brij-diagram.py

#!/usr/bin/python
# edited 22 Aug 2014 to correct COG scale & print COG
# brij-diagram.py -- Generates a PS picture of bridge assemblies.
# Ref: <http://puzzling.stackexchange.com/questions/2138/make-a-wide-tower-of-bridge-shapes>

# Each program parameter is 2 letters a...e plus an optional depth.
# Eg: "cd" (or "cd0") says to connect side c of new piece to side d of
# 0-previous piece, ie the just-previous piece.  "ae2" says to connect
# side a of new piece to side e of 2-previous piece.

# Examples of use to generate and view three sample diagrams:
#   ./brij-diagram.py da dc ca ca ea3 > t.ps; gs t.ps
#   ./brij-diagram.py ca ae cd ca da ae2 > t.ps; gs t.ps
#   ./brij-diagram.py ee ca ca ca ca > t.ps; gs t.ps
# Also, can make .jpg files via commands like:
# gs -sDEVICE=jpeg -sPAPERSIZE=letter -sOutputFile=t.jpg - < t.ps

from math import sin, cos, pi, sqrt, atan2
import sys
#---------------------------------------------------------
def docInitString(bbx, bby):
    import datetime
    now = str(datetime.datetime.now())[:-7]
    return '''%!PS-Adobe-1.0
%%Creator: brij-diagram.py
%%Title: Show "bridge shapes" stackups
%%CreationDate: {}
%%Pages: (atend)
%%DocumentFonts: NewCenturySchlbk-Bold
%%BoundingBox: 0 0 {} {}
%%EndComments'''.format(now, bbx, bby)
#---------------------------------------------------------
def fontSizeString(fsize):
    return '''% Select a font
/NewCenturySchlbk-Bold findfont {} scalefont setfont'''.format(fsize)
#---------------------------------------------------------
def rotate(angle,point):
    x, y = point
    s, c = sin(angle), cos(angle)
    return (x*c-y*s, x*s+y*c)
#---------------------------------------------------------
def pdelta(p1, p2):
    return (p2[0]-p1[0], p2[1]-p1[1])
#---------------------------------------------------------
# Compute rotation angle and translation amount so that new side nside
# coincides with old side oside. The caller can say ra, ro =
# rotrans(oside, nside) and then for each point p in new polygon can
# say pt = pdelta(ro, rotate(ra, p)) to get rotated/translated point pt.
def rotrans(oside, nside):
    (b, c),   (h, g)   = oside, nside     # Unpack side-pairs to points
    (dx, dy), (ex, ey) = pdelta(b, c), pdelta(g, h) # Get deltas of pairs
    ra = atan2(dy, dx)-atan2(ey, ex)      # Get angles of sides
    gr, hr = rotate(ra, g), rotate(ra, h) # Rotate ends of new side
    ro = pdelta(c,hr)                     # ro+hr = c, ro+gr = b
    return ra, ro
#---------------------------Main program-----------------
fscale, bbx, bby = 18, 612, 612
lmarg, rmarg, tmarg, ff = 60, 60, 60, 200
lx, rx, by, ty = lmarg, bbx-rmarg, 30, bby-tmarg
bwide, bhigh = 10, 18
xscale, yscale = (rx-lx)/bwide, (ty-by)/bhigh
scale = min(xscale, yscale)
rx, ty = lx + bwide*scale, by + bhigh*scale
print docInitString(bbx, bby)
print fontSizeString(fscale)
brij = [(0,0), (.5,sqrt(3)/2), (1.5,sqrt(3)/2), (2,0), (1,0)]
brin, cog = ['A', 'B', 'C', 'D', 'E'], (1, sqrt(3)*2/9.)
cogTotal = (0,0,0)
legs = zip(brij,brij[1:]+brij[:1])
hist = [(i,0) for i in range(6)]

for i, item in enumerate(sys.argv[1:]):
    print '\n% Processing  {}'.format(item),
    item += '0  '
    nsidel = (ord(item[0])-1) & 7
    osidel = (ord(item[1])-1) & 7
    deep = ord(item[2]) & 15
    if nsidel>4 or osidel>4 or deep>9:
        break
    print ' :  new,old,deep = {} {} {}'.format(brin[nsidel], brin[osidel], deep)
    hinx = -deep*6-6+osidel
    oside = (hist[hinx], hist[hinx+1])
    nside = legs[nsidel]
    ra, ro = rotrans(oside, nside)
    print '{} {} {} setrgbcolor'.format((0==i%3)*1, (1==i%3)*1, (2==i%3)*1)
    (ox, oy) = pdelta(ro, rotate(ra, brij[0]))
    hist.append((ox, oy))
    print '{:3.1f} {:3.1f} moveto'.format(ff+lx+scale*ox, by+scale*oy),
    for p in brij[1:]:
        (px, py) = pdelta(ro, rotate(ra, p))
        hist.append((px, py))
        print ' {:3.1f} {:3.1f} lineto'.format(ff+lx+scale*px, by+scale*py),
    hist.append((ox, oy))
    print ' fill'
    (px, py) = pdelta(ro, rotate(ra, cog))
    print '0 0 0 setrgbcolor {:3.1f} {:3.1f} moveto (.{}) show'.format(ff+lx+scale*px, by+scale*py, i)
    cogTotal = (cogTotal[0]+px, cogTotal[1]+py, cogTotal[2]+1)
    print '0.3 0.2 0.1 setrgbcolor {:3.1f} {:3.1f} moveto (*) show'.format(ff+lx+scale*cogTotal[0]/cogTotal[2]-fscale/8, by+scale*cogTotal[1]/cogTotal[2]-fscale/2)
    print '% new COG = ( {:6.3f}, {:6.3f} ), ox ox = {:8.3f} {:8.3f}'.format(cogTotal[0]/cogTotal[2], cogTotal[1]/cogTotal[2], oside[0][0], oside[1][0])

print fontSizeString(3*fscale)
print '0.3 0.2 0.1 setrgbcolor {:3.1f} {:3.1f} moveto (*) show'.format(ff+lx+scale*cogTotal[0]/cogTotal[2]-fscale/3, by+scale*cogTotal[1]/cogTotal[2]-1.5*fscale)
print 'showpage'