three.js/examples/jsm/renderers/webgl/utils/WebGLCapabilities.js

class WebGLCapabilities {

	constructor( backend ) {

		this.backend = backend;

		this.maxAnisotropy = null;

	}

	getMaxAnisotropy() {

		if ( this.maxAnisotropy !== null ) return this.maxAnisotropy;

		const gl = this.backend.gl;
		const extensions = this.backend.extensions;

		if ( extensions.has( 'EXT_texture_filter_anisotropic' ) === true ) {

			const extension = extensions.get( 'EXT_texture_filter_anisotropic' );

			this.maxAnisotropy = gl.getParameter( extension.MAX_TEXTURE_MAX_ANISOTROPY_EXT );

		} else {

			this.maxAnisotropy = 0;

		}

		return this.maxAnisotropy;

	}

}

export default WebGLCapabilities;