Using GGX instead of Blinn-Phong

I started a blog about advanced graphics programming in Unity, I just wrote a post on how to replace Blinn-Phong by GGX to get a more natural and softer specular highlight in Unity:

http://gfxdevunity.blogspot.ca/2015/05/replacing-blinn-phong-by-ggx.html

For some reasons they replaced GGX by blinn-phong, but most other engines uses GGX. It causes less specular aliasing and it looks a bit more natural.

 

I studied Unity CG include files today and accidentally found fragment of code in UnityStandardConfig.cginc which looks like this:

Code (csharp):

1.  
2. #define UNITY_BRDF_GGX 0
3.  

And in UnityStandardBRDF.cginc

Code (csharp):

1.  
2. #if UNITY_BRDF_GGX
3.     half V = SmithGGXVisibilityTerm (nl, nv, roughness);
4.     half D = GGXTerm (nh, roughness);
5. #else
6.     half V = SmithBeckmannVisibilityTerm (nl, nv, roughness);
7.     half D = NDFBlinnPhongNormalizedTerm (nh, RoughnessToSpecPower (roughness));
8. #endif
9.  

So the simplest way to use CGX is to copy Standard.shader and add one more line in CGINCLUDE block

Code (csharp):

1.  
2. CGINCLUDE
3.         #define UNITY_SETUP_BRDF_INPUT MetallicSetup
4.         #define UNITY_BRDF_CGX 1
5. ENDCG
6.  

Specular lighting changes when you do this. Does it work? I can't visually distinguish CGX and Blinn-Phong

What is actually strange, when I define UNITY_BRDF_CGX, specular highlights look harder, not softer like on your pictures.

CGX:


Blinn-Phong:

 

Yes you are right, it's probably a simpler way to do it. I should have looked into the UnityStandardConfig.cginc file

You seem to use a very low resolution texture, you might wan't to test on something more high res. It will really shows up within my test scene.

I exaggerated one of the roof smoothness a bit to highlight the changes :

 

hey, could you make the "Directional Specular" to GGX too?

 

I uploaded a new set of shaders. It will work with lightmaps:
https://dl.dropboxusercontent.com/u/24044878/Unity/GGXShaders2.zip

 

T

Thank you so much

 

My guess is that they went with Normalized Blinn Phong so that they could have consistent visuals with their mobile PBR path where they use a much lower quality Blinn Phong.

On a related note, if you want better compatibility with tools like Substance Designer and Painter I recommend you set the following:

Code (CSharp):

1. #define UNITY_BRDF_GGX 1
2. #define UNITY_GLOSS_MATCHES_MARMOSET_TOOLBAG2 0

 

I have two additional notes for further improving the mapping to the Substance tools.

First, you should change the _Metallic property from:

Code (CSharp):

1. [Gamma] _Metallic("Metallic", Range(0.0, 1.0)) = 0.0

to:

Code (CSharp):

1. _Metallic("Metallic", Range(0.0, 1.0)) = 0.0

Second, you need to make sure that your metalgloss maps' import settings are set to "Advanced" and check "Bypass sRGB Sampling".

 

so simple, yet so effective... thanks for posting this! makes a huge difference.

 

where I can find those codes? i use unity 5.0.1p3

 

@minhdaubu2
Download the archive from the first post in this thread, then you can patch the shader file and the config header.

 

I did it, but i only see that in "GGX-Standard.shader"

 

@minhdaubu2
In "GGX-Standard.shader" find the "_Metallic" property and change it to this:

Code (CSharp):

1. _Metallic("Metallic", Range(0.0, 1.0)) = 0.0

In "UnityStandardConfig.cginc", find "UNITY_BRDF_GGX" and "UNITY_GLOSS_MATCHES_MARMOSET_TOOLBAG2" and change them to this:

Code (CSharp):

1. #define UNITY_BRDF_GGX 1
2. #define UNITY_GLOSS_MATCHES_MARMOSET_TOOLBAG2 0

Finally, any time you use a metalgloss map make sure you set its import settings to "Advanced" and check "Bypass sRGB Sampling".

 

-Thank so much

 

@n00body what about Alloy shaders? do they natively agree with Substance Painter shader?

 

@modar
Yes, we use the exact same material inputs as Substance Designer/Painter, and even provide preview shaders for each tool to maximize the quality of the transfer.

 

@n00body
Great! so you are telling that I should get the same results of SP in unity if I use Alloy and the same skybox? sounds very tempting

 

@modar
It's not 100% the same, since Unity precomputes and stores its reflection probes while the Substance tools use importance sampling. However, we've found that it is a pretty close match.

Check out the crash course video if you want to see how Alloy works:

 

Now all we need is Alloy for mobile

 

@zyzyx
Hopefully once OpenGL ES 3.0 hardware is more prevalent, and Unity has figured out how to handle mobile hardware sRGB limitations.

 

Thank you G.Mika for this shaders. GGX looks gorgeous. I managed to replicate scene from UE4 with this. Here is some screenshots that shows the difference. Demo scene build and sources are available here: https://yadi.sk/d/g8lbg3frizHdF