/**
 * Animating a square.
 *
 * <p>Elie Zananiri<br>
 * CART 253, Winter 2008</p>
 */

/* global variables */
int rectX = 0;
int rectY = 50;
int rectSize = 50;
// we'll use an integer to represent direction:
// 1 -> left to right
// -1 -> right to left
int directionX = 1;
int directionY = 1;

/* built-in functions */
void setup() {
  size(300, 300);
  noStroke();
  smooth();
}

void draw() {
  background(0);
  moveSquare();
  drawSquare();
}

/* custom functions */
// moves the square erratically
void moveSquare() {
  if (rectX > (width-rectSize)) {
    // the square is too far to the right, change direction to left
    directionX = -1;
  } else if (rectX < 0) {
    // the square is too far to the left, change direction to right
    directionX = 1;
  }
  
  if (rectY > (height-rectSize)) {
    // the square is too far to the bottom, change direction to up
    directionY = -1;
  } else if (rectY < 0) {
    // the square is too far to the top, change direction to down
    directionY = 1;
  }
  
  int stepX = (int)random(5);
  int stepY = (int)random(5);
  
  rectX = rectX + (directionX*stepX);
  rectY = rectY + (directionY*stepY);
}

// draws the square
void drawSquare() {
  fill(255, 128, 0);  // orange
  rect(rectX, rectY, rectSize, rectSize);
}