avoid black disks and zero divides

Author: nedbat

curve.py

@@ -29,6 +29,9 @@ def any_from_params(cls, params):
         subcls = cls.subcurves[alg]
         return subcls.from_params(params)
 
+    def complexity(self):
+        return 0
+
     def points(self, dims, dt=0.01):
         pass
 

render.py

@@ -56,13 +56,24 @@ def __init__(self, gray=0, **kwargs):
         assert self.alpha == 1
 
     def draw_curve(self, ctx, curve, scale):
-        ctx.set_source_rgb(self.gray, self.gray, self.gray)
-        for i, (x, y) in enumerate(curve.points(["x", "y"], scale=scale, dt=self.dt)):
-            if i == 0:
-                ctx.move_to(x, y)
-            else:
-                ctx.line_to(x, y)
-        ctx.stroke()
+        if curve.complexity() < 25_000:
+            ctx.set_source_rgb(self.gray, self.gray, self.gray)
+            for i, (x, y) in enumerate(curve.points(["x", "y"], scale=scale, dt=self.dt)):
+                if i == 0:
+                    ctx.move_to(x, y)
+                else:
+                    ctx.line_to(x, y)
+            ctx.stroke()
+        else:
+            ctx.set_source_rgb(0.75, 0.75, 0.75)
+            w = scale * 0.25
+            ctx.move_to(-w, -w)
+            ctx.line_to(-w, w)
+            ctx.line_to(w, w)
+            ctx.line_to(w, -w)
+            ctx.close_path()
+            ctx.fill()
+
 
 
 class ColorLine(Render):

spirograph.py

@@ -32,6 +32,19 @@ def adjacent_teeth(t):
     teeth.remove(t)
     return teeth
 
+def adjacent_nonzero(v):
+    """
+    Four adjacent values, but not zero.
+    """
+    vals = [v - 2, v - 1, v + 1, v + 2]
+    if 0 in vals:
+        vals.remove(0)
+        if v > 0:
+            vals = [v - 3] + vals
+        else:
+            vals = vals + [v + 3]
+    assert len(vals) == 4
+    return vals
 
 @dataclass
 class Gear(Parameterized):
@@ -80,7 +93,7 @@ class Spirograph(Curve):
         name="last_gear_speed_denominator",
         key="zd",
         default=1,
-        adjacent_step=1,
+        adjacent=adjacent_nonzero,
     )
     max_cycles = None
 
@@ -123,6 +136,9 @@ def make_random(cls, rnd):
         curve.last_speed_denom = rnd.choice([1, 2])
         return curve
 
+    def complexity(self):
+        return self._cycles() * 100
+
     def _make_circles(self):
         if self.circles is not None:
             return self.circles

webapp.py

@@ -124,7 +124,7 @@ def spirographs():
     while len(thumbs) < 30:
         try:
             curve = Spirograph.make_random(random)
-            if curve._cycles() < 50:
+            if curve.complexity() < 5000:
                 thumbs.append(Thumb(curve, size=size))
         except ImpossibleCurve:
             pass