import inkex, simplepath, cubicsuperpath, dxf_templates, math

try:

from numpy import *

from numpy.linalg import solve

except:

inkex.errormsg(_("Failed to import the numpy or numpy.linalg modules. These modules are required by this extension. Please install them and try again."))

sys.exit()

def pointdistance((x1,y1),(x2,y2)):

return math.sqrt(((x2 - x1) ** 2) + ((y2 - y1) ** 2))

def get_fit(u, csp, col):

return (1-u)**3*csp[0][col] + 3*(1-u)**2*u*csp[1][col] + 3*(1-u)*u**2*csp[2][col] + u**3*csp[3][col]

class MyEffect(inkex.Effect):

def __init__(self):

inkex.Effect.__init__(self)

self.OptionParser.add_option("-R", "--ROBO", action="store", type="string", dest="ROBO")

self.dxf = []

self.handle = 255 # initiallize handle for DXF ENTITY

def output(self):

print ''.join(self.dxf)

def dxf_add(self, str):

self.dxf.append(str)

def dxf_line(self,csp):

self.dxf_add(" 0\nLINE\n 5\n%x\n100\nAcDbEntity\n 8\n0\n100\nAcDbLine\n" % self.handle)

self.dxf_add(" 10\n%f\n 20\n%f\n 30\n0.0\n 11\n%f\n 21\n%f\n 31\n0.0\n" % (csp[0][0],csp[0][1],csp[1][0],csp[1][1]))

def dxf_spline(self,csp):

knots = 8

ctrls = 4

self.dxf_add(" 0\nSPLINE\n 5\n%x\n100\nAcDbEntity\n 8\n0\n100\nAcDbSpline\n" % self.handle)

self.dxf_add(" 70\n8\n 71\n3\n 72\n%d\n 73\n%d\n 74\n0\n" % (knots, ctrls))

for i in range(2):

for j in range(4):

self.dxf_add(" 40\n%d\n" % i)

for i in csp:

self.dxf_add(" 10\n%f\n 20\n%f\n 30\n0.0\n" % (i[0],i[1]))

def ROBO_spline(self,csp):

# this spline has zero curvature at the endpoints, as in ROBO-Master

knots = 10

ctrls = 6

fits = 4

xfit = zeros((6), dtype=float64)

xfit[0] = csp[0][0]

xfit[1] = get_fit(.333, csp, 0)

xfit[2] = get_fit(.667, csp, 0)

xfit[3] = csp[3][0]

yfit = zeros((6), dtype=float64)

yfit[0] = csp[0][1]

yfit[1] = get_fit(.333, csp, 1)

yfit[2] = get_fit(.667, csp, 1)

yfit[3] = csp[3][1]

d1 = pointdistance((xfit[0],yfit[0]),(xfit[1],yfit[1]))

d2 = pointdistance((xfit[1],yfit[1]),(xfit[2],yfit[2]))

d3 = pointdistance((xfit[2],yfit[2]),(xfit[3],yfit[3]))

u1 = d1/(d1 + d2 + d3)

u2 = (d1 + d2)/(d1 + d2 + d3)

solmatrix = zeros((6,6), dtype=float64)

solmatrix[0,0] = 1

solmatrix[1,1] = (1 - u1/u2)**2

solmatrix[1,2] = (2*u2 - u1*u2 - u1)*u1/u2/u2

solmatrix[1,3] = u1*u1/u2

solmatrix[2,2] = (1 - u2)**2/(1 - u1)

solmatrix[2,3] = (2*u2 - u1*u2 - u1)*(1 - u2)/(1 - u1)/(1 - u1)

solmatrix[2,4] = ((u2 - u1)/(1 - u1))**2

solmatrix[3,5] = 1

solmatrix[4,0] = u2

solmatrix[4,1] = -u1 - u2

solmatrix[4,2] = u1

solmatrix[5,3] = 1 - u2

solmatrix[5,4] = u1 + u2 - 2

solmatrix[5,5] = 1 - u1

xctrl = solve(solmatrix, xfit)

yctrl = solve(solmatrix, yfit)

self.dxf_add(" 0\nSPLINE\n 5\n%x\n100\nAcDbEntity\n 8\n0\n100\nAcDbSpline\n" % self.handle)

self.dxf_add(" 70\n0\n 71\n3\n 72\n%d\n 73\n%d\n 74\n%d\n" % (knots, ctrls, fits))

for i in range(4):

self.dxf_add(" 40\n0\n")

self.dxf_add(" 40\n%f\n" % u1)

self.dxf_add(" 40\n%f\n" % u2)

for i in range(4):

self.dxf_add(" 40\n1\n")

for i in range(6):

self.dxf_add(" 10\n%f\n 20\n%f\n 30\n0.0\n" % (xctrl[i],yctrl[i]))

for i in range(4):

self.dxf_add(" 11\n%f\n 21\n%f\n 31\n0.0\n" % (xfit[i],yfit[i]))

def effect(self):

#References: Minimum Requirements for Creating a DXF File of a 3D Model By Paul Bourke

# NURB Curves: A Guide for the Uninitiated By Philip J. Schneider

# The NURBS Book By Les Piegl and Wayne Tiller (Springer, 1995)

self.dxf_add("999\nDXF created by Inkscape\n")

self.dxf_add(dxf_templates.r14_header)

scale = 25.4/90.0

h = inkex.unittouu(self.document.getroot().xpath('@height', namespaces=inkex.NSS)[0])

path = '//svg:path'

for node in self.document.getroot().xpath(path, namespaces=inkex.NSS):

d = node.get('d')

sim = simplepath.parsePath(d)

simplepath.scalePath(sim,scale,-scale)

simplepath.translatePath(sim,0,h*scale)

p = cubicsuperpath.CubicSuperPath(sim)

for sub in p:

for i in range(len(sub)-1):

# generate unique handle for DXF ENTITY

self.handle += 1

s = sub[i]

e = sub[i+1]

if s[1] == s[2] and e[0] == e[1]:

self.dxf_line([s[1],e[1]])

elif (self.options.ROBO == 'true'):

self.ROBO_spline([s[1],s[2],e[0],e[1]])

else:

self.dxf_spline([s[1],s[2],e[0],e[1]])

self.dxf_add(dxf_templates.r14_footer)

if __name__ == '__main__':

e = MyEffect()

e.affect()