Unity3D Script to generate a uniform N sided polygon.

DynamicUniformPoligon.cs

using System.Collections.Generic;
using UnityEngine;

[ExecuteInEditMode]
[RequireComponent(typeof(MeshFilter))]
public class DynamicUniformPoligon : MonoBehaviour
{
    private MeshFilter filter;

    public int initialSides = 3;
    public float radius = 1;

    public Gradient steppedColor;

	void Start ()
	{
	    filter = GetComponent<MeshFilter>();
	}
	
	void Update ()
	{
	    filter.mesh = GenerateMesh(initialSides);
	}

    Mesh GenerateMesh(int initialSides)
    {
        Mesh mesh = new Mesh();

        var triangles = new List<int>();
        var vertices = new List<Vector3>();
        var colors = new List<Color>();
        vertices.Add(Vector3.zero);
        colors.Add(steppedColor.Evaluate(0));
        for (int i = 0; i < initialSides; ++i)
        {
            float rotation = Mathf.PI * 2 * (i / (float) initialSides);
            vertices.Add(new Vector3(Mathf.Sin(rotation), 0, Mathf.Cos(rotation)) * radius);
            colors.Add(steppedColor.Evaluate(1));
            triangles.Add(0);
            triangles.Add(1 + i);
            triangles.Add(1 + ((i + 1) % initialSides));
        }

        mesh.vertices = vertices.ToArray();
        mesh.triangles = triangles.ToArray();
        mesh.colors = colors.ToArray();

        return mesh;
    }
}