import { vec2, vec3 } from 'gl-matrix';
type ivec3 = [number, number, number];
/**
 * Helper class to generate a sphere geometry based on a refinable icosahedron
 */
export declare class Icosahedron {
    /** @see {@link faces} */
    protected _faces: Array<ivec3>;
    /** @see {@link vertices} */
    protected _vertices: Array<vec3>;
    /** @see {@link texcoords} */
    protected _texcoords: Array<vec2>;
    /**
     * Object constructor.
     */
    constructor();
    /**
     * Returns the base vertices for the icosahedron.
     */
    protected baseVertices(): Array<vec3>;
    /**
     * Returns the base faces for the icosahedron.
     */
    protected baseFaces(): Array<ivec3>;
    /**
     * Refines the icosahedron. For each step, every triangle is split into 4.
     * @param vertices - List of vertices that is modified.
     * @param faces - List of faces that is modified.
     * @param levels - Number of levels of refinement.
     */
    protected refine(vertices: Array<vec3>, faces: Array<ivec3>, levels: number): void;
    /**
     * Splits an edge and returns the new vertex that is the center of the edge.
     * @param a - Index of first vertex.
     * @param b - Index of second vertex.
     * @param vertices - List of vertices that is modified.
     * @param cache - Cache to identify newly created vertices.
     */
    protected split(a: number, b: number, vertices: Array<vec3>, cache: Map<number, number>): number;
    /**
     * Generates the geometry of the icosahedron.
     * @param levels - Number of levels of refinement.
     */
    generateGeometry(levels: number): void;
    /**
     * Generates texture coordinates for the icosahedron.
     */
    generateTextureCoordinates(): void;
    /**
     * Read-only access to the faces of the icosahedron.
     */
    get faces(): Array<ivec3>;
    /**
     * Read-only access to the vertices of the icosahedron.
     */
    get vertices(): Array<vec3>;
    /**
     * Read-only access to the texture coordinates of the icosahedron.
     */
    get texcoords(): Array<vec2>;
}
export {};