Simulate realistic player knockback

KnockbackUtil.java

// Ported from Exerosis' kotlin example
public class KnockbackUtil {

    private static final double FRICTION = 1.0;
    private static final double HORIZONTAL = 0.40;
    private static final double VERTICAL = 0.36075;
    private static final double EXTRA_VERTICAL = 0.1;
    private static final double EXTRA_HORIZONTAL = 1.5;

    public static Vector getKnockback(Location entityLoc, Entity attacker) {
        if(attacker == null) {
            return new Vector(0.0, -0.078375, 0.0);
        }
        
        ThreadLocalRandom random = ThreadLocalRandom.current();
        
        Location from = attacker.getLocation();
        
        double deltaX = entityLoc.getX() - from.getX();
        double deltaZ = entityLoc.getZ() - from.getZ();
        double y = VERTICAL;
        
        // --- SECTION START ---
        // Comment to add consistency and improve performance
        while (deltaX * deltaX + deltaZ * deltaZ < 1.0E-4) {
            deltaX = (random.nextDouble()) - random.nextDouble() * 0.01;
            deltaZ = (random.nextDouble()) - random.nextDouble() * 0.01;
        }
        // --- SECTION END ---
        
        double distance = Math.sqrt(deltaX * deltaX + deltaZ * deltaZ) * FRICTION;
        deltaX = deltaX / distance * HORIZONTAL;
        deltaZ = deltaZ / distance * HORIZONTAL;
        
        if(!attacker.isCrouching()) {
            double yaw = from.getYaw() * Math.PI / 180;
            deltaX += -Math.sin(yaw) * EXTRA_HORIZONTAL;
            deltaZ = Math.cos(yaw) * EXTRA_HORIZONTAL;
            
            y += EXTRA_VERTICAL;
            deltaX *= 0.6;
            deltaZ *= 0.6;
        }
        
        return new Vector(deltaX, y, deltaZ);
    }
}