle example
points = list(zip(ex, ey))

# Jeff's Crazy Testpoints (Square spiral with acceleration)
polypoints = []

vertex = (0, 0)
for i in range(20):
    x = vertex[0]
    y = vertex[1]
    r = 100.0 * i / 4
    
    if i % 4 == 0:
        x += r
    if i % 4 == 1:
        y += r
    if i % 4 == 2:
        x -= r
    if i % 4 == 3:
        y -= r
    
    dist = round(Mag(vertex[0] - x, vertex[1] - y) / 10.0)
    lastvertex = vertex
    vertex = (x, y)
    
    for j in range(dist):
        a = j / dist
        a = 3 * a ** 2 - 2 * a ** 3
        px = lastvertex[0] * (1.0 - a) + vertex[0] * a
        py = lastvertex[1] * (1.0 - a) + vertex[1] * a
        
        for k in range(9):
            polypoints.append((px, py))


# Completely random points
awfulpoints = [(random() * 400 - 200, random() * 400 - 200) for i in range(100)]

fig = pyplot.figure()
ax = fig.add_subplot(111)
ax.scatter(ex, ey, s = 0.1)
ax.set_aspect("equal")

# Angle based line-welding algorithm
ax.scatter(*GregsResaw(polypoints), color = "purple", s = 0.2)
ax.scatter(*GregsResaw(awfulpoints), color = "green", s = 0.2)

# Point angles are measured around, reset for each new segment
pivot = (ex[1], ey[1])

# Previous point on last segment
last = (ex[0], ey[0])
lastsample = last

# Min Distance for filtering out dwell
mindist = 0.05

# Line ending angle change threshold degrees
anglethresh = 5

# Force line segment to end after this length
distthresh = 50

# Result
linepoints = []
linepoints.append(last)

for (x, y) in polypoints[2:]:
    lastdir = (pivot[0] - last[0], pivot[1] - last[1])
    mag = Mag(*lastdir)
    
    if mag < mindist:
        # Unreliable direction, take next point instead
        last = pivot
        pivot = (x, y)
        lastsample = (x, y)
        continue
        
    # Normalize direction
    lastdir = (lastdir[0] / mag, lastdir[1] / mag)
    
    nextdir = (x - pivot[0], y - pivot[1])
    mag = Mag(*nextdir)
    
    if mag < mindist:
        # Unreliable direction, take next point instead
        lastsample = (x, y)
        continue
    
    # Normalize direction
    nextdir = (nextdir[0] / mag, nextdir[1] / mag)
    
    # Dot
    dot = Dot(*nextdir, *lastdir)
    
    # Angle
    anglechange = math.acos(dot) * 180.0 / math.pi
    
    print(anglechange)
    
    if anglechange > anglethresh or mag > distthresh:
        # Update pivot to last point before this one
        last = lastsample
        pivot = (x, y)
        linepoints.append(lastsample)
        print("New segment")
        
    # Last sample
    lastsample = (x, y)

# Finish final segment?
linepoints.append((x, y))

# How good is this?
print(f"Number of segments: {len(linepoints) - 1}, Number of original points: {len(polypoints)}")

pyplot.plot(*GregsResaw(linepoints), color = "red", linewidth = 0.2)
pyplot.scatter(*GregsResaw(linepoints), color = "red", s = 0.5)
pyplot.show()