A space invaders game using the micro:bit. This example uses buttons, 'fibers' (like threads or tasks), the display, and the sleep functions. It is one of the more elaborate examples useful for someone wanting to build a game or understand the scheduler. This is a one-way translation of the microbit-samples repository on GitHub. Please don't try to push changes here, instead push them to the source repo at https://github.com/lancaster-university/microbit-samples

Dependencies:   microbit

Files at this revision

API Documentation at this revision

Comitter:
LancasterUniversity
Date:
Wed Jul 13 16:03:49 2016 +0100
Commit message:
Update to git: v2.0.0-rc4-5-g115d5a8

Changed in this revision

main.cpp Show annotated file Show diff for this revision Revisions of this file
microbit.lib Show annotated file Show diff for this revision Revisions of this file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Jul 13 16:03:49 2016 +0100
@@ -0,0 +1,292 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Lancaster University.
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the "Software"),
+to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+
+//
+//
+// A simple game of Space Invaders for the BBC micro:bit, using the
+// accelerometer and buttons to control the player's ship.
+//
+// As well as illustrating the use of sensors, the display and events,
+// this demonstration also provides a highly elegant example of
+// how fibers can be used to create safe and elegant programs... Note the
+// use of event handlers when the player fires, and the indepenent fibers
+// used to control the players ship, aliens, bullets and screen refresh...
+//
+//
+
+#include "MicroBit.h"
+
+#define GAME_ON         0
+#define GAME_OVER       1
+
+struct Point
+{
+    int     x;
+    int     y;
+};
+
+MicroBit        uBit;
+MicroBitImage   invaders(5,5);
+int             score;
+int             game_over;
+int             level;
+int             INVADER_SPEED = 750;
+int             PLAYER_SPEED = 150;
+int             BULLET_SPEED = 50;
+Point           player;
+Point           bullet;
+
+/**
+ * Add a new row of space invaders to the game.
+ */
+int
+addRow()
+{
+    // If we're adding a row of invaders, but we're out of space, it's game over!!
+    for (int x=0; x<5; x++)
+        if (invaders.getPixelValue(x,4))
+            return GAME_OVER;
+
+    // Otherwise, move down the invaders, and add a new role at the top.
+    invaders.shiftDown(1);
+
+    for (int x=1; x<4; x++)
+        invaders.setPixelValue(x,0,255);
+
+    return GAME_ON;
+}
+
+/*
+ * Display Game Over and show the player's score.
+ */
+void
+gameOver()
+{
+    uBit.display.clear();
+
+    uBit.display.scroll("GAME OVER! SCORE:");
+    uBit.display.scroll(score);
+}
+
+/*
+ * Calculate the speed of an invaders movement, based on the game level
+ */
+int
+invaderSpeed()
+{
+    return max(INVADER_SPEED - level*50, 50);
+}
+
+/*
+ * Determine if the are any space invaders in the given column
+ */
+bool
+invadersInColumn(int x)
+{
+    for (int y = 0; y < 5; y++)
+        if (invaders.getPixelValue(x,y))
+            return true;
+
+    return false;
+}
+
+/*
+ * Determine the number of space invaders currently on screen
+ */
+bool
+invaderCount()
+{
+    int count = 0;
+
+    for (int x=0; x<5; x++)
+        for (int y=0; y<5; y++)
+            if (invaders.getPixelValue(x,y))
+                count++;
+
+    return count;
+}
+
+/*
+ * Move space invaders on the screen.
+ */
+void
+invaderUpdate()
+{
+    bool movingRight = true;
+
+    while(!game_over)
+    {
+        // Wait for next update;    
+        uBit.sleep(invaderSpeed());
+
+        if (movingRight)
+        {
+            if(invadersInColumn(4))
+            {
+                movingRight = false;
+                if (addRow() == GAME_OVER)
+                {
+                    game_over = true;
+                    return;
+                }
+            }
+            else
+            {
+                invaders.shiftRight(1);
+            }
+        }
+        else
+        {
+            if(invadersInColumn(0))
+            {
+                movingRight = true;
+                if (addRow() == GAME_OVER)
+                {
+                    game_over = true;
+                    return;
+                }
+            }
+            else
+            {
+                invaders.shiftLeft(1);
+            }
+        }
+
+        if (invaderCount() == 0)
+        {
+            level++;
+            addRow();
+        }
+    }
+}
+
+/* 
+ * Move the bullet up the screen
+ */
+void
+bulletUpdate()
+{
+    while (!game_over)
+    {
+        uBit.sleep(BULLET_SPEED);
+        if (bullet.y != -1)
+            bullet.y--;
+
+        if (invaders.getPixelValue(bullet.x, bullet.y) > 0)
+        {
+            score++;
+            invaders.setPixelValue(bullet.x, bullet.y, 0);
+            bullet.x = -1;
+            bullet.y = -1;
+        }
+    }
+}
+
+/*
+ * Move the player across the screen.
+ */
+void
+playerUpdate()
+{
+    while (!game_over)
+    {
+        uBit.sleep(PLAYER_SPEED);
+
+        if(uBit.accelerometer.getX() < -300 && player.x > 0)
+            player.x--;
+
+        if(uBit.accelerometer.getX() > 300 && player.x < 4)
+            player.x++;
+    }
+}
+
+/*
+ * Fire a new missile from the player
+ */
+void
+fire(MicroBitEvent)
+{
+    if (bullet.y == -1)
+    {
+        bullet.y = 4;
+        bullet.x = player.x;
+    }
+}
+
+/*
+ * A simple game of space invaders
+ */
+void 
+spaceInvaders()
+{   
+    // Reset all game state.
+    game_over = 0;
+    level = 0;
+    score = 0;
+    player.x = 2;
+    player.y = 4;
+
+    bullet.x = -1;
+    bullet.y = -1;
+
+    // Add a single row of invaders at the start.. cannon fodder!
+    invaders.clear();
+    addRow();
+
+    // Spawn independent fibers to handle the movement of each player
+    create_fiber(invaderUpdate);
+    create_fiber(bulletUpdate);
+    create_fiber(playerUpdate);
+
+    // Register event handlers for button presses (either button fires!)
+    uBit.messageBus.listen(MICROBIT_ID_BUTTON_A, MICROBIT_BUTTON_EVT_CLICK, fire);
+    uBit.messageBus.listen(MICROBIT_ID_BUTTON_B, MICROBIT_BUTTON_EVT_CLICK, fire);
+
+    // Now just keep the screen refreshed.
+    while (!game_over)
+    {    
+        uBit.sleep(10);
+        uBit.display.image.paste(invaders);
+        uBit.display.image.setPixelValue(player.x, player.y, 255);
+        uBit.display.image.setPixelValue(bullet.x, bullet.y, 255);
+    }
+
+    // Display GAME OVER and score
+    gameOver();
+}
+
+int main()
+{
+    // Initialise the micro:bit runtime.
+    uBit.init();
+
+    // Welcome message
+    uBit.display.scroll("INVADERS!");
+
+    // Keep playing forever
+    while(1)
+        spaceInvaders();
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/microbit.lib	Wed Jul 13 16:03:49 2016 +0100
@@ -0,0 +1,1 @@
+https://developer.mbed.org/teams/Lancaster-University/code/microbit/#4b89e7e3494f