void positionSegment(int a, int b, int l) {
  x[b][l] = x[a][l] + cos(angle[a]) * segLength;
  y[b][l] = y[a][l] + sin(angle[a]) * segLength;
}

void reachSegment(int i, float xin, float yin, int l) {
  float dx = xin - x[i][l];
  float dy = yin - y[i][l];
  angle[i] = atan2(dy, dx);  
  targetX = xin - cos(angle[i]) * segLength;
  targetY = yin - sin(angle[i]) * segLength;
}

void segment(float x, float y, float a, float sw) {
  strokeWeight(sw);
  pushMatrix();
  translate(x, y);
  rotate(a);
  line(0, 0, segLength, 0);
  popMatrix();
}


void moveBall() {

  ballX = ballX + 1.0 * ballXDirection;
  ballY = ballY + 0.8 * ballYDirection;
  if(ballX > width-25 || ballX < 25) {
    ballXDirection *= -1;
  }
  if(ballY > height-25 || ballY < 25) {
    ballYDirection *= -1;
  }
  ellipse(ballX, ballY, 30, 30);
}