DebugDrawEx1/Assets/DebugDrawEx/Line.cs

using System.Collections.Generic;
using UnityEngine;

namespace DebugDrawEx
{
    public class Line
    {
        public Material Mat { get; set; }
        public Mesh Mesh { get; private set; }
        public bool DepthTest { get; set; }
        public float Duration { get; set; }
        private readonly List<Vector3> _vertices;
        private readonly List<Color> _colors;
        private readonly List<int> _indices;
        private static readonly int ZTest = Shader.PropertyToID("_ZTest");

        public Line()
        {
            _vertices = new List<Vector3>();
            _colors = new List<Color>();
            _indices = new List<int>();
        }

        public void AddLine(Vector3 from, Vector3 to, Color color)
        {
            _vertices.Add(from);
            _vertices.Add(to);
            _colors.Add(color);
            _colors.Add(color);
            _indices.Add(_vertices.Count - 2);
            _indices.Add(_vertices.Count - 1);
            Mesh = CreateMesh();
        
            if (Duration != 0)
                CreateGameObjectLine(from, to, color);
        }

        private void CreateGameObjectLine(Vector3 from, Vector3 to, Color color)
        {
            var go = new GameObject("line");
            go.hideFlags = HideFlags.HideAndDontSave;
            var lineMonoBehaviour = go.AddComponent<LineMonoBehaviour>();
            lineMonoBehaviour.Point1 = from;
            lineMonoBehaviour.Point2 = to;
            lineMonoBehaviour.Color = color;
            lineMonoBehaviour.Duration = Duration;
            lineMonoBehaviour.DepthTest = DepthTest;
        }

        private Mesh CreateMesh()
        {
            var newMesh = new Mesh();
            newMesh.MarkDynamic();
        
            Mat = new Material(Shader.Find("Hidden/Internal-Colored"));
            Mat.SetInt(ZTest, DepthTest ? 4 : 0);
        
            newMesh.SetVertices(_vertices);
            newMesh.SetColors(_colors);
            newMesh.SetIndices(_indices.ToArray(), MeshTopology.Lines, 0);

            return newMesh;
        }
    }
}