Unity 5 Behaviour to help with applying texture atlases to a model without changing UVs

UniformTextureAtlasMeshRenderHelper.cs

// The MIT License (MIT) - https://gist.github.com/bcatcho/1926794b7fd6491159e7
// Copyright (c) 2015 Brandon Catcho
using UnityEngine;
using System.Collections.Generic;

namespace CatchCo
{
   [RequireComponent(typeof(MeshRenderer))]
   public class UniformTextureAtlasMeshRenderHelper : MonoBehaviour
   {
      public Vector2 AtlasOffset;
      public Vector2 Size = Vector2.one;
      public bool RandomizeOnSpawn;
      public OffsetRange RandomOffsetRange;
      public List<string> TextureNames; // if there are multiple textures in a shader, list them all here
      private Material _customMat;

      private void OnDidEnterGameplay ()
      {
         if (RandomizeOnSpawn)
         {
            AtlasOffset.x = Random.Range (RandomOffsetRange.XMin, RandomOffsetRange.XMax);
            AtlasOffset.y = Random.Range (RandomOffsetRange.YMin, RandomOffsetRange.YMax);
         }
      }

      private void Start ()
      {
         var meshRenderer = GetComponent<MeshRenderer>();
         _customMat = meshRenderer.material;
         UpdateMaterials ();
      }
      
      private void UpdateMaterials ()
      {
         var scale = new Vector2 (1f / Size.x, 1f / Size.y);
         var offset = AtlasOffset.ScaleXY (scale);
         
         foreach (var tex in TextureNames)
         {
            _customMat.SetTextureOffset (tex, offset);
            _customMat.SetTextureScale (tex, scale);
         }
      }

      [System.Serializable]
      public struct OffsetRange
      {
         public int XMin;
         public int XMax;
         public int YMin;
         public int YMax;
      }
   }
}