The distance from the ray's origin to the impact point.
// 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; // Rigidbody component. var rb: Rigidbody; function Start () { rb = GetComponent.<Rigidbody>(); // Fairly high drag makes the object easier to control. rb.drag = 0.5; rb.angularDrag = 0.5; } function FixedUpdate () { // Push/turn the object based on arrow key input. rb.AddForce(Input.GetAxis("Vertical") * moveForce * transform.forward); rb.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 = rb.velocity.y; var lift = hoverError * hoverForce - upwardSpeed * hoverDamp; rb.AddForce(lift * Vector3.up); } } }
using UnityEngine; using System.Collections;
public class ExampleClass : 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; public Rigidbody rb; void Start() { rb = GetComponent<Rigidbody>(); rb.drag = 0.5F; rb.angularDrag = 0.5F; } void FixedUpdate() { rb.AddForce(Input.GetAxis("Vertical") * moveForce * transform.forward); rb.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 = rb.velocity.y; float lift = hoverError * hoverForce - upwardSpeed * hoverDamp; rb.AddForce(lift * Vector3.up); } } } }
See Also: Physics.Raycast, Physics.Linecast, Physics.RaycastAll.