entityset.cpp

/*
	Copyright 2008 Utah State University    

	This file is part of OIP.

    OIP 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.

    OIP 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 OIP.  If not, see <http://www.gnu.org/licenses/>.
*/
#include "entityset.h"

entity& entityset::add(int s)
{
	entity& r = elist[s];
	if (!r.isvalid())
	{
		entity& r2 = elist[s] = entity(s);
		if ((s & mask) == net)
			r2.setlocal();
		return r2;
	}
	r.touch();
	return r;
}

float ipdist(unsigned int s1, unsigned int s2)
{
	if ((s1 & 0xff000000) == (s2 & 0xff000000))
	{
		if ((s1 & 0xffff0000) == (s2 & 0xffff0000))
		{
			if ((s1 & 0xffffff00) == (s2 & 0xffffff00))
				return 1.75;
			else
				return 1.5;
		}
		return 1.25;
	}
	else
		return 1;
}


void entityset::process(double dt)
{
	//go through all of the entities, and apply hookes law to each of them
	map<int, entity>::iterator i = elist.begin();
	for(;i != elist.end(); i++)
	{
		float fx=0, fy=0;
		map<int, entity>::iterator j = elist.begin();
		//sum up the total force applied by all the others
		float rsq;
		for (;j != elist.end(); j++)
		{
			if ((*i).first != (*j).first)
			{
				float nk = k * ipdist((*i).second.label, (*j).second.label);
				//hookes law; linear attraction
				fx -= nk*(((*i).second.getX() - (*j).second.getX()));
				fy -= nk*(((*i).second.getY() - (*j).second.getY()));
				//coulomb repulsion
				rsq = 
					((*i).second.getX() - (*j).second.getX()) *
					((*i).second.getX() - (*j).second.getX()) +
					((*i).second.getY() - (*j).second.getY()) *
					((*i).second.getY() - (*j).second.getY());
				//some magic numbers. The "charge" of the particle goes away as it fades
				rsq /= k/(4); // * (1+(*j).second.getfadeval()));
				fx += ((*i).second.getX() - (*j).second.getX())/rsq;
				fy += ((*i).second.getY() - (*j).second.getY())/rsq;
			}
			//add a slight jitter so that they don't get stuck in the middle
			fx += (float)rand()/RAND_MAX * .001 - .0005;
			fy += (float)rand()/RAND_MAX * .001 - .0005;
			//rather than using hookes law, what if we just repulse from the sides?
			//they should distribute themselves neatly
			//They appear to just slap themselves on the sides
			/*
			//left side
			rsq = 
				((*i).second.getX()) *
				((*i).second.getX());
			rsq /= k/100;
			fx += ((*i).second.getX())/rsq;
			//right side
			rsq = 
				((*i).second.getX() - 1) *
				((*i).second.getX() - 1);
			rsq /= k/100;
			fx += ((*i).second.getX() - 1)/rsq;
			//top
			rsq = 
				((*i).second.getY()) *
				((*i).second.getY());
			rsq /= k/100;
			fy += ((*i).second.getY())/rsq;
			//bottom
			rsq = 
				((*i).second.getY() - 1) *
				((*i).second.getY() - 1);
			rsq /= k/100;
			fy += ((*i).second.getY() - 1)/rsq;
			// */
		}
		


		(*i).second.move(fx, fy, damp, dt);
	}
}

void entityset::draw(SDL_Surface*s)
{
	xscale = s->w;
	yscale = s->h;
	
	map<int, entity>::iterator j = elist.begin();
	//draw them, and do some housekeeping
	while (j != elist.end())
	{
		(*j).second.draw(s);
		if ((*j).second.deleteme())
			elist.erase(j++);
		else
			j++;
	}
}

/*
 * find an entity that contains the location, given in screen coords
 */
entity* entityset::find(int x, int y)
{
	map<int, entity>::iterator j = elist.begin();
	for (;j != elist.end();j++)
	{
		//TODO getX and getY are in world coordinates, yet getW and getH are not
		if (
			(*j).second.getX() * xscale - (*j).second.getW()/2 < x &&
			(*j).second.getY() * yscale - (*j).second.getH()/2 < y &&
			(*j).second.getX() * xscale + (*j).second.getW()/2 > x &&
			(*j).second.getY() * yscale + (*j).second.getH()/2 > y
			)
			return &((*j).second);
	}
	return NULL;
}