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authorHamilton Kibbe <hamilton.kibbe@gmail.com>2017-09-22 08:50:40 -0400
committerGitHub <noreply@github.com>2017-09-22 08:50:40 -0400
commit8301011abd5961ab6edb2bf91e61d82658df6b9a (patch)
tree215d5ab9177fd6bf8d18d4c3c57f11cd7716fff3 /gerber/utils.py
parent7ad6c3f6acfe1fe995c9f087e7ef7a51add60afe (diff)
parent385de1df0c957d904528aec0c94a78d85444a413 (diff)
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Merge pull request #73 from kliment/master
Remove dependency on scipy by adding quickhull implementation to utils
Diffstat (limited to 'gerber/utils.py')
-rw-r--r--gerber/utils.py115
1 files changed, 112 insertions, 3 deletions
diff --git a/gerber/utils.py b/gerber/utils.py
index 06adfd7..817a36e 100644
--- a/gerber/utils.py
+++ b/gerber/utils.py
@@ -24,8 +24,7 @@ files.
"""
import os
-from math import radians, sin, cos
-from scipy.spatial import ConvexHull
+from math import radians, sin, cos, sqrt, atan2, pi
MILLIMETERS_PER_INCH = 25.4
@@ -339,7 +338,117 @@ def listdir(directory, ignore_hidden=True, ignore_os=True):
files = [f for f in files if not f in os_files]
return files
+def ConvexHull_qh(points):
+ #a hull must be a planar shape with nonzero area, so there must be at least 3 points
+ if(len(points)<3):
+ raise Exception("not a planar shape")
+ #find points with lowest and highest X coordinates
+ minxp=0;
+ maxxp=0;
+ for i in range(len(points)):
+ if(points[i][0]<points[minxp][0]):
+ minxp=i;
+ if(points[i][0]>points[maxxp][0]):
+ maxxp=i;
+ if minxp==maxxp:
+ #all points are collinear
+ raise Exception("not a planar shape")
+ #separate points into those above and those below the minxp-maxxp line
+ lpoints=[]
+ rpoints=[]
+ #to detemine if point X is on the left or right of dividing line A-B, compare slope of A-B to slope of A-X
+ #slope is (By-Ay)/(Bx-Ax)
+ a=points[minxp]
+ b=points[maxxp]
+ slopeab=atan2(b[1]-a[1],b[0]-a[0])
+ for i in range(len(points)):
+ p=points[i]
+ if i == minxp or i == maxxp:
+ continue
+ slopep=atan2(p[1]-a[1],p[0]-a[0])
+ sdiff=slopep-slopeab
+ if(sdiff<pi):sdiff+=2*pi
+ if(sdiff>pi):sdiff-=2*pi
+ if(sdiff>0):
+ lpoints+=[i]
+ if(sdiff<0):
+ rpoints+=[i]
+ hull=[minxp]+_findhull(rpoints, maxxp, minxp, points)+[maxxp]+_findhull(lpoints, minxp, maxxp, points)
+ hullo=_optimize(hull,points)
+ return hullo
+
+def _optimize(hull,points):
+ #find triplets that are collinear and remove middle point
+ toremove=[]
+ newhull=hull[:]
+ l=len(hull)
+ for i in range(l):
+ p1=hull[i]
+ p2=hull[(i+1)%l]
+ p3=hull[(i+2)%l]
+ #(p1.y-p2.y)*(p1.x-p3.x)==(p1.y-p3.y)*(p1.x-p2.x)
+ if (points[p1][1]-points[p2][1])*(points[p1][0]-points[p3][0])==(points[p1][1]-points[p3][1])*(points[p1][0]-points[p2][0]):
+ toremove+=[p2]
+ for i in toremove:
+ newhull.remove(i)
+ return newhull
+
+def _distance(a, b, x):
+ #find the distance between point x and line a-b
+ return abs((b[1]-a[1])*x[0]-(b[0]-a[0])*x[1]+b[0]*a[1]-a[0]*b[1])/sqrt((b[1]-a[1])**2 + (b[0]-a[0])**2 );
+
+def _findhull(idxp, a_i, b_i, points):
+ #if no points in input, return no points in output
+ if(len(idxp)==0):
+ return [];
+ #find point c furthest away from line a-b
+ farpoint=-1
+ fdist=-1.0;
+ for i in idxp:
+ d=_distance(points[a_i], points[b_i], points[i])
+ if(d>fdist):
+ fdist=d;
+ farpoint=i
+ if(fdist<=0):
+ #none of the points have a positive distance from line, bad things have happened
+ return []
+ #separate points into those inside triangle, those outside triangle left of far point, and those outside triangle right of far point
+ a=points[a_i]
+ b=points[b_i]
+ c=points[farpoint]
+ slopeac=atan2(c[1]-a[1],c[0]-a[0])
+ slopecb=atan2(b[1]-c[1],b[0]-c[0])
+ lpoints=[]
+ rpoints=[]
+ for i in idxp:
+ if i==farpoint:
+ #ignore triangle vertex
+ continue
+ x=points[i]
+ #if point x is left of line a-c it's in left set
+ slopeax=atan2(x[1]-a[1],x[0]-a[0])
+ if slopeac==slopeax:
+ continue
+ sdiff=slopeac-slopeax
+ if(sdiff<-pi):sdiff+=2*pi
+ if(sdiff>pi):sdiff-=2*pi
+ if(sdiff<0):
+ lpoints+=[i]
+ else:
+ #if point x is right of line b-c it's in right set, otherwise it's inside triangle and can be ignored
+ slopecx=atan2(x[1]-c[1],x[0]-c[0])
+ if slopecx==slopecb:
+ continue
+ sdiff=slopecx-slopecb
+ if(sdiff<-pi):sdiff+=2*pi
+ if(sdiff>pi):sdiff-=2*pi
+ if(sdiff>0):
+ rpoints+=[i]
+ #the hull segment between points a and b consists of the hull segment between a and c, the point c, and the hull segment between c and b
+ ret=_findhull(rpoints, farpoint, b_i, points)+[farpoint]+_findhull(lpoints, a_i, farpoint, points)
+ return ret
+
def convex_hull(points):
- vertices = ConvexHull(points).vertices
+ vertices = ConvexHull_qh(points)
return [points[idx] for idx in vertices]