ExperienceUtils.php

<?php
 
/*
 *
 *  ____            _        _   __  __ _                  __  __ ____
 * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
 * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
 * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
 * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * @author PocketMine Team
 * @link http://www.pocketmine.net/
 *
 *
 */
 
declare(strict_types=1);
 
namespace pocketmine\entity\utils;
 
use pocketmine\math\Math;
use pocketmine\utils\AssumptionFailedError;
use function count;
use function max;
 
abstract class ExperienceUtils{
 
    public static function getXpToReachLevel(int $level) : int{
        if($level <= 16){
            return $level ** 2 + $level * 6;
        }elseif($level <= 31){
            return (int) ($level ** 2 * 2.5 - 40.5 * $level + 360);
        }
 
        return (int) ($level ** 2 * 4.5 - 162.5 * $level + 2220);
    }
 
    public static function getXpToCompleteLevel(int $level) : int{
        if($level <= 15){
            return 2 * $level + 7;
        }elseif($level <= 30){
            return 5 * $level - 38;
        }else{
            return 9 * $level - 158;
        }
    }
 
    public static function getLevelFromXp(int $xp) : float{
        if($xp < 0){
            throw new \InvalidArgumentException("XP must be at least 0");
        }
        if($xp <= self::getXpToReachLevel(16)){
            $a = 1;
            $b = 6;
            $c = 0;
        }elseif($xp <= self::getXpToReachLevel(31)){
            $a = 2.5;
            $b = -40.5;
            $c = 360;
        }else{
            $a = 4.5;
            $b = -162.5;
            $c = 2220;
        }
 
        $x = Math::solveQuadratic($a, $b, $c - $xp);
        if(count($x) === 0){
            throw new AssumptionFailedError("Expected at least 1 solution");
        }
 
        return max($x); //we're only interested in the positive solution
    }
}