Tetra.cs

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

[ExecuteInEditMode] . // Runs the code in the editor as well as in Play mode
[RequireComponent(typeof(MeshFilter), typeof(MeshRenderer))] . // Create the required components when you first add the script
public class Tetra : MonoBehaviour {

	// Use this for initialization
	void Start () {
	
	// Get the meshfilter component from the current gameobject
        MeshFilter meshFilter = GetComponent<MeshFilter>();
        
	// Create an empty mesh if there isn't already one on the meshfilter
        mesh = new Mesh();
         
	// Calculate the vertex positions
        Vector3 p0 = new Vector3(0,0,0);
        Vector3 p1 = new Vector3(1,0,0);
        Vector3 p2 = new Vector3(0.5f,0,Mathf.Sqrt(0.75f));
        Vector3 p3 = new Vector3(0.5f,Mathf.Sqrt(0.75f),Mathf.Sqrt(0.75f)/3);
         
	// Assign the vertices to the mesh
        mesh.vertices = new Vector3[]{
            p0,p1,p2,
            p0,p2,p3,
            p2,p1,p3,
            p0,p3,p1
        };
        mesh.triangles = new int[]{
            0,1,2,
            3,4,5,
            6,7,8,
            9,10,11
        };
         
        mesh.RecalculateNormals();
        mesh.RecalculateBounds();
		
	meshFilter.sharedMesh = mesh;
	}
	
	// Update is called once per frame
	void Update () {
		
	}
}