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sfc/slicer.py: FreeCAD-based slicer, first commit

This commit is contained in:
Werner Almesberger 2015-01-18 21:03:49 -03:00
parent ae8d393859
commit 79a821052f

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sfc/slicer.py Executable file
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#!/usr/bin/python
#
# slicer.py - FreeCAD-based STL to Gnuplot slicer
#
# Written 2015 by Werner Almesberger
# Copyright 2015 by Werner Almesberger
#
# This program//library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
import sys
sys.path.append("/usr/lib/freecad/lib")
import FreeCAD, Part, Mesh
import os, getopt
from FreeCAD import Base
from math import hypot
epsilon = 0.0001 # acceptable math rounding error and slicing offset
mech_eps = 0.01 # acceptable mechanical deviation
margin = None # draw a workpiece at the specified xy distance around
# the model (default: none)
def dist(a, b):
pa = a.Point
pb = b.Point
return hypot(pa[0] - pb[0], pa[1] - pb[1])
def print_vec(v):
p = v.Point
print p[0], " ", p[1], " ", p[2] - epsilon
def usage():
print >>sys.stderr, "usage:", sys.argv[0], "file.stl"
sys.exit(1)
#
# FreeCAD prints progress information to stdout instead of stderr.
# We don't want that ...
#
stdout = os.dup(1)
os.dup2(2, 1)
sys.stdout = os.fdopen(stdout, "w")
opts, args = getopt.getopt(sys.argv[1:], "b:")
for opt, arg in opts:
if opt == "-b":
margin = float(arg)
else:
assert False
if len(args) != 1:
usage()
#
# Read the STL mesh
#
mesh = Mesh.Mesh(args[0])
#
# The 2.5D model consists of "plateaus" (facets parallel to the xy plane) and
# "walls" (facets parallel to the z axis). Anything else is an error and will
# produce incorrect results.
#
# We use plateau facets only for their z position, as indication where to mill
# a plateau. Wall facets are kept for later use.
#
vert = Mesh.Mesh()
z_raw = {}
max_nz = 0
inclined = 0
for facet in mesh.Facets:
if abs(facet.Normal.z) >= 1 - epsilon:
z_raw[facet.Points[0][2]] = 1
else:
nz = abs(facet.Normal.z)
if nz > epsilon:
inclined += 1
max_nz = max(max_nz, nz)
v1 = Base.Vector(facet.Points[0])
v2 = Base.Vector(facet.Points[1])
v3 = Base.Vector(facet.Points[1])
vert.addFacet(v1, v2, v3)
if inclined:
print >>sys.stderr # FreeCAD progress reporting messes up newlines
print >>sys.stderr, inclined, "inclined facets, maximum normal", max_nz
#
# @@@ This is perhaps a bit too paranoid
#
# I wrote the Z noise filtering because I had mis-read perfectly good
# distinct coordinates as being essentially the same value but with
# rounding errors.
#
z_levels = []
last = None
for z in sorted(z_raw.keys(), reverse = True):
if last is None or last - z > epsilon:
z_levels.append(z)
last = z
#
# Convert the walls to a FreeCAD shape
#
shape = Part.Shape()
shape.makeShapeFromMesh(mesh.Topology, mech_eps)
bb = shape.BoundBox
#
# Iterate over all plateaus and determine how they intersect with the walls.
# For this, we add a small offset to the z position so that we intersect above
# the plateau.
#
for z in z_levels:
print "# level z = ", z
if margin is not None:
print bb.XMin - margin, " ", bb.YMin - margin, " ", z
print bb.XMax + margin, " ", bb.YMin - margin, " ", z
print bb.XMax + margin, " ", bb.YMax + margin, " ", z
print bb.XMin - margin, " ", bb.YMax + margin, " ", z
print bb.XMin - margin, " ", bb.YMin - margin, " ", z
print
for wire in shape.slice(Base.Vector(0, 0, 1), z + epsilon):
print "# wire = ", wire
first = None
last = None
for e in wire.Edges:
v = e.Vertexes[0]
if first is None:
first = v
if last is None or dist(v, last) >= mech_eps:
print_vec(v)
last = v
if first is not None:
print_vec(first)
print
print
#
# That's all, folks !
#