Відкрита Мова Відтінювання – Open Shading Language¶

Open Shading Language (OSL) is a programmable shading system developed for advanced rendering engines. It allows technical artists and developers to write custom shader code using a C-like scripting language.

In Blender, OSL can be used within Cycles to define custom surface, volume, and displacement shaders. This gives users full control over shading behavior, enabling procedural effects, advanced lighting models, and custom geometry-based material logic that may not be possible with built-in shader nodes alone.

Unlike node-based materials, OSL shaders are authored as text scripts using Blender’s internal Text Editor or loaded from external .osl or .oso files. These scripts are then compiled and used in the Shader Editor through the Script Node.

Порада

OSL is especially useful for generating procedural textures, custom BRDFs, or implementing research prototypes. It also allows sharing shaders across compatible rendering applications that support the OSL standard.

Usage – Використання¶

To use Open Shading Language (OSL) in Blender, follow these steps:

Enable OSL Rendering

In the Render Properties enable Open Shading Language.
Add a Script Node

In the Shader Editor add Script Node then in the node’s properties:
- Set the Mode to Internal to use a Blender text data-block, or
- Set it to External to load a shader file from disk (either .osl or compiled .oso).
For the internal mode, create a new text data-block in the Text Editor, then write or paste your OSL code there.

Blender will compile the OSL source file automatically. If the source is .osl, it will be compiled into .oso bytecode. Compilation errors will be shown in the system console.
Use Shader Outputs

Once compiled, the node’s outputs will reflect the output parameters defined in the OSL code. These outputs can be connected to any part of the material node tree.

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 non-deformed 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 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.

Limitations – Обмеження¶

Важливо

OSL is not supported with GPU rendering unless using the OptiX backend.

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.