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WebGPUPathTracer: Get megakernel working in Firefox, Safari #745

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Merged
gkjohnson merged 1 commit into from
Mar 10, 2026
Merged

WebGPUPathTracer: Get megakernel working in Firefox, Safari #745

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37 changes: 17 additions & 20 deletions src/webgpu/compute/PathTracerMegaKernel.js
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Original file line number Diff line number Diff line change
@@ -1,11 +1,12 @@
import { DataTexture, Matrix3, Matrix4, Vector2, StorageTexture } from 'three/webgpu';
import { ndcToCameraRay } from '../lib/wgsl/common.wgsl.js';
import { ComputeKernel } from './ComputeKernel.js';
import { texture, sampler, uniform, globalId, textureStore, wgslFn } from 'three/tsl';
import { texture, sampler, uniform, globalId, textureStore } from 'three/tsl';
import { pcgRand2, pcgRand3, pcgInit } from '../nodes/random.wgsl.js';
import { getSurfaceRecordFunc, lambertBsdfFunc } from '../nodes/material.wgsl.js';
import { sampleEnvironmentFn, weightedAlphaBlendFn } from '../nodes/sampling.wgsl.js';
import { proxy } from '../lib/nodes/NodeProxy.js';
import { wgslTagFn } from '../lib/nodes/WGSLTagFnNode.js';

export class PathTracerMegaKernel extends ComputeKernel {

Expand Down Expand Up @@ -46,15 +47,12 @@ export class PathTracerMegaKernel extends ComputeKernel {
globalId: globalId,
};

const shader = wgslFn( /* wgsl */`
const shader = wgslTagFn/* wgsl */`

fn compute(

// indices and target
globalId: vec3u,
prevOutputTarget: texture_storage_2d<rgba32float, read>,
outputTarget: texture_storage_2d<rgba32float, write>,
sampleCountTarget: texture_storage_2d<r32uint, read_write>,

// tiles
offset: vec2u,
Expand Down Expand Up @@ -104,7 +102,7 @@ export class PathTracerMegaKernel extends ComputeKernel {

// to screen coordinates
let indexUV = offset + globalId.xy;
let targetDimensions = textureDimensions( outputTarget );
let targetDimensions = textureDimensions( ${ parameters.outputTarget } );
if ( indexUV.x >= targetDimensions.x || indexUV.y >= targetDimensions.y ) {

return;
Expand All @@ -129,7 +127,6 @@ export class PathTracerMegaKernel extends ComputeKernel {
let hitResult = bvh_RaycastFirstHit( ray );
if ( hitResult.didHit ) {


let object = bvh_transforms.value[ hitResult.objectIndex ];
var material = bvh_materials.value[ object.materialIndex ];

Expand Down Expand Up @@ -169,23 +166,23 @@ export class PathTracerMegaKernel extends ComputeKernel {

}

let sampleCount = textureLoad( sampleCountTarget, indexUV ).r + 1;
let prevColor = textureLoad( prevOutputTarget, indexUV );
let sampleCount = textureLoad( ${ parameters.sampleCountTarget }, indexUV ).r + 1;
let prevColor = textureLoad( ${ parameters.prevOutputTarget }, indexUV );
let blendedColor = weightedAlphaBlend( prevColor, resultColor, 1.0 / f32( sampleCount ) );
textureStore( sampleCountTarget, indexUV, vec4( sampleCount ) );
textureStore( outputTarget, indexUV, blendedColor );
textureStore( ${ parameters.sampleCountTarget }, indexUV, vec4( sampleCount ) );
textureStore( ${ parameters.outputTarget }, indexUV, blendedColor );

}

`, [
proxy( 'bvhData.value.storage.materials', parameters ),
proxy( 'bvhData.value.structs.material', parameters ),
proxy( 'bvhData.value.structs.transform', parameters ),
proxy( 'bvhData.value.fns.raycastFirstHit', parameters ),
proxy( 'bvhData.value.fns.sampleTrianglePoint', parameters ),
ndcToCameraRay, pcgRand2, pcgRand3, pcgInit, lambertBsdfFunc,
sampleEnvironmentFn, getSurfaceRecordFunc, weightedAlphaBlendFn,
] );
${ [
proxy( 'bvhData.value.storage.materials', parameters ),
proxy( 'bvhData.value.structs.material', parameters ),
proxy( 'bvhData.value.structs.transform', parameters ),
proxy( 'bvhData.value.fns.raycastFirstHit', parameters ),
proxy( 'bvhData.value.fns.sampleTrianglePoint', parameters ),
ndcToCameraRay, pcgRand2, pcgRand3, pcgInit, lambertBsdfFunc,
sampleEnvironmentFn, getSurfaceRecordFunc, weightedAlphaBlendFn,
] }`;

super( shader( parameters ) );

Expand Down
19 changes: 8 additions & 11 deletions src/webgpu/compute/ZeroOutKernel.js
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Original file line number Diff line number Diff line change
@@ -1,29 +1,26 @@
import { StorageTexture } from 'three/webgpu';
import { ComputeKernel } from './ComputeKernel.js';
import { textureStore, wgslFn, globalId } from 'three/tsl';
import { textureStore, globalId } from 'three/tsl';
import { wgslTagFn } from '../lib/nodes/WGSLTagFnNode.js';

export class ZeroOutKernel extends ComputeKernel {

constructor( { textureType = 'rgba32float' } ) {
constructor() {

const params = {
globalId: globalId,
outputTarget: textureStore( new StorageTexture( 1, 1 ) ).toWriteOnly(),
};

const fn = wgslFn( /* wgsl */`
const fn = wgslTagFn/* wgsl */`
fn compute( globalId: vec3u ) -> void {

fn compute(
globalId: vec3u,
outputTarget: texture_storage_2d<${ textureType }, write>,
) -> void {

textureStore( outputTarget, globalId.xy, vec4( 0, 0, 0, 1 ) );
textureStore( ${ params.outputTarget }, globalId.xy, vec4( 0, 0, 0, 1 ) );

}
` )( params );
`;

super( fn );
super( fn( params ) );

this.defineUniformAccessors( {
target: params.outputTarget,
Expand Down
6 changes: 6 additions & 0 deletions src/webgpu/lib/nodes/NodeProxy.js
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,12 @@ class ProxyCallNode extends Node {

export class NodeProxy {

get isNode() {

return true;

}

// getter for the node being proxied to
get proxyNode() {

Expand Down
16 changes: 8 additions & 8 deletions src/webgpu/lib/nodes/WGSLTagFnNode.js
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Original file line number Diff line number Diff line change
Expand Up @@ -62,18 +62,17 @@ function getIncludeNode( arg ) {

if ( arg.functionNode ) return arg.functionNode;
if ( arg.isStruct ) return arg.layout;
return null;
else return null;

}
} else if ( arg.isNode ) {

if ( arg && arg.isNode ) {
return new PropertyRefNode( arg );

if ( arg.functionNode ) return arg.functionNode;
if ( arg.isStructLayoutNode || arg.isCodeNode ) return arg;
} else {

}
return null;

return null;
}

}

Expand Down Expand Up @@ -116,6 +115,7 @@ function normalizeArgs( args ) {
if ( typeof arg === 'function' && arg.functionNode ) return new PropertyRefNode( arg.functionNode );
if ( typeof arg === 'function' && arg.isStruct ) return arg.layout;
if ( arg && arg.isNode && arg.functionNode ) return new InlineCallNode( arg );
if ( arg && arg.isNode ) return new PropertyRefNode( arg );
return arg;

} );
Expand Down Expand Up @@ -240,7 +240,7 @@ export class WGSLTagFnNode extends FunctionNode {
const { type } = this.getNodeFunction( builder );
const nodeCode = builder.getCodeFromNode( this, type );

nodeCode.code = fullCode.replace( /\/\/.+[\n\r]/g, '' ).replace( /->\s*void/, '' ).replace( /\s+/g, ' ' ).trim();
nodeCode.code = fullCode.replace( /\/\/.+[\n\r]/g, '' ).replace( /->\s*void/, '' ).trim();

return result;

Expand Down