webgpu_compute_sort_bitonic.html 18 KB

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  1. <html lang="en">
  2. <head>
  3. <title>three.js webgpu - storage pbo external element</title>
  4. <meta charset="utf-8">
  5. <meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
  6. <link type="text/css" rel="stylesheet" href="main.css">
  7. </head>
  8. <body>
  9. <div id="info">
  10. <a href="https://threejs.org" target="_blank" rel="noopener">three.js</a>
  11. <br /> This example demonstrates a bitonic sort running step by step in a compute shader.
  12. <br /> The left canvas swaps values within workgroup local arrays. The right swaps values within storage buffers.
  13. <br /> Reference implementation by <a href="https://poniesandlight.co.uk/reflect/bitonic_merge_sort/">Tim Gfrerer</a>
  14. <br />
  15. <div id="local_swap" style="
  16. position: absolute;
  17. top: 150px;
  18. left: 0;
  19. padding: 10px;
  20. background: rgba( 0, 0, 0, 0.5 );
  21. color: #fff;
  22. font-family: monospace;
  23. font-size: 12px;
  24. line-height: 1.5;
  25. pointer-events: none;
  26. text-align: left;
  27. "></div>
  28. <div id="global_swap" style="
  29. position: absolute;
  30. top: 150px;
  31. right: 0;
  32. padding: 10px;
  33. background: rgba( 0, 0, 0, 0.5 );
  34. color: #fff;
  35. font-family: monospace;
  36. font-size: 12px;
  37. line-height: 1.5;
  38. pointer-events: none;
  39. text-align: left;
  40. "></div>
  41. </div>
  42. <script type="importmap">
  43. {
  44. "imports": {
  45. "three": "../build/three.webgpu.js",
  46. "three/webgpu": "../build/three.webgpu.js",
  47. "three/tsl": "../build/three.tsl.js",
  48. "three/addons/": "./jsm/"
  49. }
  50. }
  51. </script>
  52. <script type="module">
  53. import * as THREE from 'three';
  54. import { storage, If, vec3, not, uniform, uv, uint, float, Fn, vec2, abs, int, invocationLocalIndex, workgroupArray, uvec2, floor, instanceIndex, workgroupBarrier, atomicAdd, atomicStore, workgroupId } from 'three/tsl';
  55. import { GUI } from 'three/addons/libs/lil-gui.module.min.js';
  56. const StepType = {
  57. NONE: 0,
  58. // Swap values within workgroup local buffer.
  59. FLIP_LOCAL: 1,
  60. DISPERSE_LOCAL: 2,
  61. // Swap values within global data buffer.
  62. FLIP_GLOBAL: 3,
  63. DISPERSE_GLOBAL: 4,
  64. };
  65. const timestamps = {
  66. local_swap: document.getElementById( 'local_swap' ),
  67. global_swap: document.getElementById( 'global_swap' )
  68. };
  69. const localColors = [ 'rgb(203, 64, 203)', 'rgb(0, 215, 215)' ];
  70. const globalColors = [ 'rgb(1, 150, 1)', 'red' ];
  71. // Total number of elements and the dimensions of the display grid.
  72. const size = 16384;
  73. const gridDim = Math.sqrt( size );
  74. const getNumSteps = () => {
  75. const n = Math.log2( size );
  76. return ( n * ( n + 1 ) ) / 2;
  77. };
  78. // Total number of steps in a bitonic sort with 'size' elements.
  79. const MAX_STEPS = getNumSteps();
  80. const WORKGROUP_SIZE = [ 64 ];
  81. const effectController = {
  82. // Sqr root of 16834
  83. gridWidth: uniform( gridDim ),
  84. gridHeight: uniform( gridDim ),
  85. highlight: uniform( 1 ),
  86. 'Display Mode': 'Swap Zone Highlight'
  87. };
  88. const gui = new GUI();
  89. gui.add( effectController, 'Display Mode', [ 'Elements', 'Swap Zone Highlight' ] ).onChange( () => {
  90. if ( effectController[ 'Display Mode' ] === 'Elements' ) {
  91. effectController.highlight.value = 0;
  92. } else {
  93. effectController.highlight.value = 1;
  94. }
  95. } );
  96. // Allow Workgroup Array Swaps
  97. init();
  98. // Global Swaps Only
  99. init( true );
  100. // When forceGlobalSwap is true, force all valid local swaps to be global swaps.
  101. async function init( forceGlobalSwap = false ) {
  102. let currentStep = 0;
  103. let nextStepGlobal = false;
  104. const aspect = ( window.innerWidth / 2 ) / window.innerHeight;
  105. const camera = new THREE.OrthographicCamera( - aspect, aspect, 1, - 1, 0, 2 );
  106. camera.position.z = 1;
  107. const scene = new THREE.Scene();
  108. const nextAlgoBuffer = new THREE.StorageInstancedBufferAttribute( new Uint32Array( 1 ).fill( forceGlobalSwap ? StepType.FLIP_GLOBAL : StepType.FLIP_LOCAL ), 1 );
  109. const nextAlgoStorage = storage( nextAlgoBuffer, 'uint', nextAlgoBuffer.count ).setPBO( true ).label( 'NextAlgo' );
  110. const nextBlockHeightBuffer = new THREE.StorageInstancedBufferAttribute( new Uint32Array( 1 ).fill( 2 ), 1 );
  111. const nextBlockHeightStorage = storage( nextBlockHeightBuffer, 'uint', nextBlockHeightBuffer.count ).setPBO( true ).label( 'NextBlockHeight' );
  112. const nextBlockHeightRead = storage( nextBlockHeightBuffer, 'uint', nextBlockHeightBuffer.count ).setPBO( true ).label( 'NextBlockHeight' ).toReadOnly();
  113. const highestBlockHeightBuffer = new THREE.StorageInstancedBufferAttribute( new Uint32Array( 1 ).fill( 2 ), 1 );
  114. const highestBlockHeightStorage = storage( highestBlockHeightBuffer, 'uint', highestBlockHeightBuffer.count ).setPBO( true ).label( 'HighestBlockHeight' );
  115. const counterBuffer = new THREE.StorageBufferAttribute( 1, 1 );
  116. const counterStorage = storage( counterBuffer, 'uint', counterBuffer.count ).setPBO( true ).toAtomic().label( 'Counter' );
  117. const array = new Uint32Array( Array.from( { length: size }, ( _, i ) => {
  118. return i;
  119. } ) );
  120. const randomizeDataArray = () => {
  121. let currentIndex = array.length;
  122. while ( currentIndex !== 0 ) {
  123. const randomIndex = Math.floor( Math.random() * currentIndex );
  124. currentIndex -= 1;
  125. [ array[ currentIndex ], array[ randomIndex ] ] = [
  126. array[ randomIndex ],
  127. array[ currentIndex ],
  128. ];
  129. }
  130. };
  131. randomizeDataArray();
  132. const currentElementsBuffer = new THREE.StorageInstancedBufferAttribute( array, 1 );
  133. const currentElementsStorage = storage( currentElementsBuffer, 'uint', size ).setPBO( true ).label( 'Elements' );
  134. const tempBuffer = new THREE.StorageInstancedBufferAttribute( array, 1 );
  135. const tempStorage = storage( tempBuffer, 'uint', size ).setPBO( true ).label( 'Temp' );
  136. const randomizedElementsBuffer = new THREE.StorageInstancedBufferAttribute( size, 1 );
  137. const randomizedElementsStorage = storage( randomizedElementsBuffer, 'uint', size ).setPBO( true ).label( 'RandomizedElements' );
  138. const getFlipIndices = ( index, blockHeight ) => {
  139. const blockOffset = ( index.mul( 2 ).div( blockHeight ) ).mul( blockHeight );
  140. const halfHeight = blockHeight.div( 2 );
  141. const idx = uvec2(
  142. index.modInt( halfHeight ),
  143. blockHeight.sub( index.modInt( halfHeight ) ).sub( 1 )
  144. );
  145. idx.x.addAssign( blockOffset );
  146. idx.y.addAssign( blockOffset );
  147. return idx;
  148. };
  149. const getDisperseIndices = ( index, blockHeight ) => {
  150. const blockOffset = ( ( index.mul( 2 ) ).div( blockHeight ) ).mul( blockHeight );
  151. const halfHeight = blockHeight.div( 2 );
  152. const idx = uvec2(
  153. index.modInt( halfHeight ),
  154. ( index.modInt( halfHeight ) ).add( halfHeight )
  155. );
  156. idx.x.addAssign( blockOffset );
  157. idx.y.addAssign( blockOffset );
  158. return idx;
  159. };
  160. const localStorage = workgroupArray( 'uint', 64 * 2 );
  161. // Swap the elements in local storage
  162. const localCompareAndSwap = ( idxBefore, idxAfter ) => {
  163. If( localStorage.element( idxAfter ).lessThan( localStorage.element( idxBefore ) ), () => {
  164. atomicAdd( counterStorage.element( 0 ), 1 );
  165. const temp = localStorage.element( idxBefore ).toVar();
  166. localStorage.element( idxBefore ).assign( localStorage.element( idxAfter ) );
  167. localStorage.element( idxAfter ).assign( temp );
  168. } );
  169. };
  170. const globalCompareAndSwap = ( idxBefore, idxAfter ) => {
  171. // If the later element is less than the current element
  172. If( currentElementsStorage.element( idxAfter ).lessThan( currentElementsStorage.element( idxBefore ) ), () => {
  173. // Apply the swapped values to temporary storage.
  174. atomicAdd( counterStorage.element( 0 ), 1 );
  175. tempStorage.element( idxBefore ).assign( currentElementsStorage.element( idxAfter ) );
  176. tempStorage.element( idxAfter ).assign( currentElementsStorage.element( idxBefore ) );
  177. } ).Else( () => {
  178. // Otherwise apply the existing values to temporary storage.
  179. tempStorage.element( idxBefore ).assign( currentElementsStorage.element( idxBefore ) );
  180. tempStorage.element( idxAfter ).assign( currentElementsStorage.element( idxAfter ) );
  181. } );
  182. };
  183. const computeInitFn = Fn( () => {
  184. randomizedElementsStorage.element( instanceIndex ).assign( currentElementsStorage.element( instanceIndex ) );
  185. } );
  186. const computeBitonicStepFn = Fn( () => {
  187. const nextBlockHeight = nextBlockHeightStorage.element( 0 ).toVar();
  188. const nextAlgo = nextAlgoStorage.element( 0 ).toVar();
  189. // Get ids of indices needed to populate workgroup local buffer.
  190. // Use .toVar() to prevent these values from being recalculated multiple times.
  191. const localOffset = uint( WORKGROUP_SIZE[ 0 ] ).mul( 2 ).mul( workgroupId.x ).toVar();
  192. const localID1 = invocationLocalIndex.mul( 2 );
  193. const localID2 = invocationLocalIndex.mul( 2 ).add( 1 );
  194. // If we will perform a local swap, then populate the local data
  195. If( nextAlgo.lessThanEqual( uint( StepType.DISPERSE_LOCAL ) ), () => {
  196. localStorage.element( localID1 ).assign( currentElementsStorage.element( localOffset.add( localID1 ) ) );
  197. localStorage.element( localID2 ).assign( currentElementsStorage.element( localOffset.add( localID2 ) ) );
  198. } );
  199. workgroupBarrier();
  200. // TODO: Convert to switch block.
  201. If( nextAlgo.equal( uint( StepType.FLIP_LOCAL ) ), () => {
  202. const idx = getFlipIndices( invocationLocalIndex, nextBlockHeight );
  203. localCompareAndSwap( idx.x, idx.y );
  204. } ).ElseIf( nextAlgo.equal( uint( StepType.DISPERSE_LOCAL ) ), () => {
  205. const idx = getDisperseIndices( invocationLocalIndex, nextBlockHeight );
  206. localCompareAndSwap( idx.x, idx.y );
  207. } ).ElseIf( nextAlgo.equal( uint( StepType.FLIP_GLOBAL ) ), () => {
  208. const idx = getFlipIndices( instanceIndex, nextBlockHeight );
  209. globalCompareAndSwap( idx.x, idx.y );
  210. } ).ElseIf( nextAlgo.equal( uint( StepType.DISPERSE_GLOBAL ) ), () => {
  211. const idx = getDisperseIndices( instanceIndex, nextBlockHeight );
  212. globalCompareAndSwap( idx.x, idx.y );
  213. } );
  214. // Ensure that all invocations have swapped their own regions of data
  215. workgroupBarrier();
  216. // Populate output data with the results from our swaps
  217. If( nextAlgo.lessThanEqual( uint( StepType.DISPERSE_LOCAL ) ), () => {
  218. currentElementsStorage.element( localOffset.add( localID1 ) ).assign( localStorage.element( localID1 ) );
  219. currentElementsStorage.element( localOffset.add( localID2 ) ).assign( localStorage.element( localID2 ) );
  220. } );
  221. // If the previous algorithm was global, we execute an additional compute step to sync the current buffer with the output buffer.
  222. } );
  223. const computeSetAlgoFn = Fn( () => {
  224. const nextBlockHeight = nextBlockHeightStorage.element( 0 ).toVar();
  225. const nextAlgo = nextAlgoStorage.element( 0 );
  226. const highestBlockHeight = highestBlockHeightStorage.element( 0 ).toVar();
  227. nextBlockHeight.divAssign( 2 );
  228. If( nextBlockHeight.equal( 1 ), () => {
  229. highestBlockHeight.mulAssign( 2 );
  230. if ( forceGlobalSwap ) {
  231. If( highestBlockHeight.equal( size * 2 ), () => {
  232. nextAlgo.assign( StepType.NONE );
  233. nextBlockHeight.assign( 0 );
  234. } ).Else( () => {
  235. nextAlgo.assign( StepType.FLIP_GLOBAL );
  236. nextBlockHeight.assign( highestBlockHeight );
  237. } );
  238. } else {
  239. If( highestBlockHeight.equal( size * 2 ), () => {
  240. nextAlgo.assign( StepType.NONE );
  241. nextBlockHeight.assign( 0 );
  242. } ).ElseIf( highestBlockHeight.greaterThan( WORKGROUP_SIZE[ 0 ] * 2 ), () => {
  243. nextAlgo.assign( StepType.FLIP_GLOBAL );
  244. nextBlockHeight.assign( highestBlockHeight );
  245. } ).Else( () => {
  246. nextAlgo.assign( forceGlobalSwap ? StepType.FLIP_GLOBAL : StepType.FLIP_LOCAL );
  247. nextBlockHeight.assign( highestBlockHeight );
  248. } );
  249. }
  250. } ).Else( () => {
  251. if ( forceGlobalSwap ) {
  252. nextAlgo.assign( StepType.DISPERSE_GLOBAL );
  253. } else {
  254. nextAlgo.assign( nextBlockHeight.greaterThan( WORKGROUP_SIZE[ 0 ] * 2 ).select( StepType.DISPERSE_GLOBAL, StepType.DISPERSE_LOCAL ) );
  255. }
  256. } );
  257. nextBlockHeightStorage.element( 0 ).assign( nextBlockHeight );
  258. highestBlockHeightStorage.element( 0 ).assign( highestBlockHeight );
  259. } );
  260. const computeAlignCurrentFn = Fn( () => {
  261. currentElementsStorage.element( instanceIndex ).assign( tempStorage.element( instanceIndex ) );
  262. } );
  263. const computeResetBuffersFn = Fn( () => {
  264. currentElementsStorage.element( instanceIndex ).assign( randomizedElementsStorage.element( instanceIndex ) );
  265. } );
  266. const computeResetAlgoFn = Fn( () => {
  267. nextAlgoStorage.element( 0 ).assign( forceGlobalSwap ? StepType.FLIP_GLOBAL : StepType.FLIP_LOCAL );
  268. nextBlockHeightStorage.element( 0 ).assign( 2 );
  269. highestBlockHeightStorage.element( 0 ).assign( 2 );
  270. atomicStore( counterStorage.element( 0 ), 0 );
  271. } );
  272. // Initialize each value in the elements buffer.
  273. const computeInit = computeInitFn().compute( size );
  274. // Swap a pair of elements in the elements buffer.
  275. const computeBitonicStep = computeBitonicStepFn().compute( size / 2 );
  276. // Set the conditions for the next swap.
  277. const computeSetAlgo = computeSetAlgoFn().compute( 1 );
  278. // Align the current buffer with the temp buffer if the previous sort was executed in a global scope.
  279. const computeAlignCurrent = computeAlignCurrentFn().compute( size );
  280. // Reset the buffers and algorithm information after a full bitonic sort has been completed.
  281. const computeResetBuffers = computeResetBuffersFn().compute( size );
  282. const computeResetAlgo = computeResetAlgoFn().compute( 1 );
  283. const material = new THREE.MeshBasicNodeMaterial( { color: 0x00ff00 } );
  284. const display = Fn( () => {
  285. const { gridWidth, gridHeight, highlight } = effectController;
  286. const newUV = uv().mul( vec2( gridWidth, gridHeight ) );
  287. const pixel = uvec2( uint( floor( newUV.x ) ), uint( floor( newUV.y ) ) );
  288. const elementIndex = uint( gridWidth ).mul( pixel.y ).add( pixel.x );
  289. const colorChanger = currentElementsStorage.element( elementIndex );
  290. const subtracter = float( colorChanger ).div( gridWidth.mul( gridHeight ) );
  291. const color = vec3( subtracter.oneMinus() ).toVar();
  292. If( highlight.equal( 1 ).and( not( nextAlgoStorage.element( 0 ).equal( StepType.NONE ) ) ), () => {
  293. const boolCheck = int( elementIndex.modInt( nextBlockHeightRead.element( 0 ) ).lessThan( nextBlockHeightRead.element( 0 ).div( 2 ) ) );
  294. color.z.assign( nextAlgoStorage.element( 0 ).lessThanEqual( StepType.DISPERSE_LOCAL ) );
  295. color.x.mulAssign( boolCheck );
  296. color.y.mulAssign( abs( boolCheck.sub( 1 ) ) );
  297. } );
  298. return color;
  299. } );
  300. material.colorNode = display();
  301. const plane = new THREE.Mesh( new THREE.PlaneGeometry( 1, 1 ), material );
  302. scene.add( plane );
  303. const renderer = new THREE.WebGPURenderer( { antialias: false, trackTimestamp: true } );
  304. renderer.setPixelRatio( window.devicePixelRatio );
  305. renderer.setSize( window.innerWidth / 2, window.innerHeight );
  306. const animate = () => {
  307. renderer.render( scene, camera );
  308. };
  309. renderer.setAnimationLoop( animate );
  310. document.body.appendChild( renderer.domElement );
  311. renderer.domElement.style.position = 'absolute';
  312. renderer.domElement.style.top = '0';
  313. renderer.domElement.style.left = '0';
  314. renderer.domElement.style.width = '50%';
  315. renderer.domElement.style.height = '100%';
  316. if ( forceGlobalSwap ) {
  317. renderer.domElement.style.left = '50%';
  318. scene.background = new THREE.Color( 0x212121 );
  319. } else {
  320. scene.background = new THREE.Color( 0x313131 );
  321. }
  322. await renderer.computeAsync( computeInit );
  323. renderer.info.autoReset = false;
  324. const stepAnimation = async function () {
  325. renderer.info.reset();
  326. if ( currentStep !== MAX_STEPS ) {
  327. renderer.compute( computeBitonicStep );
  328. if ( nextStepGlobal ) {
  329. renderer.compute( computeAlignCurrent );
  330. }
  331. renderer.compute( computeSetAlgo );
  332. currentStep ++;
  333. } else {
  334. renderer.compute( computeResetBuffers );
  335. renderer.compute( computeResetAlgo );
  336. currentStep = 0;
  337. }
  338. const algo = new Uint32Array( await renderer.getArrayBufferAsync( nextAlgoBuffer ) );
  339. algo > StepType.DISPERSE_LOCAL ? ( nextStepGlobal = true ) : ( nextStepGlobal = false );
  340. const totalSwaps = new Uint32Array( await renderer.getArrayBufferAsync( counterBuffer ) );
  341. renderer.render( scene, camera );
  342. timestamps[ forceGlobalSwap ? 'global_swap' : 'local_swap' ].innerHTML = `
  343. Compute ${forceGlobalSwap ? 'Global' : 'Local'}: ${renderer.info.compute.frameCalls} pass in ${renderer.info.compute.timestamp.toFixed( 6 )}ms<br>
  344. Total Swaps: ${totalSwaps}<br>
  345. <div style="display: flex; flex-direction:row; justify-content: center; align-items: center;">
  346. ${forceGlobalSwap ? 'Global Swaps' : 'Local Swaps'} Compare Region&nbsp;
  347. <div style="background-color: ${ forceGlobalSwap ? globalColors[ 0 ] : localColors[ 0 ]}; width:12.5px; height: 1em; border-radius: 20%;"></div>
  348. &nbsp;to Region&nbsp;
  349. <div style="background-color: ${ forceGlobalSwap ? globalColors[ 1 ] : localColors[ 1 ]}; width:12.5px; height: 1em; border-radius: 20%;"></div>
  350. </div>`;
  351. if ( currentStep === MAX_STEPS ) {
  352. setTimeout( stepAnimation, 1000 );
  353. } else {
  354. setTimeout( stepAnimation, 50 );
  355. }
  356. };
  357. stepAnimation();
  358. window.addEventListener( 'resize', onWindowResize );
  359. function onWindowResize() {
  360. renderer.setSize( window.innerWidth / 2, window.innerHeight );
  361. const aspect = ( window.innerWidth / 2 ) / window.innerHeight;
  362. const frustumHeight = camera.top - camera.bottom;
  363. camera.left = - frustumHeight * aspect / 2;
  364. camera.right = frustumHeight * aspect / 2;
  365. camera.updateProjectionMatrix();
  366. renderer.render( scene, camera );
  367. }
  368. }
  369. </script>
  370. </body>
  371. </html>
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