Відкрита Мова Відтінювання – Open Shading Language#

Cycles Only

It is also possible to create your own nodes using Open Shading Language (OSL). These nodes will only work with the CPU and OptiX rendering backend.

Для вмикання цього увімкніть стяг Open Shading Language у властивостях рендера, що дасть її використання як системи відтінення.

Примітка

Some OSL features are not available when using the OptiX backend. Examples include:

Memory usage reductions offered by features like on-demand texture loading and mip-mapping are not available.
Texture lookups require OSL to be able to determine a constant image file path for each texture call.
Some noise functions are not available. Examples include Cell, Simplex, and Gabor.
The trace function is not functional. As a result of this, the Ambient Occlusion and Bevel nodes do not work.

Вузол «Скрипт» – Script Node#

OSL was designed for node-based shading, and each OSL shader corresponds to one node in a node setup. To add an OSL shader, add a script node and link it to a text data-block or an external file. Input and output sockets will be created from the shader parameters on clicking the update button in the Node or the Text editor.

OSL shaders can be linked to the node in a few different ways. With the Internal mode, a text data-block is used to store the OSL shader, and the OSO bytecode is stored in the node itself. This is useful for distributing a blend-file with everything packed into it.

The External mode can be used to specify a .osl file from a drive, and this will then be automatically compiled into a .oso file in the same directory. It is also possible to specify a path to a .oso file, which will then be used directly, with compilation done manually by the user. The third option is to specify just the module name, which will be looked up in the shader search path.

Шлях пошуку шейдерів розміщується у тому ж місці, де і шлях для скриптів або конфігурації:

Linux

$HOME/.config/blender/4.2/shaders/

Windows

C:\Users\$user\AppData\Roaming\Blender Foundation\Blender\4.2\shaders\

macOS

/Users/$USER/Library/Application Support/Blender/4.2/shaders/

Порада

For use in production, we suggest to use a node group to wrap shader script nodes, and link that into other blend-files. This makes it easier to make changes to the node afterwards as sockets are added or removed, without having to update the script nodes in all files.

Написання Шейдерів – Writing Shaders#

For more details on how to write shaders, see the OSL Documentation.

Here is a simple example:

shader simple_material(
    color Diffuse_Color = color(0.6, 0.8, 0.6),
    float Noise_Factor = 0.5,
    output closure color BSDF = diffuse(N))
{
    color material_color = Diffuse_Color * mix(1.0, noise(P * 10.0), Noise_Factor);
    BSDF = material_color * diffuse(N);
}

Замикання – Closures#

OSL is different from, for example, RSL or GLSL, in that it does not have a light loop. There is no access to lights in the scene, and the material must be built from closures that are implemented in the renderer itself. This is more limited, but also makes it possible for the renderer to do optimizations and ensure all shaders can be importance sampled.

Доступні замикання – closures у Cycles відповідають вузлам шейдерів та їх роз’ємам; детальніше про те, що вони роблять та значення цих параметрів, дивіться shader nodes manual.

Дивись також

Documentation on OSL’s built-in closures.

BSDF#

diffuse(N)
oren_nayar(N, roughness)
diffuse_ramp(N, colors[8])
phong_ramp(N, exponent, colors[8])
diffuse_toon(N, size, smooth)
glossy_toon(N, size, smooth)
translucent(N)
reflection(N)
refraction(N, ior)
transparent()
microfacet_ggx(N, roughness)
microfacet_ggx_aniso(N, T, ax, ay)
microfacet_ggx_refraction(N, roughness, ior)
microfacet_beckmann(N, roughness)
microfacet_beckmann_aniso(N, T, ax, ay)
microfacet_beckmann_refraction(N, roughness, ior)
ashikhmin_shirley(N, T, ax, ay)
ashikhmin_velvet(N, roughness)

Hair – Волосся#

hair_reflection(N, roughnessu, roughnessv, T, offset)
hair_transmission(N, roughnessu, roughnessv, T, offset)
principled_hair(N, absorption, roughness, radial_roughness, coat, offset, IOR)

BSSRDF#

Used to simulate subsurface scattering.

bssrdf(method, N, radius, albedo)#

Параметри:

method (string) –
Метод рендерингу для симулювання підповерхневого розсіювання.
- burley: An approximation to physically-based volume scattering. This method is less accurate than random_walk however, in some situations this method will resolve noise faster.
- random_walk_skin: Provides accurate results for thin and curved objects. Random Walk uses true volumetric scattering inside the mesh, which means that it works best for closed meshes. Overlapping faces and holes in the mesh can cause problems.
- random_walk: Behaves similarly to random_walk_skin but modulates the Radius based on the Color, Anisotropy, and IOR. This method thereby attempts to retain greater surface detail and color than random_walk_skin.
N (vector) – Normal vector of the surface point being shaded.
radius (vector) – Average distance that light scatters below the surface. Higher radius gives a softer appearance, as light bleeds into shadows and through the object. The scattering distance is specified separately for the RGB channels, to render materials such as skin where red light scatters deeper. The X, Y and Z values are mapped to the R, G and B values, respectively.
albedo (color) – Колір поверхні, або фізично кажучи, ймовірність того, що світло відбивається для кожної довжини хвилі.

Volume – Об’єм#

henyey_greenstein(g)
absorption()

Інше – Other#

emission()
ambient_occlusion()
holdout()
background()

Attributes – Атрибути#

Geometry attributes can be read through the getattribute() function. This includes UV maps, color attributes and any attributes output from geometry nodes.

The following built-in attributes are available through getattribute() as well.

geom:generated: Automatically generated texture coordinates, from undeformed mesh.
geom:uv: Стандартна розкладка UV для рендера.
geom:tangent: Default tangent vector along surface, in object space.
geom:undisplaced: Position before displacement, in object space.
geom:dupli_generated: For instances, generated coordinate from instancer object.
geom:dupli_uv: For instances, UV coordinate from instancer object.
geom:trianglevertices: Three vertex coordinates of the triangle.
geom:numpolyvertices: Кількість вершин полігона (завжди повертає три поточні).
geom:polyvertices: Масив координат вершин полігона (завжди поточно три вершини).
geom:name: Ім’я об’єкта.
geom:is_smooth: Is mesh face smooth or flat shaded.
geom:is_curve: Is object a curve or not.
geom:curve_intercept: 0..1 coordinate for point along the curve, from root to tip.
geom:curve_thickness: Thickness of the curve in object space.
geom:curve_length: Length of the curve in object space.
geom:curve_tangent_normal: Нормаль Тангенса пасма.
geom:is_point: Is point in a point cloud or not.
geom:point_radius: Radius of point in point cloud.
geom:point_position: Center position of point in point cloud.
geom:point_random: Random number, different for every point in point cloud.
path:ray_length: Відстань променя з моменту останнього потрапляння.
object:random: Random number, different for every object instance.
object:index: Object unique instance index.
object:location: Локація об’єкта.
material:index: Material unique index number.
particle:index: Particle unique instance number.
particle:age: Вік частинки у кадрах.
particle:lifetime: Загальна тривалість життя частинки у кадрах.
particle:location: Локація частинки.
particle:size: Розмір частинки.
particle:velocity: Скорість частинки.
particle:angular_velocity: Кутова скорість частинки.

Простеження – Trace#

CPU Only

We support the trace(point pos, vector dir, ...) function, to trace rays from the OSL shader. The «shade» parameter is not supported currently, but attributes can be retrieved from the object that was hit using the getmessage("trace", ..) function. See the OSL specification for details on how to use this.

Ця функція не може використовуватися замість освітлювання; головне її призначення дозволити шейдерам «пробувати» найближчу геометрію, наприклад, для застосування проектованої текстури, що може бути блокована геометрією, застосувати більше «зношення» до виставленої геометрії або зробити інші ефекти подібні на загороду оточення.

Metadata – Метадані#

Metadata on parameters controls their display in the user interface. The following metadata is supported:

[[ string label = "My Label" ]]: Name of parameter in in the user interface
[[ string widget = "null" ]]: Hide parameter in the user interface.
[[ string widget = "boolean" ]] and [[ string widget = "checkbox" ]]: Display integer parameter as a boolean checkbox.