float birdx=50;
float birdy=50;
float dx=2, dy=1;
boolean falling=false;

void setup() {
size (640,480);
}


void draw() {
 
 background(150,255,255);
movebird();
drawbird(birdx, birdy); 
}
  
   void keyPressed(){
     if (key=='f') falling=true; // bird will fall when f is pressed
     else falling=false;         //bird will fly when other key is pressed
    }
 
 
  void drawbird(float x, float y) { //draws the bird
      fill(0);
      triangle(x,y, x+35,y,x,y+20);
}


  void movebird() {
    if (falling){
      birdy =birdy+dy; //moves bird down when f is pressed
    }else{
      birdx =birdx + dx;
      birdy =birdy + dy;
    }
    if(birdx>width) dx= -dx; // when bird touches end of right screen it changes direction
    if(birdy>height) dy= -dy;// when bird touches end of bottom screen it changes direction
    if (birdx<0) dx= -dx;    // when bird touches end left of screen it changes direction
    if (birdy<0) dy= -dy;    // when bird touches end top of screen it changes direction
  }