Released version of ballgame.py to the wild, the book is now ready!

Adventure8/ballgame.py

@@ -1 +1,209 @@
-secrets here
+# Adventure 8: ballgame.py
+#
+# From the book: "Adventures in Minecraft", 2nd Edition
+# written by David Whale and Martin O'Hanlon, Wiley, 2017
+# http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1119439582.html
+#
+# This program is a complete mini-game involving rolling a ball on a table
+
+# Import necessary modules
+import microbit
+import mcpi.minecraft as minecraft
+import mcpi.block as block
+import time
+import random
+
+# CONSTANTS
+# Change these to vary the size/difficulty of the game
+TABLE_WIDTH = 20
+TABLE_DEPTH = 20
+TREASURE_COUNT = 25
+TABLE = block.STONE.id
+BALL = block.CACTUS.id
+TREASURE = block.GOLD_BLOCK.id
+
+# Connect to the Minecraft game and
+# let the player know that the micro:bit is connected
+mc = minecraft.Minecraft.create()
+mc.postToChat("BBC micro:bit joined the game")
+
+# VARIABLES
+
+table_x = None
+table_y = None
+table_z = None
+ball_x = None
+ball_y = None
+ball_z = None
+speed_x = 0
+speed_z = 0
+remaining = 1
+
+# Build a complete game table
+def build_table(x, y, z):
+    global table_x, table_y, table_z
+    # Put a small gap around the edge in case of nearby mountains
+    GAP = 10
+    mc.setBlocks(x-GAP, y, z-GAP, x+TABLE_WIDTH+GAP, y+GAP, z+TABLE_DEPTH+GAP,
+                 block.AIR.id)
+    # Build the table as a big block
+    mc.setBlocks(x-1, y, z-1, x+TABLE_WIDTH+1, y+1, z+TABLE_DEPTH+1, TABLE)
+    # Carve out the middle, this creates the wall around the table
+    mc.setBlocks(x, y+1, z, x+TABLE_WIDTH, y+1, z+TABLE_DEPTH, block.AIR.id)
+    # Remember where the table was built, for later
+    table_x = x
+    table_y = y
+    table_z = z
+
+# Place random treasure blocks on the table
+def place_treasure():
+    y = table_y
+    for i in range(TREASURE_COUNT):
+        # BUGFIX: Prevent block being re-created in same pos
+        # which would make it impossible to complete the game
+        while True:
+            # Choose a random position for the next block
+            x = random.randint(0, TABLE_WIDTH) + table_x
+            z = random.randint(0, TABLE_DEPTH) + table_z
+            # Is it already a treasure block?
+            b = mc.getBlock(x,y,z)
+            if b == TREASURE: continue # if so, loop round to try again
+            # Place treasure at the new random location
+            mc.setBlock(x, y, z, TREASURE)
+            break # break out of loop to move to next treasure block
+        # BUGFIX END
+
+# Move the ball based on the present ball speed
+def move_ball():
+    new_x = ball_x - speed_x
+    new_z = ball_z - speed_z
+    if ball_x != new_x or ball_z != new_z: # prevent screen flicker
+        # Don't draw the ball if it falls off the table for some reason
+        if is_on_table(new_x, new_z):
+            move_ball_to(new_x, ball_y, new_z)
+
+# Move the ball to a specific position on the table
+def move_ball_to(x, y, z):
+    global ball_x, ball_y, ball_z
+    # Clear the existing ball if it has already been built
+    if ball_x is not None:
+        mc.setBlock(ball_x, ball_y, ball_z, block.AIR.id)
+    # Update our record of where the ball is now
+    ball_x = x
+    ball_y = y
+    ball_z = z
+    # Build a block where the ball needs to be
+    mc.setBlock(ball_x, ball_y, ball_z, BALL)
+
+# Calculate a new speed value, given the existing speed and amount of tilt.
+# You can change this algorithm to make the acceleration and deceleration of
+# the ball more life-like
+def new_speed(speed, tilt):
+    # Create a dead spot when the micro:bit is flat to slow/stop the ball
+    if abs(tilt) < 300: tilt = 0
+    # Reduce the range of the tilt to roughly -3..+3
+    tilt = tilt / 300
+    # Adjust the speed gradually each time, to simulate simple acceleration
+    if tilt < speed:
+        speed = speed - 1
+    elif tilt > speed:
+        speed = speed + 1
+    return speed
+
+# Sense the amount of tilt of the micro:bit and update the speed variables
+def check_tilt():
+    global speed_x, speed_z
+    speed_x = new_speed(speed_x, microbit.accelerometer.get_x())
+    speed_z = new_speed(speed_z, microbit.accelerometer.get_y())
+    #print(speed_x, speed_z)
+
+# Work out if a given ball position is on the table or not.
+# This can be used to prevent the ball rolling off the table.
+# It can also be used to sense if it rolls off the table.
+def is_on_table(x, z):
+    if x < table_x or x > table_x + TABLE_WIDTH:
+        return False
+    if z < table_z or z > table_z + TABLE_DEPTH:
+        return False
+    return True
+
+# Check what is below the ball, and action it accordingly
+def check_below():
+    global remaining
+    # What is below the ball?
+    block_below = mc.getBlock(ball_x, ball_y-1, ball_z)
+    if block_below == TREASURE:
+        # It's treasure, so collect it and update the count of remaining items
+        mc.setBlock(ball_x, ball_y-1, ball_z, block.AIR.id)
+        remaining = remaining - 1
+        microbit.display.show(remaining)
+    elif block_below == block.AIR.id:
+        # It's a hole, so introduce a time-penalty
+        move_ball_to(ball_x, ball_y-1, ball_z)
+        while not microbit.button_b.was_pressed():
+            time.sleep(0.1)
+        # Bounce the ball out to a random new position
+        move_ball_to(table_x + random.randint(0, TABLE_WIDTH), table_y+1,
+                     table_z + random.randint(0, TABLE_DEPTH))
+
+# Wait for the user to start the game
+def wait_for_start():
+    # A helpful message so that the user knows what to do
+    mc.postToChat("press B to start")
+    microbit.display.show("?")
+    # Wait for the B button to be pressed on the micro:bit
+    while not microbit.button_b.was_pressed():
+        time.sleep(0.1)
+
+    # Countdown 5,4,3,2,1
+    for t in range(6):
+        microbit.display.show(str(5-t))
+        time.sleep(0.5)
+
+# Build the complete game with table and treasure
+def build_game():
+    global speed_x, speed_z, remaining
+
+    # Get Steve's position, so the table can be built nearby
+    pos = mc.player.getTilePos()
+    # Build the table close by
+    build_table(pos.x, pos.y-2, pos.z)
+    # Start the ball at a random position
+    move_ball_to(table_x + random.randint(0, TABLE_WIDTH), table_y+1,
+                 table_z + random.randint(0, TABLE_DEPTH))
+    # Place all the treasure at random locations
+    place_treasure()
+    # Place Steve at a good viewing point
+    mc.player.setTilePos(table_x + TABLE_WIDTH/2, table_y+1, table_z)
+    # Start off the game variables at sensible values
+    remaining = TREASURE_COUNT
+    speed_x = 0
+    speed_z = 0
+
+# Play one complete game from start to end
+def play_game():
+    # Remember what time the game was started
+    start_time = time.time()
+    # Loop around a game loop until all treasure is collected
+    while remaining > 0:
+        # Slow things down a bit, this loop runs 10 times per second
+        time.sleep(0.1)
+        # Find out how much the user is tilting the micro:bit
+        check_tilt()
+        # Move the ball based on the tilt
+        move_ball()
+        # Process treasure or air blocks below the ball
+        check_below()
+    # Remember what time the game finished
+    end_time = time.time()
+    # Display the total game time taken to collect all treasure
+    mc.postToChat("game time=" + str(int(end_time-start_time)))
+
+# The main program.
+# Loops forever, until you press CTRL-C
+while True:
+    wait_for_start()
+    build_game()
+    play_game()
+
+# END