Flag to toggle backface culling?

Hey all,
I wrote a transparent shader which I use for things like gold coins, chests ect...

By default the shader has "Cull Back" so that the backside of the object doesn't render, but for some of the objects, I need to turn culling off, "Cull Off". Right now I have 2 copies of the same shader, 1 with culling on and 1 with culling off.

I don't particularly like the fact that I need 2 identical shaders just to toggle backface culling, so I would like to add a property to the shader, for example "_CullOff", which would be a slider, from 0 to 1 (0 = Cull Off, 1 = Cull Back), so that I can use the same shader for 2 different materials, and toggle culling with the exposed property.

Is there another way to toggle culling in a shader without using "Cull Off/Back" in the Pass? It would be nice to be able to toggle culling at runtime too...I just don't know how to do that.

Thanks in advance for your help!
Stephane

 

I don't think so, pre-processor stuff doesn't work outside of the CGPROGRAM block.

 

That's what I was afraid of...can anyone confirm this?
Thanks Farfarer!

 

You could write the shader in a CGINCLUDE block and then just define the passes, but there's no easy way to choose between subshaders / passes either

 

True, good idea though
Thanks for the help guys.

 

I know this thread is very old; but it was the first result on my google search and I will probably forget how to do it and need it again so:

Code (CSharp):

1. Properties
2. {
3.     // add selector inside properties:
4.     [Enum(UnityEngine.Rendering.CullMode)] _CullMode("Cull Mode", Int) = 0
5. }
6. SubShader
7. {
8.     // set cull mode inside subshader:
9.     Cull [_CullMode]
10. }

 

You are a legend.
I am now wondering how many other switches can be implemented using this method.

 

You can also do it with ZTest:

Code (CSharp):

1. Properties
2. {
3.     [Enum(UnityEngine.Rendering.CompareFunction)] _ZTest ("ZTest", Float) = 0
4. }
5. SubShader
6. {
7.     ZTest [_ZTest]
8. }
9.  

I guess it can also be done with blend, there is UnityEngine.Rendering.BlendMode enum, but I haven't tried it.

 

Here are the ones I know of:

Code (CSharp):

1.  
2. [Enum(UnityEngine.Rendering.BlendMode)] _Src ("Source Blending", Float) = 1
3. [Enum(UnityEngine.Rendering.BlendMode)] _Dst ("Destination Blending", Float) = 1
4. [Enum(UnityEngine.Rendering.CompareFunction)] _ZTest("ZTest", Float) = 0    
5. [Enum(UnityEngine.Rendering.CullMode)] _CullMode("Cull Mode", Int) = 0
6. [Enum(UnityEngine.Rendering.CompareFunction)] _StencilComp ("Stencil Comparison", Float) = 3
7. [Enum(UnityEngine.Rendering.StencilOp)] _StencilOp ("Stencil Operation", Float) = 2
8.  

You can probably find more if you look through the UnityEngine.Rendering documentation; they are accessible in c# as well.