X-Git-Url: http://deadsoftware.ru/gitweb?a=blobdiff_plain;f=src%2Fgame%2Fg_grid.pas;h=2afca2f3c16c0db534a6ec68cb4bb665c200e186;hb=cb39caa8b879b70aa096476a2e919d4a298f1fa5;hp=b4dca5eecf483d5255bbee3591398cd584e9fa7c;hpb=50912450ee87c328528a80f1f3992268cfdc341b;p=d2df-sdl.git

diff --git a/src/game/g_grid.pas b/src/game/g_grid.pas
index b4dca5e..2afca2f 100644
--- a/src/game/g_grid.pas
+++ b/src/game/g_grid.pas
@@ -15,6 +15,11 @@
  *)
 // universal spatial grid
 {$INCLUDE ../shared/a_modes.inc}
+{$IF DEFINED(D2F_DEBUG)}
+  {.$DEFINE D2F_DEBUG_RAYTRACE}
+  {.$DEFINE D2F_DEBUG_XXQ}
+  {.$DEFINE D2F_DEBUG_MOVER}
+{$ENDIF}
 unit g_grid;
 
 interface
@@ -27,13 +32,16 @@ type
   public
     type TGridQueryCB = function (obj: ITP; tag: Integer): Boolean is nested; // return `true` to stop
     type TGridRayQueryCB = function (obj: ITP; tag: Integer; x, y, prevx, prevy: Integer): Boolean is nested; // return `true` to stop
+    type TGridAlongQueryCB = function (obj: ITP; tag: Integer): Boolean is nested; // return `true` to stop
+
+    type TCellQueryCB = procedure (x, y: Integer) is nested; // top-left cell corner coords
 
     const TagDisabled = $40000000;
     const TagFullMask = $3fffffff;
 
   private
     const
-      GridDefaultTileSize = 32;
+      GridDefaultTileSize = 32; // must be power of two!
       GridCellBucketSize = 8; // WARNING! can't be less than 2!
 
   private
@@ -60,7 +68,13 @@ type
       TGridInternalCB = function (grida: Integer; bodyId: TBodyProxyId): Boolean of object; // return `true` to stop
 
   private
-    mTileSize: Integer;
+    //mTileSize: Integer;
+    const mTileSize = GridDefaultTileSize;
+
+  public
+    const tileSize = mTileSize;
+
+  private
     mMinX, mMinY: Integer; // so grids can start at any origin
     mWidth, mHeight: Integer; // in tiles
     mGrid: array of Integer; // mWidth*mHeight, index in mCells
@@ -73,8 +87,14 @@ type
     mProxyCount: Integer; // currently used
     mProxyMaxCount: Integer;
 
+  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;
@@ -91,19 +111,27 @@ type
     function getProxyEnabled (pid: TBodyProxyId): Boolean; inline;
     procedure setProxyEnabled (pid: TBodyProxyId; val: Boolean); inline;
 
+    function getGridWidthPx (): Integer; inline;
+    function getGridHeightPx (): Integer; 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=-1): TBodyProxyId;
-    procedure removeBody (aObj: TBodyProxyId); // WARNING! this WILL destroy proxy!
+    procedure removeBody (body: TBodyProxyId); // WARNING! this WILL destroy proxy!
 
-    procedure moveBody (body: TBodyProxyId; dx, dy: Integer);
-    procedure resizeBody (body: TBodyProxyId; sx, sy: Integer);
-    procedure moveResizeBody (body: TBodyProxyId; dx, dy, sx, sy: Integer);
+    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;
+
     //WARNING: don't modify grid while any query is in progress (no checks are made!)
     //         you can set enabled/disabled flag, tho (but iterator can still return objects disabled inside it)
     // no callback: return `true` on the first hit
@@ -111,29 +139,230 @@ type
 
     //WARNING: don't modify grid while any query is in progress (no checks are made!)
     //         you can set enabled/disabled flag, tho (but iterator can still return objects disabled inside it)
-    // no callback: return `true` on the first hit
-    function forEachAtPoint (x, y: Integer; cb: TGridQueryCB; tagmask: Integer=-1): ITP;
+    // no callback: return object on the first hit or nil
+    function forEachAtPoint (x, y: Integer; cb: TGridQueryCB; tagmask: Integer=-1; exittag: PInteger=nil): ITP;
 
     //WARNING: don't modify grid while any query is in progress (no checks are made!)
     //         you can set enabled/disabled flag, tho (but iterator can still return objects disabled inside it)
     // cb with `(nil)` will be called before processing new tile
-    // no callback: return `true` on the nearest hit
-    function traceRay (x0, y0, x1, y1: Integer; cb: TGridRayQueryCB; tagmask: Integer=-1): ITP; overload;
-    function traceRay (out ex, ey: Integer; x0, y0, x1, y1: Integer; cb: TGridRayQueryCB; tagmask: Integer=-1): ITP;
+    // no callback: return object of the nearest hit or nil
+    // if `inverted` is true, trace will register bodies *exluding* tagmask
+    //WARNING: don't change tags in callbacks here!
+    function traceRay (const x0, y0, x1, y1: Integer; cb: TGridRayQueryCB; tagmask: Integer=-1): ITP; overload;
+    function traceRay (out ex, ey: Integer; const ax0, ay0, ax1, ay1: Integer; cb: TGridRayQueryCB; tagmask: Integer=-1): ITP;
+
+    //function traceRayWhileIn (const x0, y0, x1, y1: Integer; tagmask: Integer=-1): ITP; overload;
+    //function traceRayWhileIn (out ex, ey: Integer; const ax0, ay0, ax1, ay1: Integer; tagmask: Integer=-1): ITP;
+
+    //WARNING: don't modify grid while any query is in progress (no checks are made!)
+    //         you can set enabled/disabled flag, tho (but iterator can still return objects disabled inside it)
+    // trace line along the grid, calling `cb` for all objects in passed cells, in no particular order
+    //WARNING: don't change tags in callbacks here!
+    function forEachAlongLine (const x0, y0, x1, y1: Integer; cb: TGridAlongQueryCB; tagmask: Integer=-1; log: Boolean=false): ITP;
 
+    // debug
+    procedure forEachBodyCell (body: TBodyProxyId; cb: TCellQueryCB);
+    function forEachInCell (x, y: Integer; cb: TGridQueryCB): ITP;
     procedure dumpStats ();
 
     //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
   end;
 
 
+// you are not supposed to understand this
+// returns `true` if there is an intersection, and enter coords
+// enter coords will be equal to (x0, y0) if starting point is inside the box
+// if result is `false`, `inx` and `iny` are undefined
+function lineAABBIntersects (x0, y0, x1, y1: Integer; bx, by, bw, bh: Integer; out inx, iny: Integer): Boolean;
+
+function distanceSq (x0, y0, x1, y1: Integer): Integer; inline;
+
+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;
 
 
+// ////////////////////////////////////////////////////////////////////////// //
+procedure swapInt (var a: Integer; var b: Integer); inline; var t: Integer; begin t := a; a := b; b := t; 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;
+
+function distanceSq (x0, y0, x1, y1: Integer): Integer; inline; begin result := (x1-x0)*(x1-x0)+(y1-y0)*(y1-y0); end;
+
+
+// ////////////////////////////////////////////////////////////////////////// //
+// you are not supposed to understand this
+// returns `true` if there is an intersection, and enter coords
+// enter coords will be equal to (x0, y0) if starting point is inside the box
+// if result is `false`, `inx` and `iny` are undefined
+function lineAABBIntersects (x0, y0, x1, y1: Integer; bx, by, bw, bh: Integer; out inx, iny: Integer): Boolean;
+var
+  wx0, wy0, wx1, wy1: Integer; // window coordinates
+  stx, sty: Integer; // "steps" for x and y axes
+  dsx, dsy: Integer; // "lengthes" for x and y axes
+  dx2, dy2: Integer; // "double lengthes" for x and y axes
+  xd, yd: Integer; // current coord
+  e: Integer; // "error" (as in bresenham algo)
+  rem: Integer;
+  //!term: Integer;
+  d0, d1: PInteger;
+  xfixed: Boolean;
+  temp: Integer;
+begin
+  result := false;
+  // why not
+  inx := x0;
+  iny := y0;
+  if (bw < 1) or (bh < 1) then exit; // impossible box
+
+  if (x0 = x1) and (y0 = y1) then
+  begin
+    // check this point
+    result := (x0 >= bx) and (y0 >= by) and (x0 < bx+bw) and (y0 < by+bh);
+    exit;
+  end;
+
+  // check if staring point is inside the box
+  if (x0 >= bx) and (y0 >= by) and (x0 < bx+bw) and (y0 < by+bh) then begin result := true; exit; end;
+
+  // clip rectange
+  wx0 := bx;
+  wy0 := by;
+  wx1 := bx+bw-1;
+  wy1 := by+bh-1;
+
+  // horizontal setup
+  if (x0 < x1) then
+  begin
+    // from left to right
+    if (x0 > wx1) or (x1 < wx0) then exit; // out of screen
+    stx := 1; // going right
+  end
+  else
+  begin
+    // from right to left
+    if (x1 > wx1) or (x0 < wx0) then exit; // out of screen
+    stx := -1; // going left
+    x0 := -x0;
+    x1 := -x1;
+    wx0 := -wx0;
+    wx1 := -wx1;
+    swapInt(wx0, wx1);
+  end;
+
+  // vertical setup
+  if (y0 < y1) then
+  begin
+    // from top to bottom
+    if (y0 > wy1) or (y1 < wy0) then exit; // out of screen
+    sty := 1; // going down
+  end
+  else
+  begin
+    // from bottom to top
+    if (y1 > wy1) or (y0 < wy0) then exit; // out of screen
+    sty := -1; // going up
+    y0 := -y0;
+    y1 := -y1;
+    wy0 := -wy0;
+    wy1 := -wy1;
+    swapInt(wy0, wy1);
+  end;
+
+  dsx := x1-x0;
+  dsy := y1-y0;
+
+  if (dsx < dsy) then
+  begin
+    d0 := @yd;
+    d1 := @xd;
+    swapInt(x0, y0);
+    swapInt(x1, y1);
+    swapInt(dsx, dsy);
+    swapInt(wx0, wy0);
+    swapInt(wx1, wy1);
+    swapInt(stx, sty);
+  end
+  else
+  begin
+    d0 := @xd;
+    d1 := @yd;
+  end;
+
+  dx2 := 2*dsx;
+  dy2 := 2*dsy;
+  xd := x0;
+  yd := y0;
+  e := 2*dsy-dsx;
+  //!term := x1;
+
+  xfixed := false;
+  if (y0 < wy0) then
+  begin
+    // clip at top
+    temp := dx2*(wy0-y0)-dsx;
+    xd += temp div dy2;
+    rem := temp mod dy2;
+    if (xd > wx1) then exit; // x is moved out of clipping rect, nothing to do
+    if (xd+1 >= wx0) then
+    begin
+      yd := wy0;
+      e -= rem+dsx;
+      if (rem > 0) then begin Inc(xd); e += dy2; end;
+      xfixed := true;
+    end;
+  end;
+
+  if (not xfixed) and (x0 < wx0) then
+  begin
+    // clip at left
+    temp := dy2*(wx0-x0);
+    yd += temp div dx2;
+    rem := temp mod dx2;
+    if (yd > wy1) or (yd = wy1) and (rem >= dsx) then exit;
+    xd := wx0;
+    e += rem;
+    if (rem >= dsx) then begin Inc(yd); e -= dx2; end;
+  end;
+
+  (*
+  if (y1 > wy1) then
+  begin
+    // clip at bottom
+    temp := dx2*(wy1-y0)+dsx;
+    term := x0+temp div dy2;
+    rem := temp mod dy2;
+    if (rem = 0) then Dec(term);
+  end;
+
+  if (term > wx1) then term := wx1; // clip at right
+
+  Inc(term); // draw last point
+  //if (term = xd) then exit; // this is the only point, get out of here
+  *)
+
+  if (sty = -1) then yd := -yd;
+  if (stx = -1) then begin xd := -xd; {!term := -term;} end;
+  //!dx2 -= dy2;
+
+  inx := d0^;
+  iny := d1^;
+  result := true;
+end;
+
+
 // ////////////////////////////////////////////////////////////////////////// //
 procedure TBodyGridBase.TBodyProxyRec.setup (aX, aY, aWidth, aHeight: Integer; aObj: ITP; aTag: Integer);
 begin
@@ -149,19 +378,25 @@ 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);
@@ -170,6 +405,7 @@ begin
   for idx := 0 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
@@ -196,6 +432,7 @@ begin
 end;
 
 
+// ////////////////////////////////////////////////////////////////////////// //
 procedure TBodyGridBase.dumpStats ();
 var
   idx, mcb, cidx, cnt: Integer;
@@ -216,6 +453,60 @@ begin
 end;
 
 
+procedure TBodyGridBase.forEachBodyCell (body: TBodyProxyId; cb: TCellQueryCB);
+var
+  g, f, cidx: Integer;
+  cc: PGridCell;
+begin
+  if (body < 0) or (body > High(mProxies)) or not assigned(cb) then exit;
+  for g := 0 to High(mGrid) do
+  begin
+    cidx := mGrid[g];
+    while (cidx <> -1) do
+    begin
+      cc := @mCells[cidx];
+      for f := 0 to GridCellBucketSize-1 do
+      begin
+        if (cc.bodies[f] = -1) then break;
+        if (cc.bodies[f] = body) then cb((g mod mWidth)*mTileSize+mMinX, (g div mWidth)*mTileSize+mMinY);
+      end;
+      // next cell
+      cidx := cc.next;
+    end;
+  end;
+end;
+
+
+function TBodyGridBase.forEachInCell (x, y: Integer; cb: TGridQueryCB): ITP;
+var
+  f, cidx: Integer;
+  cc: PGridCell;
+begin
+  result := Default(ITP);
+  if not assigned(cb) then exit;
+  Dec(x, mMinX);
+  Dec(y, mMinY);
+  if (x < 0) or (y < 0) or (x >= mWidth*mTileSize) or (y > mHeight*mTileSize) then exit;
+  cidx := mGrid[(y div mTileSize)*mWidth+(x div mTileSize)];
+  while (cidx <> -1) do
+  begin
+    cc := @mCells[cidx];
+    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;
+    end;
+    // next cell
+    cidx := cc.next;
+  end;
+end;
+
+
+// ////////////////////////////////////////////////////////////////////////// //
+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
   // fix coords
@@ -225,6 +516,58 @@ begin
 end;
 
 
+function TBodyGridBase.getBodyXY (body: TBodyProxyId; out rx, ry: Integer): Boolean; inline;
+begin
+  if (body >= 0) and (body < Length(mProxies)) then
+  begin
+    with mProxies[body] do begin rx := mX; ry := mY; end;
+    result := true;
+  end
+  else
+  begin
+    rx := 0;
+    ry := 0;
+    result := false;
+  end;
+end;
+
+
+function TBodyGridBase.getBodyWH (body: TBodyProxyId; out rw, rh: Integer): Boolean; inline;
+begin
+  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.getBodyDims (body: TBodyProxyId; out rx, ry, rw, rh: Integer): Boolean; inline;
+begin
+  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) then result := ((mProxies[pid].mTag and TagDisabled) = 0) else result := false;
@@ -247,9 +590,11 @@ begin
 end;
 
 
-function TBodyGridBase.allocCell: Integer;
+// ////////////////////////////////////////////////////////////////////////// //
+function TBodyGridBase.allocCell (): Integer;
 var
   idx: Integer;
+  pc: PGridCell;
 begin
   if (mFreeCell < 0) then
   begin
@@ -259,14 +604,15 @@ begin
     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;
-  mFreeCell := mCells[result].next;
-  mCells[result].next := -1;
-  mCells[result].bodies[0] := -1;
+  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;
@@ -276,15 +622,19 @@ procedure TBodyGridBase.freeCell (idx: Integer);
 begin
   if (idx >= 0) and (idx < Length(mCells)) then
   begin
-    //if mCells[idx].body = -1 then exit; // the thing that should not be
-    mCells[idx].bodies[0] := -1;
-    mCells[idx].next := mFreeCell;
+    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;
@@ -323,10 +673,13 @@ begin
 end;
 
 
+// ////////////////////////////////////////////////////////////////////////// //
 function TBodyGridBase.forGridRect (x, y, w, h: Integer; cb: TGridInternalCB; bodyId: TBodyProxyId): Boolean;
+const
+  tsize = mTileSize;
 var
   gx, gy: Integer;
-  gw, gh, tsize: Integer;
+  gw, gh: Integer;
 begin
   result := false;
   if (w < 1) or (h < 1) or not assigned(cb) then exit;
@@ -337,7 +690,7 @@ begin
   if (x+w <= 0) or (y+h <= 0) then exit;
   gw := mWidth;
   gh := mHeight;
-  tsize := mTileSize;
+  //tsize := mTileSize;
   if (x >= gw*tsize) or (y >= gh*tsize) then exit;
   for gy := y div tsize to (y+h-1) div tsize do
   begin
@@ -354,6 +707,7 @@ begin
 end;
 
 
+// ////////////////////////////////////////////////////////////////////////// //
 function TBodyGridBase.inserter (grida: Integer; bodyId: TBodyProxyId): Boolean;
 var
   cidx: Integer;
@@ -366,24 +720,49 @@ begin
   pc := mGrid[grida];
   if (pc <> -1) then
   begin
-    pi := @mCells[pc];
-    f := 0;
-    for f := 0 to High(TGridCell.bodies) do
+    {$IF DEFINED(D2F_DEBUG)}
+    cidx := pc;
+    while (cidx <> -1) do
+    begin
+      pi := @mCells[cidx];
+      for f := 0 to GridCellBucketSize-1 do
+      begin
+        if (pi.bodies[f] = -1) then break;
+        if (pi.bodies[f] = bodyId) then raise Exception.Create('trying to insert already inserted proxy');
+      end;
+      cidx := pi.next;
+    end;
+    {$ENDIF}
+    cidx := pc;
+    while (cidx <> -1) do
     begin
-      if (pi.bodies[f] = -1) then
+      pi := @mCells[cidx];
+      // check "has room" flag
+      if (pi.bodies[GridCellBucketSize-1] = -1) then
       begin
         // can add here
-        pi.bodies[f] := bodyId;
-        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)
+      cidx := 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] := bodyId;
-  mCells[cidx].bodies[1] := -1;
-  mCells[cidx].next := pc;
+  pi := @mCells[cidx];
+  pi.bodies[0] := bodyId;
+  pi.bodies[1] := -1;
+  pi.next := pc;
   mGrid[grida] := cidx;
 end;
 
@@ -397,23 +776,21 @@ begin
 end;
 
 
-// absolutely not tested
+// assume that we cannot have one object added to bucket twice
 function TBodyGridBase.remover (grida: Integer; bodyId: TBodyProxyId): Boolean;
 var
-  f: Integer;
-  pidx, idx, tmp: Integer;
+  f, c: Integer;
+  pidx, cidx: Integer;
   pc: PGridCell;
 begin
   result := false; // never stop
   // find and remove cell
-  pidx := -1;
-  idx := mGrid[grida];
-  while (idx >= 0) do
-  begin
-    tmp := mCells[idx].next;
-    pc := @mCells[idx];
-    f := 0;
-    while (f < High(TGridCell.bodies)) do
+  pidx := -1; // previous cell index
+  cidx := mGrid[grida]; // current cell index
+  while (cidx <> -1) do
+  begin
+    pc := @mCells[cidx];
+    for f := 0 to GridCellBucketSize-1 do
     begin
       if (pc.bodies[f] = bodyId) then
       begin
@@ -421,32 +798,25 @@ begin
         if (f = 0) and (pc.bodies[1] = -1) 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);
-        end
-        else
+          if (pidx = -1) then mGrid[grida] := pc.next else mCells[pidx].next := pc.next;
+          freeCell(cidx);
+          exit;
+        end;
+        // remove element from bucket
+        for c := f to GridCellBucketSize-2 do
         begin
-          // remove element from bucket
-          Inc(f);
-          while (f < High(TGridCell.bodies)) do
-          begin
-            pc.bodies[f-1] := pc.bodies[f];
-            if (pc.bodies[f] = -1) then break;
-            Inc(f);
-          end;
-          pc.bodies[High(TGridCell.bodies)] := -1; // just in case
+          pc.bodies[c] := pc.bodies[c+1];
+          if (pc.bodies[c] = -1) then break;
         end;
-        exit; // assume that we cannot have one object added to bucket twice
+        pc.bodies[GridCellBucketSize-1] := -1; // "has free room" flag
+        exit;
       end;
-      Inc(f);
     end;
-    pidx := idx;
-    idx := tmp;
+    pidx := cidx;
+    cidx := pc.next;
   end;
 end;
 
-// absolutely not tested
 procedure TBodyGridBase.removeInternal (body: TBodyProxyId);
 var
   px: PBodyProxyRec;
@@ -457,6 +827,7 @@ begin
 end;
 
 
+// ////////////////////////////////////////////////////////////////////////// //
 function TBodyGridBase.insertBody (aObj: ITP; aX, aY, aWidth, aHeight: Integer; aTag: Integer=-1): TBodyProxyId;
 begin
   aTag := aTag and TagFullMask;
@@ -465,43 +836,232 @@ begin
 end;
 
 
-procedure TBodyGridBase.removeBody (aObj: TBodyProxyId);
+procedure TBodyGridBase.removeBody (body: TBodyProxyId);
 begin
-  if (aObj < 0) or (aObj > High(mProxies)) then exit; // just in case
-  removeInternal(aObj);
-  freeProxy(aObj);
+  if (body < 0) or (body > High(mProxies)) then exit; // just in case
+  removeInternal(body);
+  freeProxy(body);
 end;
 
 
-procedure TBodyGridBase.moveResizeBody (body: TBodyProxyId; dx, dy, sx, sy: Integer);
+// ////////////////////////////////////////////////////////////////////////// //
+procedure TBodyGridBase.moveResizeBody (body: TBodyProxyId; nx, ny, nw, nh: Integer);
 var
   px: PBodyProxyRec;
+  x0, y0, w, h: Integer;
 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;
-  removeInternal(body);
   px := @mProxies[body];
-  Inc(px.mX, dx);
-  Inc(px.mY, dy);
-  Inc(px.mWidth, sx);
-  Inc(px.mHeight, sy);
-  insertInternal(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) div mTileSize <> (nx+nw) div mTileSize) or
+     ((y0+h) div mTileSize <> (ny+nh) div mTileSize) then
+  begin
+    removeInternal(body);
+    px.mX := nx+mMinX;
+    px.mY := ny+mMinY;
+    px.mWidth := nw;
+    px.mHeight := nh;
+    insertInternal(body);
+  end
+  else
+  begin
+    px.mX := nx+mMinX;
+    px.mY := ny+mMinY;
+    px.mWidth := nw;
+    px.mHeight := nh;
+  end;
 end;
 
-procedure TBodyGridBase.moveBody (body: TBodyProxyId; dx, dy: Integer);
+//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
-  moveResizeBody(body, dx, dy, 0, 0);
+  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 (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
+        if (gx < ngx0) or (gx > ngx1) then
+        begin
+          // 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
+          // heavy checks
+          for gy := ogy0 to ogy1 do
+          begin
+            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;
+        end;
+      end;
+    end;
+    // 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 (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}
+  end;
+  // update coordinates
+  px.mX := nx+mMinX;
+  px.mY := ny+mMinY;
 end;
 
-procedure TBodyGridBase.resizeBody (body: TBodyProxyId; sx, sy: Integer);
+procedure TBodyGridBase.resizeBody (body: TBodyProxyId; nw, nh: Integer);
+var
+  px: PBodyProxyRec;
+  x0, y0, w, h: Integer;
 begin
-  moveResizeBody(body, 0, 0, sx, sy);
+  if (body < 0) or (body > High(mProxies)) then exit; // just in case
+  // check if tile coords was changed
+  px := @mProxies[body];
+  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) div mTileSize <> (x0+nw) div mTileSize) or
+     ((y0+h) div mTileSize <> (y0+nh) div mTileSize) then
+  begin
+    // crossed tile boundary, do heavy work
+    removeInternal(body);
+    px.mWidth := nw;
+    px.mHeight := nh;
+    insertInternal(body);
+  end
+  else
+  begin
+    // nothing to do with the grid, just fix size
+    px.mWidth := nw;
+    px.mHeight := nh;
+  end;
 end;
 
 
 // ////////////////////////////////////////////////////////////////////////// //
 // no callback: return `true` on the first hit
-function TBodyGridBase.forEachAtPoint (x, y: Integer; cb: TGridQueryCB; tagmask: Integer=-1): ITP;
+function TBodyGridBase.forEachAtPoint (x, y: Integer; cb: TGridQueryCB; tagmask: Integer=-1; exittag: PInteger=nil): ITP;
 var
   f: Integer;
   idx, curci: Integer;
@@ -511,15 +1071,25 @@ var
   ptag: Integer;
 begin
   result := Default(ITP);
+  if (exittag <> nil) then exittag^ := 0;
   tagmask := tagmask and TagFullMask;
   if (tagmask = 0) then exit;
 
+  {$IF DEFINED(D2F_DEBUG_XXQ)}
+  if (assigned(cb)) then e_WriteLog(Format('0: grid pointquery: (%d,%d)', [x, y]), MSG_NOTIFY);
+  {$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 exit;
 
   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);
@@ -534,26 +1104,44 @@ begin
   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 High(TGridCell.bodies) do
+    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
+      {$IF DEFINED(D2F_DEBUG_XXQ)}
+      if (assigned(cb)) then e_WriteLog(Format('  proxy #%d; qm:%u; tag:%08x; tagflag:%d  %u', [cc.bodies[f], px.mQueryMark, px.mTag, (px.mTag and tagmask), LongWord(px.mObj)]), MSG_NOTIFY);
+      {$ENDIF}
+      // shit. has to do it this way, so i can change tag in callback
+      if (px.mQueryMark <> lq) then
       begin
-        if (x >= px.mX) and (y >= px.mY) and (x < px.mX+px.mWidth) and (y < px.mY+px.mHeight) then
+        px.mQueryMark := lq;
+        ptag := px.mTag;
+        if ((ptag and TagDisabled) = 0) and ((ptag and tagmask) <> 0) and
+           (x >= px.mX) and (y >= px.mY) and (x < px.mX+px.mWidth) and (y < px.mY+px.mHeight) then
         begin
-          px.mQueryMark := lq;
           if assigned(cb) then
           begin
-            if cb(px.mObj, ptag) then begin result := px.mObj; exit; end;
+            if cb(px.mObj, ptag) then
+            begin
+              result := px.mObj;
+              if (exittag <> nil) then exittag^ := ptag;
+              exit;
+            end;
           end
           else
           begin
             result := px.mObj;
+            if (exittag <> nil) then exittag^ := ptag;
             exit;
           end;
         end;
@@ -564,8 +1152,11 @@ begin
 end;
 
 
+// ////////////////////////////////////////////////////////////////////////// //
 // no callback: return `true` on the first hit
 function TBodyGridBase.forEachInAABB (x, y, w, h: Integer; cb: TGridQueryCB; tagmask: Integer=-1; allowDisabled: Boolean=false): ITP;
+const
+  tsize = mTileSize;
 var
   idx: Integer;
   gx, gy: Integer;
@@ -574,7 +1165,7 @@ var
   cc: PGridCell = nil;
   px: PBodyProxyRec;
   lq: LongWord;
-  tsize, gw: Integer;
+  gw: Integer;
   x0, y0: Integer;
   ptag: Integer;
 begin
@@ -591,7 +1182,7 @@ begin
   Dec(y, mMinY);
 
   gw := mWidth;
-  tsize := mTileSize;
+  //tsize := mTileSize;
 
   if (x+w <= 0) or (y+h <= 0) then exit;
   if (x >= gw*tsize) or (y >= mHeight*tsize) then exit;
@@ -621,28 +1212,26 @@ begin
       while (curci <> -1) do
       begin
         cc := @mCells[curci];
-        for f := 0 to High(TGridCell.bodies) do
+        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) and (px.mQueryMark <> lq) then
-          //if ((ptag and TagDisabled) = 0) and ((ptag and tagmask) <> 0) and (px.mQueryMark <> lq) then
-          //if ( ((ptag and TagDisabled) = 0) = ignoreDisabled) and ((ptag and tagmask) <> 0) and (px.mQueryMark <> lq) then
+          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;
+          if assigned(cb) then
           begin
-            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;
-            px.mQueryMark := lq;
-            if assigned(cb) then
-            begin
-              if cb(px.mObj, ptag) then begin result := px.mObj; exit; end;
-            end
-            else
-            begin
-              result := px.mObj;
-              exit;
-            end;
+            if cb(px.mObj, ptag) then begin result := px.mObj; exit; end;
+          end
+          else
+          begin
+            result := px.mObj;
+            exit;
           end;
         end;
         curci := cc.next;
@@ -654,7 +1243,7 @@ end;
 
 // ////////////////////////////////////////////////////////////////////////// //
 // no callback: return `true` on the nearest hit
-function TBodyGridBase.traceRay (x0, y0, x1, y1: Integer; cb: TGridRayQueryCB; tagmask: Integer=-1): ITP;
+function TBodyGridBase.traceRay (const x0, y0, x1, y1: Integer; cb: TGridRayQueryCB; tagmask: Integer=-1): ITP;
 var
   ex, ey: Integer;
 begin
@@ -663,47 +1252,449 @@ end;
 
 
 // no callback: return `true` on the nearest hit
-function TBodyGridBase.traceRay (out ex, ey: Integer; x0, y0, x1, y1: Integer; cb: TGridRayQueryCB; tagmask: Integer=-1): ITP;
+// you are not supposed to understand this
+function TBodyGridBase.traceRay (out ex, ey: Integer; const ax0, ay0, ax1, ay1: Integer; cb: TGridRayQueryCB; tagmask: Integer=-1): ITP;
+const
+  tsize = mTileSize;
 var
-  i: Integer;
-  dx, dy, d: Integer;
-  xerr, yerr: Integer;
-  incx, incy: Integer;
-  stepx, stepy: Integer;
-  x, y: Integer;
-  maxx, maxy: Integer;
-  tsize: Integer; // tile size
-  gw, gh: Integer;
-  ccidx: Integer;
-  curci: Integer;
-  cc: PGridCell;
+  wx0, wy0, wx1, wy1: Integer; // window coordinates
+  stx, sty: Integer; // "steps" for x and y axes
+  dsx, dsy: Integer; // "lengthes" for x and y axes
+  dx2, dy2: Integer; // "double lengthes" for x and y axes
+  xd, yd: Integer; // current coord
+  e: Integer; // "error" (as in bresenham algo)
+  rem: Integer;
+  term: Integer;
+  xptr, yptr: PInteger;
+  xfixed: Boolean;
+  temp: Integer;
+  prevx, prevy: Integer;
+  lastDistSq: Integer;
+  ccidx, curci: Integer;
   hasUntried: Boolean;
+  lastGA: Integer = -1;
+  ga, x, y: Integer;
+  lastObj: ITP;
+  wasHit: Boolean = false;
+  gw, gh, minx, miny, maxx, maxy: Integer;
+  cc: PGridCell;
   px: PBodyProxyRec;
   lq: LongWord;
-  prevX, prevY: Integer;
-  minx, miny: Integer;
-  ptag: Integer;
-  lastDistSq, distSq: Integer;
-  wasHit: Boolean = false;
-  lastObj: ITP;
-  lastWasInGrid: Boolean;
-  tbcross: Boolean;
-  f: Integer;
+  f, ptag, distSq: Integer;
+  x0, y0, x1, y1: Integer;
 begin
   result := Default(ITP);
   lastObj := Default(ITP);
   tagmask := tagmask and TagFullMask;
-  if (tagmask = 0) then begin ex := x0; ey := y0; exit; end;
+  ex := ax1; // why not?
+  ey := ay1; // why not?
+  if (tagmask = 0) then exit;
 
-  minx := mMinX;
-  miny := mMinY;
+  if (ax0 = ax1) and (ay0 = ay1) then
+  begin
+    result := forEachAtPoint(ax0, ay0, nil, tagmask, @ptag);
+    if (result <> nil) then
+    begin
+      if assigned(cb) and not cb(result, ptag, ax0, ay0, ax0, ay0) then result := Default(ITP);
+    end;
+    exit;
+  end;
 
-  dx := x1-x0;
-  dy := y1-y0;
+  lastDistSq := distanceSq(ax0, ay0, ax1, ay1)+1;
+
+  gw := mWidth;
+  gh := mHeight;
+  minx := mMinX;
+  miny := mMinY;
+  maxx := gw*tsize-1;
+  maxy := gh*tsize-1;
+
+  {$IF DEFINED(D2F_DEBUG_RAYTRACE)}
+  if assigned(dbgRayTraceTileHitCB) then e_WriteLog(Format('TRACING: (%d,%d)-(%d,%d) [(%d,%d)-(%d,%d)]; maxdistsq=%d', [ax0, ay0, ax1, ay1, minx, miny, maxx, maxy, lastDistSq]), MSG_NOTIFY);
+  {$ENDIF}
+
+  x0 := ax0;
+  y0 := ay0;
+  x1 := ax1;
+  y1 := ay1;
+
+  // offset query coords to (0,0)-based
+  Dec(x0, minx);
+  Dec(y0, miny);
+  Dec(x1, minx);
+  Dec(y1, miny);
+
+  // clip rectange
+  wx0 := 0;
+  wy0 := 0;
+  wx1 := maxx;
+  wy1 := maxy;
+
+  // horizontal setup
+  if (x0 < x1) then
+  begin
+    // from left to right
+    if (x0 > wx1) or (x1 < wx0) then exit; // out of screen
+    stx := 1; // going right
+  end
+  else
+  begin
+    // from right to left
+    if (x1 > wx1) or (x0 < wx0) then exit; // out of screen
+    stx := -1; // going left
+    x0 := -x0;
+    x1 := -x1;
+    wx0 := -wx0;
+    wx1 := -wx1;
+    swapInt(wx0, wx1);
+  end;
+
+  // vertical setup
+  if (y0 < y1) then
+  begin
+    // from top to bottom
+    if (y0 > wy1) or (y1 < wy0) then exit; // out of screen
+    sty := 1; // going down
+  end
+  else
+  begin
+    // from bottom to top
+    if (y1 > wy1) or (y0 < wy0) then exit; // out of screen
+    sty := -1; // going up
+    y0 := -y0;
+    y1 := -y1;
+    wy0 := -wy0;
+    wy1 := -wy1;
+    swapInt(wy0, wy1);
+  end;
+
+  dsx := x1-x0;
+  dsy := y1-y0;
+
+  if (dsx < dsy) then
+  begin
+    xptr := @yd;
+    yptr := @xd;
+    swapInt(x0, y0);
+    swapInt(x1, y1);
+    swapInt(dsx, dsy);
+    swapInt(wx0, wy0);
+    swapInt(wx1, wy1);
+    swapInt(stx, sty);
+  end
+  else
+  begin
+    xptr := @xd;
+    yptr := @yd;
+  end;
+
+  dx2 := 2*dsx;
+  dy2 := 2*dsy;
+  xd := x0;
+  yd := y0;
+  e := 2*dsy-dsx;
+  term := x1;
+
+  xfixed := false;
+  if (y0 < wy0) then
+  begin
+    // clip at top
+    temp := dx2*(wy0-y0)-dsx;
+    xd += temp div dy2;
+    rem := temp mod dy2;
+    if (xd > wx1) then exit; // x is moved out of clipping rect, nothing to do
+    if (xd+1 >= wx0) then
+    begin
+      yd := wy0;
+      e -= rem+dsx;
+      if (rem > 0) then begin Inc(xd); e += dy2; end;
+      xfixed := true;
+    end;
+  end;
+
+  if (not xfixed) and (x0 < wx0) then
+  begin
+    // clip at left
+    temp := dy2*(wx0-x0);
+    yd += temp div dx2;
+    rem := temp mod dx2;
+    if (yd > wy1) or (yd = wy1) and (rem >= dsx) then exit;
+    xd := wx0;
+    e += rem;
+    if (rem >= dsx) then begin Inc(yd); e -= dx2; end;
+  end;
+
+  if (y1 > wy1) then
+  begin
+    // clip at bottom
+    temp := dx2*(wy1-y0)+dsx;
+    term := x0+temp div dy2;
+    rem := temp mod dy2;
+    if (rem = 0) then Dec(term);
+  end;
+
+  if (term > wx1) then term := wx1; // clip at right
+
+  Inc(term); // draw last point
+  //if (term = xd) then exit; // this is the only point, get out of here
+
+  if (sty = -1) then yd := -yd;
+  if (stx = -1) then begin xd := -xd; term := -term; end;
+  dx2 -= dy2;
+
+  // first move, to skip starting point
+  // DON'T DO THIS! loop will take care of that
+  if (xd = term) then
+  begin
+    result := forEachAtPoint(ax0, ay0, nil, tagmask, @ptag);
+    if (result <> nil) then
+    begin
+      if assigned(cb) then
+      begin
+        if cb(result, ptag, ax0, ay0, ax0, ay0) then
+        begin
+          ex := ax0;
+          ey := ay0;
+        end
+        else
+        begin
+          result := nil;
+        end;
+      end
+      else
+      begin
+        ex := ax0;
+        ey := ay0;
+      end;
+    end;
+    exit;
+  end;
+
+  prevx := xptr^+minx;
+  prevy := yptr^+miny;
+  (*
+  // move coords
+  if (e >= 0) then begin yd += sty; e -= dx2; end else e += dy2;
+  xd += stx;
+  // done?
+  if (xd = term) then exit;
+  *)
+
+  {$IF DEFINED(D2F_DEBUG)}
+  if (xptr^ < 0) or (yptr^ < 0) or (xptr^ >= gw*tsize) and (yptr^ >= gh*tsize) then raise Exception.Create('raycaster internal error (0)');
+  {$ENDIF}
+  // DON'T DO THIS! loop will take care of that
+  //lastGA := (yptr^ div tsize)*gw+(xptr^ div tsize);
+  //ccidx := mGrid[lastGA];
+
+  {$IF DEFINED(D2F_DEBUG_RAYTRACE)}
+  //if assigned(dbgRayTraceTileHitCB) then e_WriteLog('1:TRACING!', MSG_NOTIFY);
+  {$ENDIF}
+
+  {$IF DEFINED(D2F_DEBUG_RAYTRACE)}
+  if assigned(dbgRayTraceTileHitCB) then dbgRayTraceTileHitCB((xptr^ div tsize*tsize)+minx, (yptr^ div tsize*tsize)+miny);
+  {$ENDIF}
+
+  //if (dbgShowTraceLog) then e_WriteLog(Format('raycast start: (%d,%d)-(%d,%d); xptr^=%d; yptr^=%d', [ax0, ay0, ax1, ay1, xptr^, yptr^]), MSG_NOTIFY);
+
+  // 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;
+
+  ccidx := -1;
+  // draw it; can omit checks
+  while (xd <> term) do
+  begin
+    // check cell(s)
+    {$IF DEFINED(D2F_DEBUG)}
+    if (xptr^ < 0) or (yptr^ < 0) or (xptr^ >= gw*tsize) and (yptr^ >= gh*tsize) then raise Exception.Create('raycaster internal error (0)');
+    {$ENDIF}
+    // new tile?
+    ga := (yptr^ div tsize)*gw+(xptr^ div tsize);
+    {$IF DEFINED(D2F_DEBUG_RAYTRACE)}
+    if assigned(dbgRayTraceTileHitCB) then e_WriteLog(Format(' xd=%d; term=%d; gx=%d; gy=%d; ga=%d; lastga=%d', [xd, term, xptr^, yptr^, ga, lastGA]), MSG_NOTIFY);
+    {$ENDIF}
+    if (ga <> lastGA) then
+    begin
+      // yes
+      {$IF DEFINED(D2F_DEBUG)}
+      if assigned(dbgRayTraceTileHitCB) then dbgRayTraceTileHitCB((xptr^ div tsize*tsize)+minx, (yptr^ div tsize*tsize)+miny);
+      {$ENDIF}
+      if (ccidx <> -1) then
+      begin
+        // signal cell completion
+        if assigned(cb) then
+        begin
+          if cb(nil, 0, xptr^+minx, yptr^+miny, prevx, prevy) then begin result := lastObj; exit; end;
+        end
+        else if wasHit then
+        begin
+          result := lastObj;
+          exit;
+        end;
+      end;
+      lastGA := ga;
+      ccidx := mGrid[lastGA];
+    end;
+    // has something to process in this tile?
+    if (ccidx <> -1) then
+    begin
+      // process cell
+      curci := ccidx;
+      hasUntried := false; // this will be set to `true` if we have some proxies we still want to process at the next step
+      // convert coords to map (to avoid ajdusting coords inside the loop)
+      x := xptr^+minx;
+      y := yptr^+miny;
+      // process cell list
+      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]];
+          ptag := px.mTag;
+          if ((ptag and TagDisabled) = 0) and ((ptag and tagmask) <> 0) and (px.mQueryMark <> lq) then
+          begin
+            // can we process this proxy?
+            if (x >= px.mX) and (y >= px.mY) and (x < px.mX+px.mWidth) and (y < px.mY+px.mHeight) then
+            begin
+              px.mQueryMark := lq; // mark as processed
+              if assigned(cb) then
+              begin
+                if cb(px.mObj, ptag, x, y, prevx, prevy) then
+                begin
+                  result := lastObj;
+                  ex := prevx;
+                  ey := prevy;
+                  exit;
+                end;
+                (*
+                  {$IF DEFINED(D2F_DEBUG_RAYTRACE)}
+                  distSq := distanceSq(ax0, ay0, prevx, prevy);
+                  if assigned(dbgRayTraceTileHitCB) then e_WriteLog(Format('  hit(%d): a=(%d,%d), h=(%d,%d), p=(%d,%d); distsq=%d; lastsq=%d', [cc.bodies[f], ax0, ay0, x, y, prevx, prevy, distSq, lastDistSq]), MSG_NOTIFY);
+                  if (distSq < lastDistSq) then
+                  begin
+                    wasHit := true;
+                    lastDistSq := distSq;
+                    ex := prevx;
+                    ey := prevy;
+                    lastObj := px.mObj;
+                  end;
+                  {$ENDIF}
+                *)
+              end
+              else
+              begin
+                // remember this hitpoint if it is nearer than an old one
+                distSq := distanceSq(ax0, ay0, prevx, prevy);
+                {$IF DEFINED(D2F_DEBUG_RAYTRACE)}
+                if assigned(dbgRayTraceTileHitCB) then e_WriteLog(Format('  hit(%d): a=(%d,%d), h=(%d,%d), p=(%d,%d); distsq=%d; lastsq=%d', [cc.bodies[f], ax0, ay0, x, y, prevx, prevy, distSq, lastDistSq]), MSG_NOTIFY);
+                {$ENDIF}
+                if (distSq < lastDistSq) then
+                begin
+                  wasHit := true;
+                  lastDistSq := distSq;
+                  ex := prevx;
+                  ey := prevy;
+                  lastObj := px.mObj;
+                end;
+              end;
+            end
+            else
+            begin
+              // this is possibly interesting proxy, set "has more to check" flag
+              hasUntried := true;
+            end;
+          end;
+        end;
+        // next cell
+        curci := cc.next;
+      end;
+      // still has something interesting in this cell?
+      if not hasUntried then
+      begin
+        // nope, don't process this cell anymore; signal cell completion
+        ccidx := -1;
+        if assigned(cb) then
+        begin
+          if cb(nil, 0, x, y, prevx, prevy) then begin result := lastObj; exit; end;
+        end
+        else if wasHit then
+        begin
+          result := lastObj;
+          exit;
+        end;
+      end;
+    end;
+    //putPixel(xptr^, yptr^);
+    // move coords
+    prevx := xptr^+minx;
+    prevy := yptr^+miny;
+    if (e >= 0) then begin yd += sty; e -= dx2; end else e += dy2;
+    xd += stx;
+  end;
+  // we can travel less than one cell
+  if wasHit and not assigned(cb) then
+  begin
+    result := lastObj;
+  end
+  else
+  begin
+    ex := ax1; // why not?
+    ey := ay1; // why not?
+  end;
+end;
+
+
+// ////////////////////////////////////////////////////////////////////////// //
+//FIXME! optimize this with real tile walking
+function TBodyGridBase.forEachAlongLine (const x0, y0, x1, y1: Integer; cb: TGridAlongQueryCB; tagmask: Integer=-1; log: Boolean=false): ITP;
+const
+  tsize = mTileSize;
+var
+  i: Integer;
+  dx, dy, d: Integer;
+  xerr, yerr: Integer;
+  incx, incy: Integer;
+  stepx, stepy: Integer;
+  x, y: Integer;
+  maxx, maxy: Integer;
+  gw, gh: Integer;
+  ccidx: Integer;
+  curci: Integer;
+  cc: PGridCell;
+  px: PBodyProxyRec;
+  lq: LongWord;
+  minx, miny: Integer;
+  ptag: Integer;
+  lastWasInGrid: Boolean;
+  tbcross: Boolean;
+  f: Integer;
+  //tedist: Integer;
+begin
+  log := false;
+  result := Default(ITP);
+  tagmask := tagmask and TagFullMask;
+  if (tagmask = 0) or not assigned(cb) then exit;
+
+  minx := mMinX;
+  miny := mMinY;
+
+  dx := x1-x0;
+  dy := y1-y0;
 
   if (dx > 0) then incx := 1 else if (dx < 0) then incx := -1 else incx := 0;
   if (dy > 0) then incy := 1 else if (dy < 0) then incy := -1 else incy := 0;
 
+  if (incx = 0) and (incy = 0) then exit; // just incase
+
   dx := abs(dx);
   dy := abs(dy);
 
@@ -724,14 +1715,13 @@ begin
   lq := mLastQuery;
 
   // cache various things
-  tsize := mTileSize;
+  //tsize := mTileSize;
   gw := mWidth;
   gh := mHeight;
   maxx := gw*tsize-1;
   maxy := gh*tsize-1;
 
   // setup distance and flags
-  lastDistSq := (x1-x0)*(x1-x0)+(y1-y0)*(y1-y0)+1;
   lastWasInGrid := (x >= 0) and (y >= 0) and (x <= maxx) and (y <= maxy);
 
   // setup starting tile ('cause we'll adjust tile vars only on tile edge crossing)
@@ -741,21 +1731,26 @@ begin
   xerr := -d;
   yerr := -d;
 
+  if (log) then e_WriteLog(Format('tracing: (%d,%d)-(%d,%d)', [x, y, x1-minx, y1-miny]), MSG_NOTIFY);
+
   // now trace
-  for i := 1 to d do
+  i := 0;
+  while (i < d) do
   begin
-    // prevs are always in map coords
-    prevX := x+minx;
-    prevY := y+miny;
+    Inc(i);
     // do one step
     xerr += dx;
     yerr += dy;
     // invariant: one of those always changed
+    {$IF DEFINED(D2F_DEBUG)}
     if (xerr < 0) and (yerr < 0) then raise Exception.Create('internal bug in grid raycaster (0)');
+    {$ENDIF}
     if (xerr >= 0) then begin xerr -= d; x += incx; stepx := incx; end else stepx := 0;
     if (yerr >= 0) then begin yerr -= d; y += incy; stepy := incy; end else stepy := 0;
     // invariant: we always doing a step
+    {$IF DEFINED(D2F_DEBUG)}
     if ((stepx or stepy) = 0) then raise Exception.Create('internal bug in grid raycaster (1)');
+    {$ENDIF}
     begin
       // check for crossing tile/grid boundary
       if (x >= 0) and (y >= 0) and (x <= maxx) and (y <= maxy) then
@@ -771,97 +1766,385 @@ begin
         // crossed tile edge?
         if tbcross then
         begin
-          // had something in the cell we're leaving?
-          if (ccidx <> -1) then
+          // setup new cell index
+          ccidx := mGrid[(y div tsize)*gw+(x div tsize)];
+          if (log) then e_WriteLog(Format(' stepped to new tile (%d,%d) -- (%d,%d)', [(x div tsize), (y div tsize), x, y]), MSG_NOTIFY);
+        end
+        else
+        if (ccidx = -1) then
+        begin
+          // we have nothing interesting here anymore, jump directly to tile edge
+          (*
+          if (incx = 0) then
           begin
-            // yes, signal cell completion
-            if assigned(cb) then
+            // vertical line
+            if (incy < 0) then tedist := y-(y and (not tsize)) else tedist := (y or (tsize-1))-y;
+            if (tedist > 1) then
             begin
-              if cb(nil, 0, x+minx, y+miny, prevX, prevY) then begin result := lastObj; exit; end;
-            end
-            else if wasHit then
+              if (log) then e_WriteLog(Format('  doing vertical jump from tile (%d,%d) - (%d,%d) by %d steps', [(x div tsize), (y div tsize), x, y, tedist]), MSG_NOTIFY);
+              y += incy*tedist;
+              Inc(i, tedist);
+              if (log) then e_WriteLog(Format('   jumped to tile (%d,%d) - (%d,%d) by %d steps', [(x div tsize), (y div tsize), x, y, tedist]), MSG_NOTIFY);
+            end;
+          end
+          else if (incy = 0) then
+          begin
+            // horizontal line
+            if (incx < 0) then tedist := x-(x and (not tsize)) else tedist := (x or (tsize-1))-x;
+            if (tedist > 1) then
             begin
-              result := lastObj;
-              exit;
+              if (log) then e_WriteLog(Format('  doing horizontal jump from tile (%d,%d) - (%d,%d) by %d steps', [(x div tsize), (y div tsize), x, y, tedist]), MSG_NOTIFY);
+              x += incx*tedist;
+              Inc(i, tedist);
+              if (log) then e_WriteLog(Format('   jumped to tile (%d,%d) - (%d,%d) by %d steps', [(x div tsize), (y div tsize), x, y, tedist]), MSG_NOTIFY);
             end;
           end;
-          // setup new cell index
-          ccidx := mGrid[(y div tsize)*gw+(x div tsize)];
+          *)
+          (*
+           else if (
+          // get minimal distance to tile edges
+          if (incx < 0) then tedist := x-(x and (not tsize)) else if (incx > 0) then tedist := (x or (tsize+1))-x else tedist := 0;
+          {$IF DEFINED(D2F_DEBUG)}
+          if (tedist < 0) then raise Exception.Create('internal bug in grid raycaster (2.x)');
+          {$ENDIF}
+          if (incy < 0) then f := y-(y and (not tsize)) else if (incy > 0) then f := (y or (tsize+1))-y else f := 0;
+          {$IF DEFINED(D2F_DEBUG)}
+          if (f < 0) then raise Exception.Create('internal bug in grid raycaster (2.y)');
+          {$ENDIF}
+          if (tedist = 0) then tedist := f else if (f <> 0) then tedist := minInt(tedist, f);
+          // do jump
+          if (tedist > 1) then
+          begin
+            if (log) then e_WriteLog(Format('  doing jump from tile (%d,%d) - (%d,%d) by %d steps', [(x div tsize), (y div tsize), x, y, tedist]), MSG_NOTIFY);
+            xerr += dx*tedist;
+            yerr += dy*tedist;
+            if (xerr >= 0) then begin x += incx*((xerr div d)+1); xerr := (xerr mod d)-d; end;
+            if (yerr >= 0) then begin y += incy*((yerr div d)+1); yerr := (yerr mod d)-d; end;
+            Inc(i, tedist);
+            if (log) then e_WriteLog(Format('   jumped to tile (%d,%d) - (%d,%d) by %d steps', [(x div tsize), (y div tsize), x, y, tedist]), MSG_NOTIFY);
+          end;
+          *)
         end;
       end
       else
       begin
-        // out of grid, had something in the last processed cell?
-        if (ccidx <> -1) then
+        // out of grid
+        if lastWasInGrid then exit; // oops, stepped out of the grid -- there is no way to return
+      end;
+    end;
+
+    // has something to process in the current cell?
+    if (ccidx <> -1) then
+    begin
+      // process cell
+      curci := ccidx;
+      // convert coords to map (to avoid ajdusting coords inside the loop)
+      //Inc(x, minx);
+      //Inc(y, miny);
+      // process cell list
+      while (curci <> -1) do
+      begin
+        cc := @mCells[curci];
+        for f := 0 to GridCellBucketSize-1 do
         begin
-          // yes, signal cell completion
-          ccidx := -1;
-          if assigned(cb) then
-          begin
-            if cb(nil, 0, x+minx, y+miny, prevX, prevY) then begin result := lastObj; exit; end;
-          end
-          else if wasHit then
+          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
-            result := lastObj;
-            exit;
+            px.mQueryMark := lq; // mark as processed
+            if cb(px.mObj, ptag) then begin result := px.mObj; exit; end;
           end;
         end;
-        if lastWasInGrid then exit; // oops, stepped out of the grid -- there is no way to return
+        // next cell
+        curci := cc.next;
       end;
+      ccidx := -1; // don't process this anymore
+      // convert coords to grid
+      //Dec(x, minx);
+      //Dec(y, miny);
     end;
+  end;
+end;
 
-    // has something to process in the current cell?
+
+// ////////////////////////////////////////////////////////////////////////// //
+(*
+function TBodyGridBase.traceRayWhileIn (const x0, y0, x1, y1: Integer; tagmask: Integer=-1): ITP; overload;
+var
+  ex, ey: Integer;
+begin
+  result := traceRayWhileIn(ex, ey, x0, y0, x1, y1, tagmask);
+end;
+
+
+// FUCKIN' PASTA!
+function TBodyGridBase.traceRayWhileIn (out ex, ey: Integer; const ax0, ay0, ax1, ay1: Integer; tagmask: Integer=-1): ITP;
+const
+  tsize = mTileSize;
+var
+  wx0, wy0, wx1, wy1: Integer; // window coordinates
+  stx, sty: Integer; // "steps" for x and y axes
+  dsx, dsy: Integer; // "lengthes" for x and y axes
+  dx2, dy2: Integer; // "double lengthes" for x and y axes
+  xd, yd: Integer; // current coord
+  e: Integer; // "error" (as in bresenham algo)
+  rem: Integer;
+  term: Integer;
+  xptr, yptr: PInteger;
+  xfixed: Boolean;
+  temp: Integer;
+  prevx, prevy: Integer;
+  lastDistSq: Integer;
+  ccidx, curci: Integer;
+  hasUntried: Boolean;
+  lastGA: Integer = -1;
+  ga, x, y: Integer;
+  lastObj: ITP;
+  wasHit: Boolean = false;
+  gw, gh, minx, miny, maxx, maxy: Integer;
+  cc: PGridCell;
+  px: PBodyProxyRec;
+  lq: LongWord;
+  f, ptag, distSq: Integer;
+  x0, y0, x1, y1: Integer;
+  inx, iny: Integer;
+begin
+  result := Default(ITP);
+  lastObj := Default(ITP);
+  tagmask := tagmask and TagFullMask;
+  ex := ax1; // why not?
+  ey := ay1; // why not?
+  if (tagmask = 0) then exit;
+
+  if (ax0 = ax1) and (ay0 = ay1) then exit; // doesn't matter
+
+  // we should start inside
+  if (forEachAtPoint(ax0, ay0, nil, tagmask, @ptag) = nil) then
+  begin
+    ex := ax0; // why not?
+    ey := ay0; // why not?
+    exit;
+  end;
+
+  lastDistSq := distanceSq(ax0, ay0, ax1, ay1)+1;
+
+  gw := mWidth;
+  gh := mHeight;
+  minx := mMinX;
+  miny := mMinY;
+  maxx := gw*tsize-1;
+  maxy := gh*tsize-1;
+
+  x0 := ax0;
+  y0 := ay0;
+  x1 := ax1;
+  y1 := ay1;
+
+  // offset query coords to (0,0)-based
+  Dec(x0, minx);
+  Dec(y0, miny);
+  Dec(x1, minx);
+  Dec(y1, miny);
+
+  // clip rectange
+  wx0 := 0;
+  wy0 := 0;
+  wx1 := maxx;
+  wy1 := maxy;
+
+  // horizontal setup
+  if (x0 < x1) then
+  begin
+    // from left to right
+    if (x0 > wx1) or (x1 < wx0) then exit; // out of screen
+    stx := 1; // going right
+  end
+  else
+  begin
+    // from right to left
+    if (x1 > wx1) or (x0 < wx0) then exit; // out of screen
+    stx := -1; // going left
+    x0 := -x0;
+    x1 := -x1;
+    wx0 := -wx0;
+    wx1 := -wx1;
+    swapInt(wx0, wx1);
+  end;
+
+  // vertical setup
+  if (y0 < y1) then
+  begin
+    // from top to bottom
+    if (y0 > wy1) or (y1 < wy0) then exit; // out of screen
+    sty := 1; // going down
+  end
+  else
+  begin
+    // from bottom to top
+    if (y1 > wy1) or (y0 < wy0) then exit; // out of screen
+    sty := -1; // going up
+    y0 := -y0;
+    y1 := -y1;
+    wy0 := -wy0;
+    wy1 := -wy1;
+    swapInt(wy0, wy1);
+  end;
+
+  dsx := x1-x0;
+  dsy := y1-y0;
+
+  if (dsx < dsy) then
+  begin
+    xptr := @yd;
+    yptr := @xd;
+    swapInt(x0, y0);
+    swapInt(x1, y1);
+    swapInt(dsx, dsy);
+    swapInt(wx0, wy0);
+    swapInt(wx1, wy1);
+    swapInt(stx, sty);
+  end
+  else
+  begin
+    xptr := @xd;
+    yptr := @yd;
+  end;
+
+  dx2 := 2*dsx;
+  dy2 := 2*dsy;
+  xd := x0;
+  yd := y0;
+  e := 2*dsy-dsx;
+  term := x1;
+
+  xfixed := false;
+  if (y0 < wy0) then
+  begin
+    // clip at top
+    temp := dx2*(wy0-y0)-dsx;
+    xd += temp div dy2;
+    rem := temp mod dy2;
+    if (xd > wx1) then exit; // x is moved out of clipping rect, nothing to do
+    if (xd+1 >= wx0) then
+    begin
+      yd := wy0;
+      e -= rem+dsx;
+      if (rem > 0) then begin Inc(xd); e += dy2; end;
+      xfixed := true;
+    end;
+  end;
+
+  if (not xfixed) and (x0 < wx0) then
+  begin
+    // clip at left
+    temp := dy2*(wx0-x0);
+    yd += temp div dx2;
+    rem := temp mod dx2;
+    if (yd > wy1) or (yd = wy1) and (rem >= dsx) then exit;
+    xd := wx0;
+    e += rem;
+    if (rem >= dsx) then begin Inc(yd); e -= dx2; end;
+  end;
+
+  if (y1 > wy1) then
+  begin
+    // clip at bottom
+    temp := dx2*(wy1-y0)+dsx;
+    term := x0+temp div dy2;
+    rem := temp mod dy2;
+    if (rem = 0) then Dec(term);
+  end;
+
+  if (term > wx1) then term := wx1; // clip at right
+
+  Inc(term); // draw last point
+  //if (term = xd) then exit; // this is the only point, get out of here
+
+  if (sty = -1) then yd := -yd;
+  if (stx = -1) then begin xd := -xd; term := -term; end;
+  dx2 -= dy2;
+
+  // first move, to skip starting point
+  // DON'T DO THIS! loop will take care of that
+  if (xd = term) then
+  begin
+    result := forEachAtPoint(ax0, ay0, nil, tagmask, @ptag);
+    if (result <> nil) and ((ptag and tagmask) <> 0) then result := nil;
+    exit;
+  end;
+
+  prevx := xptr^+minx;
+  prevy := yptr^+miny;
+
+  // 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;
+
+  ccidx := -1;
+  // draw it; can omit checks
+  while (xd <> term) do
+  begin
+    // check cell(s)
+    // new tile?
+    ga := (yptr^ div tsize)*gw+(xptr^ div tsize);
+    if (ga <> lastGA) then
+    begin
+      // yes
+      lastGA := ga;
+      ccidx := mGrid[lastGA];
+      // no objects in cell == exit
+      if (ccidx = -1) then exit;
+    end;
+    // has something to process in this tile?
     if (ccidx <> -1) then
     begin
       // process cell
       curci := ccidx;
-      hasUntried := false; // this will be set to `true` if we have some proxies we still want to process at the next step
       // convert coords to map (to avoid ajdusting coords inside the loop)
-      Inc(x, minx);
-      Inc(y, miny);
+      x := xptr^+minx;
+      y := yptr^+miny;
+      wasHit := false;
       // process cell list
       while (curci <> -1) do
       begin
         cc := @mCells[curci];
-        for f := 0 to High(TGridCell.bodies) do
+        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
+          if ((ptag and TagDisabled) = 0) and (px.mQueryMark <> lq) then
           begin
+function lineAABBIntersects (x0, y0, x1, y1: Integer; bx, by, bw, bh: Integer; out inx, iny: Integer): Boolean;
             // can we process this proxy?
             if (x >= px.mX) and (y >= px.mY) and (x < px.mX+px.mWidth) and (y < px.mY+px.mHeight) then
             begin
               px.mQueryMark := lq; // mark as processed
-              if assigned(cb) then
+              if ((ptag and tagmask) = 0) then
               begin
-                if cb(px.mObj, ptag, x, y, prevX, prevY) then
-                begin
-                  result := lastObj;
-                  ex := prevX;
-                  ey := prevY;
-                  exit;
-                end;
-              end
-              else
+                result := px.mObj;
+                ex := x;
+                ey := y;
+                exit;
+              end;
+              // march out of the panel/cell
+              while (xd <> term) do
               begin
-                // remember this hitpoint if it is nearer than an old one
-                distSq := (prevX-x0)*(prevX-x0)+(prevY-y0)*(prevY-y0);
-                if (distSq < lastDistSq) then
-                begin
-                  wasHit := true;
-                  lastDistSq := distSq;
-                  ex := prevX;
-                  ey := prevY;
-                  lastObj := px.mObj;
-                end;
+                if (e >= 0) then begin yd += sty; e -= dx2; end else e += dy2;
+                xd += stx;
+                // new cell?
+                ga := (yptr^ div tsize)*gw+(xptr^ div tsize);
+                if (ga <> lastGA) then break;
+                // out of panel?
+                if not ((x >= px.mX) and (y >= px.mY) and (x < px.mX+px.mWidth) and (y < px.mY+px.mHeight)) then break;
               end;
-            end
-            else
-            begin
-              // this is possibly interesting proxy, set "has more to check" flag
-              hasUntried := true;
             end;
           end;
         end;
@@ -875,7 +2158,7 @@ begin
         ccidx := -1;
         if assigned(cb) then
         begin
-          if cb(nil, 0, x, y, prevX, prevY) then begin result := lastObj; exit; end;
+          if cb(nil, 0, x, y, prevx, prevy) then begin result := lastObj; exit; end;
         end
         else if wasHit then
         begin
@@ -883,12 +2166,26 @@ begin
           exit;
         end;
       end;
-      // convert coords to grid
-      Dec(x, minx);
-      Dec(y, miny);
     end;
+    //putPixel(xptr^, yptr^);
+    // move coords
+    prevx := xptr^+minx;
+    prevy := yptr^+miny;
+    if (e >= 0) then begin yd += sty; e -= dx2; end else e += dy2;
+    xd += stx;
+  end;
+  // we can travel less than one cell
+  if wasHit and not assigned(cb) then
+  begin
+    result := lastObj;
+  end
+  else
+  begin
+    ex := ax1; // why not?
+    ey := ay1; // why not?
   end;
 end;
+*)
 
 
 end.