This is a material that I’m working on but something seems to be wrong.
I’ve used 2.79 and 2.8 but the Cycles Render in 2.8 is a complete mess.
This is thge node setup I’ve used in both.
This is Eevee.
Does anyone have an idea what it could be?
While creating the material in 2.8. Blender crashed a lot and it had something to do with the displacement.
If the viewport and F12 render look differently in this regard, likely is a bug. What might make a difference is the settings for the subdivision rates for Preview and Render in the Geometry tab. Maybe you can set these to the same value and check again, (if not done so already).
Something changed. Note how the displacement input socket is now blue. It now supports vector displacement. Try using the Vector/Displacement node, which has grey inputs that accept you float/color input.
I was checking the nodes in 2.79 nightly build, can’t fire up 2.80 right now. Node names may be different.
It looks like a bug where grey input considered as first channel in vector displacement (or maybe you need to convert grey input via some new node before feeding it to displacement output).
That’s not a bug. There’s a separate Displacement node now. Or you can just multiply it by the normal vector if you like.
Ah, right. The problem is probably that he was using a color value for input. If it were a scalar value, 2.8 should automatically insert a Vertex Displacement node.
Thanks for the help. The vector displacement node seems to do the trick. It is not the same but with some tweaks here and there could be. Thank you all. 
Hi I am new to Blender, may I know how actually u solve this problem using the vector displacement node?
Thanks for reply!!
Hi. I would need to know what you are trying to achive. Can you post a pic of your node setup so I can see how I can help. 
Thanks a lot. I would like to do the glowing crack on my material surface, when I follow the tutorial, the multiply node do not show the same result in the tutorial. As you can see, it end up become the way it looks in the preview.
Can you upload the Blend File so that I can directly look at it. I cant recreate it as it is, because I dont have all the textures you are using.
Hi.
https://docs.blender.org/manual/en/latest/render/cycles/materials/displacement.html
Displacement, bump or both options are in Material tab, Settings, Surface, etc
Remember that for Displacement what Blender Manual says: It requires the mesh to be finely subdivided
I would like to create something similar to these, but the cracks doesnt show the depth . and i would like to add in glowing effect in the cracks.
Thanks for reply !!
Here is what I`ve got so far but it is not quite as in those 2 videos.
Glowing cracks
Glowing cracks with simple edge glow.
Edge glow.
Low light render with reflections.
Here the node setup used. It is for Blender 2.8.
Thanks for helping me !! The glowing cracks u did was enough for me right now.
I will try more methods to get the result i most wanted.
Thanks again!
No problem. I`m glad that I could help.
Can I ask why you are using Vector Displacement node instead of Displacement node?
I have understood that Vector displacement maps are to achieve things like these:
https://docs.arnoldrenderer.com/display/A5AFMUG/Vector+Map
For no particular reason just used it because last time I used it, it worked. 
Now that you have mentioned it, I’ve compared those 2 nodes and realized that Vector Displacement Node when the light source is hitting the object inverts the displacement and Displacement Node doesn’t do that.
So, in this case, it would be better to use the Displacement Node.
Displacement Node
Vector Displacement Node
I have to look a bit at those two and learn more about the way they displace the surface. 
Thank you for pointing that out. 
Displacement node is explained in link to Blender manual that I had shared above:
https://docs.blender.org/manual/en/latest/render/cycles/materials/displacement.html
Here is a simple example of the possibilities (Blender 2.8):
displacement_node.blend (898.9 KB)
You change to Cycles “Rendered” view. The first is Bump Only, the second Displacement Only and the third both (as you can see in Material tab). In each of them you play decreasing the levels of subdivisions in Subdivision Surf Modifier to see what happens, while you are in Rendered view.
Also as Cycles experimental feature, you have Adaptive Subdivision:
https://docs.blender.org/manual/en/latest/render/cycles/settings/objects/adaptive_subsurf.html
