Add breakout example

examples/basic/breakout.py

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+import random
+import colorsys
+
+WIDTH = 600
+HEIGHT = 800
+BALL_SIZE = 4
+MARGIN = 50
+
+BRICKS_X = 10
+BRICKS_Y = 5
+BRICK_W = (WIDTH - 2 * MARGIN) // BRICKS_X
+BRICK_H = 25
+
+ball = ZRect(WIDTH / 2, HEIGHT / 2, BALL_SIZE, BALL_SIZE)
+bat = ZRect(WIDTH / 2, HEIGHT - 50, 80, 12)
+
+bricks = []
+
+
+def reset():
+    """Reset bricks and ball."""
+    # First, let's do bricks
+    del bricks[:]
+    for x in range(BRICKS_X):
+        for y in range(BRICKS_Y):
+            brick = ZRect(
+                (x * BRICK_W + MARGIN, y * BRICK_H + MARGIN),
+                (BRICK_W, BRICK_H)
+            )
+            hue = (x + y) / BRICKS_X
+            saturation = (y / BRICKS_Y) * 0.5 + 0.5
+            r, g, b = colorsys.hsv_to_rgb(
+                h=hue,
+                s=saturation,
+                v=0.8,
+            )
+            brick.color = r * 255, g * 255, b * 255
+            r, g, b = colorsys.hsv_to_rgb(
+                h=hue,
+                s=saturation * 0.7,
+                v=1.0,
+            )
+            brick.highlight = r * 255, g * 255, b * 255
+            bricks.append(brick)
+
+    # Now reset the ball
+    ball.center = (WIDTH / 2, HEIGHT / 2)
+    ball.vel = (random.uniform(-200, 200), 400)
+
+
+# Reset bricks and ball at start
+reset()
+
+
+def draw():
+    screen.clear()
+    for brick in bricks:
+        screen.draw.filled_rect(brick, brick.color)
+        screen.draw.line(brick.bottomleft, brick.topleft, brick.highlight)
+        screen.draw.line(brick.topleft, brick.topright, brick.highlight)
+
+    screen.draw.filled_rect(bat, 'pink')
+    screen.draw.filled_circle(ball.center, 4, 'white')
+
+
+def update():
+    # When you have fast moving objects, like the ball, a good trick
+    # is to run the update step several times per frame with tiny time steps.
+    # This makes it more likely that collisions will be handled correctly.
+    for _ in range(3):
+        update_step()
+
+
+def update_step():
+    x, y = ball.center
+    vx, vy = ball.vel
+
+    if ball.top > HEIGHT:
+        reset()
+        return
+
+    # Update ball based on previous velocity
+    x += vx / 180
+    y += vy / 180
+    ball.center = (x, y)
+
+    # Check for and resolve collisions
+    if ball.left < 0:
+        vx = abs(vx)
+        ball.left = -ball.left
+    elif ball.right > WIDTH:
+        vx = -abs(vx)
+        ball.right -= 2 * (ball.right - WIDTH)
+
+    if ball.top < 0:
+        vy = abs(vy)
+        ball.top *= -1
+
+    if ball.colliderect(bat):
+        vy = -abs(vy)
+        # randomise the x velocity
+        if vx > 0:
+            vx = random.uniform(50, 300)
+        else:
+            vx = random.uniform(-300, -50)
+    else:
+        for brick in bricks:
+            # There are faster ways to find the brick we are intersecting
+            # Left as an exercise for the reader
+            if ball.colliderect(brick):
+                # Work out what side we collided on
+                dx = (ball.centerx - brick.centerx) / BRICK_W
+                dy = (ball.centery - brick.centery) / BRICK_H
+                if abs(dx) > abs(dy):
+                    vx = abs(vx) if dx > 0 else -abs(vx)
+                else:
+                    vy = abs(vy) if dy > 0 else -abs(vy)
+                bricks.remove(brick)
+                break
+
+    # Write back updated position and velocity
+    ball.center = (x, y)
+    ball.vel = (vx, vy)
+
+
+def on_mouse_move(pos):
+    x, y = pos
+    bat.centerx = x
+    if bat.left < 0:
+        bat.left = 0
+    elif bat.right > WIDTH:
+        bat.right = WIDTH