playcanvas/build/playcanvas.prf/src/scene/geometry/sphere-geometry.js

PlayCanvas WebGL game engine

import { calculateTangents } from './geometry-utils.js';
import { Geometry } from './geometry.js';

class SphereGeometry extends Geometry {
		constructor(opts = {}){
				super();
				const radius = opts.radius ?? 0.5;
				const latitudeBands = opts.latitudeBands ?? 16;
				const longitudeBands = opts.longitudeBands ?? 16;
				const positions = [];
				const normals = [];
				const uvs = [];
				const indices = [];
				for(let lat = 0; lat <= latitudeBands; lat++){
						const theta = lat * Math.PI / latitudeBands;
						const sinTheta = Math.sin(theta);
						const cosTheta = Math.cos(theta);
						for(let lon = 0; lon <= longitudeBands; lon++){
								const phi = lon * 2 * Math.PI / longitudeBands - Math.PI / 2;
								const sinPhi = Math.sin(phi);
								const cosPhi = Math.cos(phi);
								const x = cosPhi * sinTheta;
								const y = cosTheta;
								const z = sinPhi * sinTheta;
								const u = 1 - lon / longitudeBands;
								const v = 1 - lat / latitudeBands;
								positions.push(x * radius, y * radius, z * radius);
								normals.push(x, y, z);
								uvs.push(u, 1 - v);
						}
				}
				for(let lat = 0; lat < latitudeBands; ++lat){
						for(let lon = 0; lon < longitudeBands; ++lon){
								const first = lat * (longitudeBands + 1) + lon;
								const second = first + longitudeBands + 1;
								indices.push(first + 1, second, first);
								indices.push(first + 1, second + 1, second);
						}
				}
				this.positions = positions;
				this.normals = normals;
				this.uvs = uvs;
				this.uvs1 = uvs;
				this.indices = indices;
				if (opts.calculateTangents) {
						this.tangents = calculateTangents(positions, normals, uvs, indices);
				}
		}
}

export { SphereGeometry };