From 417d980a80c7d266afca9e27a455b7d2b936625e Mon Sep 17 00:00:00 2001
From: Michael Fogleman <fogleman@gmail.com>
Date: Fri, 13 Jan 2017 22:18:02 -0500
Subject: [PATCH] examples

---
 examples/circles.py      | 42 ++++++++++++++++++++++++
 examples/field.py        | 70 ++++++++++++++++++++++++++++++++++++++++
 examples/motor_test.py   | 27 ++++++++++++++--
 examples/poisson_disc.py | 57 ++++++++++++++++++++++++++++++++
 examples/stars.py        | 46 ++++++++++++++++++++++++++
 5 files changed, 239 insertions(+), 3 deletions(-)
 create mode 100644 examples/circles.py
 create mode 100644 examples/field.py
 create mode 100644 examples/poisson_disc.py
 create mode 100644 examples/stars.py

diff --git a/examples/circles.py b/examples/circles.py
new file mode 100644
index 0000000..46b3f1d
--- /dev/null
+++ b/examples/circles.py
@@ -0,0 +1,42 @@
+import axi
+import math
+import random
+
+def circle(cx, cy, r, n):
+    points = []
+    for i in range(n + 1):
+        a = 2 * math.pi * i / n
+        x = cx + math.cos(a) * r
+        y = cy + math.sin(a) * r
+        points.append((x, y))
+    return points
+
+def random_points_on_circle(cx, cy, r, n):
+    result = []
+    a = random.random() * 2 * math.pi
+    da = 2 * math.pi / n
+    for i in range(n):
+        x = cx + math.cos(a) * r
+        y = cy + math.sin(a) * r
+        result.append((x, y))
+        a += da
+    return result
+
+def add(x, y, r, paths):
+    if r < 1:
+        return
+    paths.append(circle(x, y, r, 90))
+    points = random_points_on_circle(x, y, r, 2)
+    for x, y in points:
+        add(x, y, r / 2, paths)
+
+def main():
+    paths = []
+    add(0, 0, 64, paths)
+    drawing = axi.Drawing(paths).rotate_and_scale_to_fit(11, 8.5).sort_paths()
+    im = drawing.render()
+    im.write_to_png('out.png')
+    axi.draw(drawing)
+
+if __name__ == '__main__':
+    main()
diff --git a/examples/field.py b/examples/field.py
new file mode 100644
index 0000000..411284a
--- /dev/null
+++ b/examples/field.py
@@ -0,0 +1,70 @@
+import axi
+import random
+import time
+
+from math import hypot, atan2, sin, cos, pi
+
+class Model(object):
+    def __init__(self):
+        self.particles = []
+
+    def add(self, x, y, m=1.0):
+        self.particles.append((x, y, m))
+
+    def test(self, x, y):
+        dx = 0
+        dy = 0
+        for px, py, pm in self.particles:
+            d = hypot(x - px, y - py)
+            if abs(d) < 1e-8:
+                return (0, 0)
+            angle = atan2(y - py, x - px)
+            dx += pm * cos(angle) / d
+            dy += pm * sin(angle) / d
+        angle = atan2(dy, dx) + pi / 2
+        dx = cos(angle)
+        dy = sin(angle)
+        return (dx, dy)
+
+def polygon(sides, d):
+    x = 0.5
+    y = 0.5
+    rotation = 0
+    angle = 2 * pi / sides
+    angles = [angle * i + rotation for i in range(sides)]
+    return [(x + cos(a) * d, y + sin(a) * d) for a in angles]
+
+def create_path(model, scale, ox, oy, x, y, m, length):
+    result = []
+    n = int(length * 32)
+    f = float(length) / scale / n
+    for j in range(n):
+        result.append((ox + x * scale, oy + y * scale))
+        dx, dy = model.test(x, y)
+        x += dx * f * m
+        y += dy * f * m
+        if x < 0 or y < 0 or x > 1 or y > 1:
+            break
+    return result
+
+def main():
+    # axi.reset()
+    # return
+
+    model = Model()
+    for x, y in polygon(5, 0.35):
+        model.add(x, y, 1)
+    model.add(0.5, 0.5, 0.1)
+
+    paths = []
+    for _ in range(500):
+        x = random.random()
+        y = random.random()
+        path = create_path(model, 8.5, 1.25, 0, x, y, -1, 3)
+        paths.append(path)
+
+    drawing = axi.Drawing(paths).sort_paths().simplify_paths(0.001)
+    axi.draw(drawing)
+
+if __name__ == '__main__':
+    main()
diff --git a/examples/motor_test.py b/examples/motor_test.py
index b593a3c..3c18690 100644
--- a/examples/motor_test.py
+++ b/examples/motor_test.py
@@ -1,7 +1,17 @@
 import axi
+import math
 import random
 import time
 
+def circle(cx, cy, radius, n, rotation):
+    points = []
+    for i in range(n + 1):
+        a = 2 * math.pi * i / n + rotation
+        x = cx + math.cos(a) * radius
+        y = cy + math.sin(a) * radius
+        points.append((x, y))
+    return points
+
 def main():
     d = axi.Device()
     d.pen_up()
@@ -10,9 +20,20 @@ def main():
     points = []
     points.append((0, 0))
     for i in range(10):
-        x = random.random() * 11
-        y = random.random() * 8.5
-        points.append((x, y))
+        while True:
+            x = random.random() * 11
+            y = random.random() * 8.5
+            r = random.random() * 4
+            if x - r < 0 or x + r > 11:
+                continue
+            if y - r < 0 or y + r > 8.5:
+                continue
+            break
+        rotation = random.random() * 2 * math.pi
+        c = circle(x, y, r, 90, rotation)
+        if random.random() < 0.5:
+            c = list(reversed(c))
+        points.extend(c)
     points.append((0, 0))
     d.run_path(points)
     d.wait()
diff --git a/examples/poisson_disc.py b/examples/poisson_disc.py
new file mode 100644
index 0000000..48e1933
--- /dev/null
+++ b/examples/poisson_disc.py
@@ -0,0 +1,57 @@
+import random
+
+from math import pi, sin, cos, hypot, floor
+
+class Grid(object):
+    def __init__(self, r):
+        self.r = r
+        self.size = r / 2 ** 0.5
+        self.cells = {}
+
+    def points(self):
+        return self.cells.values()
+
+    def normalize(self, x, y):
+        i = int(floor(x / self.size))
+        j = int(floor(y / self.size))
+        return (i, j)
+
+    def nearby(self, x, y):
+        result = []
+        i, j = self.normalize(x, y)
+        for p in xrange(i - 2, i + 3):
+            for q in xrange(j - 2, j + 3):
+                if (p, q) in self.cells:
+                    result.append(self.cells[(p, q)])
+        return result
+
+    def insert(self, x, y):
+        for bx, by in self.nearby(x, y):
+            if hypot(x - bx, y - by) < self.r:
+                return False
+        i, j = self.normalize(x, y)
+        self.cells[(i, j)] = (x, y)
+        return True
+
+def poisson_disc(x1, y1, x2, y2, r, n):
+    x = x1 + (x2 - x1) / 2.0
+    y = y1 + (y2 - y1) / 2.0
+    active = [(x, y)]
+    grid = Grid(r)
+    grid.insert(x, y)
+    while active:
+        ax, ay = random.choice(active)
+        for i in xrange(n):
+            a = random.random() * 2 * pi
+            d = random.random() * r + r
+            x = ax + cos(a) * d
+            y = ay + sin(a) * d
+            if x < x1 or y < y1 or x > x2 or y > y2:
+                continue
+            if not grid.insert(x, y):
+                continue
+            active.append((x, y))
+            break
+        else:
+            active.remove((ax, ay))
+    return grid.points()
diff --git a/examples/stars.py b/examples/stars.py
new file mode 100644
index 0000000..71873b7
--- /dev/null
+++ b/examples/stars.py
@@ -0,0 +1,46 @@
+import axi
+import math
+import random
+
+from axi.spatial import Index
+from poisson_disc import poisson_disc
+
+def perturb_points(points, deviation):
+    result = []
+    for x, y in points:
+        a = random.random() * 2 * math.pi
+        r = random.gauss(0, deviation)
+        x += math.cos(a) * r
+        y += math.sin(a) * r
+        result.append((x, y))
+    return result
+
+def star(x, y, r):
+    sides = 5
+    a = random.random() * 2 * math.pi
+    angle = 2 * math.pi / sides
+    angles = [angle * i + a for i in range(sides)]
+    points = [(x + math.cos(a) * r, y + math.sin(a) * r) for a in angles]
+    points = perturb_points(points, 0.04)
+    points.append(points[0])
+    return points[0::2] + points[1::2]
+
+def main():
+    points = poisson_disc(0, 0, 11, 8.5, 0.4, 64)
+    index = Index(points)
+    paths = []
+    for x1, y1 in points:
+        index.remove((x1, y1))
+        x2, y2 = index.nearest((x1, y1))
+        index.insert((x1, y1))
+        d = math.hypot(x2 - x1, y2 - y1)
+        paths.append(star(x1, y1, d / 2))
+    drawing = axi.Drawing(paths)
+    drawing = drawing.remove_paths_outside(11, 8.5)
+    drawing = drawing.sort_paths()
+    # im = drawing.render()
+    # im.write_to_png('out.png')
+    axi.draw(drawing)
+
+if __name__ == '__main__':
+    main()