Initial commit

simulation/ball.py

@@ -0,0 +1,37 @@
+from geometry.point import Point
+from geometry.vector import Vector
+from geometry.validation import expect_type
+from simulation.drawing import centered_circle
+from turtle import begin_fill, end_fill, fillcolor
+
+class Ball:
+    def __init__(self, position, velocity=None, mass=1, radius=20, color="black"):
+        expect_type(position, Point)
+        self.position = position
+        self.velocity = velocity or Vector()
+        expect_type(self.velocity, Vector)
+        self.acceleration = Vector()
+        self.radius = radius
+        self.mass = mass
+        self.color = color
+
+    def update(self):
+        """Update the ball's position and velocity at this moment. 
+        
+        """
+        self.velocity += self.acceleration
+        self.position += self.velocity
+        self.acceleration = Vector()
+
+    def collided_with(self, other_ball):
+        """Checks whether this ball collided with another ball.
+        """
+        return (self.position - other_ball.position).mag() <= self.radius + other_ball.radius
+
+    def draw(self):
+        "Draws a colored ball."
+        fillcolor(self.color)
+        begin_fill()
+        centered_circle(self.radius)
+        end_fill()
+