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ttt2medial.py
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ttt2medial.py
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import openvoronoi as ovd # https://github.com/aewallin/openvoronoi
import ttt # https://github.com/aewallin/truetype-tracer
import ngc_writer # https://github.com/aewallin/linuxcnc-scripts
import math
import time
ngc_writer.clearance_height=10
ngc_writer.feed_height = 2
ngc_writer.feed = 200
ngc_writer.plunge_feed = 100
ngc_writer.metric = True # set False for inch.
def printMedial(vd, scale):
maw = ovd.MedialAxisWalk( vd.getGraph() )
toolpath = maw.walk()
for chain in toolpath:
n = 0
for move in chain:
for point in move:
if n==0: # don't draw anything on the first iteration
p = point[0]
zdepth = scale*point[1]
ngc_writer.pen_up();
ngc_writer.xy_rapid_to( scale*p.x, scale*p.y );
ngc_writer.pen_down( z= -zdepth )
else:
p = point[0]
z = point[1]
ngc_writer.line_to( scale*p.x, scale*p.y, scale*(-z) )
n=n+1
return
# this function inserts point-sites into vd
def insert_polygon_points(vd, polygon):
pts=[]
for p in polygon:
pts.append( ovd.Point( p[0], p[1] ) )
id_list = []
#print "inserting ",len(pts)," point-sites:"
m=0
for p in pts:
id_list.append( vd.addVertexSite( p ) )
#print " ",m," added vertex ", id_list[ len(id_list) -1 ]
m=m+1
return id_list
# this function inserts line-segments into vd
def insert_polygon_segments(vd,id_list):
j=0
#print "inserting ",len(id_list)," line-segments:"
for n in range(len(id_list)):
n_nxt = n+1
if n==(len(id_list)-1):
n_nxt=0
#print " ",j,"inserting segement ",id_list[n]," - ",id_list[n_nxt]
vd.addLineSite( id_list[n], id_list[n_nxt])
j=j+1
# this function takes all segments from ttt and inserts them into vd
def insert_many_polygons(vd,segs):
polygon_ids =[]
t_before = time.time()
for poly in segs:
poly_id = insert_polygon_points(vd,poly)
polygon_ids.append(poly_id)
t_after = time.time()
pt_time = t_after-t_before
t_before = time.time()
for ids in polygon_ids:
insert_polygon_segments(vd,ids)
t_after = time.time()
seg_time = t_after-t_before
return [pt_time, seg_time]
# this translates segments from ttt
def translate(segs,x,y):
out = []
for seg in segs:
seg2 = []
for p in seg:
p2 = []
p2.append(p[0] + x)
p2.append(p[1] + y)
seg2.append(p2)
out.append(seg2)
return out
# modify by deleting last point (since it is identical to the first point)
def modify_segments(segs):
segs_mod =[]
for seg in segs:
first = seg[0]
last = seg[ len(seg)-1 ]
assert( first[0]==last[0] and first[1]==last[1] )
seg.pop()
seg.reverse() # to get interior or exterior offsets. Try commenting out this and see what happens.
segs_mod.append(seg)
return segs_mod
# scale all segs so that the overall length becomes desired_length
def scale_segs(segs, current_length, desired_length):
#print " current = ",current_length
out=[]
scale = float(desired_length) / float(current_length)
#print " scale = ",scale
for seg in segs:
seg2 = []
for p in seg:
p2 = []
p2.append(p[0] * scale)
p2.append(p[1] * scale)
seg2.append(p2)
out.append(seg2)
return [out,scale]
# get segments from ttt
def ttt_segments(text):
wr = ttt.SEG_Writer()
wr.arc = False # approximate arcs with lines
wr.conic = False # approximate conic with arc/line
wr.cubic = False # approximate cubic with arc/line
wr.conic_biarc_subdivision = 10 # this has no effect?
wr.conic_line_subdivision = 50 # =10 increasesn nr of points to 366, = 5 gives 729 pts
wr.cubic_biarc_subdivision = 10 # no effect?
wr.cubic_line_subdivision = 10 # no effect?
wr.scale = 1
wr.setFont(3)
# 0 freeserif
# 1 freeserif bold
# 2 freeserif italic
# 3 freeserif bold italic
# 4 "/usr/share/fonts/truetype/freefont/FreeMonoBold.ttf" );
# 5 "/usr/share/fonts/truetype/freefont/FreeMonoBoldOblique.ttf" );
# 6 "/usr/share/fonts/truetype/freefont/FreeMonoOblique.ttf" )
# 7 "/usr/share/fonts/truetype/freefont/FreeSans.ttf" );
# 8 "/usr/share/fonts/truetype/freefont/FreeSansBold.ttf" );
# 9 "/usr/share/fonts/truetype/freefont/FreeSansBoldOblique.ttf" );
# 10 "/usr/share/fonts/truetype/freefont/FreeSansOblique.ttf" );
ttt.ttt(text,wr)
segs = wr.get_segments()
ext = wr.extents
return [ext, segs]
def get_scaled_segs( chars):
# generate segs with scale 1
[extents, segs] = ttt_segments( chars )
# translate so lower left corner is at (0,0)
segs = translate(segs, -extents.minx, -extents.miny )
# scale to fit within unit circle
current_length = extents.maxx-extents.minx
current_height = extents.maxy-extents.miny
[segs,scale] = scale_segs(segs, current_length, 0.6)
segs = modify_segments(segs) # removes duplicate points
return [segs, extents,scale]
if __name__ == "__main__":
vd = ovd.VoronoiDiagram(1,120) # parameters: (r,bins)
# float r = radius within which all geometry is located. it is best to use 1 (unit-circle) for now.
# int bins = number of bins for grid-search (affects performance, should not affect correctness)
vd.set_silent(True) # suppress Warnings!
mytext = "-Hello."
text_length = 123 # desired text length in user units (set mm or inch for ngc_writer at the top of this file!)
[segs, extents, scale] = get_scaled_segs( mytext )
print_scale= float(text_length)/float(0.6)
times = insert_many_polygons(vd,segs) # insert segments into vd
# count the number of segments
num_segs = 0
for s in segs:
num_segs = num_segs + len(s)
text_length = (extents.maxx-extents.minx)*scale*print_scale
text_height = (extents.maxy-extents.miny)*scale*print_scale
# print comments to g-code file
print "( ttt2medial.py - experimental v-carving script )"
print "( TTT++",ttt.version()," )"
print "( OpenVoronoi",ovd.version()," )"
print "( number of polygons: ", len(segs)," )"
print "( number of segments: ", num_segs ," )"
print "( text length: ", text_length ," )"
print "( text height: ",text_height," )"
print "( VD built in %02.3f seconds = %02f us* n*log2{n} )" % ( sum(times), 1e6*float(sum(times))/(float(num_segs)*float(math.log10(num_segs)/math.log10(2))) )
print "( VD check: ", vd.check(), " )"
pi = ovd.PolygonInterior( True ) # filter so that only polygon interior remains
vd.filter_graph(pi)
ma = ovd.MedialAxis() # filter so that only medial axis remains
vd.filter_graph(ma)
ngc_writer.preamble()
printMedial( vd , print_scale) # the actual cutting g-code
ngc_writer.postamble()