Visit all Houdini points while trying to only follow edges in the input geometry. For Houdini Python node.

visit_once_by_edges.py

import numpy as np
from python_tsp.heuristics import solve_tsp_simulated_annealing

node = hou.pwd()
geo = node.geometry()


def construct_distance_matrix(edges):
    # Find the maximum index to determine the size of the matrix
    max_index = max(max(edge) for edge in edges)
    
    # Initialize the distance matrix with a large value to discourage leaving existing edges
    distance_matrix = np.zeros((max_index + 1, max_index + 1))
    distance_matrix.fill(1e9)
    
    # Give the existing edges a low distance
    for pt1, pt2 in edges:
        # Bidirectional edges
        distance_matrix[pt1, pt2] = 1
        distance_matrix[pt2, pt1] = 1
        
    # "Trick" the solver to not have to go back to the origin
    distance_matrix[:, 0] = 0
    
    return distance_matrix
    

def find_path(edges):
    dist_matrix = construct_distance_matrix(edges)
    
    # Solve the TSP using dynamic programming
    path_indices, d = solve_tsp_simulated_annealing(
        dist_matrix,
        alpha=0.995,  # Better solutions, but slower
        max_processing_time=3,  # Seconds
    )

    return path_indices


def get_edges(geo):
    """Return 2-tuples describing edges in the input geometry"""
    edges = []
    
    for prim in geo.prims():
        edge = [pt.number() for pt in list(prim.points())]
        assert len(edge) == 2
        edges += [edge]
        
    return edges

edges = get_edges(geo)
path = find_path(edges)

# Erase the edges in the input and replace them with a polygon representing our solved path
geo.deletePrims(geo.prims(), True)
line = geo.createPolygon()
for pt_idx in path:
    line.addVertex(geo.point(pt_idx))