How to save emissive Material assets using "_EMISSION" keyword by script?

Question

I have an editor script that generates emissive Material assets using the Standard shader. This works by first creating a temporary Material, then enabling the keyword "_EMISSION" and finally saving the asset using AssetDatabase (example code below).

  public static class EmissiveMaterialCreator
  {
      [MenuItem("Debug/Create Emissive Material Asset")]
      public static void CreateEmissiveMaterialAsset()
      {
          Material material = CreateEmissiveMaterial();
          AssetDatabase.CreateAsset(material, "Assets/EmissiveMaterial.asset");
      }
      private static Material CreateEmissiveMaterial()
      {
          Material material = new Material(Shader.Find("Standard"));
  
          material.name = "Emissive Material";
          material.color = Color.white;
  
          material.EnableKeyword("_EMISSION");
          material.SetColor("_EmissionColor", Color.blue);
  
          return material;
      }
  }

However when using this script, the asset created doesn't have an enabled toggle at the property "Emission", and the material does not render correctly in the scene and during GI baking.

I realized when playing with the asset file that toggling this property manually in the inspector, a property "m_LightmapFlags" in the file changes from 4 to 2, but when created by script this value is never set to 2, which would enable to "Emission" toggle.

  %YAML 1.1
  %TAG !u! tag:unity3d.com,2011:
  --- !u!21 &2100000
  Material:
    serializedVersion: 6
    m_ObjectHideFlags: 0
    m_CorrespondingSourceObject: {fileID: 0}
    m_PrefabInstance: {fileID: 0}
    m_PrefabAsset: {fileID: 0}
    m_Name: EmissiveMaterial
    m_Shader: {fileID: 46, guid: 0000000000000000f000000000000000, type: 0}
    m_ShaderKeywords: _EMISSION
    m_LightmapFlags: 4
    ...

My question now is how should I proceed to change this property so that the materials get saved properly ?

Answer 1

Best Answer

Answer by JulienEmoko · Mar 29 at 12:20 PM

The solution is to set the field globalIlluminationFlags of the Material to whichever value is required. In my case, the emission has to be baked, so the value to set is BakedEmissive.

Tip : if the material is not emissive, the value would be EmissiveIsBlack.

 private static Material CreateEmissiveMaterial()
 {
     Material material = new Material(Shader.Find("Standard"));
 
     material.name = "Emissive Material";
     material.color = Color.white;
 
     material.EnableKeyword("_EMISSION");
     material.globalIlluminationFlags = MaterialGlobalIlluminationFlags.BakedEmissive;
 
     material.SetColor("_EmissionColor", Color.blue);
 
     return material;
 }

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How to save emissive Material assets using "_EMISSION" keyword by script?

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