Confusion about Blend Material

[swizzelz]

Hi, I don't know if this is user error or not. But I'm having some trouble getting a Blend Material to act predictably.

I know there have been a couple threads about stacking shaders to get the same effect, and some issues with the bump not working right yet (?). But those threads were started before the blend was implemented, so I'm not quite sure what state it's in

I have a simple blend material with one base and one coat material (simple reflection to emulate a clearcoat). The problem is that the base doesn't seem to be rendering correctly. Only the base shaders diffuse color will render, despite having a reflection map, etc. I can't seem to get any other attributes to work. The coat layer is showing up fine, but if I do anything that allows the base to show through, all I get is its diffuse color.

Is this a known issue? Is there a specific order to stack the materials, and are shader items still needed?

Thanks for any help - loving vray in modo!!

[vladimir.nedev]

The sub-materials of the V-Ray blend material need to be created in the Schematic. They can be put in the Shader Tree, but they won't use any textures defined in there.
The textures must be connected in the Schematic (which requires MODO 801 or later).

You can have many nested V-Ray blend materials, or you can have one V-Ray blend material with sub-materials of the same type. In both of these cases, it is not clear
which of the sub-materials should use the shader tree textures and which should not. Also, you can put a sub-material anywhere in the shader tree, so again it won't
be well defined what group masks should be used to determine the sub-material's textures.

Eventually we might try to do blend materials with sub-materials defined in the shader tree, but it won't be in the initial version for sure.

And of course, you can still use MODO's way of defining a blend material, by using more than one Shader item. Just remember to have the top Shader item have opacity <100%, as otherwise
the V-Ray for MODO exporter will assume it completely masks the Shaders below. This is for performance reasons, as it can be hard to determine whether a material has transparent areas
at export time - determining this will create a lot of edge cases.

The MODO way of defining a blend material can be very useful, if you want to add a coat layer on many different items that have different base materials.
Something which is not easily done in other software (3dsMax, Maya), and requires scripting.

You can combine both ways of course with 2 or more Shader items, with one or more of them having a V-Ray Blend material below them.

Bump mapping should work with the blend material. If you add a texture with "Bump"/"Normal" as the effect, above the blend material, it will affect the normals
for all sub-materials. Or you can connect the bump/normal texture in the Schematic to any of the sub-materials (which can be blend materials as well) to
their "Bump value"/"Normal map" channels.
This post has some screenshots of this :
http://forums.chaosgroup.com/showthr...049#post649049

Greetings,
Vladimir Nedev

[vladimir.nedev]

By the way, can you post screen-shots of how you tried to setup the blend material in the shader tree ?
There have been other suggestions for this, and it will be best if I can consider as many implementations as possible, so I can choose the most
intuitive one, if and when we decide to add this.

Greetings,
Vladimir Nedev

[swizzelz]

Thank you for the clear explanation! That makes perfect sense and I got things working no problem.

I do think it's a little un-intuitive having to go to the schematic for this one special case. I'll be happy to post a screenshot of how I thought it was going to work. Initially I was just guessing, and had all my sub-materials stacked accordingly in one group. I then considered that might be causing some conflicts I wasn't aware of, so I tried organizing them in to groups, which of course didn't work either

I think my second attempt would be a nice solution for people who are already used to the shader tree: the sub-materials would need to be in their own groups so they're clustered with any maps they use. And the Blend Material could be anywhere in the tree, but once it points to the materials, they're part of the Blend and stop affecting anything else (which is what happens now, yes?). That way you still use the shader tree to organize a Blend Material, but you have to do it in a way that is specific/the Blend material understands.

As for doing it the modo way with shaders, I personally prefer the Vray Blend material - because it's one dedicated "node" that I know is blending things on top of each other in a clear way, without having to set it up in the tree and meticulously trouble-shoot if I have something wrong.

Anyway I'll post a screenshot when I can. But I basically described what I did above. Thanks again for your reply! Great get your feedback directly

[vladimir.nedev]

, but once it points to the materials, they're part of the Blend and stop affecting anything else (which is what happens now, yes?)

Actually the sub-materials continue to work normally at the moment. If you don't want them to affect anything by themselves,
you should put them in the new "Nodes" folder that MODO 801 has in the shader tree.

The nice thing about the MODO way of blending materials, and generally with the shader tree, is that you can easily create
a huge number of different materials by using combinations of material tag/part tag/selection tag/object group masks.

Greetings,
Vladimir Nedev

[swizzelz]

I agree, the shader tree can be pretty powerful once you get your head around it.

As for the nodes folder, would I need to put the material items as well as all connected maps for that material there?

Can I simply turn the visibility off for those materials instead?

[swizzelz]

Here's a screenshot.

I simply stacked the material items in the tree the way that made sense for me. Blend on top with the blend amount gradient above that. Below that, the first coat in its own group. And below that, the base material with all it's textures.

Pretty straight-forward I think.

If you can make the Blend Material work without having to open the Schematic, I think that would be helpful and a more direct integration with modos shader tree.

[vladimir.nedev]

As for the nodes folder, would I need to put the material items as well as all connected maps for that material there?

If you don't want the maps to affect anything in the shader tree, yes, you should put them in the "Nodes" folder. It can be further organized
by creating sub-folders in it.

Can I simply turn the visibility off for those materials instead?

You can turn the visibility of materials, but turning off the visibility of textures will actually disable them for the Schematic as well.
Somewhat inconsistent, maybe I should change that.

Greetings,
Vladimir Nedev

[vladimir.nedev]

Here's a screenshot.

I simply stacked the material items in the tree the way that made sense for me. Blend on top with the blend amount gradient above that. Below that, the first coat in its own group. And below that, the base material with all it's textures.

Pretty straight-forward I think.

If you can make the Blend Material work without having to open the Schematic, I think that would be helpful and a more direct integration with modos shader tree.

[ATTACH=CONFIG]24258[/ATTACH]

Actually this setup is something you can use instead of putting materials/textures in the "Nodes" folder.
Because the blend material is on top of the other materials, it will override them, meaning that they and their textures won't affect the shader tree.
Of course, you still need to make the Schematic connections.

If you save a material preset (using MODO's preset system) and then bring it back, it will show up very similar to what you have in
your screenshot, everything that came from the "Nodes" folder, will be put below the blend material in the shader tree.
I don't know why MODO does this, but setting up a blend material like this might break this use-case, so we probably won't do it exactly like this.

Somebody else suggested tagging the "Group mask" item with a special texture effect. So in your case the "Gloss" item will have its
effect set to "vblend Base material" instead of "(all)". You will also need to have another group that has the coat layer textures and material
that has its effect set to "vblend Coat material 1".

We won't do this for the initial release though, I fear it might break stuff, because it's not something the shader tree was designed for.

Greetings,
Vladimir Nedev

[swizzelz]

Interesting, thanks for the help.

As for visibility of textures being used by blend materials, I think it makes sense to me to have the Blend listen to the visibility. Its sort of "respecting" the shader tree logic that way.

Yea, I like the idea of being able to leave things in the shader tree and not moving them down to the Nodes folder. I like the grouping idea, it leaves everything in the shader tree (if you prefer, that is). And, if you changed the group tagging as you described, I think that would take care of all the confusion because the groups would be clearly designated. If the user wants to use that material anywhere else they can utilize the Library or simply duplicate it and move it elsewhere in the tree.

Just a thought, would the user then put that materials own vblend Amount (x) texture (if any) in to it's own group? To use my example, I have a gradient exposing the coat layer. Would I then put that gradient in to the coats group? Maybe it wouldn't matter if that gradient is set to vblend Amount...

Just thinking outloud. Thanks again.

[vladimir.nedev]

Just a thought, would the user then put that materials own vblend Amount (x) texture (if any) in to it's own group? To use my example, I have a gradient exposing the coat layer. Would I then put that gradient in to the coats group? Maybe it wouldn't matter if that gradient is set to vblend Amount...

The "vblend amount (x)" textures should probably be outside the coat's group, as they affect the blend material itself, not the coat material.
And you might have nested blend materials where the material inside the coat's group is another blend material with its own "vblend amount" textures.

Greetings,
Vladimir Nedev

[swizzelz]

Even better... I didn't think about nested materials.

[John_Do]

Hello,

I would like to know if there are still plans to get the V-Ray Blend Material working in the Shader Tree, is it on the todo ? ( by defining sub-materials at the group level )

And I was wondering if there any performance loss by making blended materials in the Modo way ( with Shader items ) rather than with the V-Ray Blend Material ? If yes, what is the order of magnitude ?

Thanks

[vladimir.nedev]

I would like to know if there are still plans to get the V-Ray Blend Material working in the Shader Tree, is it on the todo ? ( by defining sub-materials at the group level )

It's on the todo list, but I am not sure if I will be able to do it at all.
It makes the material export a lot more complicated, so it will require quite a bit of time to do.

And I was wondering if there any performance loss by making blended materials in the Modo way ( with Shader items ) rather than with the V-Ray Blend Material ? If yes, what is the order of magnitude ?

I don't think there should be any performance penalty. Just make sure to always use "Normal" blend mode. Mixing with "Add" will create nested blend materials internally, as each one can only be in "normal" or "additive" mode.

Greetings,
Vladimir Nedev

[Robert]

You actually don't need the blend material at all, as you can use Modos 'shader' node to blend materials very easy in shadertree, incl. all the filtering through shader groups that are not supported in schematic.
It works excellent and fast. But of course you first need to dig into it to get the idea.
My biggest problems with the schematic vesion came out of to downpoints:
1. No support for shader groups in schematic, so you can simple change a properity do to an item exceptiong or tag. (Modo limitation)
2. No thumbnail preview leaves you blind when editing or do color correct. Indeed it did cost me a lot time to find out what all the V-Ray nodes really doing.