// Movable, levitating object.
    
    // This works by measuring the distance to ground with a
    // raycast then applying a force that decreases as the object
    // reaches the desired levitation height.
    
    // Vary the parameters below to
    // get different control effects. For example, reducing the
    // hover damping will tend to make the object bounce if it
    // passes over an object underneath.
    
    // Forward movement force.
    var moveForce = 1.0;
    
    // Torque for left/right rotation.
    var rotateTorque = 1.0;
    
    // Desired hovering height.
    var hoverHeight = 4.0;
    
    // The force applied per unit of distance below the desired height.
    var hoverForce = 5.0;
    
    // The amount that the lifting force is reduced per unit of upward speed.
    // This damping tends to stop the object from bouncing after passing over
    // something.
    var hoverDamp = 0.5;
    
    
    
    function Start () {
        // Fairly high drag makes the object easier to control.
        rigidbody.drag = 0.5;
        rigidbody.angularDrag = 0.5;
    }
    
    
    function FixedUpdate () {
        // Push/turn the object based on arrow key input.
        rigidbody.AddForce(Input.GetAxis("Vertical") * moveForce * transform.forward);
        rigidbody.AddTorque(Input.GetAxis("Horizontal") * rotateTorque * Vector3.up);
        
        var hit: RaycastHit;
        var downRay = new Ray(transform.position, -Vector3.up);
        
        // Cast a ray straight downwards.
        if (Physics.Raycast(downRay, hit)) {
            // The "error" in height is the difference between the desired height
            // and the height measured by the raycast distance.
            var hoverError = hoverHeight - hit.distance;
            
            // Only apply a lifting force if the object is too low (ie, let
            // gravity pull it downward if it is too high).
            if (hoverError > 0) {
                // Subtract the damping from the lifting force and apply it to
                // the rigidbody. 
                var upwardSpeed = rigidbody.velocity.y;
                var lift = hoverError * hoverForce - upwardSpeed * hoverDamp;
                rigidbody.AddForce(lift * Vector3.up);
            }
        }
    }

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public float moveForce = 1.0F;
    public float rotateTorque = 1.0F;
    public float hoverHeight = 4.0F;
    public float hoverForce = 5.0F;
    public float hoverDamp = 0.5F;
    void Start() {
        rigidbody.drag = 0.5F;
        rigidbody.angularDrag = 0.5F;
    }
    void FixedUpdate() {
        rigidbody.AddForce(Input.GetAxis("Vertical") * moveForce * transform.forward);
        rigidbody.AddTorque(Input.GetAxis("Horizontal") * rotateTorque * Vector3.up);
        RaycastHit hit;
        Ray downRay = new Ray(transform.position, -Vector3.up);
        if (Physics.Raycast(downRay, out hit)) {
            float hoverError = hoverHeight - hit.distance;
            if (hoverError > 0) {
                float upwardSpeed = rigidbody.velocity.y;
                float lift = hoverError * hoverForce - upwardSpeed * hoverDamp;
                rigidbody.AddForce(lift * Vector3.up);
            }
        }
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public moveForce as single = 1.0F

    public rotateTorque as single = 1.0F

    public hoverHeight as single = 4.0F

    public hoverForce as single = 5.0F

    public hoverDamp as single = 0.5F

    def Start():
        rigidbody.drag = 0.5F
        rigidbody.angularDrag = 0.5F

    def FixedUpdate():
        rigidbody.AddForce(((Input.GetAxis('Vertical') * moveForce) * transform.forward))
        rigidbody.AddTorque(((Input.GetAxis('Horizontal') * rotateTorque) * Vector3.up))
        hit as RaycastHit
        downRay as Ray = Ray(transform.position, -Vector3.up)
        if Physics.Raycast(downRay, hit):
            hoverError as single = (hoverHeight - hit.distance)
            if hoverError > 0:
                upwardSpeed as single = rigidbody.velocity.y
                lift as single = ((hoverError * hoverForce) - (upwardSpeed * hoverDamp))
                rigidbody.AddForce((lift * Vector3.up))