public void update() {
Vector2D prevVector = main.getPosition().subtract(previous.getPosition());
Vector2D nextVector = next.getPosition().subtract(main.getPosition());
double angleRad =
Math.acos(prevVector.dot(nextVector) / (prevVector.norm() * nextVector.norm()));
double angle = Math.toDegrees(angleRad);
if (prevVector.crossMag(nextVector) > 0) {
angle = 360.0 - angle;
}
double forceMag = ANGLE_CONSTANT * (angle - 90.0);
forces.put(previous, prevVector.rotate270().scaleTo(NEIGHBOR_ANGLE_SCALE * forceMag));
forces.put(main, normals.get(main).scaleTo(forceMag));
forces.put(next, nextVector.rotate270().scaleTo(NEIGHBOR_ANGLE_SCALE * forceMag));
}
