VectorLine

using UnityEngine;
using System.Collections;
 
[RequireComponent(typeof (Camera))]
public class VectorLine : MonoBehaviour
{
	public int numberOfPoints = 2;
	public Color lineColor = Color.red;
	public int lineWidth = 3;
	public bool drawLines = true;
 
	private Material lineMaterial;
	private Vector2[] linePoints;
	private Camera cam;
 
	void Awake()
	{
		lineMaterial = new Material( "Shader \"Lines/Colored Blended\" {" +
        "SubShader { Pass {" +
        "   BindChannels { Bind \"Color\",color }" +
        "   Blend SrcAlpha OneMinusSrcAlpha" +
        "   ZWrite Off Cull Off Fog { Mode Off }" +
        "} } }");
		lineMaterial.hideFlags = HideFlags.HideAndDontSave;
		lineMaterial.shader.hideFlags = HideFlags.HideAndDontSave;
		cam = camera;
	}
 
	// Creates a simple two point line
	void Start()
	{
		linePoints = new Vector2[2];
	}
 
	// Sets line endpoints to center of screen and mouse position
	void Update()
	{
		linePoints[0] = new Vector2(0.5f, 0.5f);
		linePoints[1] = new Vector2(Input.mousePosition.x/Screen.width, Input.mousePosition.y/Screen.height);
	}
 
	void OnPostRender()
	{
		if (!drawLines || linePoints == null || linePoints.Length < 2)
			return;
 
		float nearClip = cam.nearClipPlane + 0.00001f;
		int end = linePoints.Length - 1;
		float thisWidth = 1f/Screen.width * lineWidth * 0.5f;
 
		lineMaterial.SetPass(0);
		GL.Color(lineColor);
 
		if (lineWidth == 1)
		{
	        GL.Begin(GL.LINES);
	        for (int i = 0; i < end; ++i)
			{
	            GL.Vertex(cam.ViewportToWorldPoint(new Vector3(linePoints[i].x, linePoints[i].y, nearClip)));
	            GL.Vertex(cam.ViewportToWorldPoint(new Vector3(linePoints[i+1].x, linePoints[i+1].y, nearClip)));
        	}
    	}
    	else
		{
	        GL.Begin(GL.QUADS);
	        for (int i = 0; i < end; ++i)
			{
	            Vector3 perpendicular = (new Vector3(linePoints[i+1].y, linePoints[i].x, nearClip) -
	                                 new Vector3(linePoints[i].y, linePoints[i+1].x, nearClip)).normalized * thisWidth;
	            Vector3 v1 = new Vector3(linePoints[i].x, linePoints[i].y, nearClip);
	            Vector3 v2 = new Vector3(linePoints[i+1].x, linePoints[i+1].y, nearClip);
	            GL.Vertex(cam.ViewportToWorldPoint(v1 - perpendicular));
	            GL.Vertex(cam.ViewportToWorldPoint(v1 + perpendicular));
	            GL.Vertex(cam.ViewportToWorldPoint(v2 + perpendicular));
	            GL.Vertex(cam.ViewportToWorldPoint(v2 - perpendicular));
        	}
    	}
    	GL.End();
	}
 
	void OnApplicationQuit()
	{
		DestroyImmediate(lineMaterial);
	}
}

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
 
[RequireComponent(typeof (Camera))]
public class VectorLines : MonoBehaviour
{
	// Lists of properties for each line
	public Color lineColor;
	public int lineWidth;
	public bool drawLines = true;
 
	// Material and camera
	private Material lineMaterial;
	private Camera cam;
 
	// List of lines (each a list of vertices) and getter/setter
	private List<List<Vector2>> linePoints;
 
	void Awake()
	{
		lineMaterial = new Material( "Shader \"Lines/Colored Blended\" {" +
        "SubShader { Pass {" +
        "   BindChannels { Bind \"Color\",color }" +
        "   Blend SrcAlpha OneMinusSrcAlpha" +
        "   ZWrite Off Cull Off Fog { Mode Off }" +
        "} } }");
		lineMaterial.hideFlags = HideFlags.HideAndDontSave;
		lineMaterial.shader.hideFlags = HideFlags.HideAndDontSave;
		cam = camera;
	}
 
	public void InitializeLines(List<List<Vector2>> newPointsList)
	{
		// Creates new list of points
		linePoints = new List<List<Vector2>>();
		for (int i = 0; i < newPointsList.Count; ++i)
		{
			List<Vector2> newList = new List<Vector2>();
			for (int j = 0; j < newPointsList[i].Count; ++j)
			{
				newList.Add(newPointsList[i][j]);
			}
			linePoints.Add(newList);
		}
	}
 
	public void UpdateLines(List<List<Vector2>> updatedPoints)
	{
		// Sets all points of list to update list of points
		for (int i = 0; i < linePoints.Count; ++i)
			for (int j = 0; j < linePoints[i].Count; ++j)
				linePoints[i][j] = updatedPoints[i][j];
	}
 
	void OnPostRender()
	{
		// Cycles through each separate line
		for (int i = 0; i < linePoints.Count; ++i)
		{
			if (!drawLines || linePoints == null || linePoints[i].Count < 2)
				return;
 
			float nearClip = cam.nearClipPlane + 0.00001f;
			int end = linePoints[i].Count - 1;
			float thisWidth = 1f/Screen.width * lineWidth * 0.5f;
 
			lineMaterial.SetPass(0);
			GL.Color(lineColor);
 
			if (lineWidth == 1)
			{
		        GL.Begin(GL.LINES);
		        for (int j = 0; j < end; ++j)
				{
		            GL.Vertex(cam.ViewportToWorldPoint(new Vector3(linePoints[i][j].x, linePoints[i][j].y, nearClip)));
		            GL.Vertex(cam.ViewportToWorldPoint(new Vector3(linePoints[i][j+1].x, linePoints[i][j+1].y, nearClip)));
	        	}
	    	}
	    	else
			{
		        GL.Begin(GL.QUADS);
		        for (int j = 0; j < end; ++j)
				{
		            Vector3 perpendicular = (new Vector3(linePoints[i][j+1].y, linePoints[i][j].x, nearClip) -
		                                 new Vector3(linePoints[i][j].y, linePoints[i][j+1].x, nearClip)).normalized * thisWidth;
		            Vector3 v1 = new Vector3(linePoints[i][j].x, linePoints[i][j].y, nearClip);
		            Vector3 v2 = new Vector3(linePoints[i][j+1].x, linePoints[i][j+1].y, nearClip);
		            GL.Vertex(cam.ViewportToWorldPoint(v1 - perpendicular));
		            GL.Vertex(cam.ViewportToWorldPoint(v1 + perpendicular));
		            GL.Vertex(cam.ViewportToWorldPoint(v2 + perpendicular));
		            GL.Vertex(cam.ViewportToWorldPoint(v2 - perpendicular));
	        	}
	    	}
	    	GL.End();
		}
	}
 
	void OnApplicationQuit()
	{
		DestroyImmediate(lineMaterial);
	}
}