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inset.py
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inset.py
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from math import *
from trianglemath import *
class Vec2D:
def __init__(self, x, y):
self.set(x, y)
def set(self, x, y):
self.x = x
self.y = y
def times(self, t):
return Vec2D(self.x*t, self.y*t)
def add(self, v):
self.x += v.x
self.y += v.y
def plus(self, v):
return Vec2D(self.x+v.x, self.y+v.y)
def minus(self, v):
return Vec2D(self.x-v.x, self.y-v.y)
def len(self):
return sqrt(self.x*self.x+self.y*self.y)
def normalize(self):
l = self.len()
self.x /= l
self.y /= l
def asTripple(self,z):
return [self.x, self.y, z]
def scalarProduct(self, v):
return self.x*v.x + self.y*v.y
def interpolate(self, v, t):
return Vec2D(self.x*t+v.x*(1.0-t), self.y*t+v.y*(1.0-t))
class MetaCADLine:
def __init__(self, s, e):
self.start = Vec2D(s.x, s.y);
self.end = Vec2D(e.x, e.y);
self.dir = self.end.minus(self.start);
self.normal = Vec2D(self.dir.x, self.dir.y);
self.normal.normalize();
self.normal.set(-self.normal.y, self.normal.x);
def parallelMove(self, d):
move = self.normal.times(d);
self.start.add(move);
self.end.add(move);
def intersect(self, l):
solve = LinearSolve2(l.dir.x, -self.dir.x, l.dir.y, -self.dir.y, self.start.x-l.start.x, self.start.y-l.start.y);
if (solve.error):
return None
else:
point = self.start.plus(self.dir.times(solve.x2));
return Vec2D(point.x,point.y);
# matrix looks like this
# a b
# c d
def det(a, b, c, d):
return a*d-b*c;
# solves system of 2 linear equations in 2 unknown
class LinearSolve2:
# the equations look like thsi looks like this
# x1*a + x2*b = r1
# x1*c + x2*d = r2
def __init__(self, a, b, c, d, r1, r2):
q=det(a,b,c,d);
if (abs(q) < 0.000000001):
self.error = True;
else:
self.error = False;
self.x1=det(r1,b,r2,d)/q;
self.x2=det(a,r1,c,r2)/q;
def asVec2D(l):
return Vec2D(l[0], l[1])
def insetPoly(poly, inset):
points = []
inverted = []
for i in range(0, len(poly)):
iprev = (i+len(poly)-1)%len(poly);
inext = (i+1)%len(poly)
prev = MetaCADLine(asVec2D(poly[iprev]), asVec2D(poly[i]));
oldnorm = Vec2D(prev.normal.x, prev.normal.y)
next = MetaCADLine(asVec2D(poly[i]), asVec2D(poly[inext]));
prev.parallelMove(inset);
next.parallelMove(inset);
intersect=prev.intersect(next);
if intersect == None:
# take parallel moved poly[i]
# from the line thats longer (in case we have a degenerate line in there)
if (prev.dir.length() < next.dir.length()):
intersect = Vec2D(next.start.x, next.start.y);
else:
intersect = Vec2D(prev.end.x, prev.end.y);
points.append(intersect.asTripple(poly[i][2]));
if (len(points) >= 2):
newLine = MetaCADLine(asVec2D(points[iprev]), asVec2D(points[i]));
diff = newLine.normal.minus(oldnorm).len()
if (diff > 0.1):
pass
#print "error inverting"
#exit()
else:
pass
#print "ok"
istart = -1
ilen = 0
for i in range(0, len(poly)):
iprev = (i+len(poly)-1)%len(poly);
inext = (i+1)%len(poly)
prev = MetaCADLine(asVec2D(poly[iprev]), asVec2D(poly[i]));
oldnorm = Vec2D(prev.normal.x, prev.normal.y)
newLine = MetaCADLine(asVec2D(points[iprev]), asVec2D(points[i]));
diff = newLine.normal.minus(oldnorm).len()
if (diff > 0.1):
#print "wrong dir detected"
if (istart == -1):
istart = i
ilen = 1
else:
ilen += 1
else:
if (ilen > 0):
if (istart == 0 ):
pass
#print "oh noes"
#exit()
else:
#print "trying to save: ", istart, i
idxs = (len(poly)+istart-1)%len(poly)
idxe = (i)%len(poly)
p1 = points[idxs]
p2 = points[idxe]
#points[idxs] = p2
#points[idxe] = p1
for j in range(istart, i):
t = float(1+j-istart)/(1+i-istart)
#print t
points[j] = [p2[0]*t + p1[0]*(1-t), p2[1]*t + p1[1]*(1-t), p2[2]*t + p1[2]*(1-t)]
istart = -1
ilen = 0
iprev = (i+len(poly)-1)%len(poly);
inext = (i+1)%len(poly)
return points