Three.ez - InstancedMesh2

Simplify your three.js application development with three.ez!

InstancedMesh2 is an alternative version of InstancedMesh that offers advantages:

• frustum culling for each instance
• sorting
• visibility for each instance
• each instance can have an object similar to Object3D to simplify its use
• spatial indexing (BVH) for fast raycasting and frustum culling
• LOD
• shadow LOD

import { InstancedMesh2 } from '@three.ez/instanced-mesh';

const myInstancedMesh = new InstancedMesh2(renderer, count, geometry, material);

myInstancedMesh.updateInstances((obj, index) => {
  obj.position.z = index;
  obj.rotateY(Math.PI);
});

myInstancedMesh.computeBVH();

This library has two dependencies:

• three.js r159+
• bvh.js

Live Examples

These examples use vite, and some mobile devices may run out of memory.

• 1kk static trees
• Instances array dynamic
• Sorting
• Custom material
• Dynamic BVH (no vite)
• Fast raycasting
• LOD
• Shadow LOD

More examples will be added soon...

Frustum Culling

Avoiding rendering objects outside the camera frustum can drastically improve performance (especially for complex geometries).

Frustum culling by default is performed by iterating all instances, but it is possible to speed up this process by creating a spatial indexing data structure (BVH).

By default perObjectFrustumCulled is true.

Sorting

Sorting should be used to decrease overdraw and render transparent objects.

By default sortObjects is false.

import { createRadixSort } from '@three.ez/instanced-mesh';

myInstancedMesh.sortObjects = true;
myInstancedMesh.customSort = createRadixSort(myInstancedMesh);

Visibility

Set the visibility status of each instance like this:

myInstancedMesh.setVisibilityAt(false, 0);
myInstancedMesh.instances[0].visible = false; // if instances array is created

Instances Array

It is possible to create an array of InstancedEntity (Object3D-like) in order to easily change the visibility, apply transformations and add custom data to each instance, using more memory.

myInstancedMesh.createInstances((obj, index) => {
  obj.position.random();
});

myInstancedMesh.instances[0].visible = false;

myInstancedMesh.instances[1].userData = {};

myInstancedMesh.instances[2].position.random();
myInstancedMesh.instances[2].quaternion.random();
myInstancedMesh.instances[2].scale.random();
myInstancedMesh.instances[2].updateMatrix(); // necessary after transformations

myInstancedMesh.instances[3].rotateX(Math.PI);
myInstancedMesh.instances[3].updateMatrix(); // necessary after transformations

Spatial Indexing Data Structure (Dynamic BVH)

To speed up raycasting and frustum culling, a spatial indexing data structure can be created to contain the boundingBoxes of all instances.
This works very well if the instances are mostly static (updating a BVH can be expensive) and scattered in world space.

// call this function after all instances have been valued
myInstancedMesh.computeBVH({ margin: 0, highPrecision: false });

If all instances are static set the margin to 0.

Setting a margin makes BVH updating faster, but may make raycasting and frustum culling slightly slower.

LOD

Work in progress...

Shadow LOD

Work in progress...

Raycasting tips

If you are not using a BVH, you can set the raycastOnlyFrustum property to true to avoid iterating over all instances.

It's also highly recommended to use three-mesh-bvh to create a geometry BVH.

API

InstancedMesh2

export type Entity<T> = InstancedEntity & T;
export type UpdateEntityCallback<T> = (obj: Entity<T>, index: number) => void;

export interface BVHParams {
    margin?: number;
    highPrecision?: boolean;
}

export declare class InstancedMesh2<TCustomData = {}, TGeometry extends BufferGeometry = BufferGeometry, TMaterial extends Material | Material[] = Material, TEventMap extends Object3DEventMap = Object3DEventMap> extends Mesh<TGeometry, TMaterial, TEventMap> {
    type: 'InstancedMesh2';
    isInstancedMesh2: true;
    instances: Entity<TCustomData>[];
    instanceIndex: GLInstancedBufferAttribute;
    matricesTexture: DataTexture;
    colorsTexture: DataTexture;
    morphTexture: DataTexture;
    boundingBox: Box3;
    boundingSphere: Sphere;
    instancesCount: number;
    bvh: InstancedMeshBVH;
    perObjectFrustumCulled: boolean;
    sortObjects: boolean;
    customSort: any;
    raycastOnlyFrustum: boolean;
    visibilityArray: boolean[];
    customDepthMaterial: MeshDepthMaterial;
    customDistanceMaterial: MeshDistanceMaterial;
    get count(): number;
    get maxCount(): number;
    get material(): TMaterial;
    set material(value: TMaterial);
    /** THIS MATERIAL AND GEOMETRY CANNOT BE SHARED */
    constructor(renderer: WebGLRenderer, count: number, geometry: TGeometry, material?: TMaterial);
    updateInstances(onUpdate: UpdateEntityCallback<Entity<TCustomData>>): void;
    createInstances(onInstanceCreation?: UpdateEntityCallback<Entity<TCustomData>>): void;
    computeBVH(config?: BVHParams): void;
    disposeBVH(): void;
    setMatrixAt(id: number, matrix: Matrix4): void;
    getMatrixAt(id: number, matrix?: Matrix4): Matrix4;
    setVisibilityAt(id: number, visible: boolean): void;
    getVisibilityAt(id: number): boolean;
    setColorAt(id: number, color: ColorRepresentation): void;
    getColorAt(id: number, color?: Color): Color;
    setUniformAt(id: number, name: string, value: UniformValue): void;
    getMorphAt(index: number, object: Mesh): void;
    setMorphAt(index: number, object: Mesh): void;
    raycast(raycaster: Raycaster, result: Intersection[]): void;
    computeBoundingBox(): void;
    computeBoundingSphere(): void;
    copy(source: InstancedMesh2, recursive?: boolean): this;
    dispose(): this;
}

InstancedEntity

export type UniformValueNoNumber = Vector2 | Vector3 | Vector4 | Matrix3 | Matrix4;
export type UniformValue = number | UniformValueNoNumber;

export declare class InstancedEntity {
    isInstanceEntity: true;
    readonly id: number;
    readonly owner: InstancedMesh2;
    position: Vector3;
    scale: Vector3;
    quaternion: Quaternion;
    get visible(): boolean;
    set visible(value: boolean);
    get color(): Color;
    set color(value: ColorRepresentation);
    get matrix(): Matrix4;
    get matrixWorld(): Matrix4;
    constructor(owner: InstancedMesh2<any, any, any>, index: number);
    updateMatrix(): void;
    setUniform(name: string, value: UniformValue): void;
    copyTo(target: Mesh): void;
    applyMatrix4(m: Matrix4): this;
    applyQuaternion(q: Quaternion): this;
    rotateOnAxis(axis: Vector3, angle: number): this;
    rotateOnWorldAxis(axis: Vector3, angle: number): this;
    rotateX(angle: number): this;
    rotateY(angle: number): this;
    rotateZ(angle: number): this;
    translateOnAxis(axis: Vector3, distance: number): this;
    translateX(distance: number): this;
    translateY(distance: number): this;
    translateZ(distance: number): this;
}

Utils

export declare function patchShader(shader: string): string;

export declare function createRadixSort(target: InstancedMesh2): typeof radixSort<InstancedRenderItem>;

export declare function createTexture_float(count: number): DataTexture;
export declare function createTexture_vec2(count: number): DataTexture;
export declare function createTexture_vec3(count: number): DataTexture;
export declare function createTexture_vec4(count: number): DataTexture;
export declare function createTexture_mat3(count: number): DataTexture;
export declare function createTexture_mat4(count: number): DataTexture;

How Does It Work?

It works similarly to BatchedMesh: matrices, colors, etc. are stored in Texture instead of InstancedAttribute.
The only InstancedAttribute is used to store the indices of the instances to be rendered.

If you create a custom material, you will need to use Texture instead of InstancedBufferAttribute (don't worry, there are utility methods).

Installation

You can install it via npm using the following command:

npm install @three.ez/instanced-mesh

Or you can import it from CDN:

<script type="importmap">
{
  "imports": {
    "three": "https://cdn.jsdelivr.net/npm/[email protected]/build/three.module.js",
    "three/addons/": "https://cdn.jsdelivr.net/npm/[email protected]/examples/jsm/",
    "@three.ez/instanced-mesh": "https://cdn.jsdelivr.net/npm/@three.ez/instanced-mesh/index.js",
    "bvh.js": "https://cdn.jsdelivr.net/npm/bvh.js/index.js"
  }
}
</script>

Questions?

If you have questions or need assistance, you can ask on our discord server.

Future Work

• Dynamic count
• Simplify SetUniformAt

Like it?

If you find this project helpful, I would greatly appreciate it if you could leave a star on this repository!
This helps me know that you appreciate my work and encourages me to continue improving it.
Thank you so much for your support! 🌟

Special thanks to

• gkjohnson
• manthrax
• jungle_hacker

References

• three-mesh-bvh
• ErinCatto_DynamicBVH
• BatchedMesh