merge two obj to one

two-obj-to-one.py

import sys

if(len(sys.argv)!=4):
  print('Usage: ', sys.argv[0], 'input1.obj input2.obj output.obj')
  sys.exit()

import vtk

def read(f):
  reader = vtk.vtkOBJReader()
  reader.SetFileName(f)
  reader.Update()
  return reader.GetOutput()

def output(f, obj, offset):
  for i in range(obj.GetNumberOfPoints()):
    pt = obj.GetPoint(i)
    f.write('v %.5f %.5f %.5f\n' % (pt[0], pt[1], pt[2]))

  for i in range(obj.GetNumberOfCells()):
    cell = obj.GetCell(i)
    f.write('f %d %d %d\n'% (cell.GetPointId(0)+1+offset, cell.GetPointId(1)+1+offset, cell.GetPointId(2)+1+offset))

obj1 = read(sys.argv[1])
obj2 = read(sys.argv[2])

with open(sys.argv[3], 'w') as f:
  output(f, obj1, 0)
  output(f, obj2, obj1.GetNumberOfPoints())