Two colors tube

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

public class GuideScript : MonoBehaviour {

    public AnimationCurve anim;

    Mesh mesh;
    public MeshFilter meshFilter;
    public float widthTube;
    public float lengthTube;
    public float angle;
    public int pointsPerLine;
    public int numberSegments;
    public float vel;


    public List<Vector3> vs;

    void Start(){

        mesh = new Mesh();
        vs = new List<Vector3>();

        for(int i=0;i<(pointsPerLine+1)*(numberSegments+1);i++){
            vs.Add(Vector3.zero);
        }

        mesh.SetVertices(vs);

        int[] inds = new int[6*pointsPerLine*numberSegments];
        List<Vector2> uvs = new List<Vector2>();

        int k=0;
        for(int i=0;i<numberSegments;i++){
            for(int j=0;j<pointsPerLine;j++){

                uvs.Add(new Vector2(1f*j/pointsPerLine,1f*i/numberSegments));

                inds[k+1] = j+i*(pointsPerLine+1);
                inds[k+0] = (j+1)+i*(pointsPerLine+1);
                inds[k+2] = (j+1)+(i+1)*(pointsPerLine+1);

                inds[k+4] = (j+1)+(i+1)*(pointsPerLine+1);
                inds[k+3] = j+(i+1)*(pointsPerLine+1);
                inds[k+5] = j+i*(pointsPerLine+1);

                k+=6;
            }

            uvs.Add(new Vector2(1f,1f*i/numberSegments));

        }


        for(int j=0;j<pointsPerLine+1;j++){

            uvs.Add(new Vector2(1f*j/pointsPerLine,1f));
        }


        mesh.SetUVs(0,uvs);
        mesh.SetIndices(inds,MeshTopology.Triangles,0);
        mesh.Optimize();
        meshFilter.mesh = mesh;

    }


    void Update () {

        angle += vel*anim.Evaluate(Time.time)*Time.deltaTime;
        vs = new List<Vector3>();
        for(int i=0;i<(numberSegments+1);i++){
            float t = angle-lengthTube*i/(numberSegments+1);
            t%=2f;
            t-=1f;
            Curve(t);
        }

        mesh.SetVertices(vs);
        mesh.Optimize();

    }

    void Curve(float angle){

        if(angle>=-1f && angle<0f){

            Curve1(angle);

        }else if(angle>=0f && angle<1f){

            Curve2(angle);
        }

    }

    void Curve1(float angle){

        Vector3 v,vo;

        v.x = 1f+Mathf.Cos(2f*Mathf.PI*angle+Mathf.PI);
        v.y = Mathf.Sin(2f*Mathf.PI*angle+Mathf.PI);
        v.z = Mathf.Cos(Mathf.PI*angle);

        Vector3 dir;
        dir.x = -Mathf.Sin(2f*Mathf.PI*angle+Mathf.PI);
        dir.y = Mathf.Cos(2f*Mathf.PI*angle+Mathf.PI);
        dir.z = 0;

        Vector3 dirOrto;
        dirOrto.x = dir.y;
        dirOrto.y = -dir.x;
        dirOrto.z = 0f;

        Vector3 biOrto = Vector3.Cross(dir,dirOrto);


        for(int i=0;i<pointsPerLine+1;i++){
            vo = dirOrto*Mathf.Cos(Mathf.PI*2f*i/pointsPerLine);
            vo+= biOrto*Mathf.Sin(Mathf.PI*2f*i/pointsPerLine);
            vo*=widthTube;
            vo+=v;
            vs.Add(vo);
        }

        transform.position = v;

    }

    void Curve2(float angle){

        Vector3 v,vo;

        v.x = -1f+Mathf.Cos(-2f*Mathf.PI*angle);
        v.y = Mathf.Sin(-2f*Mathf.PI*angle);
        v.z = Mathf.Cos(Mathf.PI*angle);

        Vector3 dir;
        dir.x = Mathf.Sin(-2f*Mathf.PI*angle);
        dir.y = -Mathf.Cos(-2f*Mathf.PI*angle);
        dir.z = 0f;

        Vector3 dirOrto;
        dirOrto.x = dir.y;
        dirOrto.y = -dir.x;
        dirOrto.z = 0f;

        Vector3 biOrto = Vector3.Cross(dir,dirOrto);

        for(int i=0;i<pointsPerLine+1;i++){
            vo = dirOrto*Mathf.Cos(Mathf.PI*2f*i/pointsPerLine);
            vo+= biOrto*Mathf.Sin(Mathf.PI*2f*i/pointsPerLine);
            vo*=widthTube;
            vo+=v;
            vs.Add(vo);
        }

        transform.position = v;


    }
}