( M A P )
: +pos ( x1 y1 x2 y2 -- x y )
  <rot + >rot + swap ;

var tileselect
8 const MAXTILE

: mouseworldpos mousepos scrollpos +pos ;
: world>tile 4 >> swap 4 >> swap ;
: mousetile mouseworldpos world>tile ;
: tile ( x y -- ptr ) mapsize drop * + map + ;

1 const WALKABLE
2 const DRIVABLE

array tileflags
( grass )    WALKABLE b,
( dirt )     WALKABLE b,
( water )    0 b,
( pavement ) WALKABLE DRIVABLE | b,
( brick )    0 b,
( forest )   0 b,
( roof )     0 b,
( brick )    0 b,
( window )   0 b,

: mapflag? ( x y flag -- b ) >rot tile b@ tileflags + b@ & ;
: walkable? ( x y -- b ) WALKABLE mapflag? ;
: drivable? ( x y -- b ) DRIVABLE mapflag? ;

: tick-mapedit
  tileselect @
  ^< key-pressed if 1 - then
  ^> key-pressed if 1 + then
  dup 0 < if drop MAXTILE then
  dup MAXTILE > if drop 0 then
  tileselect !

  MOUSEL mousedown if tileselect @ mousetile tile b! then
  MOUSER clicked if mouseworldpos world>tile swap . . then ;

: copy-mapseg ( neww oldw y -- )
  r> ( oldw neww r: y )
  2dup min >rot ( copyw neww oldw )
  r@ * map + ( copyw neww src )
  swap r< * map + ( copyw src dst )
  swap <rot memmove ;

: resize-map ( neww newh -- )
  swap mapsize r> ( newh neww oldw r: oldh )
  2dup < if 1 r< else r< 1 - 0 then ( newh neww copyw ystart ylim )
  for 2dup i copy-mapseg next
  drop swap mapsize! ;

: save-map ( filename -- )
  fdeactivate swap overwrite
  mapsize swap fput fput
  mapsize * map fwrite
  factivate ;

: load-map ( filename -- )
  fdeactivate swap open
  fget fget
  2dup * map fread
  mapsize!
  factivate ;