_10_Loops

int batX = 240;
int batY = 700;

int ballX = 240;
int ballY = 400;

int ballXspeed = 5;
int ballYspeed = -5;

//
final int ballSize = 10;
final int screenWidth = 480;
final int screenHeight = 800;

final int batSize = 50;
final int batHeight = 25;

//
boolean gamePlaying = true;

//
final int blocksPerRow = 10;
final int blockWidth = screenWidth / blocksPerRow;
final int blockHeight = 20;

//===================================
void setup() {
  size( screenWidth, screenHeight );
  background( 0 );
  noCursor();
}

//
//The draw() function is nice and simple
//====================================
void draw() {
  background( 0 );
 
  if( gamePlaying ) {
    drawBlocks();
    moveTheBat();
    moveTheBall();
  } else {
    gameOver();
  }
}

//void drawBlocks()
//
//This function introduces a few new programming
//ideas.  The first one is quite simple.  You can
//have variables _inside_ a function; called 'local'
//variables, these values are 'trapped' inside the
//function and can't be used anywhere outside it, so
//the names 'counter' and 'rowPosition' only exist
//in the drawBlocks() function.  You can store any
//number you like in them but when the function ends,
//they are forgotten.
//
//The second idea is the 'for' loop.  In programming,
//you almost always have to do something over and over
//again.  They way you can repeat a piece of code is to
//put it inside a loop.
//
//A loop is just a block of code plus a counter variable.
//The block of code runs over and over until the counter
//reaches a certain value.
//
//The 'for' loop has four separate parts:
//
//  for( ONE; TWO; THREE ) {
//    FOUR;
//  }
//
//ONE: this is the bit that sets the _starting_ value for
//the counter.
//TWO: this is the bit that checks if the counter has reached
//the final value (it is a lot like the code in an 'if' test
//THREE: this bit makes the counter count up (or down).
//FOUR: this is the block of code which gets repeated however
//many times the loop goes round.
//==================================//
void drawBlocks() {
  int counter;
  int rowPosition = 50;
 
  fill( 200 );
 
  // The parts of a for loop:
  //   |   ONE    |     TWO    |       THREE          |  //
  for( counter = 0; counter < 4; counter = counter + 1 ) {
    // FOUR
    drawOneRow( rowPosition );
    rowPosition = rowPosition + blockHeight;
  }
}

//===================================//
void drawOneRow( int rowLevel ) {
  int counter;
 
  for( counter = 0; counter < blocksPerRow; counter = counter + 1 ) {
    rect( blockWidth * counter + 1, rowLevel + 1, blockWidth - 2, blockHeight - 2 );
  }
}


//====================================
void moveTheBat() {
  fill( 255 );
 
  batX = mouseX;
 
  //if the bat 'hits' the left edge move it back
  if( batX < batSize ) {
    batX = batSize;
  }
 
  //if the bat 'hits' the right edge move it
  if( batX > screenWidth - batSize ) {
    batX = screenWidth - batSize;
  }
 
  rect( batX - batSize, batY, batSize * 2, batHeight );
}


//=======================================
void moveTheBall() {
  ballX = ballX + ballXspeed;
  ballY = ballY + ballYspeed;
 
  if( ballX < ballSize ) {
    ballX = ballSize;
    ballXspeed = ballXspeed * -1;
  }
 
  if( ballX > screenWidth - ballSize ) {
    ballX = screenWidth - ballSize;
    ballXspeed = ballXspeed * -1;
  }
 
  if( ballY < ballSize ) {
    ballY = ballSize;
    ballYspeed = ballYspeed * -1;
  }
 
  if( ballHitBat() ) {
    ballYspeed = ballYspeed * -1;
  }
 
  if( ballY > screenHeight ) {
    gamePlaying = false;
  }
 
  rect( ballX - ballSize, ballY - ballSize, ballSize * 2, ballSize * 2 );
}

//======================================
void gameOver() {
  fill( 255 );
  text("Game Over", 200, 400);
}

//======================================
boolean ballHitBat() {
  if( ballY + ballSize >= batY ) {
    if( ballY + ballSize <= batY + ballSize * 2 ) {
      if( ballX > batX - batSize ) {
        if( ballX < batX + batSize ) {
          //the ball has hit the bat so return the answer is 'true'
          return true;
        }
      }
    }
  }
  //if we get this far then the ball hasn't hit, return the answer 'false'
  return false;
}