Car Paint Shader for Blender V 1.0.1

ATTENTION:
This shader is constantly updated, there are some parts that will be updated as soon as I find alternatives to some parts.

Car Paint Shader

This is a shader for car bodies paint, and can simulate many types of modern body paint.

The shader is simple to use, but some parameters are directly linked to others and for correct use read the documentation below.

With this BSDF shader it is possible to obtain a wide range of automotive paints, modulating the various parameters described below.

The shader works also with Eevee, maybe not with Optix.

Documentation

Main Color

This is the main color of the material.

Edge Tint

This is the color of the external edges and is usually the same main color but with a darker shade than the main color, but a different color can also be used to obtain particular paints.

Edge Tint Blend

This value gradually modulates the two colors, and it is preferable not to go beyond a value of 0.750, otherwise the border color will occlude the main one, with different colors the result will be greater, while with shades with similar colors it creates the right effect.

Metallic

This value modulates the metallic component of the material, from 0 to 1,000. With a minimum value even non-metallic paints benefit from it, therefore it is advisable to use it even when non-metallic paints are not to be made with a maximum value that does not exceed more than 0.5. while if you intend to create a metallic paint the value should be between 0.550 and 1.0

Roughness

This value modulates the roughness of the surface, this is also influenced by the weight of the Coat value, in fact if Coat is set to high values ​​the edges will also be affected by the Coat Roughness value, so if the paint must be opaque, it will be necessary to set the value of Coat Weight to very low values ​​or to 0.

IOR

This is the refractive index of the materials, and it influences the specularity of the material, usually it is not necessary to change this index as the default value should be suitable for all types of painting.

Coat Tint

This is the color of the glossy film that covers the paint, white is suitable for all common types, but you can change if you need to create particular paints that have different reflections compared to common colors, for example pearl white or similar.

Coat Weight

This value modulates the extent of the Coat finish of the paint, and also influences the roughness value, in fact you can have a matte paint with shiny edges since this value affects the light at angles above or 60°, a useful effect for non-glossy paints. Metallic, which thus can obtain opaque parts and have only limited reflections on the edges of the normals and is a value that can also be influenced by the IOR value. This value conditions the visibility of the Wight Orange Peel value, in fact if you want an orange peel effect on the paint you will also have to modulate this parameter; if it is set to zero, it will not be possible to obtain an orange peel effect.

Coat Roughness

This parameter controls the roughness of the Coat, it is usually a value that should be kept very low on glossy paints, this value also changes the value of the orange peel effect of the paints, in fact if you have set a value of Orange Peel Scale different from 0 this will make the Coat surface wavy, in fact Orange Peel is linked to the parameters that control the Coat.

Coat IOR

This controls the refractive index of the gloss finish, the default value is valid for all paint types, but you can play with this value if you want something that is not common.

Flake Base Scale

This value controls the size of the shiny scales and also that of orange peel, this can be set to lower values ​​than the others that control the scale, for example from 10,000 to 50,000. may be an optimal range.

Flake Scale

This parameter controls the scale value of the scales and is the secondary parameter but the one that should be useful in determining the right scale.

Flake Bump Strength

This parameter controls the intensity of the bump map of the flakes, but also conditions the roughness factor of the paint, and is a value that is directly related to the Flake Radius Blend parameter, in fact for a correct effect, the value of Flake Radius Blend should be set from a minimum of 0.20 to a maximum of 0.900, but a lot depends on your needs, in fact you can also use very low values, but avoid using too high values. With this value you can give a flake-based roughness, and it also works somewhat as a roughness..

Flake Amount

This value gradually modulates the quantity of flakes, and affects the number of flakes also visible in the pigmentation, it is a value that also controls the density relative to the value used by Flake bump Strength.

Flake Radius Blend

This parameter modulates the extension of the flake finish on the surface, when you do not want to have any flake effect this must be set to the value 0, this parameter currently has no influence on the base map for the flake bump, which currently in this version of the shader cannot be controlled.

Flake Color Holo

This parameter modulates the color intensity from a gray scale to that typical of holographic flakes on car body paints. 0 is gray and 1,000 is multi color with the typical holographic color. At the moment this parameter is not gradual, but in the next versions I hope to find a solution to improve this control.

Orange Peel Scale

This value controls the secondary scale of the orange peel effect.

Weight Orange Peel

This value controls the intensity of the orange peel effect and is closely related to the Coat values, so for correct use ensure that the Coat weight control values ​​are not 0 or too low.

Thin Film Thickness

The thickness of the film in nanometers. A value of 0 disables simulation. The interference effect is strongest between about 100 and 1000 nanometers, as this is close to the wavelengths of visible light. This value does not currently work with metallic paints, so if the Metallic value is set high it will be unnoticeable but works very well with a non-metallic or partially metallic paint.

Thin Film IOR

Index of refraction (IOR) of the thin film. The common range for this value is between 1.0 (vacuum and air) to approximately 2.0, although some materials may achieve higher values. The default value of 1.33 is a good approximation for water. Note that when the value is set to 1.0 or the material's main IOR, the thin film effect disappears as the film optically blends with the air or material.

From the Blender Manual for Thin Film

Thin Film simulates the effect of interference in a thin film placed over the material. This causes the specular reflection to be colored in a way that is highly dependent on the viewing angle, film thickness, and index of refraction (IOR) of the film and the material itself.

This effect is commonly observed e.g. oily films, soap bubbles or glass coatings. Although its influence is most noticeable in specular highlights, it also affects transmission.

Thin film interference is currently only applied to dielectric materials. Support for thin films on Metallic is planned in the future.