Vray Blend material

[Metin_7]

Hi guys,

Just wondering what's the correct use of the new VRayBlend material. If I want to make a carpaint material, should I first use a non-reflective VRay material as the base layer and then:

1: simply add a very reflective VRay material in the coating layer?

or

2: add a very reflective as well as very refractive material in the coating layer, so it really behaves as a thin transparent layer over the base layer?

Thanks in advance for your feedback.

[Paul Oblomov]

Just use Additive mode in VRayBlend. It's really faster, than Max material. Use base - Default VRay mat. with Fresnel on; Coating - well it depends on what you need to see -=- I used the same material, slightly darker with noise in reflection/highlight glossy slot and it slyghtly glossier . Additive mode is on - so you can clearly see the noise, immitating speckle of metallic paint. But it works for closeups only. . .

[Metin_7]

Thanks very much Paul. This is useful info.

[Metin_7]

Ok, I've tried the additive mode, but I get a warning that my material becomes physically incorrect and will render slower as well. I don't like that to be honest.

What if I approach it with a real refractive V-Ray material as a coating layer on top of a standard V-Ray material, without using additive mode?

[Paul Oblomov]

Well additve is just plain shellac, which is used in most of the carpaint tutorials.
That's why I used it And I saw real carpaint, and tried to simulate it - without shellac - I can't figure out how to do that. Output map certanly can help, but it's too complicated in most cases.
I think you shouldn't try that "real" approach...

[vlado]

A typical car paing material would be a VRayMtl as a base material, with diffuse and glossy components, and a VRayMtl with pure white mirror reflections and black diffuse as a coat material.

To adjust the strength of the mirror reflections, change the blend amount in the blend material.

In general, you should avoid the additive (shellac) mode - there is rarely any case where you would want it.

Best regards,
Vlado

[Metin_7]

Cool, thanks Vlado!

[cpnichols]

I have had some arguments with Vlado about additive mode (friendly ones)... and I finally have to say that I agree with him. There may be times when you want a special effect to have it, but it is not physically correct as it can produce reflections that are brighter than the environment which makes no sense.

[Metin_7]

Vlado, you mentioned setting the coating material's diffuse color to black, like when you create a dielectric V-Ray material. But the difference between a black coating material and a white one is still very apparent. In other words: to create convincing white teeth you need to set the diffuse color of both materials to (near) white, or else it will be too dark when setting the coating material's diffuse to black or even grey.

Unless ... you create a real dielectric coating material using refraction.

[vlado]

But the difference between a black coating material and a white one is still very apparent.

If your reflection color for that material is pure white (and without fresnel reflections), then the diffuse color has no effect whatsoever.

Best regards,
Vlado

[Metin_7]

Ah, it's monsieur Fresnel who tricked me indeed. But Fresnel is necessary for realistic carpaint reflections.

Wait, I could accomplish the Fresnel effect using a Falloff map in the Blend amount slot of course. Gonna try that.

[Metin_7]

Works fine! I like the VRayBlend material! It enables you to create nice complex materials.

Vlado, is there a significant rendertime increase as you add layers in a VrayBlend material?

[vlado]

Vlado, is there a significant rendertime increase as you add layers in a VrayBlend material?

There is, of course, some time increase as there are more things to calculate, but compared to a complex system of standard Shellacs or Blends, it's a lot faster.

Best regards,
Vlado

[Metin_7]

Ok, thanks. I know enough and will definitely play with this new toy.

[Da_elf]

im guessing we will have a new egz_carpint material out soon using the new blend material. but if you want. convert egz's old carpaint material to see how he does his
to convert it just put it in slot 1 then type this into maxscript listner

meditmaterials[2] = copy meditmaterials[1].delegate