Diff: main.cpp

Revision:

0:efccf53eee4c

--- /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();
+}
+