Diff: SecurityUnlockDemo-Animation.cpp

Revision:

2:444eeedb41f0

Parent:

1:316582aec4fb

Child:

3:0e554d8d5a19

diff -r 316582aec4fb -r 444eeedb41f0 SecurityUnlockDemo-Animation.cpp
--- a/SecurityUnlockDemo-Animation.cpp	Sat Jun 01 20:43:11 2019 +0000
+++ b/SecurityUnlockDemo-Animation.cpp	Sat Jun 01 21:04:17 2019 +0000
@@ -4,6 +4,14 @@
 //
 // Fredric L. Rice, June 2019
 //
+// This module draws a mushroom on the display and then animates it as
+// the mushroom moves around "randomly." Every 10 moves or so it will
+// "teleport" to a "random" place on the screen.
+//
+// The random number generator provided by mbed is not very good
+// so we attempt to use the analog inputs on PF_3, PF_4, PF_5 to help
+// drive some randomness.
+//
 // ----------------------------------------------------------------------
 
 #include "mbed.h"                           // The mbed operating system
@@ -92,10 +100,23 @@
     // After about 1 second we want to remove that message from
     // the screen so we maintain this count down timer
     static uint16_t u16_teleportMessageRemovalCountDown;
+    
+    // In an effort to assist the random number generator we will read
+    // vaues from some of the analog inputs which should be near zero
+    // but perhaps not entirely
+    static AnalogIn st_analog1(PF_3);
+    static AnalogIn st_analog2(PF_4);
+    static AnalogIn st_analog3(PF_5);
 
 // ----------------------------------------------------------------------
 // AnimationDrawSpriteAtThisLocation()
 //
+// This function will draw or erase the sprite at the X and Y 
+// coordinate position passed to it, or it will erase the sprite
+// depending upon the argument passed to it.
+//
+// The colors that are supported are described in the sprite's
+// bit mapping.
 //
 // ----------------------------------------------------------------------
 static void AnimationDrawOrEraseSpriteAtThisLocation(uint16_t u16_thisX, uint16_t u16_thisY, bool b_drawSprite)
@@ -229,6 +250,13 @@
 // ----------------------------------------------------------------------
 // AnimationMoveSprite()
 //
+// This function is the one that performs the actual move by 1 pixel
+// of the sprite. The sprite is erased from the screen and then the
+// new location is computed. If that places the sprite outside of the
+// boundaries, a new direction is selected and then the proposed
+// new location is selected.
+//
+// Once there is a new sprite location proposed, it gets re-drawn.
 //
 // ----------------------------------------------------------------------
 static void AnimationMoveSprite(void)
@@ -369,6 +397,12 @@
 // ----------------------------------------------------------------------
 // AnimationThread()
 //
+// This is the main thread for the animation functionality. The thread
+// usually runs forever however there is a mechanism for terminating
+// it provided in this module.
+//
+// The thread wakes up about 40 times a second so that the animation
+// can move fairly quickly and smoothly.
 //
 // ----------------------------------------------------------------------
 void AnimationThread(void)
@@ -387,6 +421,9 @@
 // ----------------------------------------------------------------------
 // AnimationPerformAnimation()
 //
+// This function is called when it is time to start animating the
+// sprite. It checks to make sure that the animation thread is not
+// yet started before it starts the animation.
 //
 // ----------------------------------------------------------------------
 void AnimationPerformAnimation(uint32_t u32_randomSeeder)
@@ -402,6 +439,10 @@
     
         // Flag the fact that the thread is running
         b_animationThreadRunning = true;
+        
+        // In an effort to add more "randomness," read some of the
+        // analog inputs and add their values, if any, to the seed
+        u32_randomSeeder = (st_analog1 * 100) + (st_analog2 * 100) + (st_analog3 * 100);
     
         // In order to "seed" the random number generator, we acquire
         // and discard up to 2000 random numbers
@@ -419,6 +460,8 @@
 // ----------------------------------------------------------------------
 // AnimationStopAnimation()
 //
+// In the event the animation thread needs to be stopped, this function
+// may be called to terminate the animation thread.
 //
 // ----------------------------------------------------------------------
 void AnimationStopAnimation(void)