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

PlayCanvas WebGL game engine

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

/**
 * A procedural sphere-shaped geometry.
 *
 * The size and tesselation properties of the sphere can be controlled via constructor parameters. By
 * default, the function will create a sphere centered on the object space origin with a radius of
 * 0.5 and 16 segments in both longitude and latitude.
 *
 * Note that the sphere is created with UVs in the range of 0 to 1.
 *
 * @category Graphics
 */ class SphereGeometry extends Geometry {
    /**
     * Create a new SphereGeometry instance.
     *
     * @param {object} [opts] - An object that specifies optional inputs for the function as follows:
     * @param {number} [opts.radius] - The radius of the sphere (defaults to 0.5).
     * @param {number} [opts.latitudeBands] - The number of divisions along the latitudinal axis of the
     * sphere (defaults to 16).
     * @param {number} [opts.longitudeBands] - The number of divisions along the longitudinal axis of
     * the sphere (defaults to 16).
     * @param {boolean} [opts.calculateTangents] - Generate tangent information (defaults to false).
     */ constructor(opts = {}){
        super();
        var _opts_radius;
        // Check the supplied options and provide defaults for unspecified ones
        var radius = (_opts_radius = opts.radius) != null ? _opts_radius : 0.5;
        var _opts_latitudeBands;
        var latitudeBands = (_opts_latitudeBands = opts.latitudeBands) != null ? _opts_latitudeBands : 16;
        var _opts_longitudeBands;
        var longitudeBands = (_opts_longitudeBands = opts.longitudeBands) != null ? _opts_longitudeBands : 16;
        // Variable declarations
        var positions = [];
        var normals = [];
        var uvs = [];
        var indices = [];
        for(var lat = 0; lat <= latitudeBands; lat++){
            var theta = lat * Math.PI / latitudeBands;
            var sinTheta = Math.sin(theta);
            var cosTheta = Math.cos(theta);
            for(var lon = 0; lon <= longitudeBands; lon++){
                // Sweep the sphere from the positive Z axis to match a 3DS Max sphere
                var phi = lon * 2 * Math.PI / longitudeBands - Math.PI / 2;
                var sinPhi = Math.sin(phi);
                var cosPhi = Math.cos(phi);
                var x = cosPhi * sinTheta;
                var y = cosTheta;
                var z = sinPhi * sinTheta;
                var u = 1 - lon / longitudeBands;
                var v = 1 - lat / latitudeBands;
                positions.push(x * radius, y * radius, z * radius);
                normals.push(x, y, z);
                uvs.push(u, 1 - v);
            }
        }
        for(var lat1 = 0; lat1 < latitudeBands; ++lat1){
            for(var lon1 = 0; lon1 < longitudeBands; ++lon1){
                var first = lat1 * (longitudeBands + 1) + lon1;
                var 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; // UV1 = UV0 for sphere
        this.indices = indices;
        if (opts.calculateTangents) {
            this.tangents = calculateTangents(positions, normals, uvs, indices);
        }
    }
}

export { SphereGeometry };