NYUSH2020S_4_arrays

/* IxLab 2020S -  NYU Shanghai
 *  recorded to introduce concepts 
 *  Ideas for exercises to practice: 
 *  Add a third ball bouncing
 *  Make the size different for dif. balls
 *  Make the color different for dif. balls
 */


float x1, y1;        //position of the ball 1
float x2, y2;        //position of the ball 2
float spdX1, spdY1;  //speed of the ball 1
float spdX2, spdY2;  //speed of the ball 2
color c;           //color of the ball
int d = 20;

void setup() {
  size(400, 400);

  x1 = random(width);
  y1 = random(height);
  x2 = random(width);
  y2 = random(height);
  noStroke();
  spdX1 = random(-10, 10);
  spdY1 = random(-10, 10);
  spdX2 = random(-10, 10);
  spdY2 = random(-10, 10);
}

void draw() {
  background(125);

  fill(c);
  ellipse (x1, y1, d, d); 
  ellipse (x2, y2, d, d); 
  x1 = x1 + spdX1;
  y1 = y1 + spdY1;
  x2 = x2 + spdX2;
  y2 = y2 + spdY2;

  if ((x1 > width-d/2) || (x1 < d/2)) {  // x is too big
    spdX1 *= -1;  // spdX = -spdX;
  }
  if ((y1 > height-d/2) || (y1 < d/2)) {  // x is too big
    spdY1 *= -1;
  }

  if ((x2 > width-d/2) || (x2 < d/2)) {  // x is too big
    spdX2 *= -1;  // spdX = -spdX;
  }
  if ((y2 > height-d/2) || (y2 < d/2)) {  // x is too big
    spdY2 *= -1;
  }

  //if ((x2 > width) || (x2 < 0)) {  // x is too big
  //  spdX *= -1;  // spdX = -spdX;
  //}
  //if ((y2 > height) || (y2 < 0)) {  // x is too big
  //  spdY *= -1;
  //}
}

void mousePressed() {
  c = color(random(0, 255), random(0, 255), random(0, 255));
}

void keyPressed() {
}