three.js/src/utils.js

function arrayMin( array ) {

	if ( array.length === 0 ) return Infinity;

	let min = array[ 0 ];

	for ( let i = 1, l = array.length; i < l; ++ i ) {

		if ( array[ i ] < min ) min = array[ i ];

	}

	return min;

}

function arrayMax( array ) {

	if ( array.length === 0 ) return - Infinity;

	let max = array[ 0 ];

	for ( let i = 1, l = array.length; i < l; ++ i ) {

		if ( array[ i ] > max ) max = array[ i ];

	}

	return max;

}

function arrayNeedsUint32( array ) {

	// assumes larger values usually on last

	for ( let i = array.length - 1; i >= 0; -- i ) {

		if ( array[ i ] >= 65535 ) return true; // account for PRIMITIVE_RESTART_FIXED_INDEX, #24565

	}

	return false;

}

const TYPED_ARRAYS = {
	Int8Array: Int8Array,
	Uint8Array: Uint8Array,
	Uint8ClampedArray: Uint8ClampedArray,
	Int16Array: Int16Array,
	Uint16Array: Uint16Array,
	Int32Array: Int32Array,
	Uint32Array: Uint32Array,
	Float32Array: Float32Array,
	Float64Array: Float64Array
};

function getTypedArray( type, buffer ) {

	return new TYPED_ARRAYS[ type ]( buffer );

}

function createElementNS( name ) {

	return document.createElementNS( 'http://www.w3.org/1999/xhtml', name );

}

function createCanvasElement() {

	const canvas = createElementNS( 'canvas' );
	canvas.style.display = 'block';
	return canvas;

}

const _cache = {};

function warnOnce( message ) {

	if ( message in _cache ) return;

	_cache[ message ] = true;

	console.warn( message );

}

function probeAsync( gl, sync, interval ) {

	return new Promise( function ( resolve, reject ) {

		function probe() {

			switch ( gl.clientWaitSync( sync, gl.SYNC_FLUSH_COMMANDS_BIT, 0 ) ) {

				case gl.WAIT_FAILED:
					reject();
					break;

				case gl.TIMEOUT_EXPIRED:
					setTimeout( probe, interval );
					break;

				default:
					resolve();

			}

		}

		setTimeout( probe, interval );

	} );

}

function toNormalizedProjectionMatrix( projectionMatrix ) {

	const m = projectionMatrix.elements;

	// Convert [-1, 1] to [0, 1] projection matrix
	m[ 2 ] = 0.5 * m[ 2 ] + 0.5 * m[ 3 ];
	m[ 6 ] = 0.5 * m[ 6 ] + 0.5 * m[ 7 ];
	m[ 10 ] = 0.5 * m[ 10 ] + 0.5 * m[ 11 ];
	m[ 14 ] = 0.5 * m[ 14 ] + 0.5 * m[ 15 ];

}

function toReversedProjectionMatrix( projectionMatrix ) {

	const m = projectionMatrix.elements;
	const isPerspectiveMatrix = m[ 11 ] === - 1;

	// Reverse [0, 1] projection matrix
	if ( isPerspectiveMatrix ) {

		m[ 10 ] = - m[ 10 ] - 1;
		m[ 14 ] = - m[ 14 ];

	} else {

		m[ 10 ] = - m[ 10 ];
		m[ 14 ] = - m[ 14 ] + 1;

	}

}

export { arrayMin, arrayMax, arrayNeedsUint32, getTypedArray, createElementNS, createCanvasElement, warnOnce, probeAsync, toNormalizedProjectionMatrix, toReversedProjectionMatrix };