#!/usr/bin/env python
#
# stl2obj.py: Script to convert .stl ASCII (3D systems) mesh into .obj ASCII mesh (wavefront).
#
#
# Copyright (C) 2010  Clement Creusot
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import sys      
import string   
import os.path  
import getopt




def print_help():
    print "Usage: "+os.path.basename(sys.argv[0])+" [OPTIONS] filein.stl"
    print "   Options: -o OUTPUT_FILE"
    print "               Write the output mesh in OUTPUT_FILE"
    print "            -b Use binary STL representation"
    print "            -f Fast (dont try to find multiply defined point"
    print "               , create 3 points per facet)"
    sys.exit()

def print_error(*str):
    print "ERROR: ",
    for i in str:
        print i,
    print
    sys.exit()


# Reading the parameters
try:
    optlist, args = getopt.getopt(sys.argv[1:], 'hbfo:')
except getopt.GetoptError, err:
    print str(err)
    print_help()

if len(args) < 1:
    print_help()

# verify the argument is an stl file
stlfilename = args[0]
if cmp(string.split(stlfilename,".")[-1].lower(), "stl") != 0:
    print_error(stlfilename,": The file is not an .stl file.")
if not os.path.exists(stlfilename):
    print_error(stlfilename,": The file doesn't exist.")

# By default the output is the stl filename followed by '.obj'
objfilename = stlfilename+".obj"


# use options
useBinary = False
useFast = False
for opt,value in optlist:
    if opt in ("-h", "--help"):
        print_help()
    elif opt=='-o':
        objfilename = value
    elif opt=='-b':
        useBinary = True
        print_error("Binary read not yet implemented.")
    elif opt=='-f':
        useFast = True
    else:
        print "Unhandled option"
        print_help()
 

pointList = []
facetList = []

def GetPointId(point,list):
    global useFast
    if not useFast:
        for i,pts in enumerate(list):
            if pts[0] == point[0] and pts[1] == point[1] and pts[2] == point[2] :
                #obj start to count at 1
                return i+1
    list.append(point)
    #obj start to count at 1
    return len(list)

# start reading the STL file
stlfile = open(stlfilename, "r")
line = stlfile.readline()
lineNb = 1
while line != "":
    tab = string.split(string.strip(line))        
    if len(tab) > 0:
        if cmp(tab[0],"facet") == 0:
            print lineNb
            vertices = []
            normal = map(float,tab[2:])
            while cmp(tab[0],"endfacet") != 0:
                if cmp(tab[0],"vertex") == 0:
                    pts = map(float,tab[1:])
                    vertices.append(GetPointId(pts,pointList))
                line = stlfile.readline()
                lineNb = lineNb +1
                tab = string.split(string.strip(line))        
            if len(vertices) == 0:
                print_error("Unvalid facet description at line ",lineNb)
            facetList.append({"vertices":vertices, "normal": normal})

    line = stlfile.readline()
    lineNb = lineNb +1    

        
stlfile.close()



# Write the target file
objfile = open(objfilename, "w")
objfile.write("# File type: ASCII OBJ\n")
objfile.write("# Generated from "+os.path.basename(stlfilename)+"\n")

for pts in pointList:
    objfile.write("v "+string.join(map(str,pts)," ")+"\n")

for f in facetList:
    objfile.write("f "+string.join(map(str,f["vertices"])," ")+"\n")

objfile.close()