Lab 1 :: Applied OOP

<< back to Procedural Morphology homepage

Class notes

Example / Create a ball on mouseClick

// following array will hold our ball instances
// we'll keep track of how many balls there are with the int currentBall
Ball[] ballies = new Ball[500];
int currentBall = 0;

// setup
//........................................................
void setup() {
   size(200, 200);
   background(150);
   smooth();
}

// draw
//........................................................
void draw() {
   background(150);
   // use a loop to cycle through and tell all the balls to update
   for (int i=0; i<currentBall; i++) {
       if (i == currentBall -1) { // check to see if this is the last ball
         ballies[i].update(true);
      } else {
         ballies[i].update(false);
      }
   }
}

// mousePressed()
//........................................................
void mousePressed() {
   ballies[currentBall] = new Ball(
                  mouseX,      // x position
                  mouseY,     // y postion
                  random(0.5,1.5),    // x speed
                  random(0.5,1.5)     // y speed
                  );  // end of ball arguments
   currentBall++;
   }

// ball class
//........................................................
class Ball {
   // ball fields
   float x;
   float y;
   float speedX;
   float speedY;

   // ball constructor
   Ball(float _x, float _y, float _speedX, float _speedY) {
      x = _x;
      y = _y;
      speedX = _speedX;
      speedY = _speedY;
   }

   // ball methods
   void update(boolean isLast) {
      position();
      checkCollisions();
      drawBall(isLast);
   }

   void position() {
      x += speedX;
      y += speedY;
   }

   void drawBall(boolean isLast) {
      if (isLast) {
         stroke (255,0,0);
      } else {
         stroke(0);
      }
      strokeWeight(5);
      ellipse(x, y, 10, 10);
   }

   void checkCollisions() {
      if(x > width || x < 0) {
         speedX *= -1;
      }
      if(y > height || y < 0) {
         speedY *= -1;
      }
   }
}

Example / Using push and popmatrix within the ball

// following array will hold our ball instances
Ball[] ballies = new Ball[15];

// setup
//........................................................
void setup() {
   size(200, 200);
   background(150);
   smooth();
   // use a loop to fill the array with instances of the ball object
   for (int i=0; i<ballies.length; i++) {
      ballies[i] = new Ball(
                  random(width),      // x position
                  random(height),     // y postion
                  random(0.5,1.5),    // x speed
                  random(0.5,1.5)    // y speed
                  );  // end of ball arguments
   }
}

// draw
//........................................................
void draw() {
   background(150);
   // use a loop to cycle through and tell all the balls to update
   for (int i=0; i<ballies.length; i++) {
      ballies[i].update();
   }
}

// ball class (notice that it has not changed since previous example)
//........................................................
class Ball {
   // ball fields
   float x;
   float y;
   float speedX;
   float speedY;

   // ball constructor
   Ball(float _x, float _y, float _speedX, float _speedY) {
      x = _x;
      y = _y;
      speedX = _speedX;
      speedY = _speedY;
   }

   // ball methods
   void update() {
      position();
      checkCollisions();
      drawBall();
   }

   void position() {
      x += speedX;
      y += speedY;
   }

   void drawBall() {
       stroke(0);
       // push the matrix so each ball can draw itself
       pushMatrix();
          translate(x,y);
          rotate( atan2(speedY, speedX) ); // atan2 gives rotation based on an (Y, X) direction
          strokeWeight(2);
        line(0,0,20,0);
          line(20,0, 18, 2);
          line(20,0, 18, -2);
        strokeWeight(5);
          ellipse(0, 0, 10, 10);
       popMatrix();
   }

   void checkCollisions() {
      if(x > width || x < 0) {
         speedX *= -1;
      }
      if(y > height || y < 0) {
         speedY *= -1;
      }
   }
}