/*
 * Copyright (C) 2009 Yuan Chuan <2eris@163.com>
 * 
 * This is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this Program.  If not, see <http://www.gnu.org/licenses/>.
 */



#include "Particle.h"

bool Particle::MoveTo(float dx,float dy)
{
	//If reached 
	//----------------------
	if(fabs(x-dx)<=vel && fabs(y-dy)<=vel)
	   return true;
	   
	// Vertical   ==90  ==270
	//----------------------
	if(x==dx){
		if(y<dy)  y+=vel;
		else      y-=vel;
		return false;
	}

	//Horizontal  ==180 ==360
	//-----------------------
	if(y==dy){
		if(x<dx)  x+=vel;
		else      x-=vel;
		return false;
	}

	//Others    <90    >90
	//----------------------
	 float ky=fabs(dy-y);
	 float kx=fabs(dx-x);
	 float k=ky/kx;

	 if(kx>=ky){
		if(x<dx)  x+=vel;
		else      x-=vel;
		if(y<dy)  y+=vel*k;
		else      y-=vel*k;
	 }
	 else if(kx<ky){
		if(x<dx)  x+=vel/k;
		else      x-=vel/k;
		if(y<dy)  y+=vel;
		else      y-=vel;
	}

	return false;
}



//--------------------------------------------
bool Particle::RotateTo(float cx,float cy)
{
	float dx=cx-x;
	float dy=cy-y;
	float theta=2*PI/0.13;

	float newX=dx*cos(-theta)-dy*sin(-theta);
	float newY=dx*sin(-theta)+dy*cos(-theta);

	return MoveTo(newX+cx,newY+cy);
}




//------------------------------------------------------------------------------