What are Keywords and How do I utilise them?

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Hi, pretty much as the title says

There are lines in some of the built in shaders like this :

 SubProgram "gles " {
 Keywords { "DIRECTIONAL" "LIGHTMAP_OFF" "DIRLIGHTMAP_OFF" "SHADOWS_OFF" }
 "!!GLES

I'd like to know how this works and what they mean if possible, I've removed them completely and nothing happens, I've tried to access them via Shader.EnableKeyword("SHADOWS_OFF"); but nothing seems to happen

Thanks in advance :)

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Answer by tanoshimi · Sep 17, 2013 at 01:05 PM

You can add custom keywords to a shader using the #pragma directive:

 #pragma MY_KEYWORD

You can then add conditional code within the shader based on whether the keyword is defined, as:

 #ifdef MY_KEYWORD
 ...
 #endif

And you can change the keyword from script, using

 Shader.EnableKeyword("MY_KEYWORD");
 Shader.DisableKeyword("MY_KEYWORD");

If you have multiple keywords and need to generate versions of your shader for each permutation of those keywords, use multi_compile:

 #pragma multi_compile KEYWORDA KEYWORDB

Note that, in your example, Shader.EnableKeyword("SHADOWS_OFF"); does nothing because it is already enabled. You need to Disable SHADOWS_OFF (I often find double negatives in these sorts of things)

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Exalia · Sep 17, 2013 at 01:08 PM 0

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Thanks! I'll have a play around with it, it makes sense why my example didn't do anything. Thanks again :)

What are Keywords and How do I utilise them?

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