CurveModifierGPU: WebGPURenderer port. (#29453)

* curve mod

* lint

* update screenshot

* use correct constant

* use filtered texture

---------

Co-authored-by: aardgoose <[email protected]>

examples/files.json

@@ -362,6 +362,7 @@
 		"webgpu_materialx_noise",
 		"webgpu_mesh_batch",
 		"webgpu_mirror",
+		"webgpu_modifier_curve",
 		"webgpu_morphtargets",
 		"webgpu_morphtargets_face",
 		"webgpu_mrt",

examples/jsm/modifiers/CurveModifierGPU.js

@@ -0,0 +1,233 @@
+// Original src: https://github.com/zz85/threejs-path-flow
+const CHANNELS = 4;
+const TEXTURE_WIDTH = 1024;
+const TEXTURE_HEIGHT = 4;
+
+import {
+	DataTexture,
+	DataUtils,
+	RGBAFormat,
+	HalfFloatType,
+	RepeatWrapping,
+	Mesh,
+	InstancedMesh,
+	LinearFilter
+} from 'three';
+
+import { modelWorldMatrix, normalLocal, vec2, vec3, vec4, mat3, varyingProperty, texture, reference, Fn, select, positionLocal } from 'three/tsl';
+
+/**
+ * Make a new DataTexture to store the descriptions of the curves.
+ *
+ * @param { number } numberOfCurves the number of curves needed to be described by this texture.
+ */
+export function initSplineTexture( numberOfCurves = 1 ) {
+
+	const dataArray = new Uint16Array( TEXTURE_WIDTH * TEXTURE_HEIGHT * numberOfCurves * CHANNELS );
+	const dataTexture = new DataTexture(
+		dataArray,
+		TEXTURE_WIDTH,
+		TEXTURE_HEIGHT * numberOfCurves,
+		RGBAFormat,
+		HalfFloatType
+	);
+
+	dataTexture.wrapS = RepeatWrapping;
+	dataTexture.wrapY = RepeatWrapping;
+	dataTexture.magFilter = LinearFilter;
+	dataTexture.minFilter = LinearFilter;
+	dataTexture.needsUpdate = true;
+
+	return dataTexture;
+
+}
+
+/**
+ * Write the curve description to the data texture
+ *
+ * @param { DataTexture } texture The DataTexture to write to
+ * @param { Curve } splineCurve The curve to describe
+ * @param { number } offset Which curve slot to write to
+ */
+export function updateSplineTexture( texture, splineCurve, offset = 0 ) {
+
+	const numberOfPoints = Math.floor( TEXTURE_WIDTH * ( TEXTURE_HEIGHT / 4 ) );
+	splineCurve.arcLengthDivisions = numberOfPoints / 2;
+	splineCurve.updateArcLengths();
+	const points = splineCurve.getSpacedPoints( numberOfPoints );
+	const frenetFrames = splineCurve.computeFrenetFrames( numberOfPoints, true );
+
+	for ( let i = 0; i < numberOfPoints; i ++ ) {
+
+		const rowOffset = Math.floor( i / TEXTURE_WIDTH );
+		const rowIndex = i % TEXTURE_WIDTH;
+
+		let pt = points[ i ];
+		setTextureValue( texture, rowIndex, pt.x, pt.y, pt.z, 0 + rowOffset + ( TEXTURE_HEIGHT * offset ) );
+		pt = frenetFrames.tangents[ i ];
+		setTextureValue( texture, rowIndex, pt.x, pt.y, pt.z, 1 + rowOffset + ( TEXTURE_HEIGHT * offset ) );
+		pt = frenetFrames.normals[ i ];
+		setTextureValue( texture, rowIndex, pt.x, pt.y, pt.z, 2 + rowOffset + ( TEXTURE_HEIGHT * offset ) );
+		pt = frenetFrames.binormals[ i ];
+		setTextureValue( texture, rowIndex, pt.x, pt.y, pt.z, 3 + rowOffset + ( TEXTURE_HEIGHT * offset ) );
+
+	}
+
+	texture.needsUpdate = true;
+
+}
+
+
+function setTextureValue( texture, index, x, y, z, o ) {
+
+	const image = texture.image;
+	const { data } = image;
+	const i = CHANNELS * TEXTURE_WIDTH * o; // Row Offset
+
+	data[ index * CHANNELS + i + 0 ] = DataUtils.toHalfFloat( x );
+	data[ index * CHANNELS + i + 1 ] = DataUtils.toHalfFloat( y );
+	data[ index * CHANNELS + i + 2 ] = DataUtils.toHalfFloat( z );
+	data[ index * CHANNELS + i + 3 ] = DataUtils.toHalfFloat( 1 );
+
+}
+
+/**
+ * Create a new set of uniforms for describing the curve modifier
+ *
+ * @param { DataTexture } Texture which holds the curve description
+ */
+export function getUniforms( splineTexture ) {
+
+	return {
+		spineTexture: splineTexture,
+		pathOffset: 0, // time of path curve
+		pathSegment: 1, // fractional length of path
+		spineOffset: 161,
+		spineLength: 400,
+		flow: 1, // int
+	};
+
+}
+
+export function modifyShader( material, uniforms, numberOfCurves ) {
+
+	const spineTexture = uniforms.spineTexture;
+
+	const pathOffset = reference( 'pathOffset', 'float', uniforms );
+	const pathSegment = reference( 'pathSegment', 'float', uniforms );
+	const spineOffset = reference( 'spineOffset', 'float', uniforms );
+	const spineLength = reference( 'spineLength', 'float', uniforms );
+	const flow = reference( 'flow', 'float', uniforms );
+
+	material.positionNode = Fn( () => {
+
+		const textureStacks = TEXTURE_HEIGHT / 4;
+		const textureScale = TEXTURE_HEIGHT * numberOfCurves;
+
+		const worldPos = modelWorldMatrix.mul( vec4( positionLocal, 1 ) ).toVar();
+
+		const bend = flow.greaterThan( 0 ).toVar();
+		const xWeight = select( bend, 0, 1 ).toVar();
+
+		const spinePortion = select( bend, worldPos.x.add( spineOffset ).div( spineLength ), 0 );
+		const mt = spinePortion.mul( pathSegment ).add( pathOffset ).mul( textureStacks ).toVar();
+
+		mt.assign( mt.mod( textureStacks ) );
+
+		const rowOffset = mt.floor().toVar();
+
+		const spinePos = texture( spineTexture, vec2( mt, rowOffset.add( 0.5 ).div( textureScale ) ) ).xyz;
+
+		const a = texture( spineTexture, vec2( mt, rowOffset.add( 1.5 ).div( textureScale ) ) ).xyz;
+		const b = texture( spineTexture, vec2( mt, rowOffset.add( 2.5 ).div( textureScale ) ) ).xyz;
+		const c = texture( spineTexture, vec2( mt, rowOffset.add( 3.5 ).div( textureScale ) ) ).xyz;
+
+		const basis = mat3( a, b, c ).toVar();
+
+		varyingProperty( 'vec3', 'curveNormal' ).assign( basis.mul( normalLocal ) );
+
+		return basis.mul( vec3( worldPos.x.mul( xWeight ), worldPos.y, worldPos.z ) ).add( spinePos );
+
+	} )();
+
+	material.normalNode = varyingProperty( 'vec3', 'curveNormal' );
+
+}
+
+/**
+ * A helper class for making meshes bend aroudn curves
+ */
+export class Flow {
+
+	/**
+	 * @param {Mesh} mesh The mesh to clone and modify to bend around the curve
+	 * @param {number} numberOfCurves The amount of space that should preallocated for additional curves
+	 */
+	constructor( mesh, numberOfCurves = 1 ) {
+
+		const obj3D = mesh.clone();
+		const splineTexure = initSplineTexture( numberOfCurves );
+		const uniforms = getUniforms( splineTexure );
+
+		obj3D.traverse( function ( child ) {
+
+			if (
+				child instanceof Mesh ||
+				child instanceof InstancedMesh
+			) {
+
+				if ( Array.isArray( child.material ) ) {
+
+					const materials = [];
+
+					for ( const material of child.material ) {
+
+						const newMaterial = material.clone();
+						modifyShader( newMaterial, uniforms, numberOfCurves );
+						materials.push( newMaterial );
+
+					}
+
+					child.material = materials;
+
+				} else {
+
+					child.material = child.material.clone();
+					modifyShader( child.material, uniforms, numberOfCurves );
+
+				}
+
+			}
+
+		} );
+
+		this.curveArray = new Array( numberOfCurves );
+		this.curveLengthArray = new Array( numberOfCurves );
+
+		this.object3D = obj3D;
+		this.splineTexure = splineTexure;
+		this.uniforms = uniforms;
+
+	}
+
+	updateCurve( index, curve ) {
+
+		if ( index >= this.curveArray.length ) throw Error( 'Index out of range for Flow' );
+
+		const curveLength = curve.getLength();
+
+		this.uniforms.spineLength = curveLength;
+		this.curveLengthArray[ index ] = curveLength;
+		this.curveArray[ index ] = curve;
+
+		updateSplineTexture( this.splineTexure, curve, index );
+
+	}
+
+	moveAlongCurve( amount ) {
+
+		this.uniforms.pathOffset += amount;
+
+	}
+
+}