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#!/usr/bin/env python3
#
# Simple tool to validate an STL.
# It checks for:
# o Any occurrence of "nan" or "inf" vertices or normals
# o Any non-manifold (dangling) edges.
#
# Usage: validatestl.py <file.stl>
#
# Based on code by Jan Squirrel Koniarik from:
# https://github.com/SquirrelCZE/pycad/
#
# Author: Marius Kintel <marius@kintel.net>
# Licence: GPL V2
#
import sys
import io
import hashlib
import os
import subprocess
import struct
import math
from collections import Counter
def read_stl(filename):
triangles = list()
with open(filename, "rb") as fd:
start = fd.read(5)
if start == b'solid':
stl_type = 'ascii'
else:
stl_type = 'binary'
print(start)
if stl_type == 'ascii':
with open(filename, "r") as fd:
triangle = {
'normal': [0, 0, 0],
'points': list()
}
for line in fd:
line = line.strip()
if line.startswith('solid'):
continue
elif line.startswith('endsolid'):
continue
elif line.startswith('outer'):
continue
elif line.startswith('facet'):
parts = line.split(' ')
for i in range(2, 5):
triangle['normal'][i-2] = float(parts[i])
continue
elif line.startswith('vertex'):
parts = line.split(' ')
point = [0, 0, 0]
for i in range(1, 4):
point[i-1] = float(parts[i])
triangle['points'].append(point)
continue
elif line.startswith('endloop'):
continue
elif line.startswith('endfacet'):
triangles.append(triangle)
triangle = {
"normal": [0, 0, 0],
"points": list()
}
continue
else: # binary
with open(filename, "rb") as fd:
data = fd.read()
count = int.from_bytes(data[80:84], byteorder='little')
for offset in range(84, 84+count*(12*4+2), 12*4+2):
try:
triangle = {
'points': list()
}
triangle['normal'] = list(
struct.unpack('fff', data[offset:offset+12]))
for p in range(1,4):
pnt = struct.unpack('fff',
data[offset+p*12:offset+p*12+12])
triangle['points'].append(pnt)
triangles.append(triangle)
except struct.error:
print("Invalid binary stl format")
return None
return Mesh(
triangles=triangles
)
class Mesh():
def __init__(self, triangles):
points = list()
p_triangles = list()
p_normals = list()
for triangle in triangles:
p_normals.append(triangle['normal'])
p_triangle = list()
for point in triangle['points']:
if point not in points:
points.append(point)
p_triangle.append(
points.index(point)
)
p_triangles.append(p_triangle)
self.points = points
self.triangles = p_triangles
self.normals = p_normals
def validateSTL(filename):
mesh = read_stl(filename);
if mesh is None:
print("Loading error")
return False
if len(mesh.triangles) < 1:
print("No triangles found")
return False
if len([n[i] for i in range(0,3) for n in mesh.points if math.isinf(n[i]) or math.isnan(n[i])]):
print("NaN of Inf vertices found")
return False
if len([n[i] for i in range(0,3) for n in mesh.normals if math.isinf(n[i]) or math.isnan(n[i])]):
print("NaN of Inf normals found")
return False
edges = Counter((t[i], t[(i+1)%3]) for i in range(0,3) for t in mesh.triangles)
reverse_edges = Counter((t[(i+1)%3], t[i]) for i in range(0,3) for t in mesh.triangles)
edges.subtract(reverse_edges)
edges += Counter() # remove zero and negative counts
if len(edges) > 0:
print("Non-manifold STL: " + str(edges))
return False
return True
if __name__ == "__main__":
retval = validateSTL(sys.argv[1])
if retval:
sys.exit(0)
else:
sys.exit(1)
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