TubeTrail.cs

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

[ExecuteInEditMode]
public class TubeTrail : MonoBehaviour
{
	public int sections = 16;
	public float radius = 0.5f;
	public int columns = 8;
	public float distance = 0.01f;
	public List<Vector3> verts = new List<Vector3> ();
	public List<Vector3> normals = new List<Vector3> ();
	public List<int> tris = new List<int> ();

	List<Vector3> points;
	MeshFilter filter;

	void OnEnable ()
	{
		Setup ();
	}

	void Setup ()
	{
		//if (verts.Count == 0)
		CreateMesh ();

		if (points == null) {
			points = new List<Vector3> ();
			for (int i = 0; i < sections; ++i)
				points.Add (Vector3.zero);
		}

		filter = GetComponent<MeshFilter> ();

		UploadVBO ();
	}


	void CreateMesh ()
	{
		if (sections < 2)
			sections = 2;

		if (columns < 4)
			columns = 4;
		
		verts.Clear ();
		normals.Clear ();
		for (int i = 0; i < sections; ++i) {			
			for (float j = 0; j < columns; ++j) {			
				verts.Add (new Vector3 (Mathf.Sin (Mathf.PI * 2 * j / columns) * radius, Mathf.Cos (Mathf.PI * 2 * j / columns) * radius, i * distance));
				normals.Add (new Vector3 (Mathf.Sin (Mathf.PI * 2 * j / columns), Mathf.Cos (Mathf.PI * 2 * j / columns), 0).normalized);
			}
		}

		if (tris.Count != sections * columns * 12) {
			Debug.Log ("Tris " + tris.Count + " != " + ((sections - 1) * columns * 12));
			tris.Clear ();

			for (int i = 0; i < sections; ++i) {
				int index = i * columns;
				int nextI = (i + 1) * columns;
				if ((i + 1) >= sections)
					nextI = index; //Dont overshoot...
			
				for (int j = 0; j < columns; ++j) {
					tris.Add (index + j);
					tris.Add (nextI + j);
					tris.Add (index + ((j + 1) % columns));

					tris.Add (index + ((j + 1) % columns));
					tris.Add (nextI + j);
					tris.Add (nextI + ((j + 1) % columns));

					//Double sided
					tris.Add (index + j);
					tris.Add (index + ((j + 1) % columns));
					tris.Add (nextI + j);

					tris.Add (index + ((j + 1) % columns));
					tris.Add (nextI + ((j + 1) % columns));
					tris.Add (nextI + j);
				}
			}
		}
	}

	void UploadVBO ()
	{
		if (filter.sharedMesh == null)
			filter.sharedMesh = new Mesh ();
		
		filter.sharedMesh.SetVertices (verts);
		filter.sharedMesh.SetTriangles (tris, 0, true);
		//filter.sharedMesh.RecalculateNormals ();
		filter.sharedMesh.SetNormals (normals);

		filter.sharedMesh.UploadMeshData (false); //set to true?
	}


	void Update ()
	{
		//Setup ();
	}
}