Diff: AliensArray.cpp

Revision:

5:2eb139b24219

Parent:

2:50feb42b982c

diff -r 107bdbbf78bf -r 2eb139b24219 AliensArray.cpp
--- a/AliensArray.cpp	Sun Apr 30 15:30:30 2017 +0000
+++ b/AliensArray.cpp	Tue May 02 18:47:22 2017 +0000
@@ -1,56 +1,67 @@
 #include "AliensArray.h"
 
-
+//constructor
 AliensArray::AliensArray()
 {
 
 }
-
+//destructor
 AliensArray::~AliensArray()
 {
 
 }
-
+//initialise function - initialises the x and y origin of the array, and the speed of movement for the array.
 void AliensArray::initialise(int x_origin, int y_origin, int speed)
 {
-  _x = x_origin;
-  _y = y_origin;
+  _x = x_origin; //sets the _x variable equal to the predefined and initialised x_origin variable.
+  _y = y_origin; //sets the _y variable equal to the predefined and initialised y_origin variable.
 
-  int direction = 0;
+  int direction = 0; // sets the direction variable equal to 0. Used to change direction of movement of the array.
 
   if (direction == 0) {
-    _velocity.x = speed * 1.5;
+    _velocity.x = speed * 1.5; // sets the velocity in the x-direction of the array equal to the predefined and initialised speed
+                               // multiplied by 1.5.
   } else if (direction == 1) {
-    _velocity.x = -speed;
+    _velocity.x = -speed * 1.5; // reverses the direction of movement in the x-direction of the alien array.
   }
 
 }
-
+//update function - updates the velocity in the x and y direction for the movement o the alien array.
 void AliensArray::update()
 {
-  _x += _velocity.x;
-  _y += _velocity.y;
+  _x += _velocity.x; // sets the _x variable equal to itself, plus the current value of the x velocity.
+  _y += _velocity.y; // sets the _y variable equal to itself, plus the current value of the y velocity.
 }
-
+//draw function - sends the command to the LCD screen to draw sprites on the screen for every render.
 void AliensArray::draw(N5110 &lcd)
 {
-  type_1_draw(lcd);
-  type_1_1_draw(lcd);
-  lcd.drawRect (0,0,84,48,0);
+  type_1_draw(lcd); //draws the first line of alien sprites on the LCD screen with regards to it's updated variables.
+  type_1_1_draw(lcd); //draws the second line of alien sprites on the LCD screen with regards to it's updated variables.
+  lcd.drawRect (0,0,84,48,0); //prints a rectangle 1 pixel thick around the outside perimeter of the LCD screen to give a border.
 
 }
-
+//line 1 draw function - sets the position of each alien sprite and tells if the alien is active.
 void AliensArray::type_1_draw(N5110 &lcd)
 {
   int add_x = 0;
-  _x_origin = _x/8;
-  _y_origin = _y;
+  _x_origin = _x/8; //sets a new variable, _x_origin, equal to the predefined _x velocity divided by 8 (sets an appropriate speed).
+  _y_origin = _y; //sets a new variable, _y_origin, equal to the predefined _y velocity.
+
+  /* For loop loops 11 times (equal to the number of alien sprites in a line).
+  * increments the perviously initialised add_x variable by 5, to be used to set the x-position of each sprite.
+  * sets the x-position of the sprite at the current iteration of the for loop equal to the add_x variable.
+  */
   for (int j = 0; j < 11; j++){
     add_x +=5;
     _array_x[0][j] = add_x;
 
   }
 
+  /* For loop scans through each sprite in the line, as done in the pervious for loop.
+  * creates a new variable named 'ind' that is equal to the value stored at the current x-index at the iretation of the for loop.
+  * checks if the current alien should be alive. If so, set the defined pixels in the shape of the required sprite,
+  * at the correct position for where the alien array has been moved to.
+  */
   for (int scan_j = 0; scan_j < 11; scan_j++){
     int ind = _array_x[0][scan_j];
 
@@ -64,7 +75,8 @@
   }
 
 }
-
+// Alien Array line 2 function - uses same techniques as the previous function, but for the second line of aliens
+// in the second row of the array.
 void AliensArray::type_1_1_draw(N5110 &lcd)
 {
   int add_x = 0;
@@ -89,25 +101,25 @@
   }
 
 }
-
+// gets the current velocity of the array.
 Vector2D AliensArray::get_velocity()
 {
-  Vector2D v = {_velocity.x,_velocity.y};
+  Vector2D v = {_velocity.x,_velocity.y}; //sets the variable v equal to a 2D vector containing the x and y members of the velocity.
   return v;
 }
-
+// gets the current position of the array.
 Vector2D AliensArray::get_pos()
 {
-  Vector2D p = {_x,_y};
+  Vector2D p = {_x,_y}; //sets the variable p equal to a 2D vector containing the x and y members of the positino.
   return p;
 }
-
+// sets the velocity of the array with regards to the x and y members of the variable v.
 void AliensArray::set_velocity(Vector2D v)
 {
   _velocity.x = v.x;
   _velocity.y = v.y;
 }
-
+// sets the position of the array with regards to the x and y members of the variable p.
 void AliensArray::set_pos(Vector2D p)
 {
   _x = p.x;