void userMovement(char k, float hfo) {
  // Move User 'basePosition'
  float finalAngle = hfo;
  switch (k) {
    case 'a':
      finalAngle -= HALF_PI;
      break;
    case 'd':
      finalAngle += HALF_PI;
      break;
    case 's':
      finalAngle +=      PI;
      break;
  }
  if (finalAngle == hfo && k != 'w')
    return;
  PVector t = PVector.fromAngle(finalAngle);
  t.setMag(USER_ACCELERATION_MAGNITUDE);
  userVelocity.add(t);
  userVelocity.limit(USER_TERMINAL_VELOCITY);
}

void mousePressed() {
  // Move Wall Endpoints
  if (mouseButton == LEFT) {
    for (int i = 0; i < walls.size(); i++) {
      Wall w = walls.get(i);
      final float d1 = PVector.dist(w.start, mouse);
      if (d1 <= PROJECTILE_RADIUS) {
        dragIndex = i;
        break;
      }
      final float d2 = PVector.dist(w.end, mouse);
      if (d2 <= PROJECTILE_RADIUS) {
        dragIndex = i;
        dragType = true;
        break;
      }
    }
  }
}

void mouseReleased() {
  dragIndex = -1;
  dragType = false;
}