Video Games Development

UNITY – JS Script – Ray casting

Ray casting is the use of ray-surface intersection tests to solve a variety of problems in computer graphics.
The first ray casting algorithm used for rendering was presented by Arthur Appel in 1968. The idea behind ray casting is to trace rays from the eye, one per pixel, and find the closest object blocking the path of that ray.

Ray casting traccia una linea da un oggetto verso l’infinito e ne rileva le intersezioni con altri oggetti. E’ come se l’oggetto avesse la capacità di vedere cosa si può intersecare con la sua traiettoria. Unity può tracciare linee di raycasting di lunghezza infinita, o limitata. Se la lunghezza è limitata tutti gli oggetti più lontani del limite imposto non saranno “visibili”. Il ray casting si basa sulla matematica dei vettori.

JAvascript Statement

static function Raycast(origin: Vector3, direction: Vector3, hitInfo: RaycastHit, distance: float = Mathf.Infinity, layerMask: int = DefaultRaycastLayers): bool;

origin: Vector3, -> l’origine del raggio (vettore)

direction: Vector3, -> la direzione del raggio (vettore)

hitInfo: RaycastHit, -> rileva se vi sono intersezioni

distance: float = Mathf.Infinity, -> lunghezza del raggio, se omesso = infinito

layerMask: int = DefaultRaycastLayers -> layer che saranno ignorati nel Ray casting

CASE 1: Raycast Debug.Log

1. Create a Sphere that falls and bource over a Cube (You have to use Physics 3D engine)

2. Attach to the Ball the script:

#pragma strict

function Update () {
		var hit : RaycastHit;
		if (Physics.Raycast (transform.position, -Vector3.up, hit)) {
			var distanceToGround = hit.distance;
                        // Casts a ray against all colliders in the scene 
                        // and returns detailed information on what was hit
			Debug.Log (distanceToGround);
		}
	}

CASE 2: Raycast Debug.Log + if

#pragma strict

function Update () {
    // function Update START -------------------------
		var hit : RaycastHit;
		if (Physics.Raycast (transform.position, -Vector3.up, hit)) {
			var distanceToGround = hit.distance;
			// Casts the ray against all colliders in the scene 
            // and returns detailed information on what was hit
			Debug.Log (distanceToGround);
			
			// Distance Controller START
			if (distanceToGround < 1)
       		{
             // Do a set of actions
             Debug.Log ("---- BOUNCE ----");
			}
			// Distance Controller END
		}
		
	// function Update END ----------------------------
	}

CASE 2: Raycast Debug.Log + if + function

#pragma strict

function Update () {
    // function Update() START -------------------------
		var hit : RaycastHit;
		
		// if Physics.raycast START
		if (Physics.Raycast (transform.position, -Vector3.up, hit)) {
			var distanceToGround = hit.distance;
			// Casts the ray against all colliders in the scene 
            // and returns detailed information on what was hit
			Debug.Log (distanceToGround);
			
			// Distance Controller START
			if (distanceToGround < 1)
       		{
             // Call a function           
             Bounce();
			}
			// Distance Controller END
		}
		// if Physics.raycast END
		
	// function Update() END ----------------------------
	}
	
	function Bounce ()
{
    Debug.Log ("---- BOUNCE FUNCTION ----");;
}

UNITY – JS Script – OnTrigger – Destroy

It will destroy the object if it enters or exit the trigger

1. Create a Sphere that falls and bource over a Box (You have to use Physics 3D engine)

2. Select the Box> Inspector> Box Collider> check ‘Is Trigger’, now the Box does not create collision, instead the Ball pass through it and this can be detected via code.

3. Attach to the Box the script

It will destroy the object if it enters the trigger

#pragma strict

function Start () {

}

// Destroy everything that enters the trigger START

	function OnTriggerEnter (other : Collider) {
		Destroy(other.gameObject);
	}

// Destroy everything that enters the trigger END


function Update () {


}

OR

It will destroy the object if it exit the trigger

#pragma strict

function Start () {

}

// Destroy everything that leaves the trigger START

	function OnTriggerExit (other : Collider) {
		Destroy(other.gameObject);
	}

// Destroy everything that leaves the trigger END


function Update () {


}