<?php
// Smooth Decrease Class 0.1 by ming0070913
Class SmoothDecrease{
	public $am, $step, $now, $round;
	
	function __construct($amplitude, $step, $round=2){
		$this->am = $amplitude;
		$this->step = $step;
		$this->round = $round;
	}
	
	function checkRemain(){
		return ($this->now < $this->step);
	}
	
	function getValue(){
		$this->now++;
		if($this->now < $this->step/2)
			$r = (1-pow($this->now/$this->step*2,2))*$this->am/2+$this->am/2;
		else
			$r = (pow(($this->step-$this->now)/$this->step*2,2))*$this->am/2;
		return round($r, $this->round);
	}
	
	function skip($step){
		$this->now += (int) $step;
	}
	
	function clear(){
		$this->now = 0;
	}
}
?>