Three scatter

Inspired by a GScatter (plugin for blender) in Three.js

Spread all types of objects/models into a geometry easily

Installation

npm i @jaimebboyjt/three-scatter

Why to use it

Three.js already comes with MeshSurfaceSampler you can think in three-scatter as an "extension" of it. I said it in quotes because is not quite true, three-scatter the approach is different and it comes with method to help scatter your Meshes.

Use three-scatter if you:

• Would like to scatter complex models (3D models with animations, rigging, etc)
• Want to align your model to the surface base, easily
• Would like to tweak in real-time (or with panels) seeds, or any property of your 3D model to scatter
• Want to remove collisions, easily.

NOTE: if performance is your must, MeshSurfaceSampler is your go to, I provided a debug option to help you, but MeshSurfaceSampler is much more performance since you can (and probably should) use InstancedMesh

Additionally you can use this library to generate only the positions

Quick Demos

• Multi-models: https://stackblitz.com/edit/vitejs-vite-kebufehm?file=package.json
• Animated models: https://stackblitz.com/edit/vitejs-vite-7fz6pccr?file=src%2Fmain.js
• TresJs: https://stackblitz.com/edit/vitejs-vite-qpspyyen?file=src%2Fcomponents%2FTheExperience.vue

How to use it

Basic (constructor)

import { ThreeScatter } from 'three-scatter'

// Count: Number of samples
// Surface: Geometry from which to sample
// Model: 3D model or models to scatter

const scatter = new ThreeScatter(count, surface, model);
scene.add(scatter);

You can also scatter more than one model:

const scatter = new ThreeScatter(count, surface, [model1, model2]);

Modifying all the 3D objects

three-scatter comes with lots of handy method for you, one of the most common ones is setAll that allow you affect all the scattered models.

const scatter = new ThreeScatter(count, surface, [model1, model2, model3]);

scatter.setAll((model, index) => {
  model.scale.set(0.1, 0.1, 0.1);
});

Take over mode

If you don't need ThreeScatter handle your models you can instantiate the class without any models, then get the positions:

const scatter = new ThreeScatter(count, surface);
const positions = scatter.getPositions()

you can still get different positions using the setSeeds method but you have to update your models manually.

NOTE: Using this approach means that no other internal method will have effects in your model

Methods

setSeeds(seed: number)

scatter.setSeeds(5); // tweak it and find the right value for you

Align models Y+up

// This method will align Y+up with the normals of the surface
scatter.alignToSurfaceNormal();

Remove collisions

// This method will remove the model that has collisions with other scattered model 
scatter.removeCollisions();

Clear group

// Dispose all the geometries and material and remove all the meshes
scatter.cleanGroup();

Get faces

// return all the faces of the surface sample, using a Triangle: https://threejs.org/docs/?q=triangle#api/en/math/Triangle
scatter.getFaces();

Get positions

// return all the positions, useful if you want to display specifics positions in your scene
scatter.getPositions();

Options

ThreeScatter allows you more control using optional parameters.

const scatter = new ThreeScatter(count, surface, model, {
  seeds<number>: 1, // seed to begin with
  useSkeletonUtils<boolean>: true // Necessary when you are scattering 3D models with rigging/animations
  randomFn<() => number>: Math.random() // if you want to have control over the random function, has to return a value from 0 to 1
});

Debug mode

ThreeScatter comes with a debug mode that will replace all your models with a low poly mesh, and find the right position, easily.

const scatter = new ThreeScatter(count, surface, model, {
  debug<boolean>: true,
  debugGeometry<Geometry>: new THREE.SphereGeometry(0.5, 3, 2) ,
  debugMaterial<Material>: new THREE.MeshBasicMaterial({ color: 0x800080 }),
});

You can also use the setDebug and removeDebug methods to control it after ThreeScatter is instantiated

scatter.setDebug(); // or
scatter.removeDebug();

Distribution

You can now set the percentage of model distribution in case you are scattering more than one model.

const scatter = new ThreeScatter(count, surface, [model1, model2], {
  distribution: [ 0.25, 0.75]
});

NOTE: In order to set the distribution property, you need to have:

1. An array of models
2. A distribution property with equal length than the array of model
3. All the numbers inside the distribution property needs to sum 1

TODO

• Distribution (when more than one model to scatter) should be base on %
• [] Distribution by axis (base on the normals)
• [] Avoid corners
• [] Density
• [] Merge geometries?
• [] Clusters

Contributing

We are open to contributions, please read the contributing guide to get started.

License

MIT

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