345 lines
9.2 KiB
JavaScript
345 lines
9.2 KiB
JavaScript
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// Original src: https://github.com/zz85/threejs-path-flow
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const CHANNELS = 4;
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const TEXTURE_WIDTH = 1024;
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const TEXTURE_HEIGHT = 4;
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import {
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DataTexture,
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RGBAFormat,
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FloatType,
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RepeatWrapping,
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Mesh,
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InstancedMesh,
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NearestFilter,
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DynamicDrawUsage,
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Matrix4
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} from 'three';
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/**
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* Make a new DataTexture to store the descriptions of the curves.
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*
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* @param { number } numberOfCurves the number of curves needed to be described by this texture.
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*/
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export function initSplineTexture( numberOfCurves = 1 ) {
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const dataArray = new Float32Array( TEXTURE_WIDTH * TEXTURE_HEIGHT * numberOfCurves * CHANNELS );
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const dataTexture = new DataTexture(
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dataArray,
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TEXTURE_WIDTH,
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TEXTURE_HEIGHT * numberOfCurves,
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RGBAFormat,
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FloatType
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);
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dataTexture.wrapS = RepeatWrapping;
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dataTexture.wrapY = RepeatWrapping;
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dataTexture.magFilter = NearestFilter;
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dataTexture.needsUpdate = true;
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return dataTexture;
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}
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/**
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* Write the curve description to the data texture
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*
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* @param { DataTexture } texture The DataTexture to write to
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* @param { Curve } splineCurve The curve to describe
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* @param { number } offset Which curve slot to write to
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*/
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export function updateSplineTexture( texture, splineCurve, offset = 0 ) {
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const numberOfPoints = Math.floor( TEXTURE_WIDTH * ( TEXTURE_HEIGHT / 4 ) );
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splineCurve.arcLengthDivisions = numberOfPoints / 2;
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splineCurve.updateArcLengths();
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const points = splineCurve.getSpacedPoints( numberOfPoints );
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const frenetFrames = splineCurve.computeFrenetFrames( numberOfPoints, true );
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for ( let i = 0; i < numberOfPoints; i ++ ) {
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const rowOffset = Math.floor( i / TEXTURE_WIDTH );
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const rowIndex = i % TEXTURE_WIDTH;
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let pt = points[ i ];
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setTextureValue( texture, rowIndex, pt.x, pt.y, pt.z, 0 + rowOffset + ( TEXTURE_HEIGHT * offset ) );
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pt = frenetFrames.tangents[ i ];
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setTextureValue( texture, rowIndex, pt.x, pt.y, pt.z, 1 + rowOffset + ( TEXTURE_HEIGHT * offset ) );
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pt = frenetFrames.normals[ i ];
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setTextureValue( texture, rowIndex, pt.x, pt.y, pt.z, 2 + rowOffset + ( TEXTURE_HEIGHT * offset ) );
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pt = frenetFrames.binormals[ i ];
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setTextureValue( texture, rowIndex, pt.x, pt.y, pt.z, 3 + rowOffset + ( TEXTURE_HEIGHT * offset ) );
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}
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texture.needsUpdate = true;
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}
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function setTextureValue( texture, index, x, y, z, o ) {
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const image = texture.image;
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const { data } = image;
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const i = CHANNELS * TEXTURE_WIDTH * o; // Row Offset
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data[ index * CHANNELS + i + 0 ] = x;
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data[ index * CHANNELS + i + 1 ] = y;
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data[ index * CHANNELS + i + 2 ] = z;
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data[ index * CHANNELS + i + 3 ] = 1;
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}
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/**
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* Create a new set of uniforms for describing the curve modifier
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*
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* @param { DataTexture } Texture which holds the curve description
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*/
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export function getUniforms( splineTexture ) {
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const uniforms = {
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spineTexture: { value: splineTexture },
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pathOffset: { type: 'f', value: 0 }, // time of path curve
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pathSegment: { type: 'f', value: 1 }, // fractional length of path
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spineOffset: { type: 'f', value: 161 },
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spineLength: { type: 'f', value: 400 },
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flow: { type: 'i', value: 1 },
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};
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return uniforms;
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}
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export function modifyShader( material, uniforms, numberOfCurves = 1 ) {
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if ( material.__ok ) return;
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material.__ok = true;
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material.onBeforeCompile = ( shader ) => {
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if ( shader.__modified ) return;
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shader.__modified = true;
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Object.assign( shader.uniforms, uniforms );
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const vertexShader = `
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uniform sampler2D spineTexture;
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uniform float pathOffset;
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uniform float pathSegment;
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uniform float spineOffset;
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uniform float spineLength;
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uniform int flow;
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float textureLayers = ${TEXTURE_HEIGHT * numberOfCurves}.;
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float textureStacks = ${TEXTURE_HEIGHT / 4}.;
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${shader.vertexShader}
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`
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// chunk import moved in front of modified shader below
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.replace( '#include <beginnormal_vertex>', '' )
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// vec3 transformedNormal declaration overriden below
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.replace( '#include <defaultnormal_vertex>', '' )
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// vec3 transformed declaration overriden below
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.replace( '#include <begin_vertex>', '' )
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// shader override
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.replace(
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/void\s*main\s*\(\)\s*\{/,
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`
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void main() {
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#include <beginnormal_vertex>
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vec4 worldPos = modelMatrix * vec4(position, 1.);
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bool bend = flow > 0;
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float xWeight = bend ? 0. : 1.;
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#ifdef USE_INSTANCING
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float pathOffsetFromInstanceMatrix = instanceMatrix[3][2];
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float spineLengthFromInstanceMatrix = instanceMatrix[3][0];
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float spinePortion = bend ? (worldPos.x + spineOffset) / spineLengthFromInstanceMatrix : 0.;
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float mt = (spinePortion * pathSegment + pathOffset + pathOffsetFromInstanceMatrix)*textureStacks;
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#else
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float spinePortion = bend ? (worldPos.x + spineOffset) / spineLength : 0.;
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float mt = (spinePortion * pathSegment + pathOffset)*textureStacks;
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#endif
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mt = mod(mt, textureStacks);
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float rowOffset = floor(mt);
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#ifdef USE_INSTANCING
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rowOffset += instanceMatrix[3][1] * ${TEXTURE_HEIGHT}.;
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#endif
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vec3 spinePos = texture2D(spineTexture, vec2(mt, (0. + rowOffset + 0.5) / textureLayers)).xyz;
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vec3 a = texture2D(spineTexture, vec2(mt, (1. + rowOffset + 0.5) / textureLayers)).xyz;
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vec3 b = texture2D(spineTexture, vec2(mt, (2. + rowOffset + 0.5) / textureLayers)).xyz;
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vec3 c = texture2D(spineTexture, vec2(mt, (3. + rowOffset + 0.5) / textureLayers)).xyz;
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mat3 basis = mat3(a, b, c);
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vec3 transformed = basis
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* vec3(worldPos.x * xWeight, worldPos.y * 1., worldPos.z * 1.)
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+ spinePos;
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vec3 transformedNormal = normalMatrix * (basis * objectNormal);
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` ).replace(
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'#include <project_vertex>',
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`vec4 mvPosition = modelViewMatrix * vec4( transformed, 1.0 );
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gl_Position = projectionMatrix * mvPosition;`
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);
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shader.vertexShader = vertexShader;
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};
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}
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/**
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* A helper class for making meshes bend aroudn curves
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*/
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export class Flow {
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/**
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* @param {Mesh} mesh The mesh to clone and modify to bend around the curve
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* @param {number} numberOfCurves The amount of space that should preallocated for additional curves
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*/
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constructor( mesh, numberOfCurves = 1 ) {
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const obj3D = mesh.clone();
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const splineTexure = initSplineTexture( numberOfCurves );
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const uniforms = getUniforms( splineTexure );
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obj3D.traverse( function ( child ) {
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if (
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child instanceof Mesh ||
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child instanceof InstancedMesh
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) {
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if ( Array.isArray( child.material ) ) {
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const materials = [];
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for ( const material of child.material ) {
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const newMaterial = material.clone();
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modifyShader( newMaterial, uniforms, numberOfCurves );
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materials.push( newMaterial );
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}
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child.material = materials;
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} else {
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child.material = child.material.clone();
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modifyShader( child.material, uniforms, numberOfCurves );
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}
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}
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} );
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this.curveArray = new Array( numberOfCurves );
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this.curveLengthArray = new Array( numberOfCurves );
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this.object3D = obj3D;
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this.splineTexure = splineTexure;
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this.uniforms = uniforms;
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}
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updateCurve( index, curve ) {
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if ( index >= this.curveArray.length ) throw Error( 'Index out of range for Flow' );
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const curveLength = curve.getLength();
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this.uniforms.spineLength.value = curveLength;
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this.curveLengthArray[ index ] = curveLength;
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this.curveArray[ index ] = curve;
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updateSplineTexture( this.splineTexure, curve, index );
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}
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moveAlongCurve( amount ) {
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this.uniforms.pathOffset.value += amount;
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}
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}
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const matrix = new Matrix4();
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/**
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* A helper class for creating instanced versions of flow, where the instances are placed on the curve.
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*/
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export class InstancedFlow extends Flow {
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/**
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*
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* @param {number} count The number of instanced elements
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* @param {number} curveCount The number of curves to preallocate for
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* @param {Geometry} geometry The geometry to use for the instanced mesh
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* @param {Material} material The material to use for the instanced mesh
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*/
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constructor( count, curveCount, geometry, material ) {
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const mesh = new InstancedMesh(
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geometry,
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material,
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count
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);
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mesh.instanceMatrix.setUsage( DynamicDrawUsage );
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mesh.frustumCulled = false;
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super( mesh, curveCount );
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this.offsets = new Array( count ).fill( 0 );
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this.whichCurve = new Array( count ).fill( 0 );
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}
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/**
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* The extra information about which curve and curve position is stored in the translation components of the matrix for the instanced objects
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* This writes that information to the matrix and marks it as needing update.
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*
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* @param {number} index of the instanced element to update
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*/
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writeChanges( index ) {
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matrix.makeTranslation(
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this.curveLengthArray[ this.whichCurve[ index ] ],
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this.whichCurve[ index ],
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this.offsets[ index ]
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);
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this.object3D.setMatrixAt( index, matrix );
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this.object3D.instanceMatrix.needsUpdate = true;
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}
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/**
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* Move an individual element along the curve by a specific amount
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*
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* @param {number} index Which element to update
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* @param {number} offset Move by how much
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*/
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moveIndividualAlongCurve( index, offset ) {
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this.offsets[ index ] += offset;
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this.writeChanges( index );
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}
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/**
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* Select which curve to use for an element
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*
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* @param {number} index the index of the instanced element to update
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* @param {number} curveNo the index of the curve it should use
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*/
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setCurve( index, curveNo ) {
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if ( isNaN( curveNo ) ) throw Error( 'curve index being set is Not a Number (NaN)' );
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this.whichCurve[ index ] = curveNo;
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this.writeChanges( index );
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}
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}
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