Polygon Generator

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PolygonGenerator : MonoBehaviour
{
    #region setup
    //mesh properties
    Mesh mesh;
    public Vector3[] polygonPoints;
    public int[] polygonTriangles;

    //polygon properties
    public bool isFilled;
    public int polygonSides;
    public float polygonRadius;
    public float centerRadius;

    void Start()
    {
        mesh = new Mesh();
        this.GetComponent<MeshFilter>().mesh = mesh;
    }

    void Update()
    {
        if(isFilled)
        {
            DrawFilled(polygonSides,polygonRadius);
        }
        else
        {
            DrawHollow(polygonSides, polygonRadius, centerRadius);
        }
    }
    #endregion

    void DrawFilled(int sides, float radius)
    {
        polygonPoints = GetCircumferencePoints(sides,radius).ToArray();
        polygonTriangles = DrawFilledTriangles(polygonPoints);
        mesh.Clear();
        mesh.vertices = polygonPoints;
        mesh.triangles = polygonTriangles;
    }

    void DrawHollow(int sides, float outerRadius, float innerRadius)
    {
        List<Vector3> pointsList = new List<Vector3>();
        List<Vector3> outerPoints = GetCircumferencePoints(sides,outerRadius);
        pointsList.AddRange(outerPoints);
        List<Vector3> innerPoints = GetCircumferencePoints(sides,innerRadius);
        pointsList.AddRange(innerPoints);

        polygonPoints = pointsList.ToArray();

        polygonTriangles = DrawHollowTriangles(polygonPoints);
        mesh.Clear();
        mesh.vertices = polygonPoints;
        mesh.triangles = polygonTriangles;
    }

    int[] DrawHollowTriangles(Vector3[] points)
    {
        int sides = points.Length/2;
        int triangleAmount = sides*2;

        List<int> newTriangles = new List<int>();
        for(int i = 0; i<sides;i++)
        {
            int outerIndex = i;
            int innerIndex = i+sides;

            //first triangle starting at outer edge i
            newTriangles.Add(outerIndex);
            newTriangles.Add(innerIndex);
            newTriangles.Add((i+1)%sides);

            //second triangle starting at outer edge i
            newTriangles.Add(outerIndex);
            newTriangles.Add(sides+((sides+i-1)%sides));
            newTriangles.Add(outerIndex+sides);
        }
        return newTriangles.ToArray();
    }

    List<Vector3> GetCircumferencePoints(int sides, float radius)
    {
        List<Vector3> points = new List<Vector3>();
        float circumferenceProgressPerStep = (float)1/sides;
        float TAU = 2*Mathf.PI;
        float radianProgressPerStep = circumferenceProgressPerStep*TAU;

        for(int i = 0; i<sides; i++)
        {
            float currentRadian = radianProgressPerStep*i;
            points.Add(new Vector3(Mathf.Cos(currentRadian)*radius, Mathf.Sin(currentRadian)*radius,0));
        }
        return points;
    }

    int[] DrawFilledTriangles(Vector3[] points)
    {
        int triangleAmount = points.Length - 2;
        List<int> newTriangles = new List<int>();
        for(int i = 0; i<triangleAmount; i++)
        {
            newTriangles.Add(0);
            newTriangles.Add(i+2);
            newTriangles.Add(i+1);
        }
        return newTriangles.ToArray();
    }
}