draw-hexagon

using UnityEngine;
using System.Collections;

public class HexaGrid : MonoBehaviour
{
    public Material mat;
    private Vector3 startVertex;
    private Vector3 mousePos;

    void Start()
    {
        startVertex = Vector3.zero;
    }

    void Update()
    {
        mousePos = Input.mousePosition;
        if (Input.GetKeyDown(KeyCode.P))
        {
            startVertex = mousePos;
            startVertex.z = 0;
        }
    }

    void OnPostRender()
    {
        if (!mat)
        {
            Debug.LogError("Please Assign a material on the inspector");
            return;
        }
        GL.PushMatrix();
        mat.SetPass(0);
        GL.Color(Color.green);
        GL.LoadOrtho();
        GL.Begin(GL.LINES);
        // second parameter should be the second position of the mouse
        Vector3[] points = CalculatePoints(startVertex, new Vector3(startVertex.x + 50, startVertex.y - 50, 0));
        for(int i = 0; i < points.Length; i++)
        {
            GL.Vertex(new Vector3(points[i].x / Screen.width, points[i].y / Screen.height, 0));
        }
        GL.End();
        GL.PopMatrix();
    }


    Vector3[] CalculatePoints(Vector3 from, Vector3 to)
    {
        Vector3[] points = new Vector3[4];
        float diameter = Vector3.Distance(from, to);
        Vector3 direction = (to - from).normalized;
        float length = diameter / 2;
        Vector3 p0p1vector = (Quaternion.AngleAxis(60, Vector3.forward) * direction);
        
       
        Vector3 p1 = from + (p0p1vector * length);

        direction = (p1 - from).normalized;
        Vector3 p1p2vector = (Quaternion.AngleAxis(-60, Vector3.forward) * direction);
        Vector3 p2 = p1 + (p1p2vector * length);
        direction = (p2 - p1).normalized;
        Vector3 p2p3vector = (Quaternion.AngleAxis(-60, Vector3.forward) * direction);
        Vector3 p3 = p2 + (p2p3vector * length);
        direction = (p3 - p2).normalized;
        Vector3 p3p4vector = (Quaternion.AngleAxis(-60, Vector3.forward) * direction);
        Vector3 p4 = p3 + (p3p4vector * length);
        direction = (p4 - p3).normalized;
        Vector3 p4p5vector = (Quaternion.AngleAxis(-60, Vector3.forward) * direction);
        Vector3 p5 = p4 + (p4p5vector * length);
        direction = (p5 - p4).normalized;
        Vector3 p5p6vector = (Quaternion.AngleAxis(-60, Vector3.forward) * direction);
        Vector3 p6 = p5 + (p5p6vector * length);
        print(string.Format("length {0} diameter {1} p0 {2} p1 {3} p2 {4} p3 {5} p4 {6} p5 {7} p6 {8}", length, diameter, from, p1, p2, p3, p4, p5, p6));
        return new Vector3[]{from, p1, p2, p3, p4, p5, p6};
    }
}