Change surface type with LWRP

This question has a long answer, unfortunately. I can not find a shortcut for this. So I search deep into LWRP scripts and found this solution and write this code. It worked for me for now, I hope it works for you.

 using UnityEngine;
 using System;
 
 public class DisplayController : MonoBehaviour
 {
     public enum SurfaceType
     {
         Opaque,
         Transparent
     }

 public enum BlendMode
 {
     Alpha,
     Premultiply,
     Additive,
     Multiply
 }
 
 public Material wallMaterial;
 

 public void ChangeWallTransparency(bool transparent)
 {
     if (transparent)
     {
         wallMaterial.SetFloat("_Surface", (float)SurfaceType.Transparent);
         wallMaterial.SetFloat("_Blend", (float)BlendMode.Alpha);
     }
     else
     {
         wallMaterial.SetFloat("_Surface", (float)SurfaceType.Opaque);
     }
     SetupMaterialBlendMode(wallMaterial);
 }

 void SetupMaterialBlendMode(Material material)
 {
     if (material == null)
         throw new ArgumentNullException("material");

     bool alphaClip = material.GetFloat("_AlphaClip") == 1;
     if (alphaClip)
         material.EnableKeyword("_ALPHATEST_ON");
     else
         material.DisableKeyword("_ALPHATEST_ON");

     SurfaceType surfaceType = (SurfaceType)material.GetFloat("_Surface");
     if (surfaceType == 0)
     {
         material.SetOverrideTag("RenderType", "");
         material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.One);
         material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.Zero);
         material.SetInt("_ZWrite", 1);
         material.DisableKeyword("_ALPHAPREMULTIPLY_ON");
         material.renderQueue = -1;
         material.SetShaderPassEnabled("ShadowCaster", true);
     }
     else
     {
         BlendMode blendMode = (BlendMode)material.GetFloat("_Blend");
         switch (blendMode)
         {
             case BlendMode.Alpha:
                 material.SetOverrideTag("RenderType", "Transparent");
                 material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.SrcAlpha);
                 material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.OneMinusSrcAlpha);
                 material.SetInt("_ZWrite", 0);
                 material.DisableKeyword("_ALPHAPREMULTIPLY_ON");
                 material.renderQueue = (int)UnityEngine.Rendering.RenderQueue.Transparent;
                 material.SetShaderPassEnabled("ShadowCaster", false);
                 break;
             case BlendMode.Premultiply:
                 material.SetOverrideTag("RenderType", "Transparent");
                 material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.One);
                 material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.OneMinusSrcAlpha);
                 material.SetInt("_ZWrite", 0);
                 material.EnableKeyword("_ALPHAPREMULTIPLY_ON");
                 material.renderQueue = (int)UnityEngine.Rendering.RenderQueue.Transparent;
                 material.SetShaderPassEnabled("ShadowCaster", false);
                 break;
             case BlendMode.Additive:
                 material.SetOverrideTag("RenderType", "Transparent");
                 material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.One);
                 material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.One);
                 material.SetInt("_ZWrite", 0);
                 material.DisableKeyword("_ALPHAPREMULTIPLY_ON");
                 material.renderQueue = (int)UnityEngine.Rendering.RenderQueue.Transparent;
                 material.SetShaderPassEnabled("ShadowCaster", false);
                 break;
             case BlendMode.Multiply:
                 material.SetOverrideTag("RenderType", "Transparent");
                 material.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.DstColor);
                 material.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.Zero);
                 material.SetInt("_ZWrite", 0);
                 material.DisableKeyword("_ALPHAPREMULTIPLY_ON");
                 material.renderQueue = (int)UnityEngine.Rendering.RenderQueue.Transparent;
                 material.SetShaderPassEnabled("ShadowCaster", false);
                 break;
         }
     }
 }
 }

You can't change in runtime the surface type to transparent in urp/lwrp, when you do it from the inspector during play mode, the editor is cheating so you can play with it and after do it properly.

The right thing to do is have a material with the transparency already set up. Then you copy the properties from the opaque to the transparent with Material.CopyPropertiesFromMaterial and pass the transparent reference to the render.

 public class Item : Monobehaviour
 {
        public Material transparentMaterial;
        
        private void SetModeTransparent()
        {
               MeshRenderer renderer = GetComponent<MeshRenderer>();
               Material originalMat = renderer.sharedMaterial;
               Material materialTrans = new Material(transparentMaterial);
               materialTrans.CopyPropertiesFromMaterial(originalMat);
               renderer.sharedMaterial = materialTrans;
        }
 }

Anyone ? :)

How did you get your question to be approved? I've been waiting for ages but nothing. How long did it take?