P4P2010-05-27

Programming for Poets, class 5/27

We went through varibles and functions again, and introduced conditionals ("if") statements. We updated our pongball program to bounce!

int ballx = 0; // start at left
int bally = 200; // and halfway down
int pballx = 0;
int pbally = 200; 
int speed = 5; // the ball moves this number of pixels between frames
int deltax = speed; // start with positive x speed (right)
int deltay = speed; // start with positive y speed (down)

 
void setup() {
       // size of our drawing window
       size(400, 400);
       // set the background color to gray
       background(128);
} 

void draw() {

      // draw over the previous ball location
      stroke(128); // gray
      fill(128); 
      drawball(pballx,pbally);

      // update the ball location
      ballx = ballx + deltax;
      bally = bally + deltay; 
      
      // check that ball is on the screen
      if(ballx>400)
      {
        println("right bounce x");
        deltax = -speed; // move left
        
      }
      
      if(bally>400)
      {
        println("bottom bounce y");
        deltay = -speed; // now move up
      }

      if(ballx<1)
      {
        println("left bounce x");
        deltax = speed; // now move right
        
      }
      
      if(bally<1)
      {
        println("top bounce y");
        deltay = speed;
      }

      // now draw ball in new location
      stroke(255);
      fill(255); //white
      drawball(ballx,bally);
      
      // save the new location for next time
      pballx = ballx;
      pbally = bally;
      
      
} 

// draw a paddle-shaped box at the given coordinates
void drawbox(int x, int y) {
      rect(30,y,10,40);
}

// draw a ball at the given coordinates
void drawball(int foo, int bar) {
      ellipse(foo,bar,10,10);
}

int myadd(int A, int B) {
  return (A+B);
}