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-rw-r--r--gerbonara/tests/test_utils.py28
-rw-r--r--gerbonara/utils.py54
2 files changed, 82 insertions, 0 deletions
diff --git a/gerbonara/tests/test_utils.py b/gerbonara/tests/test_utils.py
index 1791afe..bc3fedb 100644
--- a/gerbonara/tests/test_utils.py
+++ b/gerbonara/tests/test_utils.py
@@ -17,8 +17,14 @@
# limitations under the License.
#
+import math
+import random
+
import pytest
+
from ..cam import FileSettings
+from ..utils import convex_hull, point_in_polygon, setup_svg, Tag
+from .utils import *
def test_zero_suppression():
@@ -103,3 +109,25 @@ def test_write_format_validation():
settings = FileSettings(number_format=fmt)
settings.write_gerber_value(69.0)
+def test_convex_hull_and_point_in_polygon(tmpfile):
+ svg = tmpfile('Visualization', '.svg')
+ st = random.Random(0)
+ for _ in range(50):
+ for n in [*range(1, 10), 12, 15, 20, 30, 50, 300, 1000, 5000]:
+ w = math.sqrt(n) * 10
+ rd = lambda: round(st.random() * w)
+ rp = lambda: (rd(), rd())
+ points = {rp() for _ in range(n)}
+ hull_l = convex_hull(points)
+ hull = set(hull_l)
+
+ tags = [Tag('circle', cx=x, cy=y, r=0.2, fill=('red' if (x, y) in hull else 'black')) for x, y in points]
+ for (x0, y0), (x1, y1) in zip([hull_l[-1], *hull_l[:-1]], hull_l):
+ tags.append(Tag('path', d=f'M {x0},{y0} L {x1},{y1}', stroke_width='0.1', stroke='red', fill='none'))
+ svg.write_text(str(setup_svg(tags, bounds=((0, 0), (w, w)), margin=1)))
+
+ # all hull corners must be in the set of original points
+ assert not (hull-points)
+ for p in points-hull:
+ assert point_in_polygon(p, hull_l)
+
diff --git a/gerbonara/utils.py b/gerbonara/utils.py
index 6b2d5c1..53f6398 100644
--- a/gerbonara/utils.py
+++ b/gerbonara/utils.py
@@ -28,6 +28,7 @@ This module provides utility functions for working with Gerber and Excellon file
import os
import re
import textwrap
+from functools import reduce
from enum import Enum
import math
@@ -396,6 +397,33 @@ def arc_bounds(x1, y1, x2, y2, cx, cy, clockwise):
return (min_x+cx, min_y+cy), (max_x+cx, max_y+cy)
+def convex_hull(points):
+ '''
+ Returns points on convex hull in CCW order according to Graham's scan algorithm.
+ By Tom Switzer <thomas.switzer@gmail.com>.
+ '''
+ # https://gist.github.com/arthur-e/5cf52962341310f438e96c1f3c3398b8
+ TURN_LEFT, TURN_RIGHT, TURN_NONE = (1, -1, 0)
+
+ def cmp(a, b):
+ return (a > b) - (a < b)
+
+ def turn(p, q, r):
+ return cmp((q[0] - p[0])*(r[1] - p[1]) - (r[0] - p[0])*(q[1] - p[1]), 0)
+
+ def keep_left(hull, r):
+ while len(hull) > 1 and turn(hull[-2], hull[-1], r) != TURN_LEFT:
+ hull.pop()
+ if not len(hull) or hull[-1] != r:
+ hull.append(r)
+ return hull
+
+ points = sorted(points)
+ l = reduce(keep_left, points, [])
+ u = reduce(keep_left, reversed(points), [])
+ return l.extend(u[i] for i in range(1, len(u) - 1)) or l
+
+
def point_line_distance(l1, l2, p):
""" Calculate distance between infinite line through l1 and l2, and point p. """
# https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line
@@ -471,3 +499,29 @@ def setup_svg(tags, bounds, margin=0, arg_unit=MM, svg_unit=MM, pagecolor='white
**namespaces,
root=True)
+
+def point_in_polygon(point, poly):
+ # https://stackoverflow.com/questions/217578/how-can-i-determine-whether-a-2d-point-is-within-a-polygon
+ # https://wrfranklin.org/Research/Short_Notes/pnpoly.html
+
+ if not poly:
+ return False
+
+ res = False
+ tx, ty = point
+ xp, yp = poly[-1]
+ for x, y in poly:
+ if yp == ty == y and ((x > tx) != (xp > tx)): # test point on horizontal segment
+ return True
+ if xp == tx == x and ((y > ty) != (yp > ty)): # test point on vertical segment
+ return True
+ if ((y > ty) != (yp > ty)):
+ tmp = ((xp-x) * (ty-y) / (yp-y) + x)
+ if tx == tmp: # test point on diagonal segment
+ return True
+ elif tx < tmp:
+ res = not res
+ xp, yp = x, y
+
+ return res
+