2
$\begingroup$

I was downloading some random blender files for a project and I came across this strange piece. http://oscar.iitb.ac.in/enlargedimage.do?fileid=PH_Con01&filename=Connecting%20Wire&subject=Physics&cycles=cycles

For some reason the metal shader is this: enter image description here

This is what the render looks like: enter image description here

Is there any reason to have a semitransparent metal?If not, what should I replace it with?

$\endgroup$
  • $\begingroup$ It all depends on what you are trying to do. $\endgroup$ – user1853 Sep 26 '16 at 20:35
  • $\begingroup$ @cegaton Check my edit. $\endgroup$ – 10 Replies Sep 26 '16 at 20:37
1
$\begingroup$

That glass node does seem like a really strange choice. I can't imagine why they'd have chosen that.

If you're looking to create a basic metal shader, you would replace the glass node with a diffuse node, and for bonus points

...with another glossy shader. Then add a fresnel node (from the input section) and plug it into the fac slot on the mix node. You'll set the roughness value of both glossy nodes to about where you want them (looks like you want them pretty high, around 2.0 or so), and then adjust the glossy that's in the top slot to something lower than the other glossy (I'd start with half of whatever the other one is). This gives the proper effect of making the object slightly more reflective when viewed at a shallow angle. [Thanks 10 Replies]

It's not the perfect setup, but it's better than what the download gave you ;-)

$\endgroup$
  • 3
    $\begingroup$ I was taught (by andrew price) that you shouldn't use diffuse with metal unless the metal is mostly rust or paint. $\endgroup$ – 10 Replies Sep 26 '16 at 21:11
  • $\begingroup$ Oh that's true. I'd forgotten that metal shaders are weird that way. $\endgroup$ – Matt Sep 26 '16 at 21:20
  • $\begingroup$ Nice edit :D, thats a pretty good idea with the two glossy shaders! I had always wondered how to do fresnel with metal objects. $\endgroup$ – 10 Replies Sep 26 '16 at 22:40
  • 2
    $\begingroup$ 2 glossy nodes are over-complication that is not needed. It only adds render time and complexity. The correct way is to alter the glossy node color value with fresnel output - these 2 setups are equal: i.stack.imgur.com/Eqh7B.png $\endgroup$ – Jaroslav Jerryno Novotny Sep 27 '16 at 6:59
  • $\begingroup$ No, that's not physically correct. You've mixed the color, not the roughness. Glossy (opaque) objects become more reflective at shallow angles because the shallow viewing angle compresses irregularities making the object appear smoother, not because the object is a different color. This is certainly a valid setup if you want to change the color of the material, but it's not physically correct. $\endgroup$ – Matt Sep 28 '16 at 16:36
4
$\begingroup$

Glossy shader alone doesn't indicate metal - it indicates reflection. So it is very common in shader node groups because every material is reflective one way or another (except of some vantablack, emissive materials, etc.)

However the shader you presented is not physically correct - thus it is an example how not to construct shaders.

You don't want to mix in glossy node through mix-node with constant mixing factor - you need to mix in glossy through fresnel:

How do I create a reflective white material?

When you have a rough surface you need a specially constructed Fresnel node that accounts for the roughness (image borrowed from blenderguru but original credit goes to cynicatpro):

enter image description here

So if you add a glossy node correctly to any material (shader), you are just adding another layer of reflection - basically you are adding a clear coat - you are layering.

On some materials this makes little to no sense - like on glass. It makes a look of heavier glass - this can be achieved with IOR better.

If you need a metal shader, you are good to go with one glossy shader. Metals don't have any diffuse component:

enter image description here

This is as complicated as you will probably ever need. It has a metal rim color control and metal IOR control which you can unplug and remove for simplicity.

$\endgroup$
  • $\begingroup$ Shouldn't roughness be affected by fresnel as well? When a metal is viewed from the side the reflection is clearer. $\endgroup$ – 10 Replies Sep 26 '16 at 21:27
  • 1
    $\begingroup$ @10Replies Nope, it's vice-versa - fresnel is affected by roughness. Roughness is constant across the surface (or driven from texture), whereas fresnel is view and roughness dependent. The amount of reflection is solved with varying color value of the glossy node based on fresnel values - no need to use 2 glossy nodes. 2 glossy nodes add render time (every shader node does). $\endgroup$ – Jaroslav Jerryno Novotny Sep 27 '16 at 6:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.