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

/* global variables */
int rectX = 0;
int rectY = 50;
int rectSize = 50;
// this value is used to calculate the distance of the step but
// also to determine the minimum offset to reach the target
int easeFactor = 10;
boolean goToTarget;
int targetX;
int targetY;

/* built-in functions */
void setup() {
  size(300, 300);
  rectMode(CENTER);
  noStroke();
  smooth();
  
  goToTarget = false;
}

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

void mousePressed() {
  targetX = mouseX;
  targetY = mouseY;

  goToTarget = true;
}

/* custom functions */
// moves the square
void moveSquare() {
  // find the distance from the mouse click to the square
  int dX = targetX-rectX;
  int dY = targetY-rectY;
  
  // ease towards the target
  int stepX = dX/easeFactor;
  int stepY = dY/easeFactor;
  
  // set the new square position
  rectX += stepX;
  rectY += stepY;
  
  // check if the distance is small enough to consider it having arrived at the target
  if (abs(dX) <= easeFactor && abs(dY) <= easeFactor) {
    goToTarget = false;
  }
}

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