# Control the amount of gloss and reflection separately in a glossy BSDF material?

I can control the glossiness/reflectiveness of a material by mixing a glossy BSDF with a diffuse BSDF and setting the mix ammount, but in that case glossiness/reflectiveness are linked. Is that so because they are linked in real world? The more shiny, the more reflective, no exceptions, is that how it works? How can I control them separately?

The material is used on a plane which is the floor for an architectural visualisation. Generally I would like the scene to be realistic but with the floor and background I'd prefer not to have the limitations of real world. What I need is to be able to finetune the amount of reflection on the floor while controlling separately the intensity of highlights/gloss made by lights.

• Use the roughness value – someonewithpc Aug 19 '14 at 12:16
• Roughness blurrs out both reflections and glossiness the same. I'd need a separate roughness value for the two... – Booth Aug 19 '14 at 12:25
• So if I understand correctly, you want to control specular highlights from lamps separately from reflections of other objects? – gandalf3 Aug 19 '14 at 19:38
• @gandalf3 That's right. At the moment, if I set roughness value to blurr specular highlights from area lights just like I wish, then reflections are blurred out far too much - they are almost unnoticable. – Booth Aug 20 '14 at 12:41
• See this wiki.blender.org/index.php/Dev:2.6/Source/Render/Cycles/… , it says that Glossy BSDF's are unified for direct and indirect light, as in the real world. An option should be added to control the amount of indirect light a closure contributes, so that glossy shaders can be used without being a glossy mirror. ; So I don't think it's possible – someonewithpc Aug 20 '14 at 12:49

At the moment, the reflection and the specular highlight are a part of the same ray (reflection rays) and thus there is no way to separate them, or control attributes for either of them separately.

As someonewithpc pointed out in the comments, it is sort of planned to be implemented at some point:

Glossy BSDF's are unified for direct and indirect light, as in the real world. An option should be added to control the amount of indirect light a closure contributes, so that glossy shaders can be used without being a glossy mirror.

If you would like your entire scene to only show specular highlights and no reflections (i.e. only direct reflections of light sources), simply turn the glossy bounces down in the light paths panel:

• I see you can read my comments... – someonewithpc Aug 21 '14 at 10:18
• I read that the input node Light Path can be used to stop a material from casting shadows for example. I can see this node has Is Glossy Ray and Is Reflection Ray slots separately. Could this be used somehow to make my floor plane receive reflections but not receive/only receive a reduced ammount of specular highlights? Or use this node on the area light's shader instead of the floor material to achive the same result? – Booth Aug 23 '14 at 10:37
• No, the light path node does not help here. Is Glossy Ray indicates if the reflection (or transmission) is sharp or soft. A specular highlight is just a reflection of a light rather than a mesh. The terminology in Cycles for the distinction you want is direct/indirect light, but no controls for that exist at the moment. – brecht Sep 21 '14 at 11:22

I figured it out just recently. I was looking for more or less the same thing, only for a black marble. This black marble that I usually created in Bryce consisted of white everything, but the Diffuse and Ambient values dropped to 0, full Specularity and 10% Reflectivity. Now, how to translate that to Blender Cycles?

Add two Glossys, where the first ones color is a ColorRamp. In this ColorRamp ranging from Black to White, set the Black to 0.900, and the Fac to 0.902. Change the roughness of this Glossy to smooth out the Highlight. The second ones color is basically 0.010 on all RGB values (or #202020 in Hex). This one controls the reflectivity.

Hope this has been helpful to you.

Don't know if it's what you're meaning, but i always mix my glossy with an emission shader set to black, 0 strength. The glossy controls the sharpness of the reflections, the mix shader controls the influence of that gloss on the total image. Then on the mix shader between diffuse and glossy I use a layerweight node routed through a rgb curves node as the mix. This way I have as simple or complex control over the range of the mesh the reflections occur. I've made this setup a default material in my materials.blend file for appending to my projects. Just add the finer details like textures, bumps, normals, and the kitchen sink and it all just works pretty well.