Standard Shader emission checkbox

Using 2017.1, the standard shader now has a checkbox for "emission".



The manual does not discuss this checkbox.
https://docs.unity3d.com/Manual/StandardShaderMaterialParameters.html

Is this now some type of optimization to uncheck "Emission" if the material is not emissive?

What is the difference between unchecking "Emission" vs having it checked with black emission color?

 

You could just look at the shader code ...

Code (CSharp):

1. half3 Emission(float2 uv)
2. {
3. #ifndef _EMISSION
4.     return 0;
5. #else
6.     return tex2D(_EmissionMap, uv).rgb * _EmissionColor.rgb;
7. #endif
8. }

 

I have also question.
How can I Emission checkbox in standard shader, enabled via script?
In runtime, I want to Emission checked in script.

material.EnableKeyward("_EMISSION")?

I tried but it didn't work.

 

Keyward! => Keyword

It should work!

Code (CSharp):

1.  gameObject.GetComponent<Renderer>().material.EnableKeyword("_EMISSION");

https://docs.unity3d.com/Manual/MaterialsAccessingViaScript.html