#!/usr/bin/env python
#
# frep.py
#    functional representation solver
#
# usage
#    pcb.py | frep.py [dpi [filename]]
#
# Neil Gershenfeld 10/8/18
# (c) Massachusetts Institute of Technology 2018
#
# This work may be reproduced, modified, distributed,
# performed, and displayed for any purpose, but must
# acknowledge this project. Copyright is retained and
# must be preserved. The work is provided as is; no
# warranty is provided, and users accept all liability.
#

#
# import
#

import json,sys
from numpy import *
from PIL import Image

#
# read input
#

frep = json.load(sys.stdin)

#
# check arguments
#

if (frep['zmin'] != frep['zmax']):
   print('> 2D not (yet) supported')
   sys.exit()
if (frep['type'] != 'RGB'):
   print('types other than RGB not (yet) supported')
   sys.exit()
if (len(sys.argv) == 1):
   print('output to out.png at 100 DPI')
   filename = 'out.png'
   dpi = 100
elif (len(sys.argv) == 2):
   dpi = sys.argv[1]
   filename = 'out.png'
   print('output to out.png at '+dpi+'DPI')
   dpi = int(dpi)
elif (len(sys.argv) == 3):
   dpi = sys.argv[1]
   filename = sys.argv[2]
   print('output to '+filename+' at '+dpi+' DPI')
   dpi = int(dpi)

#
# evaluate
#

print('evaluating ...')
xmin = frep['xmin']
xmax = frep['xmax']
ymin = frep['ymin']
ymax = frep['ymax']
units = float(frep['mm_per_unit'])
delta = (25.4/dpi)/units
x = arange(xmin,xmax,delta)
y = flip(arange(ymin,ymax,delta),0)
X = outer(ones(y.size),x)
Y = outer(y,ones(x.size))
Z = frep['zmin']
f = eval(frep['function'])

#
# construct image
#

m = zeros((y.size,x.size,3),dtype=uint8)
m[:,:,0] = (f & 255)
m[:,:,1] = ((f >> 8) & 255)
m[:,:,2] = ((f >> 16) & 255)
im = Image.fromarray(m,'RGB')
im.save(filename,dpi=[dpi,dpi])