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Path tracing project using three-mesh-bvh and WebGL 2 to accelerate high quality, physically based rendering on the GPU. Features include support for GGX surface model, material information, textures, normal maps, emission, environment maps, tiled rendering, and more!

More features and capabilities in progress!



Basic Setup Example

Beauty Demos

Physically Based Materials

Lego Models

Interior Scene

Depth of Field


Skinned Geometry Support

Morph Target Support

Area Light Support

Spot Light Support

Volumetric Fog Support

Test Scenes

Material Test Orb

Transmission Preset Orb

Model Viewer Fidelity Scene Comparisons

Physical Material Database


Animation Rendering

Ambient Occlusion Material

Looking Glass Portrait Quilt Render

Running examples locally

To run and modify the examples locally, make sure you have Node and NPM installed. Check the supported versions in the test configuration.

In order to install dependencies, you will need make and a C++ compiler available.

On Debian or Ubuntu, run sudo apt install build-essential. It should just work on MacOS.

  • To install dependencies, run npm install
  • To start the demos run npm start
  • Visit http://localhost:1234/<demo-name.html>


Basic Renderer

import * as THREE from 'three';
import { FullScreenQuad } from 'three/examples/jsm/postprocessing/Pass.js';
import {
} from 'three-gpu-pathtracer';

// init scene, renderer, camera, controls, etc

renderer.outputEncoding = THREE.sRGBEncoding;
renderer.toneMapping = THREE.ACESFilmicToneMapping;

// initialize the path tracing material and renderer
const ptMaterial = new PhysicalPathTracingMaterial();
const ptRenderer = new PathTracingRenderer( renderer );
ptRenderer.setSize( window.innerWidth, window.innerHeight ); = camera;
ptRenderer.material = ptMaterial;

// if rendering transparent background
ptRenderer.alpha = true;

// init quad for rendering to the canvas
const fsQuad = new FullScreenQuad( new THREE.MeshBasicMaterial( {

	// if rendering transparent background
	blending: THREE.CustomBlending,
} ) );

// ensure scene matrices are up to date

// initialize the scene and update the material properties with the bvh, materials, etc
const generator = new PathTracingSceneGenerator();
const { bvh, textures, materials, lights } = generator.generate( scene );

// update bvh and geometry attribute textures
ptMaterial.bvh.updateFrom( bvh );

// update materials and texture arrays
ptMaterial.materialIndexAttribute.updateFrom( geometry.attributes.materialIndex );
ptMaterial.textures.setTextures( renderer, 2048, 2048, textures );
ptMaterial.materials.updateFrom( materials, textures );

// update the lights
ptMaterial.lights.updateFrom( lights );

// set the environment map
const texture = await new RGBELoader().setDataType( THREE.FloatType ).loadAsync( envMapUrl );
ptRenderer.material.envMapInfo.updateFrom( texture );


// ...

function animate() {

	// if the camera position changes call "ptRenderer.reset()"

	// update the camera and render one sample

	// if using alpha = true then the target texture will change every frame
	// so we must retrieve it before render. =;

	// copy the current state of the path tracer to canvas to display
	fsQuad.render( renderer );


Blurred Environment Map

Using a pre blurred envioronment map can help improve frame convergence time at the cost of sharp environment reflections. If performance is concern then multiple importance sampling can be disabled and blurred environment map used.

import { BlurredEnvMapGenerator } from 'three-gpu-pathtracer';

// ...

const envMap = await new RGBELoader().setDataType( THREE.FloatType ).loadAsync( envMapUrl );
const generator = new BlurredEnvMapGenerator( renderer );
const blurredEnvMap = generator.generate( envMap, 0.35 );

// render!

Dynamic Scenes

Using the dynamic scene generator the same, frequently updated scene can be converted into a single reusable geometry multiple times and BVH refit which greatly improves subsequent scene updates. See DynamicPathTracingSceneGenerator docs for more info.

import { DynamicPathTracingSceneGenerator } from 'three-gpu-pathtracer';

// ... initialize scene etc

const generator = new DynamicPathTracingSceneGenerator( scene );
const { bvh, textures, materials } = generator.generate( scene );

// ... update path tracer and render

Asynchronous Scene Generation

NOTE WebWorker syntax is inconsistently supported across bundlers and sometimes not supported at all so the PathTracingSceneWorker class is not exported from the package root. If needed the code from src/worker can be copied and modified to accomodate a particular build process.

import { PathTracingSceneWorker } from 'three-gpu-pathtracer/src/workers/PathTracingSceneWorker.js';

// ...

// initialize the scene and update the material properties with the bvh, materials, etc
const generator = new PathTracingSceneWorker();
const { bvh, textures, materials, lights } = await generator.generate( scene );

// ...



Utility class for tracking and rendering a path traced scene to a render target.


readonly samples : Number

Number of samples per pixel that have been rendered to the target.


readonly target : WebGLRenderTarget

The target being rendered to. The size of the target is updated with setSize and is initialized to a FloatType texture.

Note Target will swap render targets after every full sample when alpha is enabled.


camera = null : Camera

The camera to render with. The view offset of the camera will be updated every sample to enable anti aliasing.


material = null : ShaderMaterial

The Path Tracing material to render. This is expected to be a full screen quad material that respects the "opacity" field for every pixel so samples can be accumulated over time. The material is also expected to have cameraWorldMatrix and invProjectionMatrix fields of type Matrix4.


tiles = ( 1, 1 ) : Vector2

Number of tiles on x and y to render to. Can be used to improve the responsiveness of a page while still rendering a high resolution target.


stableNoise = false : Boolean

Whether to reset the random seed to 0 when restarting the render. If true then a consistent random sample pattern will appear when moving the camera, for example.


stableTiles = true : Boolean

Whether the initial tile is reset to the top left tile when moving the camera or if it should continue to shift every frame.


alpha = false : Boolean

Whether to support rendering scenes with transparent backgrounds. When transparent backgrounds are used two extra render targets are used, custom blending is performed, and will change on every completed sample.

Note When a transparent background is used the material used for the final render to the canvas must use the same "premultipliedAlpha" setting as the canvas otherwise the final image may look incorrect.


constructor( renderer : WebGLRenderer )


setSize( size : Vector2 ) : void

Sets the size of the target to render to.



Renders a single sample to the target.


reset() : void

Resets and restarts the render from scratch.


Renderer that supports rendering to a quilt renderer to rendering on displays such as the Looking Glass display.


viewCount = 48 : Number

The number of views to be rendered. If this is less than the product of the quiltDimensions then there will be gaps at the end of the quilt.


quiltDimensions = Vector2( 8, 6 ) : Vector2

The number of quilt patches in each dimension.


viewCone = 35 * DEG2RAD : Number

The total angle sweep for the camera views rendered across the quilt.


viewFoV = 14 * DEG2RAD : Number

The camera field of view to render.


displayDistance = 1 : Number

The distance of the viewer to the display.


displayAspect = 0.75 : Number

The aspect ratio of the display.


	displayDistance : Number,
	displayWidth : Number,
	displayHeight : Number,
) : void

Updates the displayDistance, displayAspect, and the viewFoV from viewer and display information.


Utility class for generating the set of data required for initializing the path tracing material with a bvh, geometry, materials, and textures.


generate( scene : Object3D | Array<Object3D>, options = {} : Object ) : {
	bvh : MeshBVH,
	materials : Array<Material>,
	textures : Array<Texture>,
	lights : Array<Light>

Merges the geometry in the given scene with an additional "materialIndex" attribute that references the associated material array. Also produces a set of textures referenced by the scene materials.


extends PathTracingSceneGenerator

See note in Asyncronous Generation use snippet.


async generate( scene : Object3D | Array<Object3D>, options = {} : Object ) : {
	bvh : MeshBVH,
	materials : Array<Material>,
	textures : Array<Texture>,
	lights : Array<Light>


dispose() : void


extends THREE.PerspectiveCamera

An extension of the three.js PerspectiveCamera with some other parameters associated with depth of field. These parameters otherwise do not affect the camera behavior are are for convenience of use with the PhysicalCameraUniform and pathtracer.


focusDistance = 25 : Number

The distance from the camera in meters that everything is is perfect focus.


fStop = 1.4 : Number

The fstop value of the camera. If this is changed then the bokehSize field is implicitly updated.


bokehSize : Number

The bokeh size as derived from the fStop and focal length in millimeters. If this is set then the fStop is implicitly updated.


apertureBlades = 0 : Number

The number of sides / blades on the aperture.


apertureRotation = 0 : Number

The rotation of the aperture shape in radians.


anamorphicRatio = 1 : Number

The anamorphic ratio of the lens. A higher value will stretch the bokeh effect horizontally.


extends THREE.Camera

A class indicating that the path tracer should render an equirectangular view. Does not work with three.js raster rendering.


extends THREE.SpotLight


radius = 0 : Number

The radius of the spotlight surface. Increase this value to add softness to shadows.


iesTexture = null : Texture

The loaded IES texture describing directional light intensity. These can be loaded with the IESLoader.

Premade IES profiles can be downloaded from []. And custom profiles can be generated using CNDL.


extends THREE.RectAreaLight


isCircular = false : Boolean

Whether the area light should be rendered as a circle or a rectangle.


A variation of the path tracing scene generator intended for quickly regenerating a scene BVH representation that updates frequently. Ie those with animated objects or animated skinned geometry.

In order to quickly update a dynamic scene the same BVH is reused across updates by refitting rather than regenerating. This is significantly faster but also results in a less optimal BVH after significant changes.

If geometry or materials are added or removed from the scene then reset must be called.


constructor( scene : Object3D | Array<Object3D> )

Takes the scene to convert.


generate() : {
	bvh : MeshBVH,
	materials : Array<Material>,
	textures : Array<Texture>

Generates and refits the bvh to the current scene state. The same bvh, materials, and textures objects are returns after the initial call until reset is called.


reset() : void

Resets the generator so a new BVH is generated. This must be called when geometry, objects, or materials are added or removed from the scene.


extends Loader

Loader for loading and parsing IES profile data. Load and parse functions return a DataTexture with the profile contents.


Utility for generating a PMREM blurred environment map that can be used with the path tracer.


constructor( renderer : WebGLRenderer )


generate( texture : Texture, blur : Number ) : DataTexture

Takes a texture to blur and the amount to blur it. Returns a new DataTexture that has been PMREM blurred environment map that can have distribution data generated for importance sampling.


dispose() : void

Disposes of the temporary files and textures for generation.



exponent = 2 : Number


topColor = 0xffffff : Color


bottomColor = 0x000000 : Color


constructor( resolution = 512 : Number )


update() : void


extends THREE.ShaderMaterial

Convenience base class that adds additional functions and implicitly adds object definitions for all uniforms of the shader to the object.


setDefine( name : string, value = undefined : any ) : void

Sets the define of the given name to the provided value. If the value is set to null or undefined then it is deleted from the defines of the material. If the define changed from the previous value then Material.needsUpdate is set to true.


extends MaterialBase


	// The number of ray bounces to test. Higher is better quality but slower performance.
	// TransmissiveBounces indicates the number of additional transparent or translucent surfaces
	// the ray can pass through.
	bounces = 3 : Number,
	transmissiveBounces = 10 : Number,

	// The number of additional transmissive ray bounces to allow on top of existing bounces for object opacity / transmission.
	transmissiveBounces = 5 : Number,

	// The physical camera parameters to use
	physicalCamera : PhysicalCameraUniform,

	// Geometry and BVH information
	bvh: MeshBVHUniformStruct,
	attributesArray: AttributesTextureArray,
	materialIndexAttribute: UIntVertexAttributeTexture,
	materials: MaterialsTexture,
	textures: RenderTarget2DArray,

	// Light information
	lights: LightsInfoUniformStruct,
	iesProfiles: IESProfilesTexture,

	// Environment Map information
	envMapInfo: EquirectHdrInfoUniform,
	environmentRotation: Matrix4,
	environmentIntensity = 1: Number,

	// background blur
	backgroundBlur = 0: Number,

	// Factor for alleviating bright pixels from rays that hit diffuse surfaces then
	// specular surfaces. Setting this higher alleviates fireflies but will remove some
	// specular caustics.
	filterGlossyFactor = 0: Number,

	// The equirectangular map to render as the background.
	backgroundMap = null: Texture,

	// The transparency to render the background with. Note that the "alpha" option
	// must be set to true on PathTracingRenderer for this field to work properly.
	backgroundAlpha: 1.0,



	// Whether to use multiple importance sampling to help the image converge more quickly.
	FEATURE_MIS = 1 : Number,

	// Whether to use russian roulette path termination. Path termination will kick in after
	// a minimum three bounces have been performed.



extends MeshStandardMaterial

A material used for rendering fog-like volumes within the scene. The color, emissive, and emissiveIntensity fields are all used in the render.

NOTE Since fog models many particles throughout the scene and cause many extra bounces fog materials can dramatically impact render time.


The particulate density of the volume.


extends MaterialBase

Denoise material based on BrutPitt/glslSmartDeNoise intended to be the final pass to the screen. Includes tonemapping and color space conversions.



	// sigma - sigma Standard Deviation
	// kSigma - sigma coefficient
	// kSigma * sigma = radius of the circular kernel
	sigma = 5.0 : Number,
	kSigma = 1.0 : Number,

	// edge sharpening threshold
	threshold = 0.03 : Number,



extends WebGLArrayRenderTarget

A convenience extension from WebGLArrayRenderTarget that affords easily creating a uniform texture array from an array of textures.


	renderer : WebGLRenderer,
	width : Number,
	height : Number,
	textures : Array<Texture>
) : void

Takes the rendering context to update the target for, the target dimensions of the texture array, and the array of textures to render into the 2D texture array. Every texture is stretched to the dimensions of the texture array at the same index they are provided in.


Uniform for storing the camera parameters for use with the shader.


updateFrom( camera : PerspectiveCamera | PhysicalCamera ) : void

Copies all fields from the passed PhysicalCamera if available otherwise the defaults are used.


A combined texture array used to store normal, tangent, uv, and color attributes in the same texture sampler array rather than separate samplers. Necessary to save texture slots.

Normals, tangents, uvs, and color attribute data are stored in the 1st, 2nd, 3rd, and 4th layers of the array respectively.


updateNormalAttribute( attr : BufferAttribute ) : void


updateTangentAttribute( attr : BufferAttribute ) : void


updateUvAttribute( attr : BufferAttribute ) : void


updateColorAttribute( attr : BufferAttribute ) : void


	normal : BufferAttribute,
	tangent : BufferAttribute,
	uv : BufferAttribute,
	color : BufferAttribute
) : void


extends DataTexture

Helper texture uniform for encoding materials as texture data.


threeCompatibilityTransforms = false : Boolean

Three.js materials support only a single set of UV transforms in a certain fallback priority while the pathtracer supports a unique set of transforms per texture. Set this field to true in order to use the same uv transform handling as three.js materials.

See fallback order documentation here.


setMatte( index : Number, matte : Boolean ) : void

Sets whether or not the material of the given index is matte or not. When "true" the background is rendered in place of the material.


setCastShadow( index : Number, enabled : Boolean ) : void

Sets whether or not the material of the given index will cast shadows. When "false" materials will not cast shadows on diffuse surfaces but will still be reflected. This is a good setting for lighting enclosed interiors with environment lighting.


updateFrom( materials : Array<Material>, textures : Array<Texture> ) : void

Updates the size and values of the texture to align with the provided set of materials and textures.

The "matte" and "side" values must be updated explicitly.

Note In order for volume transmission to work the "attenuationDistance" must be set to a value less than Infinity or "thickness" must be set to a value greater than 0.


Helper uniform for encoding lights as texture data with count.


updateFrom( lights : Array<Light>, iesTextures = [] : Array<Texture> ) : void

Updates the size and values of the texture to align with the provided set of lights and IES textures.


Stores the environment map contents along with the intensity distribution information to support multiple importance sampling.


updateFrom( environmentMap : Texture ) : void

Takes an environment map to process into something usable by the path tracer. Is expected to be a DataTexture so the data can be read.



mergeMeshes( meshes : Array<Mesh> ) : {
	materials : Array<Material>,
	textures : Array<Textures>,
	geometry : BufferGeometry

Merges the set of meshes into a single geometry with a materialIndex vertex attribute included on the geometry identifying the associated material in the returned materials array.


Detects whether the path tracer can run on the current device by checking whether struct precision is reliable and the material shader will compile.


constructor( renderer : WebGLRenderer, material : Material )

Takes a WebGLRenderer to use and material to test again.


detect() : {
	pass: Boolean,
	message: String

Returns pass === true if the path tracer can run. If it cannot run then a message is returned indicating why.

Shader Chunks


Set of functions for performing material scatter and PDF sampling. See the implementation for full list of functions.


Set of functions for performing light sampling. See the implementation for full list of functions.


Material and light struct definition for use with uniforms. See the implementation for full list of functions.


Set of randomness and other light transport utilities for use in a shader. See the implementation for full list of functions.


  • The project requires use of WebGL2.
  • All textures must use the same wrap and interpolation flags.
  • SpotLights, DirectionalLights, and PointLights are only supported with MIS.
  • Only MeshStandardMaterial and MeshPhysicalMaterial are supported.
  • Instanced geometry and interleaved buffers are not supported.
  • Emissive materials are supported but do not take advantage of MIS.


Sample materials

"SD Macross City Standoff Diorama" scene by tipatat

"Interior Scene" model by Allay Design

Perseverance Rover, Ingenuity Helicopter models by NASA / JPL-Caltech

Gelatinous Cube model by glenatron

Lego models courtesy of the LDraw Official Model Repository

Octopus Tea model by AzTiZ

Botanists Study model by riikkakilpelainen

Japanese Bridge Garden model by kristenlee


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