backend/libs/three/geometries/SphereGeometry.js

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

class SphereGeometry extends BufferGeometry {
	constructor(radius = 1, widthSegments = 32, heightSegments = 16, phiStart = 0, phiLength = Math.PI * 2, thetaStart = 0, thetaLength = Math.PI) {
		super();
		this.type = 'SphereGeometry';

		this.parameters = {
			radius: radius,
			widthSegments: widthSegments,
			heightSegments: heightSegments,
			phiStart: phiStart,
			phiLength: phiLength,
			thetaStart: thetaStart,
			thetaLength: thetaLength,
		};

		widthSegments = Math.max(3, Math.floor(widthSegments));
		heightSegments = Math.max(2, Math.floor(heightSegments));

		const thetaEnd = Math.min(thetaStart + thetaLength, Math.PI);

		let index = 0;
		const grid = [];

		const vertex = new Vector3();
		const normal = new Vector3();

		// buffers

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

		// generate vertices, normals and uvs

		for (let iy = 0; iy <= heightSegments; iy++) {
			const verticesRow = [];

			const v = iy / heightSegments;

			// special case for the poles

			let uOffset = 0;

			if (iy == 0 && thetaStart == 0) {
				uOffset = 0.5 / widthSegments;
			} else if (iy == heightSegments && thetaEnd == Math.PI) {
				uOffset = -0.5 / widthSegments;
			}

			for (let ix = 0; ix <= widthSegments; ix++) {
				const u = ix / widthSegments;

				// vertex

				vertex.x = -radius * Math.cos(phiStart + u * phiLength) * Math.sin(thetaStart + v * thetaLength);
				vertex.y = radius * Math.cos(thetaStart + v * thetaLength);
				vertex.z = radius * Math.sin(phiStart + u * phiLength) * Math.sin(thetaStart + v * thetaLength);

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

				// normal

				normal.copy(vertex).normalize();
				normals.push(normal.x, normal.y, normal.z);

				// uv

				uvs.push(u + uOffset, 1 - v);

				verticesRow.push(index++);
			}

			grid.push(verticesRow);
		}

		// indices

		for (let iy = 0; iy < heightSegments; iy++) {
			for (let ix = 0; ix < widthSegments; ix++) {
				const a = grid[iy][ix + 1];
				const b = grid[iy][ix];
				const c = grid[iy + 1][ix];
				const d = grid[iy + 1][ix + 1];

				if (iy !== 0 || thetaStart > 0) indices.push(a, b, d);
				if (iy !== heightSegments - 1 || thetaEnd < Math.PI) indices.push(b, c, d);
			}
		}

		// build geometry

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

	static fromJSON(data) {
		return new SphereGeometry(data.radius, data.widthSegments, data.heightSegments, data.phiStart, data.phiLength, data.thetaStart, data.thetaLength);
	}
}

export { SphereGeometry, SphereGeometry as SphereBufferGeometry };