three.js/src/geometries/LatheGeometry.js

/**
 * @author zz85 / https://github.com/zz85
 * @author bhouston / http://clara.io
 * @author Mugen87 / https://github.com/Mugen87
 */

import { Geometry } from '../core/Geometry.js';
import { Float32BufferAttribute } from '../core/BufferAttribute.js';
import { BufferGeometry } from '../core/BufferGeometry.js';
import { Vector3 } from '../math/Vector3.js';
import { Vector2 } from '../math/Vector2.js';
import { MathUtils } from '../math/MathUtils.js';

// LatheGeometry

function LatheGeometry( points, segments, phiStart, phiLength ) {

	Geometry.call( this );

	this.type = 'LatheGeometry';

	this.parameters = {
		points: points,
		segments: segments,
		phiStart: phiStart,
		phiLength: phiLength
	};

	this.fromBufferGeometry( new LatheBufferGeometry( points, segments, phiStart, phiLength ) );
	this.mergeVertices();

}

LatheGeometry.prototype = Object.create( Geometry.prototype );
LatheGeometry.prototype.constructor = LatheGeometry;

// LatheBufferGeometry

function LatheBufferGeometry( points, segments, phiStart, phiLength ) {

	BufferGeometry.call( this );

	this.type = 'LatheBufferGeometry';

	this.parameters = {
		points: points,
		segments: segments,
		phiStart: phiStart,
		phiLength: phiLength
	};

	segments = Math.floor( segments ) || 12;
	phiStart = phiStart || 0;
	phiLength = phiLength || Math.PI * 2;

	// clamp phiLength so it's in range of [ 0, 2PI ]

	phiLength = MathUtils.clamp( phiLength, 0, Math.PI * 2 );


	// buffers

	const indices = [];
	const vertices = [];
	const uvs = [];

	// helper variables

	const inverseSegments = 1.0 / segments;
	const vertex = new Vector3();
	const uv = new Vector2();

	// generate vertices and uvs

	for ( let i = 0; i <= segments; i ++ ) {

		const phi = phiStart + i * inverseSegments * phiLength;

		const sin = Math.sin( phi );
		const cos = Math.cos( phi );

		for ( let j = 0; j <= ( points.length - 1 ); j ++ ) {

			// vertex

			vertex.x = points[ j ].x * sin;
			vertex.y = points[ j ].y;
			vertex.z = points[ j ].x * cos;

			vertices.push( vertex.x, vertex.y, vertex.z );

			// uv

			uv.x = i / segments;
			uv.y = j / ( points.length - 1 );

			uvs.push( uv.x, uv.y );


		}

	}

	// indices

	for ( let i = 0; i < segments; i ++ ) {

		for ( let j = 0; j < ( points.length - 1 ); j ++ ) {

			const base = j + i * points.length;

			const a = base;
			const b = base + points.length;
			const c = base + points.length + 1;
			const d = base + 1;

			// faces

			indices.push( a, b, d );
			indices.push( b, c, d );

		}

	}

	// build geometry

	this.setIndex( indices );
	this.setAttribute( 'position', new Float32BufferAttribute( vertices, 3 ) );
	this.setAttribute( 'uv', new Float32BufferAttribute( uvs, 2 ) );

	// generate normals

	this.computeVertexNormals();

	// if the geometry is closed, we need to average the normals along the seam.
	// because the corresponding vertices are identical (but still have different UVs).

	if ( phiLength === Math.PI * 2 ) {

		const normals = this.attributes.normal.array;
		const n1 = new Vector3();
		const n2 = new Vector3();
		const n = new Vector3();

		// this is the buffer offset for the last line of vertices

		const base = segments * points.length * 3;

		for ( let i = 0, j = 0; i < points.length; i ++, j += 3 ) {

			// select the normal of the vertex in the first line

			n1.x = normals[ j + 0 ];
			n1.y = normals[ j + 1 ];
			n1.z = normals[ j + 2 ];

			// select the normal of the vertex in the last line

			n2.x = normals[ base + j + 0 ];
			n2.y = normals[ base + j + 1 ];
			n2.z = normals[ base + j + 2 ];

			// average normals

			n.addVectors( n1, n2 ).normalize();

			// assign the new values to both normals

			normals[ j + 0 ] = normals[ base + j + 0 ] = n.x;
			normals[ j + 1 ] = normals[ base + j + 1 ] = n.y;
			normals[ j + 2 ] = normals[ base + j + 2 ] = n.z;

		}

	}

}

LatheBufferGeometry.prototype = Object.create( BufferGeometry.prototype );
LatheBufferGeometry.prototype.constructor = LatheBufferGeometry;


export { LatheGeometry, LatheBufferGeometry };