backend/libs/three/geometries/RingGeometry.js

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

class RingGeometry extends BufferGeometry {
	constructor(innerRadius = 0.5, outerRadius = 1, thetaSegments = 8, phiSegments = 1, thetaStart = 0, thetaLength = Math.PI * 2) {
		super();

		this.type = 'RingGeometry';

		this.parameters = {
			innerRadius: innerRadius,
			outerRadius: outerRadius,
			thetaSegments: thetaSegments,
			phiSegments: phiSegments,
			thetaStart: thetaStart,
			thetaLength: thetaLength,
		};

		thetaSegments = Math.max(3, thetaSegments);
		phiSegments = Math.max(1, phiSegments);

		// buffers

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

		// some helper variables

		let radius = innerRadius;
		const radiusStep = (outerRadius - innerRadius) / phiSegments;
		const vertex = new Vector3();
		const uv = new Vector2();

		// generate vertices, normals and uvs

		for (let j = 0; j <= phiSegments; j++) {
			for (let i = 0; i <= thetaSegments; i++) {
				// values are generate from the inside of the ring to the outside

				const segment = thetaStart + (i / thetaSegments) * thetaLength;

				// vertex

				vertex.x = radius * Math.cos(segment);
				vertex.y = radius * Math.sin(segment);

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

				// normal

				normals.push(0, 0, 1);

				// uv

				uv.x = (vertex.x / outerRadius + 1) / 2;
				uv.y = (vertex.y / outerRadius + 1) / 2;

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

			// increase the radius for next row of vertices

			radius += radiusStep;
		}

		// indices

		for (let j = 0; j < phiSegments; j++) {
			const thetaSegmentLevel = j * (thetaSegments + 1);

			for (let i = 0; i < thetaSegments; i++) {
				const segment = i + thetaSegmentLevel;

				const a = segment;
				const b = segment + thetaSegments + 1;
				const c = segment + thetaSegments + 2;
				const d = segment + 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('normal', new Float32BufferAttribute(normals, 3));
		this.setAttribute('uv', new Float32BufferAttribute(uvs, 2));
	}

	static fromJSON(data) {
		return new RingGeometry(data.innerRadius, data.outerRadius, data.thetaSegments, data.phiSegments, data.thetaStart, data.thetaLength);
	}
}

export { RingGeometry, RingGeometry as RingBufferGeometry };