ɴsɪ

High level Rust bindings for Illumination Research’s Nodal Scene Interface – ɴsɪ.

This puts one of the most advanced 3D production offline renderers at your fingertips in Rust – 3Delight.

The Moana Island Scene, provided courtesy of Walt Disney Pictures, rendered with 3Delight|ɴsɪ.

This is a huge scene (72GB of data) made of 31 million instances, 78 million polygons defining subdivision surface geometry and 2,300 Ptex textures. The above image was rendered in less than two minutes (wall time) using 3Delight Cloud.

Example

// Create a context to send the scene to.
let ctx = nsi::Context::new(None)
    .expect("Could not create NSI context.");

// Create a dodecahedron.

// 12 regular pentagon faces.
let face_index: [i32; 60] =
    [
         0, 16,  2, 10,  8,  0,  8,  4, 14, 12,
        16, 17,  1, 12,  0,  1,  9, 11,  3, 17,
         1, 12, 14,  5,  9,  2, 13, 15,  6, 10,
        13,  3, 17, 16,  2,  3, 11,  7, 15, 13,
         4,  8, 10,  6, 18, 14,  5, 19, 18,  4,
         5, 19,  7, 11,  9, 15,  7, 19, 18,  6,
    ];

// Golden ratio.
let phi: f32 = 0.5 * (1.0 + 5_f32.sqrt());

// Golden ratio conjugate.
let phi_c: f32 = phi - 1.0;

// 20 points @ 3 vertices.
let positions: [f32; 60] =
    [
         1.,     1.,     1.,     1.,     1.,    -1.,
         1.,    -1.,     1.,     1.,    -1.,    -1.,
        -1.,     1.,     1.,    -1.,     1.,    -1.,
        -1.,    -1.,     1.,    -1.,    -1.,    -1.,
         0.,     phi_c,  phi,    0.,     phi_c, -phi,
         0.,    -phi_c,  phi,    0.,    -phi_c, -phi,
         phi_c,  phi,    0.,     phi_c, -phi,    0.,
        -phi_c,  phi,    0.,    -phi_c, -phi,    0.,
         phi,    0.,     phi_c,  phi,    0.,    -phi_c,
        -phi,    0.,     phi_c, -phi,    0.,    -phi_c,
    ];

// Create a new mesh node and call it 'dodecahedron'.
ctx.create("dodecahedron", nsi::MESH, None);

// Connect the 'dodecahedron' node to the scene's root.
ctx.connect("dodecahedron", None, nsi::ROOT, "objects", None);

// Define the geometry of the 'dodecahedron' node.
ctx.set_attribute(
    "dodecahedron",
    &[
        nsi::points!("P", &positions),
        nsi::unsigneds!("P.indices", &face_index),
        // 5 vertices per each face.
        nsi::unsigneds!("nvertices", &[5; 12]),
        // Render this as a subdivison surface.
        nsi::string!("subdivision.scheme",
            "catmull-clark"
        ),
        // Crease each of our 30 edges a bit.
        nsi::unsigneds!("subdivision.creasevertices",
            &face_index
        ),
        nsi::floats!(
            "subdivision.creasesharpness",
            &[10.; 30]
        ),
    ],
);

Also check out my Diffusion Limited Aggregation play-thingy or Polyhedron Operators for more example code (demonstrates render settings, sending meshes to the renderer, instancing, particle rendering, OSL shaders, environment (lights) and dumping a scene description to disk).

PRs are most welcome!

Getting Pixels

The crate has support for streaming pixels from the renderer, via callbacks (i.e. closures) during and/or after rendering via the output module. This module is enabled through the feature of the same name.

There is a full example showing color conversion and writing data out to 8bit/channel PNG and 32bit/channel (float) OpenEXR formats.

Dependencies

This crate depends on nsi-core which in term requires a renderer that implements the ɴsɪ API to generate images.

Currently the only renderer that does is 3Delight which, though commercial, has been and is free for personal use since over twenty years.

Note: The free version of 3Delight will render with up to 12 cores on your machine. For crazier projects you can use their cheap cloud rendering service that gives you access to unlimited CPU cores. When you register you get 1,000 cloud minutes for free which ain’t too shabby.

That being said – I hope this crate serves as inspiration for other people writing renderers, particularly in Rust, to adopt this API for scene description.

Prerequisites

Before you start it is suggested that you download a 3Delight package for your platform & install it (supported: Linux, macOS, Windows). This will allow you to create pretty pictures with the examples straight away.

It will also install 3Delight Display which you can render to as an alternative to writing images to disk. When working with this crate this is quite handy.

You can skip this step and build with the download_3delight feature. However, this will download an older version of 3Delight so this is not suggested.

Cargo Features

• output – Add support for streaming pixels from the renderer to the calling context via closures.

• jupyter – Add support for rendering to Jupyter notebooks (when using a Rust Jupyter kernel).

• toolbelt – Add convenience methods to Context.

• delight – Add some nodes & shaders specifi to 3Delight.

• nightly – Enable some unstable features (suggested if you build with a nightly toolchain)

• ustr_handles – use ustr for node handles. This will give a you a speed boost if your node names aren't changing while an app using ɴsɪ is running but is not advised otherwise (ustr are never freed).

• download_lib3delight & link_lib3delight – See next section.

Linking Style

The 3Delight dynamic library (lib3delight) can either be linked to during build or loaded at runtime.

By default the lib is loaded at runtime.

• Load lib3delight at runtime (default). This has several advantages:

  1. If you ship your application or library you can ship it without the library. It can still run and will print an informative error if the library can not be loaded.

  2. A user can install an updated version of the renderer and stuff will ‘just work’.

• Dynamically link against lib3delight.

  • lib3delight becomes a dependency. If it can not be found your lib/app will not load/start.

  • The feature is called link_lib3delight.

  • You should disable default features (default-features = false).

  • in this case:

    [dependencies]
    nsi = { version = "0.7", default-features = false, features = ["link_lib3delight"] }
    

• Download lib3delight during build.

  • lib3delight is downloaded during build. Note that this may be an outdated version. This feature mainly exists for CI purposes.

  • The feature is called download_lib3delight.

Documentation

Crate documentation can be found at docs.rs.

Docs for the C, C++, Lua & Python bindings as well as an introduction and deep dive into the API can be found here.

Getting Help

I hang out on the 3Delight Discord (I have the same user name as on GitHub). Ping me in the #lobby channel or send me a PM.

There is also a 3Delight Slack which has a dedicated, invitation only channel about ɴsɪ.

If you have more advanced questions or want to add support for the ɴsɪ API/export to ɴsɪ to your renderer/DCC app/whatever ping me and I get you an invite.