(Solved) Blender Eevee glass shader atifacts.

kanga

Hi!
Blender 2.8 stable. Win 10
Liquid inside a glass is throwing strange artifacts. Its an Evee render with a standard HDRI. Deleted the bottle but the problem remained. Increading the geometry vertically also had little effect besides raising and lowering the artifact. Any ideas appreciated.

Cheers

Zablorg

Obvious things first- is the liquid geometry contiguous, and are the normals as you'd expect?

kanga

Hi Zablorg. Yes the normals are facing the right way and the mesh is hollow.

throttlekitty

When you say "Deleted the bottle but the problem remained", you mean that you get the same artifacts when rendering the liquid mesh by itself? If you put this shader on a cylinder of similar size what happens?

edit: This looks maybe like a sorting issue, but I don't know enough about blender/eevee to really help here. Searches aren't turning up much for me.

Eric Chadwick

Looks like the kind of errors you get when alpha blending multiple meshes within the same primitive. 

Try detaching the liquid into multiple models. Then try manually re-ordering the mesh parts, by vertex order, back to front. 

Some info here that might help.
http://wiki.polycount.com/wiki/TransparencyMap#Sorting_Problems

kanga

Thanks guys!
@throttlekitty yes I separated the meshes into 2 objects. No joy.
@Eric Chadwick Thanks for the link!

Seems it is a shader issue. I found the solution is here:  https://blenderartists.org/t/realistic-glass-in-eevee/1149937 Eric Klein put up a description and the shader on gumroad. Appended the shader and it was super for the glass. Could not tint the liquid inside tho.  Eric put up an image (older shader) and that one did the trick for the fluid.

Marking this one as solved.
Thanks again. Cheers

Eric Chadwick

I wonder if Blender's "Hashed Alpha" is actually "Alpha to Coverage"?
http://wiki.polycount.com/wiki/TransparencyMap#Alpha_To_Coverage

RN

I think it might be yet another name for the dithered / stippled alpha (http://wiki.polycount.com/wiki/TransparencyMap#Screen_Space_Stipple), since EEVEE uses deferred shading.

@kanga are you sure that was an improvement? The fluid now seems solid, like mercury, instead of translucent (or maybe it's difficult to see without any objects behind it).

kanga

Hi Eric. Actually Hashed alpha gives the most attractive results look wise if it were not for the rastered result.
Hi RN.
Had another look at the shader and its for cycles. Still using it in eevee seems ok. I can get different intensities by changing the Blend mode. After more noodeling it seems for the fluid inside just a standard shader with an alpha blend mode and metalic turned up, works fine

The alpha blend is the best so far, but it still has artifacts, like the first image I posted.