End of Pong tutorial

README

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+A place for code playing around with the kivy.org framework.

pong/main.py

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+import random
+
+import kivy
+
+from kivy.app import App
+from kivy.uix.widget import Widget
+from kivy.properties import NumericProperty, ReferenceListProperty, ObjectProperty
+from kivy.vector import Vector
+from kivy.factory import Factory
+from kivy.clock import Clock
+
+#: this has stuff defined in pong.kv to style it
+class PongGame(Widget):
+    ball = ObjectProperty(None)
+    player1 = ObjectProperty(None)
+    player2 = ObjectProperty(None)
+
+    def serve_ball(self, vel=(5,0)):
+        self.ball.center = self.center
+        self.ball.velocity = vel
+
+    def update(self, *args):
+        self.ball.move()
+
+        self.player1.bounce_ball(self.ball)
+        self.player2.bounce_ball(self.ball)
+
+        if (self.ball.y < 0) or (self.ball.top > self.height):
+            self.ball.velocity_y *= -1
+
+        if (self.ball.x < 0):
+            self.player2.score += 1
+            self.serve_ball(vel=(4,0))
+
+        if (self.ball.right > self.width):
+            self.player1.score += 1
+            self.serve_ball(vel=(-4,0))
+
+    def on_touch_move(self, touch):
+        if touch.x < self.width / 3:
+            self.player1.center_y = touch.y
+
+        if touch.x > self.width - self.width / 3:
+            self.player2.center_y = touch.y
+
+class PongBall(Widget):
+
+    #: velocity of ball
+    velocity_x = NumericProperty(0)
+    velocity_y = NumericProperty(0)
+
+    #: I figure that the underscore in the variables is some
+    #: magic for making velocity.x and velocity.y
+    velocity = ReferenceListProperty(velocity_x, velocity_y)
+
+    def move(self):
+        self.pos = Vector(*self.velocity) + self.pos
+
+class PongPaddle(Widget):
+    score = NumericProperty(0)
+
+    def bounce_ball(self, ball):
+        if self.collide_widget(ball):
+            #: alias velocity
+            vx, vy = ball.velocity
+            #: cause ball to move y axis based on where
+            #: on the paddle the ball hits
+            offset = (ball.center_y-self.center_y)/(self.height/2)
+            #: Calculate new vector
+            bounced = Vector(-1*vx, vy)
+            #: increase speed
+            vel = bounced * 1.1
+            #: set new velocity
+            ball.velocity = vel.x, vel.y + offset
+
+class PongApp(App):
+    def build(self):
+        game = PongGame()
+        game.serve_ball()
+        Clock.schedule_interval(game.update, 1.0/60.0)
+        return game
+
+Factory.register("PongBall", PongBall)
+Factory.register("PongPaddle", PongPaddle)
+Factory.register("PongGame", PongGame)
+
+if __name__ in ('__android__', '__main__'):
+    PongApp().run()

pong/pong.kv

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+#:kivy 1.0.9
+
+<PongGame>:
+    ball: pong_ball
+    player1: player_left
+    player2: player_right
+
+    canvas:
+        Rectangle:
+            pos: self.center_x - 5, 0
+            size: 10, self.height
+
+    Label:
+        font_size: 70
+        center_x: root.width / 4
+        top: root.top - 50
+        text: str(root.player1.score)
+
+    Label:
+        font_size: 70
+        center_x: root.width * 3 / 4
+        top: root.top - 50
+        text: str(root.player2.score)
+
+    PongBall:
+        id: pong_ball
+        center: self.parent.center
+
+    PongPaddle:
+        id: player_left
+        x: root.x
+        center_y: root.center_y
+
+    PongPaddle:
+        id: player_right
+        x: root.width-self.width
+        center_y: root.center_y
+
+<PongBall>:
+    size: 50,50
+    canvas:
+        Ellipse:
+            pos: self.pos
+            size: self.size
+
+<PongPaddle>:
+    size: 25, 200
+    canvas:
+        Rectangle:
+            pos: self.pos
+            size: self.size