Energy Conserving Blinn-Phong

Well, might as well get this out there.

This is an "energy conserving blinn-phong" bumped specular shader. It allows for tight highlights and easy material definition ... ... Oh just have a webplayer!

WEBPLAYER

There is also an alternate shader that allows you to bind the three control values to a texture.

Shaders are attached.

Ugly screenshot time!


Shader Time!
View attachment $Finished Shaders.unitypackage

 

Does anyone know how change the thread title in this forum?

 

IIRC you need to get an admin to do it, maybe ask Aurore?

 

Ah well it doesn't really matter.

 

Thanks, this shader looks cool

 

What is an "energy conserving shader"?

 

the energy of light bouncing out of the surface of the material, should never exceed the energy of the incoming light . Just like in real life.

Diffuse + Reflection + Refraction <= 1.

 

Doh I thought it was already like that for common shaders...

 

No it isn't. You can see this, in the standard shaders, as at low Shininess levels the highlight is the same brightness as at a high shininess. So let's say a brightness of 1 covers 50 pixels. And then at lower gloss that same brightness (1) covers something like 150 pixels. And because diffuse is always the same here, you end up with something like...
150 = 50
which obviously isn't true.

 

Very cool shader man! Here are some comments.

I'd prefer the diffuse contribution to be consistent with gloss, spec and metalness set at 0. You can see in this image where I have 4 shaders, pure white, neutral grey (128rgb), your shader and one set to 100% env reflection. For some reason, the lighting on your shader is a bit flat, so the object loses form.


This is also evident when cranking up the spec and gloss. They look great, but the lowered diff contribution flattens out the object.


What I really like about this shader is that it's starting to push toward what UE4 is doing with their new physical material system - which is amazing BTW! In addition to tuning the diffuse contribution to make that feel more correct, I would consider adding in a cubemap reflection which is modulated by the spec and gloss. You could blur the cubemap by using its mips to generate a less reflective surface when dialing down the gloss.

Actually, UE4's physical material system deals with it this way. The primary modulators in their shader are "Roughness" and "Metallic". They have Specular right now, but are probably going to remove it soon.

Roughness describes how the surface scatters specular reflections on a micro level. It is the factor that determines how much reflection comes from the surface and to what degree it is blurred. Metallic controls the diffuse light spread and color reflection.

In reality, almost all surfaces have reflective qualities, so their new physical material system is based on that notion.

Lastly, rather than manually plugging in a cubemap, UE4 automatically samples light probes with cubemaps in the environment and blends between them as objects move about the scene. It would be cool to eventually implement something like this in Unity as well.

 

Hmm... A shader based on roughness and metalness you say??

...
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Also, the reason the lighting on my shader is a bit flat is, to conserve energy in a lamberian model you have to divide the diffuse by pi. So to get the same brightness, you would have to have a light intensity pi.

 

You had me at "Hello". I have no clue what that means but great work guys!

 

Does anyone know how Unreal get their diffuse contribution? Is it a simple lerp(lambert, awesome reflective), or is it more complicated than that?
Also screen shot of the shader 2.0:


There are no directional lights in the scene.
NOTE: I have had to make the shader, shader model 3.0 +
WEBPLAYER

Go fullscreen and right click to rotate.

 

Actually in 3D graphics that pi is usually simplified out. I do believe Unity does this for their shaders and I do too in my shader package.

 

Ok, good to know. Making the edits as we speak.
Also, now that I look at it, this thread might be more suitable for the WIP forum.

 

Done editing the top one.

 

Thank you for the explanation, dude

 

Just thought that I would post another image. The earlier webplayer has also been updated.
Still no directional lights in the scene.

WEBPLAYER

 

Ok the UDK style shader is here.
https://www.dropbox.com/s/8ka1oh47xxj7i8b/UDKStyleShader.unitypackage

 

Does anyone know how the pro "light probes" system lerp's the coeffs dependent on distance.

 

This is looks great, but the only thing that i still don't understand how the energy conserving shader really behave if it got litted by multiple colored light....

 

Try it out. I am giving these things away.

 

Also, for people who are too lazy (like probably would be ) to download the shader package,
At low metalness: the shader changes the highlight colour based on the light colour.
At high metalness the whole shader get's multiplied by the light colour.

 

Looks great!!

 

I did...it's just i'm still confused how did it actually behave with light

 

You can check out the paper and related notes here:
http://blog.selfshadow.com/publications/s2013-shading-course/
"Real Shading in Unreal Engine 4 (Brian Karis)"