📄 `CurveModifierGPU.js`¶

📊 Analysis Summary¶

Metric	Count
🔧 Functions	7
🧱 Classes	1
📦 Imports	20
📊 Variables & Constants	17

📚 Table of Contents¶

Imports
Variables & Constants
Functions
Classes

🛠️ File Location:¶

📂 examples/jsm/modifiers/CurveModifierGPU.js

📦 Imports¶

Name	Source
`DataTexture`	`three`
`DataUtils`	`three`
`RGBAFormat`	`three`
`HalfFloatType`	`three`
`RepeatWrapping`	`three`
`Mesh`	`three`
`InstancedMesh`	`three`
`LinearFilter`	`three`
`modelWorldMatrix`	`three/tsl`
`normalLocal`	`three/tsl`
`vec2`	`three/tsl`
`vec3`	`three/tsl`
`vec4`	`three/tsl`
`mat3`	`three/tsl`
`varyingProperty`	`three/tsl`
`texture`	`three/tsl`
`reference`	`three/tsl`
`Fn`	`three/tsl`
`select`	`three/tsl`
`positionLocal`	`three/tsl`

Variables & Constants¶

Name	Type	Kind	Value	Exported
`CHANNELS`	`4`	let/var	`4`	✗
`TEXTURE_WIDTH`	`1024`	let/var	`1024`	✗
`TEXTURE_HEIGHT`	`4`	let/var	`4`	✗
`dataArray`	`Uint16Array<ArrayBuffer>`	let/var	`new Uint16Array( TEXTURE_WIDTH * TEXTURE_HEIGHT * numberOfCurves * CHANNELS )`	✗
`dataTexture`	`any`	let/var	`new DataTexture( dataArray, TEXTURE_WIDTH, TEXTURE_HEIGHT * numberOfCurves, R...`	✗
`rowIndex`	`number`	let/var	`i % TEXTURE_WIDTH`	✗
`pt`	`any`	let/var	`points[ i ]`	✗
`image`	`any`	let/var	`texture.image`	✗
`i`	`number`	let/var	`CHANNELS * TEXTURE_WIDTH * o`	✗
`spineTexture`	`any`	let/var	`uniforms.spineTexture`	✗
`textureStacks`	`number`	let/var	`TEXTURE_HEIGHT / 4`	✗
`textureScale`	`number`	let/var	`TEXTURE_HEIGHT * numberOfCurves`	✗
`spinePos`	`any`	let/var	`texture( spineTexture, vec2( mt, rowOffset.add( 0.5 ).div( textureScale ) ) )...`	✗
`a`	`any`	let/var	`texture( spineTexture, vec2( mt, rowOffset.add( 1.5 ).div( textureScale ) ) )...`	✗
`b`	`any`	let/var	`texture( spineTexture, vec2( mt, rowOffset.add( 2.5 ).div( textureScale ) ) )...`	✗
`c`	`any`	let/var	`texture( spineTexture, vec2( mt, rowOffset.add( 3.5 ).div( textureScale ) ) )...`	✗
`materials`	`any[]`	let/var	`[]`	✗

Functions¶

`initSplineTexture(numberOfCurves: number): DataTexture`¶

JSDoc:

/**
 * Make a new DataTexture to store the descriptions of the curves.
 *
 * @private
 * @param {number} [numberOfCurves=1] - The number of curves needed to be described by this texture.
 * @returns  {DataTexture} The new data texture.
 */

Parameters:

numberOfCurves number

Returns: DataTexture

Code

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;

}

`updateSplineTexture(texture: DataTexture, splineCurve: Curve, offset: number): void`¶

JSDoc:

/**
 * Write the curve description to the data texture.
 *
 * @private
 * @param {DataTexture} texture - The data texture to write to.
 * @param {Curve} splineCurve - The curve to describe.
 * @param {number} [offset=0] - Which curve slot to write to.
 */

Parameters:

texture DataTexture
splineCurve Curve
offset number

Returns: void

Calls:

Math.floor
splineCurve.updateArcLengths
splineCurve.getSpacedPoints
splineCurve.computeFrenetFrames
setTextureValue

Code

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;

}

`setTextureValue(texture: any, index: any, x: any, y: any, z: any, o: any): void`¶

Parameters:

texture any
index any
x any
y any
z any
o any

Returns: void

Calls:

DataUtils.toHalfFloat

Code

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 );

}

`getUniforms(splineTexture: DataTexture): any`¶

JSDoc:

/**
 * Create a new set of uniforms for describing the curve modifier.
 *
 * @private
 * @param {DataTexture} splineTexture - Which holds the curve description.
 * @returns {Object} The uniforms object.
 */

Parameters:

splineTexture DataTexture

Returns: any

Code

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
    };

}

`modifyShader(material: any, uniforms: any, numberOfCurves: any): void`¶

Parameters:

material any
uniforms any
numberOfCurves any

Returns: void

Calls:

reference (from three/tsl)
complex_call_3837
varyingProperty (from three/tsl)

Code

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' );

}

`Flow.updateCurve(index: number, curve: Curve): void`¶

JSDoc:

/**
     * Updates the curve for the given curve index.
     *
     * @param {number} index - The curve index.
     * @param {Curve} curve - The curve that should be used to bend the mesh.
     */

Parameters:

index number
curve Curve

Returns: void

Calls:

Error
curve.getLength
updateSplineTexture

Code

updateCurve( index, curve ) {

        if ( index >= this.curveArray.length ) throw Error( 'Flow: Index out of range.' );

        const curveLength = curve.getLength();

        this.uniforms.spineLength = curveLength;
        this.curveLengthArray[ index ] = curveLength;
        this.curveArray[ index ] = curve;

        updateSplineTexture( this.splineTexture, curve, index );

    }

`Flow.moveAlongCurve(amount: number): void`¶

JSDoc:

/**
     * Moves the mesh along the curve.
     *
     * @param {number} amount - The offset.
     */

Parameters:

amount number

Returns: void

Code

moveAlongCurve( amount ) {

        this.uniforms.pathOffset += amount;

    }

Classes¶

`Flow`¶

Class Code

export class Flow {

    /**
     * Constructs a new Flow instance.
     *
     * @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 splineTexture = initSplineTexture( numberOfCurves );
        const uniforms = getUniforms( splineTexture );

        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.splineTexture = splineTexture;
        this.uniforms = uniforms;

    }

    /**
     * Updates the curve for the given curve index.
     *
     * @param {number} index - The curve index.
     * @param {Curve} curve - The curve that should be used to bend the mesh.
     */
    updateCurve( index, curve ) {

        if ( index >= this.curveArray.length ) throw Error( 'Flow: Index out of range.' );

        const curveLength = curve.getLength();

        this.uniforms.spineLength = curveLength;
        this.curveLengthArray[ index ] = curveLength;
        this.curveArray[ index ] = curve;

        updateSplineTexture( this.splineTexture, curve, index );

    }

    /**
     * Moves the mesh along the curve.
     *
     * @param {number} amount - The offset.
     */
    moveAlongCurve( amount ) {

        this.uniforms.pathOffset += amount;

    }

}

Methods¶

`updateCurve(index: number, curve: Curve): void`¶

Code

updateCurve( index, curve ) {

        if ( index >= this.curveArray.length ) throw Error( 'Flow: Index out of range.' );

        const curveLength = curve.getLength();

        this.uniforms.spineLength = curveLength;
        this.curveLengthArray[ index ] = curveLength;
        this.curveArray[ index ] = curve;

        updateSplineTexture( this.splineTexture, curve, index );

    }

`moveAlongCurve(amount: number): void`¶

Code

moveAlongCurve( amount ) {

        this.uniforms.pathOffset += amount;

    }

📄 CurveModifierGPU.js¶

📊 Analysis Summary¶

📚 Table of Contents¶

🛠️ File Location:¶

📦 Imports¶

Variables & Constants¶

Functions¶

initSplineTexture(numberOfCurves: number): DataTexture¶

updateSplineTexture(texture: DataTexture, splineCurve: Curve, offset: number): void¶

setTextureValue(texture: any, index: any, x: any, y: any, z: any, o: any): void¶

getUniforms(splineTexture: DataTexture): any¶

modifyShader(material: any, uniforms: any, numberOfCurves: any): void¶

Flow.updateCurve(index: number, curve: Curve): void¶

Flow.moveAlongCurve(amount: number): void¶

Classes¶

Flow¶

Methods¶

updateCurve(index: number, curve: Curve): void¶

moveAlongCurve(amount: number): void¶

📄 `CurveModifierGPU.js`¶

`initSplineTexture(numberOfCurves: number): DataTexture`¶

`updateSplineTexture(texture: DataTexture, splineCurve: Curve, offset: number): void`¶

`setTextureValue(texture: any, index: any, x: any, y: any, z: any, o: any): void`¶

`getUniforms(splineTexture: DataTexture): any`¶

`modifyShader(material: any, uniforms: any, numberOfCurves: any): void`¶

`Flow.updateCurve(index: number, curve: Curve): void`¶

`Flow.moveAlongCurve(amount: number): void`¶

`Flow`¶

`updateCurve(index: number, curve: Curve): void`¶

`moveAlongCurve(amount: number): void`¶