Re: [FreecivDev] Hex map implementation
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Artur Biesiadowski <abies@xxxxxxxxx> writes:
> I've started playing with hex map. For now just class in java, generic
> enough it could be used for some wargame if freeciv will not choose
> hexes after all.
>
> I've decided to use vertically flattened hexes. They fit into square  a
> lot simplier to make calculations/repaint etc. Normal hex should have
> proportions of 2 x sqrt(3) and they have just 2 x 2.
>
> If somebody thinks that hexes are very simple, here are two routines
> that given the point on screen (actually on map, but it's not important)
> return Point with tile coordinates.
(code snipped)
That can be done easier; the readable variant is
HexCoord PointToHex( int xp, int yp )
{
// NOTE: HexCoord(0,0)'s x() and y() just define the origin
// for the coordinate system; replace with your own
// constants. (HexCoord(0,0) is the origin in the hex
// coordinate system, but it may be offset in the x/y
// system; that's why I subtract.)
double x = 1.0 * ( xp  HexCoord(0,0).x() ) / HexXSpacing;
double y = 1.0 * ( yp  HexCoord(0,0).y() ) / HexYSpacing;
double z = 0.5 * x  y;
y = 0.5 * x + y;
int ix = floor(x+0.5);
int iy = floor(y+0.5);
int iz = floor(z+0.5);
int s = ix+iy+iz;
if( s )
{
double abs_dx = fabs(ixx);
double abs_dy = fabs(iyy);
double abs_dz = fabs(izz);
if( abs_dx >= abs_dy && abs_dx >= abs_dz )
ix = s;
else if( abs_dy >= abs_dx && abs_dy >= abs_dz )
iy = s;
else
iz = s;
}
return HexCoord( ix, ( iy  iz + (1ix%2) ) / 2 );
}
and the short variant is
HexCoord PointToHex( int xp, int yp )
{
// NOTE: First we subtract the origin of the coordinate
// system; replace with your own values
xp = X_ORIGIN;
yp = Y_ORIGIN;
int row = 1 + yp / 12;
int col = 1 + xp / 21;
int diagonal[2][12] = {
{7,6,6,5,4,4,3,3,2,1,1,0},
{0,1,1,2,3,3,4,4,5,6,6,7}
};
if( diagonal[(row+col)%2][yp%12] >= xp%21 )
col;
return HexCoord( col, (row(col%2))/2 );
}
(I can dig out where I got this from if somebody is interested, there
is some more stuff about hex tiles.)
I really don't think Hex tiles are difficult in any aspect, especially
if you're using a language with nice abstract data types. The
difficult thing is to change the thousands of places in the Freeciv
code that depend on squares.
Falk

