Accueil / npm / three@0.171.0 / examples / jsm / modifiers / CurveModifierGPU.js
CurveModifierGPU.js
// 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;
}
}