109 lines
3.9 KiB
Python
109 lines
3.9 KiB
Python
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#!/usr/bin/env python
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#
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# NopSCADlib Copyright Chris Palmer 2018
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# nop.head@gmail.com
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# hydraraptor.blogspot.com
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#
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# This file is part of NopSCADlib.
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#
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# NopSCADlib is free software: you can redistribute it and/or modify it under the terms of the
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# GNU General Public License as published by the Free Software Foundation, either version 3 of
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# the License, or (at your option) any later version.
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#
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# NopSCADlib is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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# without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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# See the GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along with NopSCADlib.
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# If not, see <https://www.gnu.org/licenses/>.
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#
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#
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# OpenSCAD produces randomly ordered STL files so source control like GIT can't tell if they have changed or not.
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# This scrip orders each triangle to start with the lowest vertex first (comparing x, then y, then z)
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# It then sorts the triangles to start with the one with the lowest vertices first (comparing first vertex, second, then third)
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# This has no effect on the model but makes the STL consistent. I.e. it makes a canonical form.
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#
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from __future__ import print_function
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import sys
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def cmz(x):
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''' Convert "-0" to "0". '''
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return '0' if x == '-0' else x
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class Vertex:
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def __init__(self, x, y, z):
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self.x, self.y, self.z = x, y, z
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self.key = (float(x), float(y), float(z))
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class Normal:
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def __init__(self, dx, dy, dz):
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self.dx, self.dy, self.dz = dx, dy, dz
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class Facet:
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def __init__(self, normal, v1, v2, v3):
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self.normal = normal
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if v1.key < v2.key:
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if v1.key < v3.key:
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self.vertices = (v1, v2, v3) #v1 is the smallest
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else:
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self.vertices = (v3, v1, v2) #v3 is the smallest
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else:
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if v2.key < v3.key:
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self.vertices = (v2, v3, v1) #v2 is the smallest
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else:
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self.vertices = (v3, v1, v2) #v3 is the smallest
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def key(self):
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return (self.vertices[0].x, self.vertices[0].y, self.vertices[0].z,
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self.vertices[1].x, self.vertices[1].y, self.vertices[1].z,
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self.vertices[2].x, self.vertices[2].y, self.vertices[2].z)
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class STL:
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def __init__(self, fname):
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self.facets = []
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with open(fname) as f:
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words = [cmz(s.strip()) for s in f.read().split()]
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if words[0] == 'solid' and words[1] == 'OpenSCAD_Model':
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i = 2
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while words[i] == 'facet':
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norm = Normal(words[i + 2], words[i + 3], words[i + 4])
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v1 = Vertex(words[i + 8], words[i + 9], words[i + 10])
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v2 = Vertex(words[i + 12], words[i + 13], words[i + 14])
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v3 = Vertex(words[i + 16], words[i + 17], words[i + 18])
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i += 21
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self.facets.append(Facet(norm, v1, v2, v3))
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self.facets.sort(key = Facet.key)
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else:
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print("Not an OpenSCAD ascii STL file")
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sys.exit(1)
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def write(self, fname):
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with open(fname,"wt") as f:
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print('solid OpenSCAD_Model', file=f)
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for facet in self.facets:
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print(' facet normal %s %s %s' % (facet.normal.dx, facet.normal.dy, facet.normal.dz), file=f)
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print(' outer loop', file=f)
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for vertex in facet.vertices:
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print(' vertex %s %s %s' % (vertex.x, vertex.y, vertex.z), file=f)
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print(' endloop', file=f)
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print(' endfacet', file=f)
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print('endsolid OpenSCAD_Model', file=f)
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def canonicalise(fname):
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stl = STL(fname)
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stl.write(fname)
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if __name__ == '__main__':
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if len(sys.argv) == 2:
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canonicalise(sys.argv[1])
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else:
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print("usage: c14n_stl file")
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sys.exit(1)
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