X-Git-Url: http://deadsoftware.ru/gitweb?a=blobdiff_plain;f=src%2Fgame%2Fg_grid.pas;h=2dfb0ce43d4ff6cb49dece8b05fe3737ca7221b5;hb=987c4a835a103345b59937e8e1be8524a6228712;hp=8ff01a629340b582ad58c0cb40046f8b80c251a3;hpb=829537fc7b2b29baaab7287e54fba2cdd8d00b5c;p=d2df-sdl.git

diff --git a/src/game/g_grid.pas b/src/game/g_grid.pas
index 8ff01a6..2dfb0ce 100644
--- a/src/game/g_grid.pas
+++ b/src/game/g_grid.pas
@@ -1,9 +1,8 @@
-(* Copyright (C)  DooM 2D:Forever Developers
+(* Copyright (C)  Doom 2D: Forever Developers
  *
  * This program 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.
+ * the Free Software Foundation, version 3 of the License ONLY.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -15,106 +14,532 @@
  *)
 // universal spatial grid
 {$INCLUDE ../shared/a_modes.inc}
-{$DEFINE grid_use_buckets}
+{$IF DEFINED(D2F_DEBUG)}
+  {.$DEFINE D2F_DEBUG_RAYTRACE}
+  {.$DEFINE D2F_DEBUG_XXQ}
+  {.$DEFINE D2F_DEBUG_MOVER}
+{$ENDIF}
+{.$DEFINE GRID_USE_ORTHO_ACCEL}
+{$DEFINE LINEAABB2}
 unit g_grid;
 
 interface
 
+uses
+  mempool;
+
+(*
+ * In order to make this usable for kind-of-recursive calls,
+ * we'll use "frame memory pool" to return results. That is,
+ * we will allocate a memory pool that will be cleared on
+ * frame start, and then used as a simple "no-free" allocator.
+ * Grid will put results into this pool, and will never bother
+ * to free it. Caller should call "release" on result, and
+ * the pool will throw away everything.
+ * No more callbacks, of course.
+ *)
+
+const
+  GridTileSize = 32; // must be power of two!
+
+type
+  PGridCellCoord = ^TGridCellCoord;
+  TGridCellCoord = record
+    x, y: Integer;
+  end;
+
+  CellCoordIter = specialize PoolIter<TGridCellCoord>;
+
 
 type
   TBodyProxyId = Integer;
 
-  generic TBodyGridBase<ITP> = class(TObject)
+  generic TBodyGridBase<ITP> = class{$IFDEF USE_MEMPOOL}(TPoolObject){$ENDIF}
   public
-    type TGridQueryCB = function (obj: ITP; tag: Integer): Boolean is nested; // return `true` to stop
+    type PITP = ^ITP;
+    type TCellQueryCB = procedure (x, y: Integer) is nested; // top-left cell corner coords
+
+    type Iter = specialize PoolIter<ITP>;
+
+    const TagDisabled = $40000000;
+    const TagFullMask = $3fffffff;
 
   private
     const
-      GridDefaultTileSize = 32;
       GridCellBucketSize = 8; // WARNING! can't be less than 2!
 
-  private
+  public
     type
       PBodyProxyRec = ^TBodyProxyRec;
       TBodyProxyRec = record
       private
         mX, mY, mWidth, mHeight: Integer; // aabb
-        mQueryMark: DWord; // was this object visited at this query?
+        mQueryMark: LongWord; // was this object visited at this query?
         mObj: ITP;
-        mTag: Integer;
+        mTag: Integer; // `TagDisabled` set: disabled ;-)
         nextLink: TBodyProxyId; // next free or nothing
 
       private
         procedure setup (aX, aY, aWidth, aHeight: Integer; aObj: ITP; aTag: Integer);
+
+        function getTag (): Integer; inline;
+        procedure setTag (v: Integer); inline;
+
+        function getEnabled (): Boolean; inline;
+        procedure setEnabled (v: Boolean); inline;
+
+        function getX1 (): Integer; inline;
+        function getY1 (): Integer; inline;
+
+      public
+        property x: Integer read mX;
+        property y: Integer read mY;
+        property width: Integer read mWidth;
+        property height: Integer read mHeight;
+        property tag: Integer read getTag write setTag;
+        property enabled: Boolean read getEnabled write setEnabled;
+        property obj: ITP read mObj;
+
+        property x0: Integer read mX;
+        property y0: Integer read mY;
+        property x1: Integer read getX1;
+        property y1: Integer read getY1;
       end;
 
+  private
+    type
       PGridCell = ^TGridCell;
       TGridCell = record
-        {$IFDEF grid_use_buckets}
         bodies: array [0..GridCellBucketSize-1] of Integer; // -1: end of list
-        {$ELSE}
-        body: Integer;
-        {$ENDIF}
         next: Integer; // in this cell; index in mCells
       end;
 
-      TGridInternalCB = function (grida: Integer): Boolean of object; // return `true` to stop
+      TCellArray = array of TGridCell;
+
+      TGridInternalCB = function (grida: Integer; bodyId: TBodyProxyId): Boolean of object; // return `true` to stop
+
+  private
+    //mTileSize: Integer;
+    const mTileSize = GridTileSize;
+    type TGetProxyFn = function (pxidx: Integer): PBodyProxyRec of object;
+
+  public
+    const tileSize = mTileSize;
+
+    type
+      TAtPointEnumerator = record
+      private
+        mCells: TCellArray;
+        curidx, curbki: Integer;
+        getpx: TGetProxyFn;
+      public
+        constructor Create (acells: TCellArray; aidx: Integer; agetpx: TGetProxyFn);
+        function MoveNext (): Boolean; inline;
+        function getCurrent (): PBodyProxyRec; inline;
+        property Current: PBodyProxyRec read getCurrent;
+      end;
 
   private
-    mTileSize: Integer;
     mMinX, mMinY: Integer; // so grids can start at any origin
     mWidth, mHeight: Integer; // in tiles
     mGrid: array of Integer; // mWidth*mHeight, index in mCells
-    mCells: array of TGridCell; // cell pool
+    mCells: TCellArray; // cell pool
     mFreeCell: Integer; // first free cell index or -1
-    mLastQuery: DWord;
+    mLastQuery: LongWord;
     mUsedCells: Integer;
     mProxies: array of TBodyProxyRec;
     mProxyFree: TBodyProxyId; // free
     mProxyCount: Integer; // currently used
     mProxyMaxCount: Integer;
 
-    mUData: TBodyProxyId; // for inserter/remover
-    mTagMask: Integer; // for iterator
-    mItCB: TGridQueryCB; // for iterator
+  public
+    dbgShowTraceLog: Boolean;
+    {$IF DEFINED(D2F_DEBUG)}
+    dbgRayTraceTileHitCB: TCellQueryCB;
+    {$ENDIF}
 
   private
-    function allocCell: Integer;
+    function allocCell (): Integer;
     procedure freeCell (idx: Integer); // `next` is simply overwritten
 
     function allocProxy (aX, aY, aWidth, aHeight: Integer; aObj: ITP; aTag: Integer): TBodyProxyId;
     procedure freeProxy (body: TBodyProxyId);
 
-    procedure insert (body: TBodyProxyId);
-    procedure remove (body: TBodyProxyId);
+    function forGridRect (x, y, w, h: Integer; cb: TGridInternalCB; bodyId: TBodyProxyId): Boolean;
+
+    function inserter (grida: Integer; bodyId: TBodyProxyId): Boolean;
+    function remover (grida: Integer; bodyId: TBodyProxyId): Boolean;
 
-    function forGridRect (x, y, w, h: Integer; cb: TGridInternalCB): Boolean;
+    function getProxyEnabled (pid: TBodyProxyId): Boolean; inline;
+    procedure setProxyEnabled (pid: TBodyProxyId; val: Boolean); inline;
 
-    function inserter (grida: Integer): Boolean;
-    function remover (grida: Integer): Boolean;
-    function iterator (grida: Integer): Boolean;
+    function getGridWidthPx (): Integer; inline;
+    function getGridHeightPx (): Integer; inline;
+
+    function getProxyById (idx: TBodyProxyId): PBodyProxyRec; inline;
 
   public
-    constructor Create (aMinPixX, aMinPixY, aPixWidth, aPixHeight: Integer; aTileSize: Integer=GridDefaultTileSize);
+    constructor Create (aMinPixX, aMinPixY, aPixWidth, aPixHeight: Integer{; aTileSize: Integer=GridDefaultTileSize});
     destructor Destroy (); override;
 
-    function insertBody (aObj: ITP; ax, ay, aWidth, aHeight: Integer; aTag: Integer=0): TBodyProxyId;
-    procedure removeBody (aObj: TBodyProxyId); // WARNING! this WILL destroy proxy!
+    function insertBody (aObj: ITP; ax, ay, aWidth, aHeight: Integer; aTag: Integer=-1): TBodyProxyId;
+    procedure removeBody (body: TBodyProxyId); // WARNING! this WILL destroy proxy!
+
+    procedure moveBody (body: TBodyProxyId; nx, ny: Integer);
+    procedure resizeBody (body: TBodyProxyId; nw, nh: Integer);
+    procedure moveResizeBody (body: TBodyProxyId; nx, ny, nw, nh: Integer);
+
+    function insideGrid (x, y: Integer): Boolean; inline;
+
+    // `false` if `body` is surely invalid
+    function getBodyXY (body: TBodyProxyId; out rx, ry: Integer): Boolean; inline;
+    function getBodyWH (body: TBodyProxyId; out rw, rh: Integer): Boolean; inline;
+    function getBodyDims (body: TBodyProxyId; out rx, ry, rw, rh: Integer): Boolean; inline;
+
+    // return number of ITP thingys put into frame pool
+    // if `firstHit` is `true`, return on first hit (obviously)
+    function forEachInAABB (x, y, w, h: Integer; tagmask: Integer=-1; allowDisabled: Boolean=false; firstHit: Boolean=false): Iter;
+
+    // return number of ITP thingys put into frame pool
+    // if `firstHit` is `true`, return on first hit (obviously)
+    function forEachAtPoint (x, y: Integer; tagmask: Integer=-1; allowDisabled: Boolean=false; firstHit: Boolean=false): Iter;
+
+    function atCellInPoint (x, y: Integer): TAtPointEnumerator;
+
+    // return object of the nearest hit or nil
+    function traceRay (const x0, y0, x1, y1: Integer; tagmask: Integer=-1): ITP; overload;
+    function traceRay (out ex, ey: Integer; const ax0, ay0, ax1, ay1: Integer; tagmask: Integer=-1): ITP;
 
-    procedure moveBody (body: TBodyProxyId; dx, dy: Integer);
-    procedure resizeBody (body: TBodyProxyId; sx, sy: Integer);
-    procedure moveResizeBody (body: TBodyProxyId; dx, dy, sx, sy: Integer);
+    // return `false` if we're still inside at the end
+    // line should be either strict horizontal, or strict vertical, otherwise an exception will be thrown
+    // `true`: endpoint will point at the last "inside" pixel
+    // `false`: endpoint will be (ax1, ay1)
+    function traceOrthoRayWhileIn (out ex, ey: Integer; ax0, ay0, ax1, ay1: Integer; tagmask: Integer=-1): Boolean;
 
-    function forEachInAABB (x, y, w, h: Integer; cb: TGridQueryCB; tagmask: Integer=-1): Boolean;
+    // trace line along the grid, put all objects from passed cells into frame pool, in no particular order
+    // return number of ITP thingys put into frame pool
+    function forEachAlongLine (ax0, ay0, ax1, ay1: Integer; tagmask: Integer=-1; log: Boolean=false): Iter;
 
+    // trace box with the given velocity; return object hit (if any)
+    // `cb` is used unconvetionally here: if it returns `false`, tracer will ignore the object
+    //WARNING: don't change tags in callbacks here!
+    function traceBox (out ex, ey: Integer; const ax0, ay0, aw, ah: Integer; const dx, dy: Integer; tagmask: Integer=-1): ITP;
+
+    // debug
+    function forEachBodyCell (body: TBodyProxyId): CellCoordIter; // this puts `TGridCellCoord` into frame pool for each cell
+    function forEachInCell (x, y: Integer): Iter; // this puts `ITP` into frame pool
     procedure dumpStats ();
+
+  public
+    //WARNING! no sanity checks!
+    property proxyEnabled[pid: TBodyProxyId]: Boolean read getProxyEnabled write setProxyEnabled;
+
+    property gridX0: Integer read mMinX;
+    property gridY0: Integer read mMinY;
+    property gridWidth: Integer read getGridWidthPx; // in pixels
+    property gridHeight: Integer read getGridHeightPx; // in pixels
+
+    property proxy[idx: TBodyProxyId]: PBodyProxyRec read getProxyById;
+  end;
+
+
+type
+  // common structure for all line tracers
+  TLineWalker = record
+  public
+    const TileSize = GridTileSize;
+
+  private
+    wx0, wy0, wx1, wy1: Integer; // window coordinates
+    stx, sty: Integer; // "steps" for x and y axes
+    stleft: Integer; // "steps left"
+    err, errinc, errmax: Integer;
+    xd, yd: Integer; // current coord
+    horiz: Boolean;
+
+  public
+    // call `setyp` after this
+    constructor Create (minx, miny, maxx, maxy: Integer);
+
+    procedure setClip (minx, miny, maxx, maxy: Integer); inline;
+
+    // this will use `w[xy][01]` to clip coords
+    // return `false` if the whole line was clipped away
+    // on `true`, you should process first point, and go on
+    function setup (x0, y0, x1, y1: Integer): Boolean;
+
+    // call this *after* doing a step
+    // WARNING! if you will do a step when this returns `true`, you will fall into limbo
+    function done (): Boolean; inline;
+
+    // as you will prolly call `done()` after doing a step anyway, this will do it for you
+    // move to next point, return `true` when the line is complete (i.e. you should stop)
+    function step (): Boolean; inline;
+
+    // move to next tile; return `true` if the line is complete (and walker state is undefined then)
+    function stepToNextTile (): Boolean; inline;
+
+    procedure getXY (out ox, oy: Integer); inline;
+
+  public
+    // current coords
+    property x: Integer read xd;
+    property y: Integer read yd;
   end;
 
 
+procedure swapInt (var a: Integer; var b: Integer); inline;
+//function minInt (a, b: Integer): Integer; inline;
+//function maxInt (a, b: Integer): Integer; inline;
+
+
 implementation
 
 uses
-  SysUtils, e_log;
+  SysUtils, e_log, g_console, geom, utils;
+
+
+// ////////////////////////////////////////////////////////////////////////// //
+procedure swapInt (var a: Integer; var b: Integer); inline; var t: Integer; begin t := a; a := b; b := t; end;
+//procedure swapInt (var a: Integer; var b: Integer); inline; begin a := a xor b; b := b xor a; a := a xor b; end;
+//function minInt (a, b: Integer): Integer; inline; begin if (a < b) then result := a else result := b; end;
+//function maxInt (a, b: Integer): Integer; inline; begin if (a > b) then result := a else result := b; end;
+
+
+// ////////////////////////////////////////////////////////////////////////// //
+constructor TLineWalker.Create (minx, miny, maxx, maxy: Integer);
+begin
+  setClip(minx, miny, maxx, maxy);
+end;
+
+procedure TLineWalker.setClip (minx, miny, maxx, maxy: Integer); inline;
+begin
+  // clip rectange
+  wx0 := minx;
+  wy0 := miny;
+  wx1 := maxx;
+  wy1 := maxy;
+end;
+
+function TLineWalker.setup (x0, y0, x1, y1: Integer): Boolean;
+var
+  sx0, sy0, sx1, sy1: Single;
+begin
+  if (wx1 < wx0) or (wy1 < wy0) then begin stleft := 0; xd := x0; yd := y0; result := false; exit; end;
+
+  if (x0 >= wx0) and (y0 >= wy0) and (x0 <= wx1) and (y0 <= wy1) and
+     (x1 >= wx0) and (y1 >= wy0) and (x1 <= wx1) and (y1 <= wy1) then
+  begin
+    result := true;
+  end
+  else
+  begin
+    sx0 := x0; sy0 := y0;
+    sx1 := x1; sy1 := y1;
+    result := clipLine(sx0, sy0, sx1, sy1, wx0, wy0, wx1, wy1);
+    if not result then begin stleft := 0; xd := x0; yd := y0; exit; end;
+    x0 := trunc(sx0); y0 := trunc(sy0);
+    x1 := trunc(sx1); y1 := trunc(sy1);
+  end;
+
+  // check for ortho lines
+  if (y0 = y1) then
+  begin
+    // horizontal
+    horiz := true;
+    stleft := abs(x1-x0)+1;
+    if (x0 < x1) then stx := 1 else stx := -1;
+    sty := 0;
+    errinc := 0;
+    errmax := 10; // anything that is greater than zero
+  end
+  else if (x0 = x1) then
+  begin
+    // vertical
+    horiz := false;
+    stleft := abs(y1-y0)+1;
+    stx := 0;
+    if (y0 < y1) then sty := 1 else sty := -1;
+    errinc := 0;
+    errmax := 10; // anything that is greater than zero
+  end
+  else
+  begin
+    // diagonal
+    if (abs(x1-x0) >= abs(y1-y0)) then
+    begin
+      // horizontal
+      horiz := true;
+      stleft := abs(x1-x0)+1;
+      errinc := abs(y1-y0)+1;
+    end
+    else
+    begin
+      // vertical
+      horiz := false;
+      stleft := abs(y1-y0)+1;
+      errinc := abs(x1-x0)+1;
+    end;
+    if (x0 < x1) then stx := 1 else stx := -1;
+    if (y0 < y1) then sty := 1 else sty := -1;
+    errmax := stleft;
+  end;
+  xd := x0;
+  yd := y0;
+  err := -errmax;
+end;
+
+function TLineWalker.done (): Boolean; inline; begin result := (stleft <= 0); end;
+
+// true: done
+function TLineWalker.step (): Boolean; inline;
+begin
+  if horiz then
+  begin
+    xd += stx;
+    err += errinc;
+    if (err >= 0) then begin err -= errmax; yd += sty; end;
+  end
+  else
+  begin
+    yd += sty;
+    err += errinc;
+    if (err >= 0) then begin err -= errmax; xd += stx; end;
+  end;
+  Dec(stleft);
+  result := (stleft <= 0);
+end;
+
+// true: done
+function TLineWalker.stepToNextTile (): Boolean; inline;
+var
+  ex, ey: Integer;
+  xwalk, ywalk, wklen: Integer; // to the respective edges
+  f: Integer;
+begin
+  result := false;
+
+  if (stleft < 2) then begin result := true; exit; end; // max one pixel left, nothing to do
+
+  // strictly horizontal?
+  if (sty = 0) then
+  begin
+    // only xd
+    if (stx < 0) then
+    begin
+      // xd: to left edge
+      ex := (xd and (not (TileSize-1)))-1;
+      stleft -= xd-ex;
+    end
+    else
+    begin
+      // xd: to right edge
+      ex := (xd or (TileSize-1))+1;
+      stleft -= ex-xd;
+    end;
+    result := (stleft <= 0);
+    xd := ex;
+    exit;
+  end;
+
+  // strictly vertical?
+  if (stx = 0) then
+  begin
+    // only xd
+    if (sty < 0) then
+    begin
+      // yd: to top edge
+      ey := (yd and (not (TileSize-1)))-1;
+      stleft -= yd-ey;
+    end
+    else
+    begin
+      // yd: to bottom edge
+      ey := (yd or (TileSize-1))+1;
+      stleft -= ey-yd;
+    end;
+    result := (stleft <= 0);
+    yd := ey;
+    exit;
+  end;
+
+  // diagonal
+
+  // calculate xwalk
+  if (stx < 0) then
+  begin
+    ex := (xd and (not (TileSize-1)))-1;
+    xwalk := xd-ex;
+  end
+  else
+  begin
+    ex := (xd or (TileSize-1))+1;
+    xwalk := ex-xd;
+  end;
+
+  // calculate ywalk
+  if (sty < 0) then
+  begin
+    ey := (yd and (not (TileSize-1)))-1;
+    ywalk := yd-ey;
+  end
+  else
+  begin
+    ey := (yd or (TileSize-1))+1;
+    ywalk := ey-yd;
+  end;
+
+  {
+  while (xd <> ex) and (yd <> ey) do
+  begin
+    if horiz then
+    begin
+      xd += stx;
+      err += errinc;
+      if (err >= 0) then begin err -= errmax; yd += sty; end;
+    end
+    else
+    begin
+      yd += sty;
+      err += errinc;
+      if (err >= 0) then begin err -= errmax; xd += stx; end;
+    end;
+    Dec(stleft);
+    if (stleft < 1) then begin result := true; exit; end;
+  end;
+  }
+
+  if (xwalk <= ywalk) then wklen := xwalk else wklen := ywalk;
+  while true do
+  begin
+    // in which dir we want to walk?
+    stleft -= wklen;
+    if (stleft <= 0) then begin result := true; exit; end;
+    if horiz then
+    begin
+      xd += wklen*stx;
+      for f := 1 to wklen do
+      begin
+        err += errinc;
+        if (err >= 0) then begin err -= errmax; yd += sty; end;
+      end;
+    end
+    else
+    begin
+      yd += wklen*sty;
+      for f := 1 to wklen do
+      begin
+        err += errinc;
+        if (err >= 0) then begin err -= errmax; xd += stx; end;
+      end;
+    end;
+    // check for walk completion
+    if (xd = ex) or (yd = ey) then exit;
+    wklen := 1;
+  end;
+end;
+
+procedure TLineWalker.getXY (out ox, oy: Integer); inline; begin ox := xd; oy := yd; end;
 
 
 // ////////////////////////////////////////////////////////////////////////// //
@@ -131,20 +556,91 @@ begin
 end;
 
 
+function TBodyGridBase.TBodyProxyRec.getTag (): Integer; inline;
+begin
+  result := mTag and TagFullMask;
+end;
+
+procedure TBodyGridBase.TBodyProxyRec.setTag (v: Integer); inline;
+begin
+  mTag := (mTag and TagDisabled) or (v and TagFullMask);
+end;
+
+function TBodyGridBase.TBodyProxyRec.getEnabled (): Boolean; inline;
+begin
+  result := ((mTag and TagDisabled) = 0);
+end;
+
+procedure TBodyGridBase.TBodyProxyRec.setEnabled (v: Boolean); inline;
+begin
+  if v then mTag := mTag and (not TagDisabled) else mTag := mTag or TagDisabled;
+end;
+
+function TBodyGridBase.TBodyProxyRec.getX1 (): Integer; inline;
+begin
+  result := mX+mWidth-1;
+end;
+
+function TBodyGridBase.TBodyProxyRec.getY1 (): Integer; inline;
+begin
+  result := mY+mHeight-1;
+end;
+
+
+// ////////////////////////////////////////////////////////////////////////// //
+constructor TBodyGridBase.TAtPointEnumerator.Create (acells: TCellArray; aidx: Integer; agetpx: TGetProxyFn);
+begin
+  mCells := acells;
+  curidx := aidx;
+  curbki := -1;
+  getpx := agetpx;
+end;
+
+
+function TBodyGridBase.TAtPointEnumerator.MoveNext (): Boolean; inline;
+begin
+  while (curidx <> -1) do
+  begin
+    while (curbki < GridCellBucketSize) do
+    begin
+      Inc(curbki);
+      if (mCells[curidx].bodies[curbki] = -1) then break;
+      result := true;
+      exit;
+    end;
+    curidx := mCells[curidx].next;
+    curbki := -1;
+  end;
+  result := false;
+end;
+
+
+function TBodyGridBase.TAtPointEnumerator.getCurrent (): PBodyProxyRec; inline;
+begin
+  result := getpx(mCells[curidx].bodies[curbki]);
+end;
+
+
 // ////////////////////////////////////////////////////////////////////////// //
-constructor TBodyGridBase.Create (aMinPixX, aMinPixY, aPixWidth, aPixHeight: Integer; aTileSize: Integer=GridDefaultTileSize);
+constructor TBodyGridBase.Create (aMinPixX, aMinPixY, aPixWidth, aPixHeight: Integer{; aTileSize: Integer=GridDefaultTileSize});
 var
   idx: Integer;
 begin
+  dbgShowTraceLog := false;
+  {$IF DEFINED(D2F_DEBUG)}
+  dbgRayTraceTileHitCB := nil;
+  {$ENDIF}
+  {
   if aTileSize < 1 then aTileSize := 1;
   if aTileSize > 8192 then aTileSize := 8192; // arbitrary limit
-  if aPixWidth < aTileSize then aPixWidth := aTileSize;
-  if aPixHeight < aTileSize then aPixHeight := aTileSize;
   mTileSize := aTileSize;
+  }
+  if (aPixWidth < mTileSize) then aPixWidth := mTileSize;
+  if (aPixHeight < mTileSize) then aPixHeight := mTileSize;
   mMinX := aMinPixX;
   mMinY := aMinPixY;
-  mWidth := (aPixWidth+aTileSize-1) div aTileSize;
-  mHeight := (aPixHeight+aTileSize-1) div aTileSize;
+  mWidth := (aPixWidth+mTileSize-1) div mTileSize;
+  mHeight := (aPixHeight+mTileSize-1) div mTileSize;
   SetLength(mGrid, mWidth*mHeight);
   SetLength(mCells, mWidth*mHeight);
   SetLength(mProxies, 8192);
@@ -152,11 +648,8 @@ begin
   // init free list
   for idx := 0 to High(mCells) do
   begin
-    {$IFDEF grid_use_buckets}
     mCells[idx].bodies[0] := -1;
-    {$ELSE}
-    mCells[idx].body := -1;
-    {$ENDIF}
+    mCells[idx].bodies[GridCellBucketSize-1] := -1; // "has free room" flag
     mCells[idx].next := idx+1;
   end;
   mCells[High(mCells)].next := -1; // last cell
@@ -170,10 +663,7 @@ begin
   mProxyFree := 0;
   mProxyCount := 0;
   mProxyMaxCount := 0;
-  mUData := 0;
-  mTagMask := -1;
-  mItCB := nil;
-  e_WriteLog(Format('created grid with size: %dx%d (tile size: %d); pix: %dx%d', [mWidth, mHeight, mTileSize, mWidth*mTileSize, mHeight*mTileSize]), MSG_NOTIFY);
+  e_WriteLog(Format('created grid with size: %dx%d (tile size: %d); pix: %dx%d', [mWidth, mHeight, mTileSize, mWidth*mTileSize, mHeight*mTileSize]), TMsgType.Notify);
 end;
 
 
@@ -186,353 +676,1202 @@ begin
 end;
 
 
+// ////////////////////////////////////////////////////////////////////////// //
 procedure TBodyGridBase.dumpStats ();
 var
-  idx, mcb, cidx, cnt: Integer;
+  idx, mcb, ccidx, cnt: Integer;
 begin
   mcb := 0;
   for idx := 0 to High(mGrid) do
   begin
-    cidx := mGrid[idx];
+    ccidx := mGrid[idx];
     cnt := 0;
-    while cidx >= 0 do
+    while ccidx >= 0 do
     begin
       Inc(cnt);
-      cidx := mCells[cidx].next;
+      ccidx := mCells[ccidx].next;
     end;
     if (mcb < cnt) then mcb := cnt;
   end;
-  e_WriteLog(Format('grid size: %dx%d (tile size: %d); pix: %dx%d; used cells: %d; max bodies in cell: %d; max proxies allocated: %d; proxies used: %d', [mWidth, mHeight, mTileSize, mWidth*mTileSize, mHeight*mTileSize, mUsedCells, mcb, mProxyMaxCount, mProxyCount]), MSG_NOTIFY);
+  e_WriteLog(Format('grid size: %dx%d (tile size: %d); pix: %dx%d; used cells: %d; max bodies in cell: %d; max proxies allocated: %d; proxies used: %d', [mWidth, mHeight, mTileSize, mWidth*mTileSize, mHeight*mTileSize, mUsedCells, mcb, mProxyMaxCount, mProxyCount]), TMsgType.Notify);
 end;
 
 
-function TBodyGridBase.allocCell: Integer;
+function TBodyGridBase.forEachBodyCell (body: TBodyProxyId): CellCoordIter;
 var
-  idx: Integer;
+  g, f, ccidx: Integer;
+  cc: PGridCell;
+  presobj: PGridCellCoord;
 begin
-  if (mFreeCell < 0) then
+  result := CellCoordIter.Create(framePool);
+  if (body < 0) or (body > High(mProxies)) then begin result.finishIt(); exit; end;
+  for g := 0 to High(mGrid) do
   begin
-    // no free cells, want more
-    mFreeCell := Length(mCells);
-    SetLength(mCells, mFreeCell+32768); // arbitrary number
-    for idx := mFreeCell to High(mCells) do
+    ccidx := mGrid[g];
+    while (ccidx <> -1) do
     begin
-      {$IFDEF grid_use_buckets}
-      mCells[idx].bodies[0] := -1;
-      {$ELSE}
-      mCells[idx].body := -1;
-      {$ENDIF}
-      mCells[idx].next := idx+1;
+      cc := @mCells[ccidx];
+      for f := 0 to GridCellBucketSize-1 do
+      begin
+        if (cc.bodies[f] = -1) then break;
+        if (cc.bodies[f] = body) then
+        begin
+          presobj := PGridCellCoord(framePool.alloc(sizeof(TGridCellCoord)));
+          presobj^.x := (g mod mWidth)*mTileSize+mMinX;
+          presobj^.y := (g div mWidth)*mTileSize+mMinY;
+          //cb((g mod mWidth)*mTileSize+mMinX, (g div mWidth)*mTileSize+mMinY);
+        end;
+      end;
+      // next cell
+      ccidx := cc.next;
     end;
-    mCells[High(mCells)].next := -1; // last cell
   end;
-  result := mFreeCell;
-  mFreeCell := mCells[result].next;
-  mCells[result].next := -1;
-  Inc(mUsedCells);
-  //e_WriteLog(Format('grid: allocated new cell #%d (total: %d)', [result, mUsedCells]), MSG_NOTIFY);
+  result.finishIt();
 end;
 
 
-procedure TBodyGridBase.freeCell (idx: Integer);
+function TBodyGridBase.forEachInCell (x, y: Integer): Iter;
+var
+  f, ccidx: Integer;
+  cc: PGridCell;
+  presobj: PITP;
 begin
-  if (idx >= 0) and (idx < High(mCells)) then
+  result := Iter.Create(framePool);
+  Dec(x, mMinX);
+  Dec(y, mMinY);
+  if (x < 0) or (y < 0) or (x >= mWidth*mTileSize) or (y > mHeight*mTileSize) then begin result.finishIt(); exit; end;
+  ccidx := mGrid[(y div mTileSize)*mWidth+(x div mTileSize)];
+  while (ccidx <> -1) do
   begin
-    //if mCells[idx].body = -1 then exit; // the thing that should not be
-    //mCells[idx].body := -1;
-    mCells[idx].next := mFreeCell;
-    mFreeCell := idx;
-    Dec(mUsedCells);
+    cc := @mCells[ccidx];
+    for f := 0 to GridCellBucketSize-1 do
+    begin
+      if (cc.bodies[f] = -1) then break;
+      //if cb(mProxies[cc.bodies[f]].mObj, mProxies[cc.bodies[f]].mTag) then begin result := mProxies[cc.bodies[f]].mObj; exit; end;
+      presobj := PITP(framePool.alloc(sizeof(ITP)));
+      //presobj^ := mProxies[cc.bodies[f]].mObj;
+      Move(mProxies[cc.bodies[f]].mObj, presobj^, sizeof(ITP));
+    end;
+    // next cell
+    ccidx := cc.next;
   end;
+  result.finishIt();
 end;
 
 
-function TBodyGridBase.allocProxy (aX, aY, aWidth, aHeight: Integer; aObj: ITP; aTag: Integer): TBodyProxyId;
-var
-  olen, idx: Integer;
-  px: PBodyProxyRec;
+// ////////////////////////////////////////////////////////////////////////// //
+function TBodyGridBase.getGridWidthPx (): Integer; inline; begin result := mWidth*mTileSize; end;
+function TBodyGridBase.getGridHeightPx (): Integer; inline; begin result := mHeight*mTileSize; end;
+
+
+function TBodyGridBase.insideGrid (x, y: Integer): Boolean; inline;
 begin
-  if (mProxyFree = -1) then
+  // fix coords
+  Dec(x, mMinX);
+  Dec(y, mMinY);
+  result := (x >= 0) and (y >= 0) and (x < mWidth*mTileSize) and (y < mHeight*mTileSize);
+end;
+
+
+function TBodyGridBase.getBodyXY (body: TBodyProxyId; out rx, ry: Integer): Boolean; inline;
+begin
+  if (body >= 0) and (body < Length(mProxies)) then
   begin
-    // no free proxies, resize list
-    olen := Length(mProxies);
-    SetLength(mProxies, olen+8192); // arbitrary number
-    for idx := olen to High(mProxies) do mProxies[idx].nextLink := idx+1;
-    mProxies[High(mProxies)].nextLink := -1;
-    mProxyFree := olen;
+    with mProxies[body] do begin rx := mX; ry := mY; end;
+    result := true;
+  end
+  else
+  begin
+    rx := 0;
+    ry := 0;
+    result := false;
   end;
-  // get one from list
-  result := mProxyFree;
-  px := @mProxies[result];
-  mProxyFree := px.nextLink;
-  px.setup(aX, aY, aWidth, aHeight, aObj, aTag);
-  // add to used list
-  px.nextLink := -1;
-  // statistics
-  Inc(mProxyCount);
-  if (mProxyMaxCount < mProxyCount) then mProxyMaxCount := mProxyCount;
 end;
 
-procedure TBodyGridBase.freeProxy (body: TBodyProxyId);
+
+function TBodyGridBase.getBodyWH (body: TBodyProxyId; out rw, rh: Integer): Boolean; inline;
 begin
-  if (body < 0) or (body > High(mProxies)) then exit; // just in case
-  if (mProxyCount = 0) then raise Exception.Create('wutafuuuuu in grid (no allocated proxies, what i should free now?)');
-  // add to free list
-  mProxies[body].mObj := nil;
-  mProxies[body].nextLink := mProxyFree;
-  mProxyFree := body;
-  Dec(mProxyCount);
+  if (body >= 0) and (body < Length(mProxies)) then
+  begin
+    with mProxies[body] do begin rw := mWidth; rh := mHeight; end;
+    result := true;
+  end
+  else
+  begin
+    rw := 0;
+    rh := 0;
+    result := false;
+  end;
 end;
 
 
-function TBodyGridBase.forGridRect (x, y, w, h: Integer; cb: TGridInternalCB): Boolean;
-var
-  gx, gy: Integer;
+function TBodyGridBase.getBodyDims (body: TBodyProxyId; out rx, ry, rw, rh: Integer): Boolean; inline;
 begin
-  result := false;
-  if (w < 1) or (h < 1) or not assigned(cb) then exit;
+  if (body >= 0) and (body < Length(mProxies)) then
+  begin
+    with mProxies[body] do begin rx := mX; ry := mY; rw := mWidth; rh := mHeight; end;
+    result := true;
+  end
+  else
+  begin
+    rx := 0;
+    ry := 0;
+    rw := 0;
+    rh := 0;
+    result := false;
+  end;
+end;
+
+
+
+// ////////////////////////////////////////////////////////////////////////// //
+function TBodyGridBase.getProxyEnabled (pid: TBodyProxyId): Boolean; inline;
+begin
+  if (pid >= 0) and (pid < Length(mProxies)) then result := ((mProxies[pid].mTag and TagDisabled) = 0) else result := false;
+end;
+
+
+procedure TBodyGridBase.setProxyEnabled (pid: TBodyProxyId; val: Boolean); inline;
+begin
+  if (pid >= 0) and (pid < Length(mProxies)) then
+  begin
+    if val then
+    begin
+      mProxies[pid].mTag := mProxies[pid].mTag and not TagDisabled;
+    end
+    else
+    begin
+      mProxies[pid].mTag := mProxies[pid].mTag or TagDisabled;
+    end;
+  end;
+end;
+
+
+function TBodyGridBase.getProxyById (idx: TBodyProxyId): PBodyProxyRec; inline;
+begin
+  if (idx >= 0) and (idx < Length(mProxies)) then result := @mProxies[idx] else result := nil;
+end;
+
+
+// ////////////////////////////////////////////////////////////////////////// //
+function TBodyGridBase.allocCell (): Integer;
+var
+  idx: Integer;
+  pc: PGridCell;
+begin
+  if (mFreeCell < 0) then
+  begin
+    // no free cells, want more
+    mFreeCell := Length(mCells);
+    SetLength(mCells, mFreeCell+32768); // arbitrary number
+    for idx := mFreeCell to High(mCells) do
+    begin
+      mCells[idx].bodies[0] := -1;
+      mCells[idx].bodies[GridCellBucketSize-1] := -1; // 'has free room' flag
+      mCells[idx].next := idx+1;
+    end;
+    mCells[High(mCells)].next := -1; // last cell
+  end;
+  result := mFreeCell;
+  pc := @mCells[result];
+  mFreeCell := pc.next;
+  pc.next := -1;
+  Inc(mUsedCells);
+  //e_WriteLog(Format('grid: allocated new cell #%d (total: %d)', [result, mUsedCells]), MSG_NOTIFY);
+end;
+
+
+procedure TBodyGridBase.freeCell (idx: Integer);
+begin
+  if (idx >= 0) and (idx < Length(mCells)) then
+  begin
+    with mCells[idx] do
+    begin
+      bodies[0] := -1;
+      bodies[GridCellBucketSize-1] := -1; // 'has free room' flag
+      next := mFreeCell;
+    end;
+    mFreeCell := idx;
+    Dec(mUsedCells);
+  end;
+end;
+
+
+// ////////////////////////////////////////////////////////////////////////// //
+function TBodyGridBase.allocProxy (aX, aY, aWidth, aHeight: Integer; aObj: ITP; aTag: Integer): TBodyProxyId;
+var
+  olen, idx: Integer;
+  px: PBodyProxyRec;
+begin
+  if (mProxyFree = -1) then
+  begin
+    // no free proxies, resize list
+    olen := Length(mProxies);
+    SetLength(mProxies, olen+8192); // arbitrary number
+    for idx := olen to High(mProxies) do mProxies[idx].nextLink := idx+1;
+    mProxies[High(mProxies)].nextLink := -1;
+    mProxyFree := olen;
+  end;
+  // get one from list
+  result := mProxyFree;
+  px := @mProxies[result];
+  mProxyFree := px.nextLink;
+  px.setup(aX, aY, aWidth, aHeight, aObj, aTag);
+  // add to used list
+  px.nextLink := -1;
+  // statistics
+  Inc(mProxyCount);
+  if (mProxyMaxCount < mProxyCount) then mProxyMaxCount := mProxyCount;
+end;
+
+procedure TBodyGridBase.freeProxy (body: TBodyProxyId);
+begin
+  if (body < 0) or (body > High(mProxies)) then exit; // just in case
+  if (mProxyCount = 0) then raise Exception.Create('wutafuuuuu in grid (no allocated proxies, what i should free now?)');
+  // add to free list
+  mProxies[body].mObj := nil;
+  mProxies[body].nextLink := mProxyFree;
+  mProxyFree := body;
+  Dec(mProxyCount);
+end;
+
+
+// ////////////////////////////////////////////////////////////////////////// //
+function TBodyGridBase.forGridRect (x, y, w, h: Integer; cb: TGridInternalCB; bodyId: TBodyProxyId): Boolean;
+var
+  gw, gh: Integer;
+  ex, ey: Integer;
+  gx, gy: Integer;
+begin
+  result := false;
+  if (w < 1) or (h < 1) or not assigned(cb) then exit;
   // fix coords
   Dec(x, mMinX);
   Dec(y, mMinY);
   // go on
   if (x+w <= 0) or (y+h <= 0) then exit;
-  if (x >= mWidth*mTileSize) or (y >= mHeight*mTileSize) then exit;
-  for gy := y div mTileSize to (y+h-1) div mTileSize do
+  gw := mWidth;
+  gh := mHeight;
+  if (x >= gw*mTileSize) or (y >= gh*mTileSize) then exit;
+  ex := (x+w-1) div mTileSize;
+  ey := (y+h-1) div mTileSize;
+  x := x div mTileSize;
+  y := y div mTileSize;
+  // clip rect
+  if (x < 0) then x := 0 else if (x >= gw) then x := gw-1;
+  if (y < 0) then y := 0 else if (y >= gh) then y := gh-1;
+  if (ex < 0) then ex := 0 else if (ex >= gw) then ex := gw-1;
+  if (ey < 0) then ey := 0 else if (ey >= gh) then ey := gh-1;
+  if (x > ex) or (y > ey) then exit; // just in case
+  // do the work
+  for gy := y to ey do
   begin
-    if (gy < 0) then continue;
-    if (gy >= mHeight) then break;
-    for gx := x div mTileSize to (x+w-1) div mTileSize do
+    for gx := x to ex do
     begin
-      if (gx < 0) then continue;
-      if (gx >= mWidth) then break;
-      if (cb(gy*mWidth+gx)) then begin result := true; exit; end;
+      result := cb(gy*gw+gx, bodyId);
+      if result then exit;
     end;
   end;
 end;
 
 
-function TBodyGridBase.inserter (grida: Integer): Boolean;
+// ////////////////////////////////////////////////////////////////////////// //
+function TBodyGridBase.inserter (grida: Integer; bodyId: TBodyProxyId): Boolean;
 var
-  cidx: Integer;
-  pc: PInteger;
-  {$IFDEF grid_use_buckets}
+  ccidx: Integer;
+  pc: Integer;
   pi: PGridCell;
   f: Integer;
-  {$ENDIF}
 begin
   result := false; // never stop
   // add body to the given grid cell
-  pc := @mGrid[grida];
-  {$IFDEF grid_use_buckets}
-  if (pc^ <> -1) then
+  pc := mGrid[grida];
+  if (pc <> -1) then
   begin
-    pi := @mCells[pc^];
-    f := 0;
-    for f := 0 to High(TGridCell.bodies) do
+    {$IF DEFINED(D2F_DEBUG)}
+    ccidx := pc;
+    while (ccidx <> -1) do
     begin
-      if (pi.bodies[f] = -1) then
+      pi := @mCells[ccidx];
+      for f := 0 to GridCellBucketSize-1 do
+      begin
+        if (pi.bodies[f] = -1) then break;
+        if (pi.bodies[f] = bodyId) then raise Exception.Create('trying to insert already inserted proxy');
+      end;
+      ccidx := pi.next;
+    end;
+    {$ENDIF}
+    ccidx := pc;
+    while (ccidx <> -1) do
+    begin
+      pi := @mCells[ccidx];
+      // check "has room" flag
+      if (pi.bodies[GridCellBucketSize-1] = -1) then
       begin
         // can add here
-        pi.bodies[f] := mUData;
-        if (f+1 < Length(TGridCell.bodies)) then pi.bodies[f+1] := -1;
-        exit;
+        for f := 0 to GridCellBucketSize-1 do
+        begin
+          if (pi.bodies[f] = -1) then
+          begin
+            pi.bodies[f] := bodyId;
+            if (f+1 < GridCellBucketSize) then pi.bodies[f+1] := -1;
+            exit;
+          end;
+        end;
+        raise Exception.Create('internal error in grid inserter');
       end;
+      // no room, go to next cell in list (if there is any)
+      ccidx := pi.next;
     end;
+    // no room in cells, add new cell to list
   end;
   // either no room, or no cell at all
-  cidx := allocCell();
-  mCells[cidx].bodies[0] := mUData;
-  mCells[cidx].bodies[1] := -1;
-  mCells[cidx].next := pc^;
-  pc^ := cidx;
-  {$ELSE}
-  cidx := allocCell();
-  //e_WriteLog(Format('  01: allocated cell for grid coords (%d,%d), body coords:(%d,%d): #%d', [gx, gy, dx, dy, cidx]), MSG_NOTIFY);
-  mCells[cidx].body := mUData;
-  mCells[cidx].next := pc^;
-  pc^ := cidx;
-  {$ENDIF}
+  ccidx := allocCell();
+  pi := @mCells[ccidx];
+  pi.bodies[0] := bodyId;
+  pi.bodies[1] := -1;
+  pi.next := pc;
+  mGrid[grida] := ccidx;
+end;
+
+
+// assume that we cannot have one object added to bucket twice
+function TBodyGridBase.remover (grida: Integer; bodyId: TBodyProxyId): Boolean;
+var
+  f, c: Integer;
+  pidx, ccidx: Integer;
+  pc: PGridCell;
+begin
+  result := false; // never stop
+  // find and remove cell
+  pidx := -1; // previous cell index
+  ccidx := mGrid[grida]; // current cell index
+  while (ccidx <> -1) do
+  begin
+    pc := @mCells[ccidx];
+    for f := 0 to GridCellBucketSize-1 do
+    begin
+      if (pc.bodies[f] = bodyId) then
+      begin
+        // i found her!
+        if (f = 0) and (pc.bodies[1] = -1) then
+        begin
+          // this cell contains no elements, remove it
+          if (pidx = -1) then mGrid[grida] := pc.next else mCells[pidx].next := pc.next;
+          freeCell(ccidx);
+          exit;
+        end;
+        // remove element from bucket
+        for c := f to GridCellBucketSize-2 do
+        begin
+          pc.bodies[c] := pc.bodies[c+1];
+          if (pc.bodies[c] = -1) then break;
+        end;
+        pc.bodies[GridCellBucketSize-1] := -1; // "has free room" flag
+        exit;
+      end;
+    end;
+    pidx := ccidx;
+    ccidx := pc.next;
+  end;
+end;
+
+
+// ////////////////////////////////////////////////////////////////////////// //
+function TBodyGridBase.insertBody (aObj: ITP; aX, aY, aWidth, aHeight: Integer; aTag: Integer=-1): TBodyProxyId;
+begin
+  aTag := aTag and TagFullMask;
+  result := allocProxy(aX, aY, aWidth, aHeight, aObj, aTag);
+  //insertInternal(result);
+  forGridRect(aX, aY, aWidth, aHeight, inserter, result);
 end;
 
 
-procedure TBodyGridBase.insert (body: TBodyProxyId);
+procedure TBodyGridBase.removeBody (body: TBodyProxyId);
 var
   px: PBodyProxyRec;
-  oudata: Integer;
 begin
   if (body < 0) or (body > High(mProxies)) then exit; // just in case
   px := @mProxies[body];
-  oudata := mUData;
-  mUData := body;
-  forGridRect(px.mX, px.mY, px.mWidth, px.mHeight, inserter);
-  mUData := oudata;
+  //removeInternal(body);
+  forGridRect(px.mX, px.mY, px.mWidth, px.mHeight, remover, body);
+  freeProxy(body);
 end;
 
 
-function TBodyGridBase.remover (grida: Integer): Boolean;
+// ////////////////////////////////////////////////////////////////////////// //
+procedure TBodyGridBase.moveResizeBody (body: TBodyProxyId; nx, ny, nw, nh: Integer);
 var
-  pidx, idx, tmp, f: Integer;
-  pc: PGridCell;
+  px: PBodyProxyRec;
+  x0, y0, w, h: Integer;
 begin
-  result := false; // never stop
-  // find and remove cell
-  pidx := -1;
-  idx := mGrid[grida];
-  while (idx >= 0) do
+  if (body < 0) or (body > High(mProxies)) then exit; // just in case
+  px := @mProxies[body];
+  x0 := px.mX;
+  y0 := px.mY;
+  w := px.mWidth;
+  h := px.mHeight;
+  {$IF DEFINED(D2F_DEBUG_MOVER)}
+  e_WriteLog(Format('proxy #%d: MOVERESIZE: xg=%d;yg=%d;w=%d;h=%d;nx=%d;ny=%d;nw=%d;nh=%d', [body, x0-mMinX, y0-mMinY, w, h, nx-mMinX, ny-mMinY, nw, nh]), MSG_NOTIFY);
+  {$ENDIF}
+  if (nx = x0) and (ny = y0) and (nw = w) and (nh = h) then exit;
+  // map -> grid
+  Dec(x0, mMinX);
+  Dec(y0, mMinY);
+  Dec(nx, mMinX);
+  Dec(ny, mMinY);
+  // did any corner crossed tile boundary?
+  if (x0 div mTileSize <> nx div mTileSize) or
+     (y0 div mTileSize <> ny div mTileSize) or
+     ((x0+w-1) div mTileSize <> (nx+nw-1) div mTileSize) or
+     ((y0+h-1) div mTileSize <> (ny+nh-1) div mTileSize) then
   begin
-    tmp := mCells[idx].next;
-    {$IFDEF grid_use_buckets}
-    pc := @mCells[idx];
-    f := 0;
-    while (f < High(TGridCell.bodies)) do
+    //writeln('moveResizeBody: cell occupation changed! old=(', x0, ',', y0, ')-(', x0+w-1, ',', y0+h-1, '); new=(', nx, ',', ny, ')-(', nx+nw-1, ',', ny+nh-1, ')');
+    //removeInternal(body);
+    forGridRect(px.mX, px.mY, px.mWidth, px.mHeight, remover, body);
+    px.mX := nx+mMinX;
+    px.mY := ny+mMinY;
+    px.mWidth := nw;
+    px.mHeight := nh;
+    //insertInternal(body);
+    forGridRect(px.mX, px.mY, nw, nh, inserter, body);
+  end
+  else
+  begin
+    px.mX := nx+mMinX;
+    px.mY := ny+mMinY;
+    px.mWidth := nw;
+    px.mHeight := nh;
+  end;
+end;
+
+
+//TODO: optimize for horizontal/vertical moves
+procedure TBodyGridBase.moveBody (body: TBodyProxyId; nx, ny: Integer);
+var
+  px: PBodyProxyRec;
+  x0, y0: Integer;
+  ogx0, ogx1, ogy0, ogy1: Integer; // old grid rect
+  ngx0, ngx1, ngy0, ngy1: Integer; // new grid rect
+  gx, gy: Integer;
+  gw, gh: Integer;
+  pw, ph: Integer;
+begin
+  if (body < 0) or (body > High(mProxies)) then exit; // just in case
+  // check if tile coords was changed
+  px := @mProxies[body];
+  x0 := px.mX;
+  y0 := px.mY;
+  if (nx = x0) and (ny = y0) then exit;
+  // map -> grid
+  Dec(x0, mMinX);
+  Dec(y0, mMinY);
+  Dec(nx, mMinX);
+  Dec(ny, mMinY);
+  // check for heavy work
+  pw := px.mWidth;
+  ph := px.mHeight;
+  ogx0 := x0 div mTileSize;
+  ogy0 := y0 div mTileSize;
+  ngx0 := nx div mTileSize;
+  ngy0 := ny div mTileSize;
+  ogx1 := (x0+pw-1) div mTileSize;
+  ogy1 := (y0+ph-1) div mTileSize;
+  ngx1 := (nx+pw-1) div mTileSize;
+  ngy1 := (ny+ph-1) div mTileSize;
+  {$IF DEFINED(D2F_DEBUG_MOVER)}
+  e_WriteLog(Format('proxy #%d: checkmove: xg=%d;yg=%d;w=%d;h=%d;nx=%d;ny=%d og:(%d,%d)-(%d,%d); ng:(%d,%d)-(%d,%d)', [body, x0, y0, pw, ph, nx, ny, ogx0, ogy0, ogx1, ogy1, ngx0, ngy0, ngx1, ngy1]), MSG_NOTIFY);
+  {$ENDIF}
+  if (ogx0 <> ngx0) or (ogy0 <> ngy0) or (ogx1 <> ngx1) or (ogy1 <> ngy1) then
+  begin
+    // crossed tile boundary, do heavy work
+    gw := mWidth;
+    gh := mHeight;
+    // cycle with old rect, remove body where it is necessary
+    // optimized for horizontal moves
+    {$IF DEFINED(D2F_DEBUG_MOVER)}
+    e_WriteLog(Format('proxy #%d: xg=%d;yg=%d;w=%d;h=%d;nx=%d;ny=%d og:(%d,%d)-(%d,%d); ng:(%d,%d)-(%d,%d)', [body, x0, y0, pw, ph, nx, ny, ogx0, ogy0, ogx1, ogy1, ngx0, ngy0, ngx1, ngy1]), MSG_NOTIFY);
+    {$ENDIF}
+    // remove stale marks
+    if not ((ogy0 >= gh) or (ogy1 < 0)) and
+       not ((ogx0 >= gw) or (ogx1 < 0)) then
     begin
-      if (pc.bodies[f] = mUData) then
+      if (ogx0 < 0) then ogx0 := 0;
+      if (ogy0 < 0) then ogy0 := 0;
+      if (ogx1 > gw-1) then ogx1 := gw-1;
+      if (ogy1 > gh-1) then ogy1 := gh-1;
+      {$IF DEFINED(D2F_DEBUG_MOVER)}
+      e_WriteLog(Format(' norm og:(%d,%d)-(%d,%d)', [ogx0, ogy0, ogx1, ogy1]), MSG_NOTIFY);
+      {$ENDIF}
+      for gx := ogx0 to ogx1 do
       begin
-        // i found her!
-        if (f = 0) and (pc.bodies[1] = -1) then
+        if (gx < ngx0) or (gx > ngx1) then
         begin
-          // this cell contains no elements, remove it
-          tmp := mCells[idx].next;
-          if (pidx = -1) then mGrid[grida] := tmp else mCells[pidx].next := tmp;
-          freeCell(idx);
+          // this column is completely outside of new rect
+          for gy := ogy0 to ogy1 do
+          begin
+            {$IF DEFINED(D2F_DEBUG_MOVER)}
+            e_WriteLog(Format('  remove0:(%d,%d)', [gx, gy]), MSG_NOTIFY);
+            {$ENDIF}
+            remover(gy*gw+gx, body);
+          end;
         end
         else
         begin
-          // remove element from bucket
-          Inc(f);
-          while (f < High(TGridCell.bodies)) do
+          // heavy checks
+          for gy := ogy0 to ogy1 do
           begin
-            pc.bodies[f-1] := pc.bodies[f];
-            if (pc.bodies[f] = -1) then break;
-            Inc(f);
+            if (gy < ngy0) or (gy > ngy1) then
+            begin
+              {$IF DEFINED(D2F_DEBUG_MOVER)}
+              e_WriteLog(Format('  remove1:(%d,%d)', [gx, gy]), MSG_NOTIFY);
+              {$ENDIF}
+              remover(gy*gw+gx, body);
+            end;
           end;
-          pc.bodies[High(TGridCell.bodies)] := -1; // just in case
         end;
-        exit; // assume that we cannot have one object added to bucket twice
       end;
-      Inc(f);
     end;
-    {$ELSE}
-    if (mCells[idx].body = mUData) then
+    // cycle with new rect, add body where it is necessary
+    if not ((ngy0 >= gh) or (ngy1 < 0)) and
+       not ((ngx0 >= gw) or (ngx1 < 0)) then
     begin
-      if (pidx = -1) then mGrid[grida] := tmp else mCells[pidx].next := tmp;
-      freeCell(idx);
-      exit; // assume that we cannot have one object added to bucket twice
+      if (ngx0 < 0) then ngx0 := 0;
+      if (ngy0 < 0) then ngy0 := 0;
+      if (ngx1 > gw-1) then ngx1 := gw-1;
+      if (ngy1 > gh-1) then ngy1 := gh-1;
+      {$IF DEFINED(D2F_DEBUG_MOVER)}
+      e_WriteLog(Format(' norm ng:(%d,%d)-(%d,%d)', [ngx0, ngy0, ngx1, ngy1]), MSG_NOTIFY);
+      {$ENDIF}
+      for gx := ngx0 to ngx1 do
+      begin
+        if (gx < ogx0) or (gx > ogx1) then
+        begin
+          // this column is completely outside of old rect
+          for gy := ngy0 to ngy1 do
+          begin
+            {$IF DEFINED(D2F_DEBUG_MOVER)}
+            e_WriteLog(Format('  insert0:(%d,%d)', [gx, gy]), MSG_NOTIFY);
+            {$ENDIF}
+            inserter(gy*gw+gx, body);
+          end;
+        end
+        else
+        begin
+          // heavy checks
+          for gy := ngy0 to ngy1 do
+          begin
+            if (gy < ogy0) or (gy > ogy1) then
+            begin
+              {$IF DEFINED(D2F_DEBUG_MOVER)}
+              e_WriteLog(Format('  insert1:(%d,%d)', [gx, gy]), MSG_NOTIFY);
+              {$ENDIF}
+              inserter(gy*gw+gx, body);
+            end;
+          end;
+        end;
+      end;
     end;
+    // done
+  end
+  else
+  begin
+    {$IF DEFINED(D2F_DEBUG_MOVER)}
+    e_WriteLog(Format('proxy #%d: GRID OK: xg=%d;yg=%d;w=%d;h=%d;nx=%d;ny=%d og:(%d,%d)-(%d,%d); ng:(%d,%d)-(%d,%d)', [body, x0, y0, pw, ph, nx, ny, ogx0, ogy0, ogx1, ogy1, ngx0, ngy0, ngx1, ngy1]), MSG_NOTIFY);
     {$ENDIF}
-    pidx := idx;
-    idx := tmp;
   end;
+  // update coordinates
+  px.mX := nx+mMinX;
+  px.mY := ny+mMinY;
 end;
 
 
-// absolutely not tested
-procedure TBodyGridBase.remove (body: TBodyProxyId);
+procedure TBodyGridBase.resizeBody (body: TBodyProxyId; nw, nh: Integer);
 var
   px: PBodyProxyRec;
-  oudata: Integer;
+  x0, y0, w, h: Integer;
 begin
   if (body < 0) or (body > High(mProxies)) then exit; // just in case
+  // check if tile coords was changed
   px := @mProxies[body];
-  oudata := mUData;
-  mUData := body;
-  forGridRect(px.mX, px.mY, px.mWidth, px.mHeight, remover);
-  mUData := oudata;
+  x0 := px.mX-mMinX;
+  y0 := px.mY-mMinY;
+  w := px.mWidth;
+  h := px.mHeight;
+  {$IF DEFINED(D2F_DEBUG_MOVER)}
+  e_WriteLog(Format('proxy #%d: RESIZE: xg=%d;yg=%d;w=%d;h=%d;nw=%d;nh=%d', [body, x0, y0, w, h, nw, nh]), MSG_NOTIFY);
+  {$ENDIF}
+  if ((x0+w-1) div mTileSize <> (x0+nw-1) div mTileSize) or
+     ((y0+h-1) div mTileSize <> (y0+nh-1) div mTileSize) then
+  begin
+    // crossed tile boundary, do heavy work
+    //removeInternal(body);
+    forGridRect(px.mX, px.mY, px.mWidth, px.mHeight, remover, body);
+    px.mWidth := nw;
+    px.mHeight := nh;
+    //insertInternal(body);
+    forGridRect(px.mX, px.mY, nw, nh, inserter, body);
+  end
+  else
+  begin
+    // nothing to do with the grid, just fix size
+    px.mWidth := nw;
+    px.mHeight := nh;
+  end;
 end;
 
 
-function TBodyGridBase.insertBody (aObj: ITP; aX, aY, aWidth, aHeight: Integer; aTag: Integer=0): TBodyProxyId;
+// ////////////////////////////////////////////////////////////////////////// //
+function TBodyGridBase.atCellInPoint (x, y: Integer): TAtPointEnumerator;
+var
+  ccidx: Integer = -1;
 begin
-  result := allocProxy(aX, aY, aWidth, aHeight, aObj, aTag);
-  insert(result);
+  Dec(x, mMinX);
+  Dec(y, mMinY);
+  if (x >= 0) and (y >= 0) and (x < mWidth*mTileSize) and (y < mHeight*mTileSize) then ccidx := mGrid[(y div mTileSize)*mWidth+(x div mTileSize)];
+  result := TAtPointEnumerator.Create(mCells, ccidx, getProxyById);
 end;
 
 
-procedure TBodyGridBase.removeBody (aObj: TBodyProxyId);
+// ////////////////////////////////////////////////////////////////////////// //
+// no callback: return `true` on the first hit
+function TBodyGridBase.forEachAtPoint (x, y: Integer; tagmask: Integer=-1; allowDisabled: Boolean=false; firstHit: Boolean=false): Iter;
+var
+  f: Integer;
+  idx, curci: Integer;
+  cc: PGridCell = nil;
+  px: PBodyProxyRec;
+  lq: LongWord;
+  ptag: Integer;
+  presobj: PITP;
 begin
-  if (aObj < 0) or (aObj > High(mProxies)) then exit; // just in case
-  remove(aObj);
-  freeProxy(aObj);
+  result := Iter.Create(framePool);
+  tagmask := tagmask and TagFullMask;
+  if (tagmask = 0) then begin result.finishIt(); exit; end;
+
+  {$IF DEFINED(D2F_DEBUG_XXQ)}
+  if (assigned(cb)) then e_WriteLog(Format('0: grid pointquery: (%d,%d)', [x, y]), MSG_NOTIFY);
+  {$ENDIF}
+
+  // make coords (0,0)-based
+  Dec(x, mMinX);
+  Dec(y, mMinY);
+  if (x < 0) or (y < 0) or (x >= mWidth*mTileSize) or (y >= mHeight*mTileSize) then begin result.finishIt(); exit; end;
+
+  curci := mGrid[(y div mTileSize)*mWidth+(x div mTileSize)];
+
+  {$IF DEFINED(D2F_DEBUG_XXQ)}
+  if (assigned(cb)) then e_WriteLog(Format('1: grid pointquery: (%d,%d) (%d,%d) %d', [x, y, (x div mTileSize), (y div mTileSize), curci]), MSG_NOTIFY);
+  {$ENDIF}
+
+  // restore coords
+  Inc(x, mMinX);
+  Inc(y, mMinY);
+
+  // increase query counter
+  Inc(mLastQuery);
+  if (mLastQuery = 0) then
+  begin
+    // just in case of overflow
+    mLastQuery := 1;
+    for idx := 0 to High(mProxies) do mProxies[idx].mQueryMark := 0;
+  end;
+  lq := mLastQuery;
+
+  {$IF DEFINED(D2F_DEBUG_XXQ)}
+  if (assigned(cb)) then e_WriteLog(Format('2: grid pointquery: (%d,%d); lq=%u', [x, y, lq]), MSG_NOTIFY);
+  {$ENDIF}
+
+  while (curci <> -1) do
+  begin
+    {$IF DEFINED(D2F_DEBUG_XXQ)}
+    //if (assigned(cb)) then e_WriteLog(Format(' cell #%d', [curci]), MSG_NOTIFY);
+    {$ENDIF}
+    cc := @mCells[curci];
+    for f := 0 to GridCellBucketSize-1 do
+    begin
+      if (cc.bodies[f] = -1) then break;
+      px := @mProxies[cc.bodies[f]];
+      {$IF DEFINED(D2F_DEBUG_XXQ)}
+      //if (assigned(cb)) then e_WriteLog(Format('  proxy #%d; qm:%u; tag:%08x; tagflag:%d  %u', [cc.bodies[f], px.mQueryMark, px.mTag, (px.mTag and tagmask), LongWord(px.mObj)]), MSG_NOTIFY);
+      {$ENDIF}
+      if (px.mQueryMark = lq) then continue;
+      px.mQueryMark := lq;
+      ptag := px.mTag;
+      if (not allowDisabled) and ((ptag and TagDisabled) <> 0) then continue;
+      if ((ptag and tagmask) = 0) then continue;
+      if (x >= px.mX) and (y >= px.mY) and (x < px.mX+px.mWidth) and (y < px.mY+px.mHeight) then
+      begin
+        presobj := PITP(framePool.alloc(sizeof(ITP)));
+        Move(px.mObj, presobj^, sizeof(ITP));
+        if (firstHit) then begin result.finishIt(); exit; end;
+      end;
+    end;
+    curci := cc.next;
+  end;
+  result.finishIt();
 end;
 
 
-procedure TBodyGridBase.moveResizeBody (body: TBodyProxyId; dx, dy, sx, sy: Integer);
+// ////////////////////////////////////////////////////////////////////////// //
+// no callback: return `true` on the first hit
+// return number of ITP thingys put into frame pool
+function TBodyGridBase.forEachInAABB (x, y, w, h: Integer; tagmask: Integer=-1; allowDisabled: Boolean=false; firstHit: Boolean=false): Iter;
 var
+  idx: Integer;
+  gx, gy: Integer;
+  sx, sy, ex, ey: Integer;
+  curci: Integer;
+  f: Integer;
+  cc: PGridCell = nil;
   px: PBodyProxyRec;
+  lq: LongWord;
+  gw, gh: Integer;
+  x0, y0: Integer;
+  ptag: Integer;
+  presobj: PITP;
 begin
-  if (body < 0) or (body > High(mProxies)) then exit; // just in case
-  if ((dx = 0) and (dy = 0) and (sx = 0) and (sy = 0)) then exit;
-  remove(body);
-  px := @mProxies[body];
-  Inc(px.mX, dx);
-  Inc(px.mY, dy);
-  Inc(px.mWidth, sx);
-  Inc(px.mHeight, sy);
-  insert(body);
+  if (w = 1) and (h = 1) then
+  begin
+    result := forEachAtPoint(x, y, tagmask, allowDisabled, firstHit);
+    exit;
+  end;
+
+  result := Iter.Create(framePool);
+  if (w < 1) or (h < 1) then begin result.finishIt(); exit; end;
+
+  tagmask := tagmask and TagFullMask;
+  if (tagmask = 0) then begin result.finishIt(); exit; end;
+
+  x0 := x;
+  y0 := y;
+
+  // fix coords
+  Dec(x, mMinX);
+  Dec(y, mMinY);
+
+  gw := mWidth;
+  gh := mHeight;
+
+  if (x+w <= 0) or (y+h <= 0) then begin result.finishIt(); exit; end;
+  if (x >= gw*mTileSize) or (y >= gh*mTileSize) then begin result.finishIt(); exit; end;
+
+  sx := x div mTileSize;
+  sy := y div mTileSize;
+  ex := (x+w-1) div mTileSize;
+  ey := (y+h-1) div mTileSize;
+
+  // clip rect
+  if (sx < 0) then sx := 0 else if (sx >= gw) then sx := gw-1;
+  if (sy < 0) then sy := 0 else if (sy >= gh) then sy := gh-1;
+  if (ex < 0) then ex := 0 else if (ex >= gw) then ex := gw-1;
+  if (ey < 0) then ey := 0 else if (ey >= gh) then ey := gh-1;
+  if (sx > ex) or (sy > ey) then begin result.finishIt(); exit; end; // just in case
+
+  // has something to do
+
+  // increase query counter
+  Inc(mLastQuery);
+  if (mLastQuery = 0) then
+  begin
+    // just in case of overflow
+    mLastQuery := 1;
+    for idx := 0 to High(mProxies) do mProxies[idx].mQueryMark := 0;
+  end;
+  //e_WriteLog(Format('grid: query #%d: (%d,%d)-(%dx%d)', [mLastQuery, minx, miny, maxx, maxy]), MSG_NOTIFY);
+  lq := mLastQuery;
+
+  // go on
+  for gy := sy to ey do
+  begin
+    for gx := sx to ex do
+    begin
+      // process cells
+      curci := mGrid[gy*gw+gx];
+      while (curci <> -1) do
+      begin
+        cc := @mCells[curci];
+        for f := 0 to GridCellBucketSize-1 do
+        begin
+          if (cc.bodies[f] = -1) then break;
+          px := @mProxies[cc.bodies[f]];
+          // shit! has to do it this way, so i can change tag in callback
+          if (px.mQueryMark = lq) then continue;
+          px.mQueryMark := lq;
+          ptag := px.mTag;
+          if (not allowDisabled) and ((ptag and TagDisabled) <> 0) then continue;
+          if ((ptag and tagmask) = 0) then continue;
+          if (x0 >= px.mX+px.mWidth) or (y0 >= px.mY+px.mHeight) then continue;
+          if (x0+w <= px.mX) or (y0+h <= px.mY) then continue;
+          presobj := PITP(framePool.alloc(sizeof(ITP)));
+          Move(px.mObj, presobj^, sizeof(ITP));
+          if (firstHit) then begin result.finishIt(); exit; end;
+        end;
+        curci := cc.next;
+      end;
+    end;
+  end;
+  result.finishIt();
 end;
 
-procedure TBodyGridBase.moveBody (body: TBodyProxyId; dx, dy: Integer);
+
+// ////////////////////////////////////////////////////////////////////////// //
+function TBodyGridBase.forEachAlongLine (ax0, ay0, ax1, ay1: Integer; tagmask: Integer=-1; log: Boolean=false): Iter;
+var
+  lw: TLineWalker;
+  ccidx: Integer;
+  cc: PGridCell;
+  px: PBodyProxyRec;
+  lq: LongWord;
+  f, ptag: Integer;
+  gw, gh, minx, miny: Integer;
+  x0, y0: Integer;
+  x1, y1: Integer;
+  cx, cy: Integer;
+  //px0, py0, px1, py1: Integer;
+  presobj: PITP;
 begin
-  moveResizeBody(body, dx, dy, 0, 0);
+  log := false;
+  result := Iter.Create(framePool);
+  tagmask := tagmask and TagFullMask;
+  if (tagmask = 0) then begin result.finishIt(); exit; end;
+
+  gw := mWidth;
+  gh := mHeight;
+  minx := mMinX;
+  miny := mMinY;
+
+  // make query coords (0,0)-based
+  x0 := ax0-minx;
+  y0 := ay0-miny;
+  x1 := ax1-minx;
+  y1 := ay1-miny;
+
+  lw := TLineWalker.Create(0, 0, gw*mTileSize-1, gh*mTileSize-1);
+  if not lw.setup(x0, y0, x1, y1) then begin result.finishIt(); exit; end; // out of screen
+
+  // increase query counter
+  Inc(mLastQuery);
+  if (mLastQuery = 0) then
+  begin
+    // just in case of overflow
+    mLastQuery := 1;
+    for f := 0 to High(mProxies) do mProxies[f].mQueryMark := 0;
+  end;
+  lq := mLastQuery;
+
+  repeat
+    lw.getXY(cx, cy);
+    // check tile
+    ccidx := mGrid[(cy div mTileSize)*gw+(cx div mTileSize)];
+    // process cells
+    while (ccidx <> -1) do
+    begin
+      cc := @mCells[ccidx];
+      for f := 0 to GridCellBucketSize-1 do
+      begin
+        if (cc.bodies[f] = -1) then break;
+        px := @mProxies[cc.bodies[f]];
+        ptag := px.mTag;
+        if ((ptag and TagDisabled) = 0) and ((ptag and tagmask) <> 0) and (px.mQueryMark <> lq) then
+        begin
+          px.mQueryMark := lq; // mark as processed
+          presobj := PITP(framePool.alloc(sizeof(ITP)));
+          Move(px.mObj, presobj^, sizeof(ITP));
+        end;
+      end;
+      // next cell
+      ccidx := cc.next;
+    end;
+    // done processing cells, move to next tile
+  until lw.stepToNextTile();
+  result.finishIt();
 end;
 
-procedure TBodyGridBase.resizeBody (body: TBodyProxyId; sx, sy: Integer);
+
+// ////////////////////////////////////////////////////////////////////////// //
+// trace box with the given velocity; return object hit (if any)
+function TBodyGridBase.traceBox (out ex, ey: Integer; const ax0, ay0, aw, ah: Integer; const dx, dy: Integer; tagmask: Integer=-1): ITP;
+var
+  gx, gy: Integer;
+  ccidx: Integer;
+  cc: PGridCell;
+  px: PBodyProxyRec;
+  lq: LongWord;
+  f, ptag: Integer;
+  minu0: Single = 100000.0;
+  u0: Single;
+  cx0, cy0, cx1, cy1: Integer;
+  hitpx: PBodyProxyRec = nil;
 begin
-  moveResizeBody(body, 0, 0, sx, sy);
+  result := Default(ITP);
+  ex := ax0+dx;
+  ey := ay0+dy;
+  if (aw < 1) or (ah < 1) then exit;
+
+  cx0 := nmin(ax0, ax0+dx);
+  cy0 := nmin(ay0, ay0+dy);
+  cx1 := nmax(ax0+aw-1, ax0+aw-1+dx);
+  cy1 := nmax(ay0+ah-1, ay0+ah-1+dy);
+
+  cx0 -= mMinX; cy0 -= mMinY;
+  cx1 -= mMinX; cy1 -= mMinY;
+
+  if (cx1 < 0) or (cy1 < 0) or (cx0 >= mWidth*mTileSize) or (cy0 >= mHeight*mTileSize) then exit;
+
+  if (cx0 < 0) then cx0 := 0;
+  if (cy0 < 0) then cy0 := 0;
+  if (cx1 >= mWidth*mTileSize) then cx1 := mWidth*mTileSize-1;
+  if (cy1 >= mHeight*mTileSize) then cy1 := mHeight*mTileSize-1;
+  // just in case
+  if (cx0 > cx1) or (cy0 > cy1) then exit;
+
+  // increase query counter
+  Inc(mLastQuery);
+  if (mLastQuery = 0) then
+  begin
+    // just in case of overflow
+    mLastQuery := 1;
+    for f := 0 to High(mProxies) do mProxies[f].mQueryMark := 0;
+  end;
+  lq := mLastQuery;
+
+  for gy := cy0 div mTileSize to cy1 div mTileSize do
+  begin
+    for gx := cx0 div mTileSize to cx1 div mTileSize do
+    begin
+      ccidx := mGrid[gy*mWidth+gx];
+      while (ccidx <> -1) do
+      begin
+        cc := @mCells[ccidx];
+        for f := 0 to GridCellBucketSize-1 do
+        begin
+          if (cc.bodies[f] = -1) then break;
+          px := @mProxies[cc.bodies[f]];
+          ptag := px.mTag;
+          if ((ptag and TagDisabled) = 0) and ((ptag and tagmask) <> 0) and (px.mQueryMark <> lq) then
+          begin
+            px.mQueryMark := lq; // mark as processed
+            if not sweepAABB(ax0, ay0, aw, ah, dx, dy, px.mX, px.mY, px.mWidth, px.mHeight, @u0) then continue;
+            if (minu0 > u0) then
+            begin
+              hitpx := px;
+              result := px.mObj;
+              minu0 := u0;
+              if (u0 = 0.0) then
+              begin
+                ex := ax0;
+                ey := ay0;
+                exit;
+              end;
+            end;
+          end;
+        end;
+        // next cell
+        ccidx := cc.next;
+      end;
+    end;
+  end;
+
+  if (minu0 <= 1.0) then
+  begin
+    ex := ax0+round(dx*minu0);
+    ey := ay0+round(dy*minu0);
+    // just in case, compensate for floating point inexactness
+    if (ex >= hitpx.mX) and (ey >= hitpx.mY) and (ex < hitpx.mX+hitpx.mWidth) and (ey < hitpx.mY+hitpx.mHeight) then
+    begin
+      ex := ax0+trunc(dx*minu0);
+      ey := ay0+trunc(dy*minu0);
+    end;
+  end;
 end;
 
 
-function TBodyGridBase.iterator (grida: Integer): Boolean;
+// ////////////////////////////////////////////////////////////////////////// //
+{.$DEFINE D2F_DEBUG_OTR}
+function TBodyGridBase.traceOrthoRayWhileIn (out ex, ey: Integer; ax0, ay0, ax1, ay1: Integer; tagmask: Integer=-1): Boolean;
 var
-  idx: Integer;
+  ccidx: Integer;
+  cc: PGridCell;
   px: PBodyProxyRec;
-  {$IFDEF grid_use_buckets}
-  pi: PGridCell;
-  f: Integer;
+  ptag: Integer;
+  minx, miny: Integer;
+  f, c0, c1: Integer;
+  x0, y0, x1, y1: Integer;
+  celly0, celly1: Integer;
+  dy: Integer;
+  filled: array[0..mTileSize-1] of Byte;
+  {$IF DEFINED(D2F_DEBUG_OTR)}
+  s: AnsiString = '';
   {$ENDIF}
+  it: Iter;
 begin
   result := false;
-  idx := mGrid[grida];
-  while (idx >= 0) do
+  ex := ax1;
+  ey := ay1;
+  if not ((ax0 = ax1) or (ay0 = ay1)) then raise Exception.Create('orthoray is not orthogonal');
+
+  tagmask := tagmask and TagFullMask;
+  if (tagmask = 0) then exit;
+
+  it := forEachAtPoint(ax0, ay0, tagmask, false, true);
+  if (it.length = 0) then begin it.release(); exit; end;
+  it.release();
+
+  minx := mMinX;
+  miny := mMinY;
+
+  // offset query coords to (0,0)-based
+  x0 := ax0-minx;
+  y0 := ay0-miny;
+  x1 := ax1-minx;
+  y1 := ay1-miny;
+
+  if (x0 = x1) then
   begin
-    {$IFDEF grid_use_buckets}
-    pi := @mCells[idx];
-    for f := 0 to High(TGridCell.bodies) do
+    if (x0 < 0) or (x0 >= mWidth*mTileSize) then exit; // oops
+    // vertical
+    if (y0 < y1) then
     begin
-      if (pi.bodies[f] = -1) then break;
-      px := @mProxies[pi.bodies[f]];
-      if (px.mQueryMark <> mLastQuery) and ((mTagMask = -1) or ((px.mTag and mTagMask) <> 0)) then
-      begin
-        //e_WriteLog(Format('  query #%d body hit: (%d,%d)-(%dx%d) tag:%d', [mLastQuery, mCells[idx].body.mX, mCells[idx].body.mY, mCells[idx].body.mWidth, mCells[idx].body.mHeight, mCells[idx].body.mTag]), MSG_NOTIFY);
-        px.mQueryMark := mLastQuery;
-        if (mItCB(px.mObj, px.mTag)) then begin result := true; exit; end;
-      end;
+      // down
+      if (y1 < 0) or (y0 >= mHeight*mTileSize) then exit;
+      //if (ay0 < 0) then ay0 := 0;
+      if (y0 < 0) then exit;
+      if (y1 >= mHeight*mTileSize) then y1 := mHeight*mTileSize-1;
+      dy := 1;
+    end
+    else
+    begin
+      // up
+      if (y0 < 0) or (y1 >= mHeight*mTileSize) then exit;
+      //if (ay1 < 0) then ay1 := 0;
+      if (y1 < 0) then exit;
+      if (y0 >= mHeight*mTileSize) then y0 := mHeight*mTileSize-1;
+      dy := -1;
     end;
-    idx := pi.next;
-    {$ELSE}
-    if (mCells[idx].body <> -1) then
+    // check tile
+    while true do
     begin
-      px := @mProxies[mCells[idx].body];
-      if (px.mQueryMark <> mLastQuery) and ((mTagMask = -1) or ((px.mTag and mTagMask) <> 0)) then
+      ccidx := mGrid[(y0 div mTileSize)*mWidth+(x0 div mTileSize)];
+      FillChar(filled, sizeof(filled), 0);
+      celly0 := y0 and (not (mTileSize-1));
+      celly1 := celly0+mTileSize-1;
+      while (ccidx <> -1) do
+      begin
+        cc := @mCells[ccidx];
+        for f := 0 to GridCellBucketSize-1 do
+        begin
+          if (cc.bodies[f] = -1) then break;
+          px := @mProxies[cc.bodies[f]];
+          ptag := px.mTag;
+          if ((ptag and TagDisabled) = 0) and ((ptag and tagmask) <> 0) and
+             (ax0 >= px.x0) and (ax0 <= px.x1) then
+          begin
+            // bound c0 and c1 to cell
+            c0 := nclamp(px.y0-miny, celly0, celly1);
+            c1 := nclamp(px.y1-miny, celly0, celly1);
+            // fill the thing
+            {$IF DEFINED(D2F_DEBUG_OTR)}
+            e_LogWritefln('**px.y0=%s; px.y1=%s; c0=%s; c1=%s; celly0=%s; celly1=%s; [%s..%s]', [px.y0-miny, px.y1-miny, c0, c1, celly0, celly1, c0-celly0, (c0-celly0)+(c1-c0)]);
+            {$ENDIF}
+            //assert(c0 <= c1);
+            FillChar(filled[c0-celly0], c1-c0+1, 1);
+          end;
+        end;
+        // next cell
+        ccidx := cc.next;
+      end;
+      {$IF DEFINED(D2F_DEBUG_OTR)}
+      s := formatstrf('  x=%s; ay0=%s; ay1=%s; y0=%s; celly0=%s; celly1=%s; dy=%s; [', [ax0, ay0, ay1, y0, celly0, celly1, dy]);
+      for f := 0 to High(filled) do if (filled[f] <> 0) then s += '1' else s += '0';
+      s += ']';
+      e_LogWriteln(s);
+      {$ENDIF}
+      // now go till we hit cell boundary or empty space
+      if (dy < 0) then
       begin
-        //e_WriteLog(Format('  query #%d body hit: (%d,%d)-(%dx%d) tag:%d', [mLastQuery, mCells[idx].body.mX, mCells[idx].body.mY, mCells[idx].body.mWidth, mCells[idx].body.mHeight, mCells[idx].body.mTag]), MSG_NOTIFY);
-        px.mQueryMark := mLastQuery;
-        if (mItCB(px.mObj, px.mTag)) then begin result := true; exit; end;
+        // up
+        while (y0 >= celly0) and (filled[y0-celly0] <> 0) do
+        begin
+          {$IF DEFINED(D2F_DEBUG_OTR)}
+          e_LogWritefln('   filled: cdy=%s; y0=%s; celly0=%s; ay0=%s; ay1=%s', [y0-celly0, y0, celly0, ay0, ay1]);
+          {$ENDIF}
+          Dec(y0);
+          Dec(ay0);
+        end;
+        {$IF DEFINED(D2F_DEBUG_OTR)}
+        e_LogWritefln('   span done: cdy=%s; y0=%s; celly0=%s; ay0=%s; ay1=%s', [y0-celly0, y0, celly0, ay0, ay1]);
+        {$ENDIF}
+        if (ay0 <= ay1) then begin ey := ay1; result := false; exit; end;
+        if (y0 >= celly0) then begin ey := ay0+1; {assert(forEachAtPoint(ex, ey, nil, tagmask) <> nil);} result := true; exit; end;
+      end
+      else
+      begin
+        // down
+        while (y0 <= celly1) and (filled[y0-celly0] <> 0) do begin Inc(y0); Inc(ay0); end;
+        if (ay0 >= ay1) then begin ey := ay1; result := false; exit; end;
+        if (y0 <= celly1) then begin ey := ay0-1; result := true; exit; end;
       end;
     end;
-    idx := mCells[idx].next;
-    {$ENDIF}
+  end
+  else
+  begin
+    // horizontal
+    assert(false);
   end;
 end;
 
-function TBodyGridBase.forEachInAABB (x, y, w, h: Integer; cb: TGridQueryCB; tagmask: Integer=-1): Boolean;
+
+// ////////////////////////////////////////////////////////////////////////// //
+function TBodyGridBase.traceRay (const x0, y0, x1, y1: Integer; tagmask: Integer=-1): ITP;
 var
-  idx: Integer;
-  otagmask: Integer;
-  ocb: TGridQueryCB;
+  ex, ey: Integer;
 begin
-  result := false;
-  if not assigned(cb) then exit;
+  result := traceRay(ex, ey, x0, y0, x1, y1, tagmask);
+end;
+
+
+// you are not supposed to understand this
+function TBodyGridBase.traceRay (out ex, ey: Integer; const ax0, ay0, ax1, ay1: Integer; tagmask: Integer=-1): ITP;
+var
+  lw: TLineWalker;
+  ccidx: Integer;
+  cc: PGridCell;
+  px: PBodyProxyRec;
+  lq: LongWord;
+  f, ptag: Integer;
+  gw, gh, minx, miny: Integer;
+  x0, y0: Integer;
+  x1, y1: Integer;
+  cx, cy: Integer;
+  px0, py0, px1, py1: Integer;
+  lastDistSq, distSq, hx, hy: Integer;
+  firstCell: Boolean = true;
+  wasHit: Boolean;
+begin
+  result := Default(ITP);
+  tagmask := tagmask and TagFullMask;
+  if (tagmask = 0) then exit;
+
+  gw := mWidth;
+  gh := mHeight;
+  minx := mMinX;
+  miny := mMinY;
+
+  // make query coords (0,0)-based
+  x0 := ax0-minx;
+  y0 := ay0-miny;
+  x1 := ax1-minx;
+  y1 := ay1-miny;
+
+  lw := TLineWalker.Create(0, 0, gw*mTileSize-1, gh*mTileSize-1);
+  if not lw.setup(x0, y0, x1, y1) then exit; // out of screen
+
+  lastDistSq := distanceSq(ax0, ay0, ax1, ay1)+1;
+
+  {$IF DEFINED(D2F_DEBUG)}
+  //if assigned(dbgRayTraceTileHitCB) then e_LogWritefln('*** traceRay: (%s,%s)-(%s,%s)', [x0, y0, x1, y1]);
+  {$ENDIF}
 
   // increase query counter
   Inc(mLastQuery);
@@ -540,17 +1879,78 @@ begin
   begin
     // just in case of overflow
     mLastQuery := 1;
-    for idx := 0 to High(mProxies) do mProxies[idx].mQueryMark := 0;
+    for f := 0 to High(mProxies) do mProxies[f].mQueryMark := 0;
   end;
-  //e_WriteLog(Format('grid: query #%d: (%d,%d)-(%dx%d)', [mLastQuery, minx, miny, maxx, maxy]), MSG_NOTIFY);
+  lq := mLastQuery;
 
-  otagmask := mTagMask;
-  mTagMask := tagmask;
-  ocb := mItCB;
-  mItCB := cb;
-  result := forGridRect(x, y, w, h, iterator);
-  mTagMask := otagmask;
-  mItCB := ocb;
+  repeat
+    lw.getXY(cx, cy);
+    {$IF DEFINED(D2F_DEBUG)}
+    if assigned(dbgRayTraceTileHitCB) then dbgRayTraceTileHitCB(cx+mMinX, cy+mMinY);
+    {$ENDIF}
+    // check tile
+    ccidx := mGrid[(cy div mTileSize)*gw+(cx div mTileSize)];
+    // process cells
+    wasHit := false;
+    while (ccidx <> -1) do
+    begin
+      cc := @mCells[ccidx];
+      for f := 0 to GridCellBucketSize-1 do
+      begin
+        if (cc.bodies[f] = -1) then break;
+        px := @mProxies[cc.bodies[f]];
+        ptag := px.mTag;
+        if ((ptag and TagDisabled) = 0) and ((ptag and tagmask) <> 0) and (px.mQueryMark <> lq) then
+        begin
+          px.mQueryMark := lq; // mark as processed
+          // get adjusted proxy coords
+          px0 := px.mX-minx;
+          py0 := px.mY-miny;
+          px1 := px0+px.mWidth-1;
+          py1 := py0+px.mHeight-1;
+          {$IF DEFINED(D2F_DEBUG)}
+          //if assigned(dbgRayTraceTileHitCB) then e_LogWritefln(' cxy=(%s,%s); pan=(%s,%s)-(%s,%s)', [cx, cy, px0, py0, px1, py1]);
+          {$ENDIF}
+          // inside?
+          if firstCell and (x0 >= px0) and (y0 >= py0) and (x0 <= px1) and (y0 <= py1) then
+          begin
+            // oops
+            ex := ax0;
+            ey := ay0;
+            result := px.mObj;
+            {$IF DEFINED(D2F_DEBUG)}
+            if assigned(dbgRayTraceTileHitCB) then e_LogWriteln('  INSIDE!');
+            {$ENDIF}
+            exit;
+          end;
+          // do line-vs-aabb test
+          if lineAABBIntersects(x0, y0, x1, y1, px0, py0, px1-px0+1, py1-py0+1, hx, hy) then
+          begin
+            // hit detected
+            distSq := distanceSq(x0, y0, hx, hy);
+            {$IF DEFINED(D2F_DEBUG)}
+            //if assigned(dbgRayTraceTileHitCB) then e_LogWritefln('  hit=(%s,%s); distSq=%s; lastDistSq=%s', [hx, hy, distSq, lastDistSq]);
+            {$ENDIF}
+            if (distSq < lastDistSq) then
+            begin
+              lastDistSq := distSq;
+              ex := hx+minx;
+              ey := hy+miny;
+              result := px.mObj;
+              wasHit := true;
+            end;
+          end;
+        end;
+      end;
+      // next cell
+      ccidx := cc.next;
+    end;
+    // done processing cells; exit if we registered a hit
+    // next cells can't have better candidates, obviously
+    if wasHit then exit;
+    firstCell := false;
+    // move to next tile
+  until lw.stepToNextTile();
 end;