stl-bool-diff.sh

#!/usr/bin/python
#
# stl-bool-diff.sh -- compute the boolean difference of two stl files.
# similar idea as stlcut, but more flexible.
#
# uses blender as a python interpreter
# /usr/bin/blender --background --python /tmp/tmpr02niw


import os
import sys
blender_py_dir = '/usr/share/blender/scripts/modules/'
sys.path.append(blender_py_dir)
import bpy
from argparse import ArgumentParser

__VERSION__ = '0.1'
__AUTHOR__ = 'Juergen Weigert <juewei@fabmail.org>'



stl_bool_method='DIFFERENCE'

def keep_only_first_mesh():
  # different versions of blender sometimes return the wrong mesh
  objects = bpy.context.scene.objects
  if len(objects) > 1:
    objects[-1].select = False
    for other in objects[:-1]:
      other.select = True
    bpy.ops.object.delete()
  objects[-1].select = True

if __name__ == "__main__":

  output_file = 'output.stl'
  parser = ArgumentParser(epilog="Version "+__VERSION__+"\n -- Written by "+__AUTHOR__+"\n ", description="Boolean operation on STL objects: Difference, Intersection, Union.")

  parser.add_argument("-i", "--intersection", action='store_true', help="calculate boolean intersection instead of difference.")
  parser.add_argument("-u", "--union", action='store_true', help="calculate boolean union instead of difference.")
  parser.add_argument("-o", "--output-file", metavar='OUTPUTFILE', help="File to save output to. Default: " + output_file)
  parser.add_argument("infile1", metavar="STLFILE1", help="The first STL input file, (from which second file is cut away)")
  parser.add_argument("infile2", metavar="STLFILE2", help="The second STL input file")
  args = parser.parse_args()      # --help is automatic
  if args.infile1      is None: parser.exit("No input file given")
  if args.infile2      is None: parser.exit("Need two intput files.")
  if args.output_file  is not None: output_file=args.output_file
  if args.intersection is not None: stl_bool_method='INTERSECTION'
  if args.union        is not None: stl_bool_method='UNION'

  # Clear scene of default box
  bpy.ops.wm.read_homefile()
  bpy.ops.object.mode_set(mode='OBJECT')
  bpy.ops.object.select_all(action='SELECT')
  bpy.ops.object.delete(use_global=True)

  mesh_pre  = [args.infile1, args.infile2]
  mesh_post = os.path.abspath(output_file)

  # When you add objects to blender, other elements are pushed back
  # by going last to first on the filenames we can preserve the index relation
  for filename in mesh_pre[::-1]:
    bpy.ops.import_mesh.stl(filepath=os.path.abspath(filename))

  mesh  = bpy.context.scene.objects[0]
  for other in bpy.context.scene.objects[1:]:
    mod = mesh.modifiers.new('boolean', 'BOOLEAN') # add boolean modifier 
    mod.object = other
    mod.operation = stl_bool_method
  
  bpy.ops.object.modifier_apply(modifier = 'boolean')
  keep_only_first_mesh()  
  bpy.ops.export_mesh.stl(filepath = mesh_post, use_mesh_modifiers = True)