Snow on top?

[Jorgensen_cg]

I wonder if it's possible to add a blend texture that is controlled so I can add a white "snow" texture on faces turning up, and all other faces gets the other texture assigned?

I thought I need to somehow add a vector control, but I can't figure out how... :-/

Thanks

[Antioche]

Maybe with a dirt procedural texture (with a Z-bias to affect only upwards facing faces) used as a mask in a Blend texture? This needs to be made for each material though, for the snow to affect the surfaces with different materials.
Otherwise, possibly simpler: post-process with photoshop, using the Normal map as a mask to overlay snow effect? This wall many materials can be affected at once.

Thibaut

[Jorgensen_cg]

Hi Thibaut

Thanks for your input. It seems to work, one problem though.... is it possible to adjust the texture position, and still use this?
I have added a texture to the model, but when I add the blend texture - the positions get reset.

Do you know if there is there a way to keep the custom positions?

[konstantin_chaos]

Hi Jorgensen_cg,

There are two things you should consider here:

1. There is a mode of the V-Ray Falloff texture that does pretty much exactly what you want (Direction: World Z).
If you combine it with a mix map you'll be able to blend two textures.
Check the 'Falloff 02' material from the Diagrammatic section of the built in material library.

2. As an alternative you can render a mask as a separate render element and then use it to add the effect in post.
In this case the Falloff map should be connected to a V-Ray Extra Texture render element.

Regards,
Konstantin

[Jorgensen_cg]

Hi Konstantin

Thanks for the contribution, I will look into the Falloff texture.

Right now I would like to see if it's possible to archive what I'm looking for without post - just for trying it.

As you can see I have some issues regarding texture placement / scale.

In the left image I have added the "truck" material to the faces, moved and scaled the textures as I like it, but when I add the blend material, the texture placement and scale gets reset.
Is there a way to aviod that? or is it a limitation of Sketchup?

Best
Jorgensen

[LionHeart1985]

I wonder if it's possible to add a blend texture that is controlled so I can add a white "snow" texture on faces turning up, and all other faces gets the other texture assigned?

I thought I need to somehow add a vector control, but I can't figure out how... :-/

Thanks

I was shortly doing some tests with dust on top of geometry like you want to archive with snow.

As i wanted to have full control about the falloff of the dust i was creating this workflow:


1.) Creating a Base Material where you want to have the Snow on top

2.) Creating a Dust (Snow) Material

3.) Creating a Blend Material - Base = Base Material | Coat 1 = Dust (Snow) Material

4.) In the "Blend" Slot - Choose a "Mix Map"

5.) Mix Map Settings: Color Top = Black, Color Bottom = White, In the "Mix Map" Slot put in a Falloff Map

6.) Falloff Settings: Color A = Black, Color B = White, Falloff Type: Towards/Away / Direction: World Z

7.) Now you are able to control the falloff in the "Mix Map Settings" by activating the "Mix Curve" / Keep the "Transition Lower" Slider down to 0 and just adjust the falloff with the "Transition Upper" Slider


This worked for me and it should also do in your case!

Cheers - Walter

[LionHeart1985]

Additionally to the workflow above i was also adding some displacement with the falloff function.

The result is not perfect yet, but i think it gets close to the material you are looking for.

[Jorgensen_cg]

Hi Walter

That sure look interesting. I will try it when I come home.

Do you know if that method allows me to keep the texture mapping on the object / faces?

Thanks

[LionHeart1985]

Hi Walter

That sure look interesting. I will try it when I come home.

Do you know if that method allows me to keep the texture mapping on the object / faces?

Thanks

Hi!

I did a test with this branch and it worked because the falloff is defined in the world Z axis.
The only difference to the first test was, that i skipped the displacement for the snow, as the branch already has a displacement asset assigned.
For sure you can combine it to one displacement material but i was too lazy for that haha...

Make sure that you are assigning the original texture (which will be the base material for the blend material) first to the object with the right UV.

After that, check that the Blend Material which you are creating for the snow, has the same size like the base material which is assigned to the object (in Sketchup Material Editor).

After that, replace the blend material with the orginial material in the V-Ray Material Editor.

[Jorgensen_cg]

Now that is cool. I’ll have to try it.

Thanks

[Jorgensen_cg]

Hi Walter


Make sure that you are assigning the original texture (which will be the base material for the blend material) first to the object with the right UV.
So I assign the material to the faces, and move around to fit as I like it?

After that, check that the Blend Material which you are creating for the snow, has the same size like the base material which is assigned to the object (in Sketchup Material Editor).
You loose me here - does the snow material have to have a image texture, to be able to adjust the in the Sketchup Material Editor?

Sorry, I'm a bit slow here :-/

1.jpg
Hi I have added a texture, and adjusted as I like, on the single faces (just for this test).

2.png
Then I created a blend material as you describe, but I can't figure out how to add it like you describe :-/

[LionHeart1985]

Hi!

I would suggest to take a closer look to this tutorial to get familiar to blend Materials first.

After that, maybe my workflow will make more sense for you.

https://youtu.be/Le0qkGHEjUQ

Cheers, Walter

[Jorgensen_cg]

I've seen the tutorial - but things get to complicated for me. Sorry.

The thing that I don't get is, when I add the blend texture, I don't get an image for the Blend texture, that I can adjust.

[konstantin_chaos]

Hi Jorgensen_cg,

If you use one of the Mix maps in the diffuse slot of your material then V-Ray will find the slotted bitmap and show it in the viewport for you to adjust and for the material to have proper UVs.



If on the other hand you use a Blend material, there isn't a texture for V-Ray to find and show in the viewport out of the box.
In this case you should go to the Binding options of the blend and select either the Texture Helper option or Custom.
The Texture Helper mode will create a generic map to let you adjust UVs in SketchUp.
The Custom mode will let you plug a custom Bitmap to be displayed in the viewport.
Alternately you can disable the toggle all together and load any texture you want in the SU material.
This will give you separate control over what's in the viewport and the material being rendered.


I hope that makes sense,
Konstantin

[Jorgensen_cg]

Hi Konstantin

Thanks for your input. Just to make sure that I have explained myself good enough, and that I understood you.
In the method you describe, you will be able to move the brick texture around, rotate and scale it on the individual faces, and transfer these information's to the blend material?

Best
Jorgensen