SkidmarkRenderer

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

public class SkidMarkRenderer : MonoBehaviour {

    public Color color = Color.white;
    public float line_width = 3.5f;
    private List<SkidMark> skidmarks = new List<SkidMark>();
    public MeshFilter meshfilter;
    //private Mesh mesh;
    private int id = -1;
    private bool redraw_mesh = false;
    public int maxSkids = 40;

    public class SkidMark {

        public List<Vector3> points = new List<Vector3>();
        public int id;

        public SkidMark (int id) {
            this.id = id;
        }
    }

    public void AddPoint(Vector3 p, int skid_id) {
        SkidMark s = skidmarks.Find(e => e.id == skid_id);
        s.points.Add(p);
        redraw_mesh = true;
    }

    public int AddSkidMark() {
        id++;
        skidmarks.Add(new SkidMark(id));
        //Debug.Log("ADD SKIDMARK!");
        if (skidmarks.Count > maxSkids) skidmarks.RemoveAt(0);
        return id;
    }

    void Update() {

        Gizmos.color = color;
        Vector3 lastpoint = Vector3.zero;
        bool first = true;

        /*foreach (SkidMark s in skidmarks) {
            first = true;
            foreach (Vector3 p in s.points) {
                if (!first) {
                    Debug.DrawLine(lastpoint, p, color);
                    Debug.Log("DRAWING!");
                }
                first = false;
                lastpoint = p;
            }
        }*/

        if (redraw_mesh) RedrawMesh();

        /*
        //DRAW MESH!

        MeshFilter mf = GetComponent<MeshFilter>();
        Mesh mesh = new Mesh();
        mf.sharedMesh = mesh;

        mesh.Clear();

        List<Vector3> vertices = new List<Vector3>();
        List<int> triangles = new List<int>();
        List<Vector2> uvs = new List<Vector2>();

        float uvx = 0;

        for (int c = 0; c < points.Count; c++) {
            Vector3 d;
            Vector3 normal;
            if (c > 0 && c < points.Count - 1) { d = points[c+1] - points[c-1]; }
            else if (c == 0) { d = points[c+1] - points[points.Count-1]; }
            else if (c == points.Count - 1) { d = points[0] - points[c-1]; }
            normal = Vector3.Cross(Vector3.up, d).normalized;

            float distance;
            if (c == points.Count-1) { distance = (points[0] - points[c]).magnitude; }
            else { distance = (points[c+1] - points[c]).magnitude; }

            //Gizmos.color = new Color(1, 1, 0, 0.8f);
            //Gizmos.DrawLine(points[c]-(normal*trackwidth), points[c]+(normal*trackwidth));
            Gizmos.DrawSphere(points[c], 0.2f);

            vertices.Add(points[c]-(normal*trackwidth));
            vertices.Add(points[c]+(normal*trackwidth));

            if (c < points.Count-1) {
                int[] t;
                t = new int[3] {0+c*2,2+c*2,1+c*2};
                triangles.AddRange(t);
                t = new int[3] {2+c*2,3+c*2,1+c*2};
                triangles.AddRange(t);
            }

            uvs.Add(new Vector2(0,uvx/points.Count));
            uvs.Add(new Vector3(1,uvx/points.Count));
            uvx += distance;
            //uvs.AddRange([new Vector2(0,0)])
        }

        int[] t_close;
        t_close = new int[3] {0+(points.Count-1)*2,0,1+(points.Count-1)*2};
        triangles.AddRange(t_close);
        t_close = new int[3] {0,1,1+(points.Count-1)*2};
        triangles.AddRange(t_close);

        //Debug.Log(triangles.ToArray()[1]);

        mesh.vertices = vertices.ToArray();
        mesh.triangles = triangles.ToArray();
        mesh.uv = uvs.ToArray();

        mesh.RecalculateNormals();
        mesh.RecalculateBounds();
        mesh.Optimize(); */
    }

    void RedrawMesh() {

        //DRAW MESH!
        redraw_mesh = false;

        MeshFilter mf = GetComponent<MeshFilter>();
        Mesh mesh = new Mesh();
        mf.sharedMesh = mesh;

        mesh.Clear();

        List<Vector3> vertices = new List<Vector3>();
        List<int> triangles = new List<int>();
        List<Vector2> uvs = new List<Vector2>();

        float uvx = 0;
        int pointcount = 0;

        foreach (SkidMark s in skidmarks) {
            List<Vector3> points = s.points;

            if (points.Count > 1) {
                Debug.Log("drawing skidmark nr: "+s.id);
                for (int c = 0; c < points.Count; c++) {
                    Vector3 d;
                    Vector3 normal;
                    if (c > 0 && c < points.Count - 1) { d = points[c+1] - points[c-1]; }
                    else if (c == 0) { d = points[c+1] - points[0]; }
                    else if (c == points.Count - 1) { d = points[c] - points[c-1]; }
                    normal = Vector3.Cross(Vector3.up, d).normalized;

                    float distance;
                    if (c == points.Count-1) { distance = (points[0] - points[c]).magnitude; }
                    else { distance = (points[c+1] - points[c]).magnitude; }

                    //Gizmos.color = new Color(1, 1, 0, 0.8f);
                    //Gizmos.DrawLine(points[c]-(normal*trackwidth), points[c]+(normal*trackwidth));
                    //Gizmos.DrawSphere(points[c], 0.2f);

                    vertices.Add(points[c]-(normal*line_width));
                    vertices.Add(points[c]+(normal*line_width));

                    if (c < points.Count-1) {
                        int[] t;
                        t = new int[3] {pointcount+c*2,pointcount+2+c*2,pointcount+1+c*2};
                        triangles.AddRange(t);
                        t = new int[3] {pointcount+2+c*2,pointcount+3+c*2,pointcount+1+c*2};
                        triangles.AddRange(t);
                    }

                    uvs.Add(new Vector2(0,uvx/points.Count));
                    uvs.Add(new Vector3(1,uvx/points.Count));
                    uvx += distance;

                    //uvs.AddRange([new Vector2(0,0)])
                }
                pointcount += (points.Count-1) * 2 + 2;
            }
        }
        /*int[] t_close;
        t_close = new int[3] {0+(points.Count-1)*2,0,1+(points.Count-1)*2};
        triangles.AddRange(t_close);
        t_close = new int[3] {0,1,1+(points.Count-1)*2};
        triangles.AddRange(t_close);*/

        //Debug.Log(triangles.ToArray()[1]);

        mesh.vertices = vertices.ToArray();
        mesh.triangles = triangles.ToArray();
        mesh.uv = uvs.ToArray();

        mesh.RecalculateNormals();
        mesh.RecalculateBounds();
        mesh.Optimize();
    }

    Vector3 CalculateBezierPoint(float t, Vector3 p0, Vector3 p1, Vector3 p2, Vector3 p3)

        {

            float u = 1.0f - t;

            float tt = t * t;

            float uu = u * u;

            float uuu = uu * u;

            float ttt = tt * t;



            Vector3 p = uuu * p0; //first term

            p += 3 * uu * t * p1; //second term

            p += 3 * u * tt * p2; //third term

            p += ttt * p3; //fourth term



    return p;

}
}