Initial commit

simulation/drawing.py

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+from turtle import *
+
+def centered_circle(radius):
+    """Draws a circle, centered on the turtle's current position.
+    The built-in circle function annoyingly draws a circle whose center
+    is one radius left of the turtle.
+    """
+    right(90)
+    penup()
+    forward(radius)
+    pendown()
+    left(90)
+    circle(radius)
+    left(90)
+    penup()
+    forward(radius)
+    pendown()
+    right(90)
+
+def draw_boundary(distance):
+    """Draws the boundary, a square `distance` from the origin on each side.
+    """
+    penup()
+    goto(-distance, -distance)
+    pendown()
+    goto(distance, -distance)
+    goto(distance, distance)
+    goto(-distance, distance)
+    goto(-distance, -distance)
+
+