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/**************************************************************************/
/* Copyright 2012 Tim Day */
/* */
/* This file is part of Evolvotron */
/* */
/* Evolvotron 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. */
/* */
/* Evolvotron 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 Evolvotron. If not, see <http://www.gnu.org/licenses/>. */
/**************************************************************************/
/*! \file
\brief Implementation of helper functions for hexagons.
*/
//! Co-ordinates of hexagon with given hex-grid coords
const XY hex_coord(int x,int y)
{
const real k=sqrt(3.0)/2.0;
return XY(
x*k,
y+((x&1) ? 0.5 : 0.0)
);
}
const std::pair<int,int> nearest_hex(real px,real py)
{
// Initial guess at which hex we're in:
const real k=sqrt(3.0)/2.0;
const int nx=static_cast<int>(rintf(px/k));
const int ny=static_cast<int>
(
(nx&1)
?
rintf(py-0.5)
:
rintf(py)
);
int hx=nx;
int hy=ny;
const XY ph=hex_coord(nx,ny);
real m2b=(XY(px,py)-ph).magnitude2();
for (int dy=-1;dy<=1;dy++)
for (int dx=-1;dx<=1;dx++)
if (!(dy==0 && dx==0))
{
const real m2=(XY(px,py)-hex_coord(nx+dx,ny+dy)).magnitude2();
if (m2<m2b)
{
hx=nx+dx;
hy=ny+dy;
m2b=m2;
}
}
return std::make_pair(hx,hy);
}
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