Developing Nodes

This guide will help you developing your first Nodarium Node written in Rust. As an example we will implement a cylinder node, which generates a 3D model of a cylinder.

Prerequesites

You need to have Rust and wasm-pack installed. Rust is the language we are going to develop our node in and wasm-pack helps us compile our rust code into a webassembly file.

# install rust
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
# install wasm-pack
cargo install wasm-pack

Clone Template

wasm-pack new my-new-node --template https://github.com/jim-fx/nodarium_template
cd my-new-node

Setup Definition

Now we create the definition file of the node. Here we define what kind of inputs our node will expect and what kind of output it produces. If you want to dive deeper into this topic, have a look at NODE_DEFINITION.md.

src/definition.json

{
  "id": "my-name/my-namespace/zylinder-node",
  "outputs": [
    "geometry"
  ],
  "inputs": {
    "height": {
      "type": "float",
      "value": 2,
    },
    "radius": {
      "type": "float",
      "value": 0.4
    }
  }
}

If we take a look at the src/lib.rs file we see that src/definition.json is included with the following line:

include_definition_file!("src/definition.json");

This procedural rust macro loads the definition.json, validates its content and embeds it in our output file.

Implement Node

This is the hardest part when developing a node, for now you can copy the following content into the src/lib.rs file:

use glam::Vec2;
use wasm_bindgen::prelude::*;

nodarium_macros::include_definition_file!("src/definition.json");

#[wasm_bindgen]
pub fn execute(input: &[i32]) -> Vec<i32> {
    let arguments = nodarium_utils::split_args(input);

    let height = nodarium_utils::evaluate_float(arguments[0]);
    let radius = nodarium_utils::evaluate_float(arguments[1]);

    let mut geometry_data = nodarium_utils::geometry::create_geometry_data(16, 16);

    let geometry = nodarium_utils::geometry::wrap_geometry_data(&mut geometry_data);

    // bottom circle
    for i in 0..8 {
        let x = radius * (2.0 * std::f32::consts::PI * i as f32 / 8.0).cos();
        let y = radius * (2.0 * std::f32::consts::PI * i as f32 / 8.0).sin();

        let vec = Vec2::new(x, y).normalize();

        // bottom circle
        geometry.positions[i * 3 + 0] = x;
        geometry.positions[i * 3 + 1] = 0.0;
        geometry.positions[i * 3 + 2] = y;

        geometry.normals[i * 3 + 0] = vec[0];
        geometry.normals[i * 3 + 1] = 0.0;
        geometry.normals[i * 3 + 2] = vec[1];

        // top circle
        geometry.positions[24 + i * 3 + 0] = x;
        geometry.positions[24 + i * 3 + 1] = height;
        geometry.positions[24 + i * 3 + 2] = y;

        geometry.normals[24 + i * 3 + 0] = vec[0];
        geometry.normals[24 + i * 3 + 1] = 0.0;
        geometry.normals[24 + i * 3 + 2] = vec[1];

        geometry.faces[i * 6 + 0] = (i + 8) as i32;
        geometry.faces[i * 6 + 1] = (i as i32 + 1) % 8;
        geometry.faces[i * 6 + 2] = (i) as i32;

        geometry.faces[i * 6 + 3] = 8 + (i % 8) as i32;
        geometry.faces[i * 6 + 4] = 8 + (i as i32 + 1) % 8;
        geometry.faces[i * 6 + 5] = (i as i32 + 1) % 8;
    }

    nodarium_utils::concat_arg_vecs(vec![geometry_data])
}

As you can see we import glam on the first line. Glam is a fantastic math library. Install it with the following command:

cargo add glam

Build time

We compile our node by running the following command:

wasm-pack build --release

This will produce a .wasm file in the pkg/ directory of our node. To check if the node works, we can drag it onto the node-graph on https://nodes.max-richter.dev and see if it loads.

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