sourcePosition	The origin of the ray.
targetPosition	The end of the ray.
hit	Holds the properties of the ray cast resulting location.
passableMask	A mask specifying which NavMesh layers can be passed when tracing the ray.

Returns
bool True if the ray is terminated before reaching target position. Otherwise returns false.

Trace a line between two points on the NavMesh.

This function follows the path of a "ray" between the specified source and target positions on the navmesh. If an obstruction is encountered along the line then a true value is returned and the position and other details of the obstructing object are stored in the hit parameter. This can be used to check if there is a clear shot or line of sight between a character and a target object. This function is preferable to the similar Physics.Raycast because the line tracing is performed in a simpler way using the navmesh and has a lower processing overhead.

	var target: Transform;
	function Update () {
		var hit: NavMeshHit;
		
		// Note the negative test condition! Using -1 for the mask 
		// indicates all layers are to be used.
		if (!NavMesh.Raycast(transform.position, target.position, hit, -1)) {
			// Target is "visible" from our position.
		}
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    public Transform target;
    void Update() {
        NavMeshHit hit;
        if (!NavMesh.Raycast(transform.position, target.position, out hit, -1)) {
        }
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	public target as Transform

	def Update() as void:
		hit as NavMeshHit
		if not NavMesh.Raycast(transform.position, target.position, , -1):
			pass