LineOfSight.cs

using UnityEngine;
using System.Collections.Generic;

public class LineOfSight : MonoBehaviour 
{
	public float apertureAngle;
	public float maxSightDistance;
	public int iterations;
	private GameObject _lineOfSightGo;

	void Start ()
	{
		_lineOfSightGo = new GameObject ("LineOfSight");
		_lineOfSightGo.AddComponent<MeshFilter>();
		_lineOfSightGo.AddComponent<MeshRenderer>();
		_lineOfSightGo.GetComponent<MeshRenderer>().sharedMaterial = new Material (Shader.Find ("Standard"));
	}

	void Update ()
	{
		_lineOfSightGo.GetComponent<MeshFilter>().mesh = GenerateSightMesh (iterations);
	}

	Mesh GenerateSightMesh (int iterations)
	{
		Mesh m = new Mesh ();
		List<Vector3> vertices = new List<Vector3>();
		List<int> triangles = new List<int>();
		Vector3 startingPoint = transform.position;
		vertices.Add (startingPoint);
		float angleStep = apertureAngle / iterations;
		RaycastHit hit;
		for (int i = 0; i <= iterations; i++)
		{
			float angle = (-apertureAngle * 0.5f) + (i * angleStep);
			Vector3 sightVector = Quaternion.AngleAxis (angle, transform.up) * transform.forward;
			if (Physics.Raycast (startingPoint, sightVector, out hit, maxSightDistance))
			{
				vertices.Add (startingPoint + sightVector * hit.distance);
			}
			else
			{
				vertices.Add (startingPoint + sightVector * maxSightDistance);
			}
			if (i >= 1)
			{
				triangles.Add (0);
				triangles.Add (i);
				triangles.Add (i + 1);
			}
		}
		m.vertices = vertices.ToArray();
		m.triangles = triangles.ToArray();
		return m;
	}
}

What's the license for this? GPL3?