Vray Blend mtl with different displacement maps

[Mnietek2707]

Any news about blending displacement? It's just strange - some attributes of material are blended and some are not. Why???

[Mnietek2707]

Yes, MANUEL_MOUSIOL is correct. Though, it's on our to-do list for a future update to implement blending of the displacement maps of the sub-materials in the VRayBlendMtl.

that was 3 years ago ...

[markus_s_cg]

+1

Bumping this thread! A Blend material where you could blend displacement maps would make it much easier! Could it be implemented in V-ray 5 before the next upgrade cycle, pleeeeaaaase?

[markus_s_cg]

Also Vray distance tex doesn't seem to take V-ray displacement into account, or does it?

[matanov]

Do you expect the displacement blend to work as the rest of the materials' components (to actually blend between layers) OR to add the values of each layer on top of the previous one (additive)?

The first one seems more logical deriving from how the rest of things work.

p.s. this change will be a part of Update 2

[^Lele^]

Before you answer, i'd like to lay out two of the possible scenarios.

a) The displacement is *always* either blended or additive.
In this case, when the blend shader is of the opposite kind (i.e. additive displacement, but blended shader), the masking may break.
b) The displacement follows the main blend shadermode.
This would mean that the whole shading would have to be set to either blended or additive so to have the displacement blended or additive.

[MANUEL_MOUSIOL]

Definitely blend!

[Muhammed_Hamed]

I think Blend

[KushKush]

Before you answer, i'd like to lay out two of the possible scenarios.

a) The displacement is *always* either blended or additive.
In this case, when the blend shader is of the opposite kind (i.e. additive displacement, but blended shader), the masking may break.
b) The displacement follows the main blend shadermode.
This would mean that the whole shading would have to be set to either blended or additive so to have the displacement blended or additive.

I think option B? I sounds like it makes sense, at least if I understood it correctly.

[^Lele^]

I have left one part implicit, for option B: if one wanted additive displacements, and used the shader in additive mode, there would be no practical way to ensure energy preservation for the resulting shader.
One could, in practice, make a shader which bounced more light than fell on it, and that would lead to problems at rendertime.

While for some simpler shaders (i.e. diffuse plus specular) a furnace lighting test (i.e. fully white, 1.0f dome.) would suffice in (manually) ensuring energy preservation, for other shaders (f.e. SSS) is nigh impossible to ensure it visually only.

The issue doesn't exist when the mode is set to blend (as components never go above 1.0f).

[caypiranha]

Before you answer, i'd like to lay out two of the possible scenarios.

a) The displacement is *always* either blended or additive.
In this case, when the blend shader is of the opposite kind (i.e. additive displacement, but blended shader), the masking may break.
b) The displacement follows the main blend shadermode.
This would mean that the whole shading would have to be set to either blended or additive so to have the displacement blended or additive.

can´t be both scenarios combined in one node, and be chosen by radio buttons for instance, wich way to go? There will be any need for both of them

[^Lele^]

It could surely be made into a separate option.
I see two issues with it, however:
a) It's highly inelegant.
Looking at Arnold, rMan and such, they have a dedicate displacement port for their shader description (typically it's surface, volume, displacement), and the mixing is done so to plug one displacement texture in it.
The rest of the shading is piped into a different port, so surface shading is blended in one place, and displacement is blended in another.
You will notice this is essentially analogous to mixing the displacements and piping them inside the displacement modifier (or in the base material's displacement slot).
b) When the blending modes for "surface" and "displacement" differ, be it with an option or not, the masking done for surface may (and very likely will) not work as well for the displacement (one will be blend, the other additive.).
We don't have a separate set of layers for displacement masking, and that too looks just not very elegant tome, somehow added to the set of normal surface layers. (disp map inside the shaders, masking outside. ugh.).

My thoughts are that we should stick to the Blend, as it seems to be the reason why it's being requested (Megascans, f.e.).
If we truly wanted to make this a viable option, we should perhaps rethink the way the blend material works (i.e. more along the lines of the other engines / Maya), which isn't trivial.

I am still unconviced it is a necessity, mind you.
It could surely be QoL to some, but it can be done today without the option in the Blend shader.
The separate displacement masking also allows for precise control, the displacement modifier is intelligent enough to not create triangles where there is no displacement, and the vraybitmap loaders are efficient at caching the mask inputs in case of reuse, regardless of the maps being instanced, so it's not particularly wasteful an approach either.

[KushKush]

My thoughts are that we should stick to the Blend, as it seems to be the reason why it's being requested (Megascans, f.e.).
If we truly wanted to make this a viable option, we should perhaps rethink the way the blend material works (i.e. more along the lines of the other engines / Maya), which isn't trivial.
.

Perhaps Chaos Group should rethink a long term solution/addition to displacement behaviour. Sure it's not going to be ready soon but it's something that I feel may come as useful when compared to other render engines.
About the blend displacement, I'm curious if the blend disp would work seamlessly with stochastic tiling blending. (Vray uvw randomizer)
Anyway I'm excited for the update, it sounds like it may make workflow a simpler.

[matanov]

Perhaps Chaos Group should rethink a long term solution/addition to displacement behaviour. Sure it's not going to be ready soon but it's something that I feel may come as useful when compared to other render engines.

Can you elaborate on this?

About the blend displacement, I'm curious if the blend disp would work seamlessly with stochastic tiling blending. (Vray uvw randomizer)

You mean like having the same displacement map for all sub-blend mtls?

[KushKush]

Can you elaborate on this?

I meant to say that perhaps the Chaos Group should continue to develop the displacement in 3ds max, adding new options/features such as support in the interactive renderer and GPU support. Lele mentioned the suggestion of looking at a long-term solution to blend material so I figured out maybe not only blend material but also how displacement works. I like Vray for its simplicity and user-friendly, I don't want to find myself in the future jumping between renderer engines just because one feature is underperforming compared to the other renderer engine.

You mean like having the same displacement map for all sub-blend mtls?

I meant to say, if there are multiple displacement maps are blended and then scattered with stochastic tiling, would it create a sort of seams with two different seamless displacement textures blended. If that makes sense.