ref: 2a6077848c4d30e8d04091a3497538ea896f2b8b
dir: /engine.c/
#ifdef unix
#include "unix.h"
#else
#include <u.h>
#include <libc.h>
#include <draw.h>
#endif
#include "engine.h"
int difficulty = DEasy;
int state;
int turn = 0;
int ptype[2] = {Human, Computer}; /* human? computer? */
int grid[SzX][SzY];
int pgrid[SzX][SzY]; /* for undo */
int ogrid[SzX][SzY]; /* so we can restart levels */
void
initlevel(void)
{
int i, cnt, x, y;
for(x = 0; x < SzX; x++)
for(y = 0; y < SzY; y++)
ogrid[x][y] = Prev;
switch(difficulty)
{
case DEasy:
cnt = 10 + nrand(5);
break;
case DMed:
cnt = 5 + nrand(5);
break;
case DHard:
cnt = 1 + nrand(5);
break;
case DImp:
default:
cnt = 0;
break;
}
ogrid[SzX/2][SzY/2] = Glenda;
for(i = 0 ; i < cnt ; i++)
{
/*
it's unlikely, but possible:
we randomly pick a cell which already have a wall or glenda inside it
*/
do
{
x = nrand(SzX);
y = nrand(SzY);
}while(ogrid[x][y] != Prev);
ogrid[x][y] = Wall;
}
memcpy(grid, ogrid, sizeof grid);
state = Start;
}
Point
movedir(int dir, Point p)
{
int x = p.x;
int y = p.y;
switch(dir)
{
case NE:
return Pt(x+(y%2?1:0), y-1);
case E:
return Pt(x+1, y);
case SE:
return Pt(x+(y%2?1:0), y+1);
case SW:
return Pt(x+(y%2?0:-1), y+1);
case W:
return Pt(x-1, y);
case NW:
return Pt(x+(y%2?0:-1), y-1);
default:
sysfatal("andrey messed up big time");
/* should we keep that line around? it might be more useful than sysfatal */
// return Pt(-1, -1);
}
}
/* reverse of movedir, tells the direction for a dst from src */
int
pointdir(Point src, Point dst)
{
Point p;
/*
if(src.x < 0 || src.x > SzX || src.y < 0 || src.y > SzY)
||(dst.x < 0 || dst.x > SzX || dst.y < 0 || dst.y > SzY)
return Err;
*/
/* hacky */
for(int i = NE ; i <= NW ; i++)
{
p = movedir(i, src);
if(p.x == dst.x && p.y == dst.y)
return i;
}
return Err;
}
/*
Point
movedir(int dir, Point p)
{
switch(dir)
{
case NE:
if(p.y % 2)
return Pt(p.x+1, p.y-1);
else
return Pt(p.x, p.y-1);
case E:
return Pt(p.x+1, p.y);
case SE:
if(p.y % 2)
return Pt(p.x+1, p.y+1);
else
return Pt(p.x, p.y+1);
case SW:
if(p.y % 2)
return Pt(p.x, p.y+1);
else
return Pt(p.x-1, p.y+1);
case W:
return Pt(p.x-1, p.y);
case NW:
if(p.y % 2)
return Pt(p.x, p.y-1);
else
return Pt(p.x-1, p.y-1);
default:
return Pt(-1, -1);
}
}
*/
int
domove(int dir, Point src)
{
Point dst;
if(src.x == 0 || src.x == SzX-1 || src.y == 0 || src.y == SzY-1)
goto done;
dst = movedir(dir, src);
if(grid[dst.x][dst.y] == Wall)
return Wall;
grid[dst.x][dst.y] = Glenda;
done:
grid[src.x][src.y] = Prev;
turn++;
return 0;
}
int
doput(Point p)
{
/* clients are expected to do their own error checking */
if(p.x > SzX || p.x < 0 || p.y > SzY || p.y < 0)
return Err;
if(grid[p.x][p.y] == Wall)
return Wall;
if(grid[p.x][p.y] == Glenda)
return Glenda;
/* take a copy for undo */
memcpy(pgrid, grid, sizeof grid);
grid[p.x][p.y] = Wall;
/* assumes defenders start game first */
if(state == Start)
state = Playing;
turn++;
/* reset the board scores */
for(int x = 0; x < SzX; x++)
for(int y = 0; y < SzY; y++)
if(grid[x][y] != Wall && grid[x][y] != Glenda)
grid[x][y] = 100;
/* we need it to check game state, even if not playing with computer */
nextglenda();
return Ok;
}
Point
findglenda(void)
{
for(int x = 0; x < SzX; x++)
for(int y = 0; y < SzY; y++)
if(grid[x][y] == 1000)
return Pt(x, y);
return Pt(-1, -1);
}
int
checknext(int dir, Point p)
{
int x = p.x;
int y = p.y;
switch(dir)
{
case NE:
return grid[x+(y%2?1:0)][y-1];
case E:
return grid[x+1][y];
case SE:
return grid[x+(y%2?1:0)][y+1];
case SW:
return grid[x+(y%2?0:-1)][y+1];
case W:
return grid[x-1][y];
case NW:
return grid[x+(y%2?0:-1)][y-1];
default:
sysfatal("andrey messed up big time");
// return -1; /* silence compiler */
}
}
/* the following two routines constitute the "game AI"
* they score the field based on the number of moves
* required to reach the edge from a particular point
* scores > 100 are "dead spots" (this assumes the field
* is not larger than ~100*2
*
* routines need to run at least twice to ensure a field is properly
* scored: there are errors that creep up due to the nature of
* traversing the board
*/
int
score1(Point p)
{
int min = 999, next;
if(p.x == 0 || p.x == SzX-1 || p.y == 0 || p.y == SzY-1)
return 1; /* we can always escape from the edges */
for(int dir = NE; dir <= NW; dir++)
{
next = checknext(dir, p);
if(next < min)
min = next;
}
if(min == 999)
return 998;
return 1+min;
}
void
calc(void)
{
for(int i = 0; i < SzX; i++) /* assumes SzX = SzY */
for(int x = i; x < SzX-i; x++)
for(int y = i; y < SzY-i; y++)
if(grid[x][y] != Wall)
grid[x][y] = score1(Pt(x, y));
}
void
nextglenda(void)
{
int min = 1000, next, dir, nextdir = 0, count = 0;
Point p = findglenda();
calc();
calc();
calc();
grid[p.x][p.y] = Glenda;
for(dir = NE; dir <= NW; dir++)
{
next = checknext(dir, p);
if(next < min)
{
min = next;
nextdir = dir;
++count;
}
else if(next == min)
nextdir = (nrand(++count) == 0) ? dir : nextdir;
}
if(min > 100 && min != 999)
state = Won;
else if(ptype[1] == Computer)
domove(nextdir, p);
if(eqpt(findglenda(), Pt(-1, -1)))
state = Lost;
}
void
restart(void)
{
turn = 0;
memcpy(grid, ogrid, sizeof grid);
state = Start;
}
void
undo(void)
{
int g[SzX][SzY];
if(state == Start || turn < 2)
return;
/* revert turn counter, can be abused by one side */
turn -= 2;
/* swap grids */
memcpy(g, grid, sizeof grid);
memcpy(grid, pgrid, sizeof grid);
memcpy(pgrid, g, sizeof grid);
}
int
checkstate(void)
{
int i, j;
for(i = 0; i < SzX; i++)
for(j = 0; j < SzY; j++)
if(grid[i][j] == 'E')
return 0;
return 1;
}