three 基础库
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import {
BufferGeometry,
Float32BufferAttribute,
LineSegments,
LineBasicMaterial,
Vector3
} from '../../../build/three.module.js';
const _v1 = new Vector3();
const _v2 = new Vector3();
class VertexTangentsHelper extends LineSegments {
constructor( object, size = 1, color = 0x00ffff ) {
const objGeometry = object.geometry;
if ( ! ( objGeometry && objGeometry.isBufferGeometry ) ) {
console.error( 'THREE.VertexTangentsHelper: geometry not an instance of THREE.BufferGeometry.', objGeometry );
return;
}
const nTangents = objGeometry.attributes.tangent.count;
//
const geometry = new BufferGeometry();
const positions = new Float32BufferAttribute( nTangents * 2 * 3, 3 );
geometry.setAttribute( 'position', positions );
super( geometry, new LineBasicMaterial( { color, toneMapped: false } ) );
this.object = object;
this.size = size;
this.type = 'VertexTangentsHelper';
//
this.matrixAutoUpdate = false;
this.update();
}
update() {
this.object.updateMatrixWorld( true );
const matrixWorld = this.object.matrixWorld;
const position = this.geometry.attributes.position;
//
const objGeometry = this.object.geometry;
const objPos = objGeometry.attributes.position;
const objTan = objGeometry.attributes.tangent;
let idx = 0;
// for simplicity, ignore index and drawcalls, and render every tangent
for ( let j = 0, jl = objPos.count; j < jl; j ++ ) {
_v1.set( objPos.getX( j ), objPos.getY( j ), objPos.getZ( j ) ).applyMatrix4( matrixWorld );
_v2.set( objTan.getX( j ), objTan.getY( j ), objTan.getZ( j ) );
_v2.transformDirection( matrixWorld ).multiplyScalar( this.size ).add( _v1 );
position.setXYZ( idx, _v1.x, _v1.y, _v1.z );
idx = idx + 1;
position.setXYZ( idx, _v2.x, _v2.y, _v2.z );
idx = idx + 1;
}
position.needsUpdate = true;
}
}
export { VertexTangentsHelper };