three 基础库
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import {
BufferAttribute,
BufferGeometry,
Color,
DynamicDrawUsage,
Matrix4,
Mesh,
MeshStandardMaterial,
Vector3
} from '../../../build/three.module.js';
function TubePainter() {
const BUFFER_SIZE = 1000000 * 3;
const positions = new BufferAttribute( new Float32Array( BUFFER_SIZE ), 3 );
positions.usage = DynamicDrawUsage;
const normals = new BufferAttribute( new Float32Array( BUFFER_SIZE ), 3 );
normals.usage = DynamicDrawUsage;
const colors = new BufferAttribute( new Float32Array( BUFFER_SIZE ), 3 );
colors.usage = DynamicDrawUsage;
const geometry = new BufferGeometry();
geometry.setAttribute( 'position', positions );
geometry.setAttribute( 'normal', normals );
geometry.setAttribute( 'color', colors );
geometry.drawRange.count = 0;
const material = new MeshStandardMaterial( {
vertexColors: true
} );
const mesh = new Mesh( geometry, material );
mesh.frustumCulled = false;
//
function getPoints( size ) {
const PI2 = Math.PI * 2;
const sides = 10;
const array = [];
const radius = 0.01 * size;
for ( let i = 0; i < sides; i ++ ) {
const angle = ( i / sides ) * PI2;
array.push( new Vector3( Math.sin( angle ) * radius, Math.cos( angle ) * radius, 0 ) );
}
return array;
}
//
const vector1 = new Vector3();
const vector2 = new Vector3();
const vector3 = new Vector3();
const vector4 = new Vector3();
const color = new Color( 0xffffff );
let size = 1;
function stroke( position1, position2, matrix1, matrix2 ) {
if ( position1.distanceToSquared( position2 ) === 0 ) return;
let count = geometry.drawRange.count;
const points = getPoints( size );
for ( let i = 0, il = points.length; i < il; i ++ ) {
const vertex1 = points[ i ];
const vertex2 = points[ ( i + 1 ) % il ];
// positions
vector1.copy( vertex1 ).applyMatrix4( matrix2 ).add( position2 );
vector2.copy( vertex2 ).applyMatrix4( matrix2 ).add( position2 );
vector3.copy( vertex2 ).applyMatrix4( matrix1 ).add( position1 );
vector4.copy( vertex1 ).applyMatrix4( matrix1 ).add( position1 );
vector1.toArray( positions.array, ( count + 0 ) * 3 );
vector2.toArray( positions.array, ( count + 1 ) * 3 );
vector4.toArray( positions.array, ( count + 2 ) * 3 );
vector2.toArray( positions.array, ( count + 3 ) * 3 );
vector3.toArray( positions.array, ( count + 4 ) * 3 );
vector4.toArray( positions.array, ( count + 5 ) * 3 );
// normals
vector1.copy( vertex1 ).applyMatrix4( matrix2 ).normalize();
vector2.copy( vertex2 ).applyMatrix4( matrix2 ).normalize();
vector3.copy( vertex2 ).applyMatrix4( matrix1 ).normalize();
vector4.copy( vertex1 ).applyMatrix4( matrix1 ).normalize();
vector1.toArray( normals.array, ( count + 0 ) * 3 );
vector2.toArray( normals.array, ( count + 1 ) * 3 );
vector4.toArray( normals.array, ( count + 2 ) * 3 );
vector2.toArray( normals.array, ( count + 3 ) * 3 );
vector3.toArray( normals.array, ( count + 4 ) * 3 );
vector4.toArray( normals.array, ( count + 5 ) * 3 );
// colors
color.toArray( colors.array, ( count + 0 ) * 3 );
color.toArray( colors.array, ( count + 1 ) * 3 );
color.toArray( colors.array, ( count + 2 ) * 3 );
color.toArray( colors.array, ( count + 3 ) * 3 );
color.toArray( colors.array, ( count + 4 ) * 3 );
color.toArray( colors.array, ( count + 5 ) * 3 );
count += 6;
}
geometry.drawRange.count = count;
}
//
const up = new Vector3( 0, 1, 0 );
const point1 = new Vector3();
const point2 = new Vector3();
const matrix1 = new Matrix4();
const matrix2 = new Matrix4();
function moveTo( position ) {
point1.copy( position );
matrix1.lookAt( point2, point1, up );
point2.copy( position );
matrix2.copy( matrix1 );
}
function lineTo( position ) {
point1.copy( position );
matrix1.lookAt( point2, point1, up );
stroke( point1, point2, matrix1, matrix2 );
point2.copy( point1 );
matrix2.copy( matrix1 );
}
function setSize( value ) {
size = value;
}
//
let count = 0;
function update() {
const start = count;
const end = geometry.drawRange.count;
if ( start === end ) return;
positions.updateRange.offset = start * 3;
positions.updateRange.count = ( end - start ) * 3;
positions.needsUpdate = true;
normals.updateRange.offset = start * 3;
normals.updateRange.count = ( end - start ) * 3;
normals.needsUpdate = true;
colors.updateRange.offset = start * 3;
colors.updateRange.count = ( end - start ) * 3;
colors.needsUpdate = true;
count = geometry.drawRange.count;
}
return {
mesh: mesh,
moveTo: moveTo,
lineTo: lineTo,
setSize: setSize,
update: update
};
}
export { TubePainter };