Making a platform game - few questions

[efilnukefesin]

unit '__pf_simplegame' (class tpf_simplegame is NOT USED ANY MORE)

unit __pf_simplegame;

interface

uses Windows,
     Messages,
     SysUtils,
     Variants,
     Classes,
     Graphics,
     Controls,
     Forms,
     Dialogs,
     DJXTimer,
     DJX,
     ExtCtrls,
     djxclasses,
     d3dx9,
     StdCtrls,
     DJXFonts,
     ComCtrls,
     djxlandscape,
     djxtextures,
     Direct3D9,
     djxrender,
     djxmeshes,
     DJXMaterials,
     DJXLights,
     __dxtexturemanager,

     udirectinput,
     directinput,

     __pf_simplemap,
     __pf_simpleplayer;

const GUID_NULL: tguid= '{00000000-0000-0000-0000-000000000000}';

type tpf_simplegamestate= (
                           pfs_playing,
                           pfs_quit 
                          );

type tpf_corners= record
                    upperleft,
                    lowerleft,
                    upperright,
                    lowerright: boolean;
                  end;

type tpf_simplegame= class
                       public
                         constructor create(handle: hwnd);

                         procedure render;

                         procedure process;

                         //map-funktionen
                         procedure load_textmap(const filename: string);
                         function map_gettilepos(const pos_x, pos_y: single): tpoint;
                         function map_getwalkable(const pos_x, pos_y: single): boolean;

                         //player-funktionen
                         procedure move_player(const dir_x, dir_y: integer);

                         procedure di_activate;
                         procedure di_deactivate;
                         procedure di_keydown;
                       private
                         fhandle: hwnd;  //handle des mutterfensters f?ºr di

                         fdjx: tdanjetx;
                         fsimplemap: tpf_simplemap;
                         fsimpleplayer: tpf_simpleplayer;
                         ftm: tdxtexturemanager;

                         fstretch_x,
                         fstretch_y: single;

                         fgamestate: tpf_simplegamestate;

                         //dinput
                         di_obj: tdiobject;
                         di_key: tkeyboardinput;
                         di_joy: TJoystickInput;

                         //eigene funktionen
                         procedure player_corners(const x, y: single; out corners: tpf_corners);

                         //properties
                         procedure setdjx(const value: tdanjetx);
                         procedure settm(const value: tdxtexturemanager);
                         procedure setstretch_x(const value: single);
                         procedure setstretch_y(const value: single);
                         function getplayerpos: tpoint;
                       published
                         property djx: tdanjetx read fdjx write setdjx;
                         property texturemanager: tdxtexturemanager read ftm write settm;
                         property stretch_x: single read fstretch_x write setstretch_x;
                         property stretch_y: single read fstretch_y write setstretch_y;
                         property state: tpf_simplegamestate read fgamestate;
                         property playerpos: tpoint read getplayerpos;
                     end;

type tpf_simplegame_2= class
                         public
                           constructor create(handle: hwnd);

                           procedure render;

                           procedure process;

                           //map-funktionen
                           procedure load_textmap(const filename: string);
                           function map_gettilepos(const pos_x, pos_y: single): tpoint;
                           function map_getwalkable(const pos_x, pos_y: single): boolean;

                           //player-funktionen
                           procedure move_player(const dir_x, dir_y: integer);

                           procedure di_activate;
                           procedure di_deactivate;
                           procedure di_keydown;
                         private
                           fhandle: hwnd;  //handle des mutterfensters f?ºr di

                           fdjx: tdanjetx;
                           fsimplemap: tpf_simplemap;
                           fsimpleplayer: tpf_simpleplayer;
                           ftm: tdxtexturemanager;

                           fstretch_x,
                           fstretch_y: single;

                           fgamestate: tpf_simplegamestate;

                           //dinput
                           di_obj: tdiobject;
                           di_key: tkeyboardinput;
                           di_joy: TJoystickInput;

                           //corners
                           CnrUL : TPoint;  // upper left  tile (x,y) player is over 
                           CnrUR : TPoint;  // upper right tile (x,y) player is over
                           CnrLL : TPoint;  // lower left  tile (x,y) player is over
                           CnrLR : TPoint;  // lower right tile (x,y) player is over

                           vx,
                           vy: single;

                           //eigene funktionen
                           procedure player_corners(const x, y: single; out corners: tpf_corners);

                           //properties
                           procedure setdjx(const value: tdanjetx);
                           procedure settm(const value: tdxtexturemanager);
                           procedure setstretch_x(const value: single);
                           procedure setstretch_y(const value: single);
                           function getplayerpos: tpoint;

                           function ClampValue(const n, l, u : integer): integer;
                           function  Floor(X : extended): integer;
                           procedure GetCornersAt(const ax, ay : single);
                           procedure update(const ATimeSlice : single);
                           function  TileIsWalkable(const tx,ty : Integer) : boolean;
                         published
                           property djx: tdanjetx read fdjx write setdjx;
                           property texturemanager: tdxtexturemanager read ftm write settm;
                           property stretch_x: single read fstretch_x write setstretch_x;
                           property stretch_y: single read fstretch_y write setstretch_y;
                           property state: tpf_simplegamestate read fgamestate;
                           property playerpos: tpoint read getplayerpos;
                       end;

implementation

{ tpf_simplegame }

constructor tpf_simplegame.create(handle: hwnd);
begin
  fhandle:= handle;

  fdjx:= nil;

  fsimplemap:= tpf_simplemap.create;
  fsimpleplayer:= tpf_simpleplayer.create;

  fsimplemap.nameintl:= 'blackblock_32px';
  fsimpleplayer.nameintl:= 'redblock_64px';
  {
  fsimpleplayer.x:= 5;
  fsimpleplayer.y:= 5;
  }
  fsimpleplayer.pos_x:= 250;
  fsimpleplayer.pos_y:= 250;

  fgamestate:= pfs_playing;
end;

procedure tpf_simplegame.di_activate;
begin
  di_obj:= tdiobject.create;
  di_key:= tkeyboardinput.create;
  di_key.DIObject:= di_obj;
  di_key.handle:= fhandle;
  di_key.init(GUID_NULL);
  di_key.Acquire;  //jetzt gehts los
end;

procedure tpf_simplegame.di_deactivate;
begin
  //freeandnil(di_key.DIData);
  freeandnil(di_key);
  freeandnil(di_joy);
  freeandnil(di_obj);
end;

procedure tpf_simplegame.di_keydown;
var s: string;
    temp_dir_x,
    temp_dir_y: integer;
begin
  //hier die controllerabfragen tun
  s:= '-';
  temp_dir_x:= 0;
  temp_dir_y:= 0;

  di_key.DIData.GetState;
  if tkeyboarddata(di_key.didata).keydown(DIK_LCONTROL) then begin
    s:= 'lcontrol';
  end;
  if tkeyboarddata(di_key.didata).keydown(DIK_RCONTROL) then begin
    s:= 'rcontrol';
  end;
  if tkeyboarddata(di_key.didata).keydown(DIK_SPACE) then begin
    s:= 'space';
  end;
  if tkeyboarddata(di_key.didata).keydown(DIK_ESCAPE) then begin
    s:= 'escape';
    fgamestate:= pfs_quit;
  end;

  if tkeyboarddata(di_key.didata).keydown(DIK_UPARROW) then begin
    s:= 'UP';
    temp_dir_y:= -1;
  end;
  if tkeyboarddata(di_key.didata).keydown(DIK_DOWNARROW) then begin
    s:= 'DOWN';
    temp_dir_y:= +1;
  end;
  if tkeyboarddata(di_key.didata).keydown(DIK_LEFTARROW) then begin
    s:= 'LEFT';
    temp_dir_x:= -1;
  end;
  if tkeyboarddata(di_key.didata).keydown(DIK_RIGHTARROW) then begin
    s:= 'RIGHT';
    temp_dir_x:= +1;
  end;

  move_player(temp_dir_x, temp_dir_y);
end;

function tpf_simplegame.getplayerpos: tpoint;
begin
  result.X:= fsimpleplayer.x;
  result.Y:= fsimpleplayer.y;
end;

procedure tpf_simplegame.load_textmap(const filename: string);
begin
  fsimplemap.loadfromtextfile(filename);
end;

function tpf_simplegame.map_gettilepos(const pos_x, pos_y: single): tpoint;
var p: tpoint;
    temp_x,
    temp_y: integer;
begin
  p.X:= -1;
  p.Y:= -1;

  //***
  temp_x:= round(pos_x/ fsimplemap.tile_width);
  temp_y:= round(pos_y/ fsimplemap.tile_height);

  temp_x:= trunc(pos_x/ fsimplemap.tile_width);
  temp_y:= trunc(pos_y/ fsimplemap.tile_height);
  //***

  if &#40;temp_x>= low&#40;fsimplemap.pattern&#91;0&#93;&#41;&#41;and &#40;temp_x<high>= low&#40;fsimplemap.pattern&#41;&#41;and &#40;temp_y<high> -1&#41;and &#40;p.Y> -1&#41; then begin
    result&#58;= fsimplemap.pattern&#91;p.y, p.x&#93;.walkable;
  end
  else begin
    result&#58;= false;
  end;
end;

procedure tpf_simplegame.player_corners&#40;const x, y&#58; single; out corners&#58; tpf_corners&#41;;
var temp_left,
    temp_right,
    temp_up,
    temp_down&#58; single;
    outofmap&#58; boolean;
begin
  temp_left&#58;= x- &#40;fsimpleplayer.width/ 2&#41;;
  temp_right&#58;= x+ &#40;fsimpleplayer.width/ 2&#41;;
  temp_up&#58;= y- &#40;fsimpleplayer.height/ 2&#41;;
  temp_down&#58;= y+ &#40;fsimpleplayer.height/ 2&#41;;

  corners.upperleft&#58;= map_getwalkable&#40;temp_left, temp_up&#41;;
  corners.upperright&#58;= map_getwalkable&#40;temp_right, temp_up&#41;;
  corners.lowerleft&#58;= map_getwalkable&#40;temp_left, temp_down&#41;;
  corners.lowerright&#58;= map_getwalkable&#40;temp_right, temp_down&#41;;
end;

procedure tpf_simplegame.move_player&#40;const dir_x, dir_y&#58; integer&#41;;
var corners&#58; tpf_corners;
    temp_dir_x,
    temp_dir_y&#58; integer;
begin
  player_corners&#40;fsimpleplayer.pos_x+ dir_x, fsimpleplayer.pos_y+ dir_x, corners&#41;;

  temp_dir_x&#58;= 0;
  temp_dir_y&#58;= 0;

  if dir_x= -1 then begin
    if corners.upperleft and corners.lowerleft then begin
      temp_dir_x&#58;= dir_x;
    end
    else begin
      temp_dir_x&#58;= 0;
    end;
  end;

  if dir_x= +1 then begin
    if corners.upperright and corners.lowerright then begin
      temp_dir_x&#58;= dir_x;
    end
    else begin
      temp_dir_x&#58;= 0;
    end;
  end;

  if dir_y= -1 then begin
    if corners.upperleft and corners.upperright then begin
      temp_dir_y&#58;= dir_y;
    end
    else begin
      temp_dir_y&#58;= 0;
    end;
  end;

  if dir_y= +1 then begin
    if corners.lowerleft and corners.lowerright then begin
      temp_dir_y&#58;= dir_y;
    end
    else begin
      temp_dir_y&#58;= 0;
    end;
  end;

  fsimpleplayer.pos_x&#58;= fsimpleplayer.pos_x+ temp_dir_x;
  fsimpleplayer.pos_y&#58;= fsimpleplayer.pos_y+ temp_dir_y;
end;

procedure tpf_simplegame.process;
begin
  //per gettickcount abfragen, abstand ca 10 ms oder was
  //****
  di_keydown;
end;

procedure tpf_simplegame.render;
begin
  fsimplemap.render;
  fsimpleplayer.render;
end;

procedure tpf_simplegame.setdjx&#40;const value&#58; tdanjetx&#41;;
begin
  fdjx&#58;= value;

  fsimplemap.djx&#58;= fdjx;
  fsimpleplayer.djx&#58;= fdjx;
end;

procedure tpf_simplegame.setstretch_x&#40;const value&#58; single&#41;;
begin
  fstretch_x&#58;= value;

  fsimplemap.stretch_x&#58;= fstretch_x;
  fsimpleplayer.stretch_x&#58;= fstretch_x;
end;

procedure tpf_simplegame.setstretch_y&#40;const value&#58; single&#41;;
begin
  fstretch_y&#58;= value;

  fsimplemap.stretch_y&#58;= fstretch_y;
  fsimpleplayer.stretch_y&#58;= fstretch_y;
end;

procedure tpf_simplegame.settm&#40;const value&#58; tdxtexturemanager&#41;;
begin
  ftm&#58;= value;

  fsimplemap.texturemanager&#58;= ftm;
  fsimpleplayer.texturemanager&#58;= ftm;
end;


&#123; tpf_simplegame_2 &#125;

constructor tpf_simplegame_2.create&#40;handle&#58; hwnd&#41;;
begin
  fhandle&#58;= handle;

  fdjx&#58;= nil;

  fsimplemap&#58;= tpf_simplemap.create;
  fsimpleplayer&#58;= tpf_simpleplayer.create;

  fsimplemap.nameintl&#58;= 'blackblock_32px';
  fsimpleplayer.nameintl&#58;= 'redblock_64px';
  &#123;
  fsimpleplayer.x&#58;= 5;
  fsimpleplayer.y&#58;= 5;
  &#125;
  fsimpleplayer.pos_x&#58;= 150;
  fsimpleplayer.pos_y&#58;= 250;

  vx&#58;= 0;
  vy&#58;= 0;

  fgamestate&#58;= pfs_playing;
end;

procedure tpf_simplegame_2.di_activate;
begin
  di_obj&#58;= tdiobject.create;
  di_key&#58;= tkeyboardinput.create;
  di_key.DIObject&#58;= di_obj;
  di_key.handle&#58;= fhandle;
  di_key.init&#40;GUID_NULL&#41;;
  di_key.Acquire;  //jetzt gehts los
end;

procedure tpf_simplegame_2.di_deactivate;
begin
  //freeandnil&#40;di_key.DIData&#41;;
  freeandnil&#40;di_key&#41;;
  freeandnil&#40;di_joy&#41;;
  freeandnil&#40;di_obj&#41;;
end;

procedure tpf_simplegame_2.di_keydown;
var s&#58; string;
    temp_dir_x,
    temp_dir_y&#58; integer;
begin
  //hier die controllerabfragen tun
  s&#58;= '-';
  temp_dir_x&#58;= 0;
  temp_dir_y&#58;= 0;

  di_key.DIData.GetState;
  if tkeyboarddata&#40;di_key.didata&#41;.keydown&#40;DIK_LCONTROL&#41; then begin
    s&#58;= 'lcontrol';
  end;
  if tkeyboarddata&#40;di_key.didata&#41;.keydown&#40;DIK_RCONTROL&#41; then begin
    s&#58;= 'rcontrol';
  end;
  if tkeyboarddata&#40;di_key.didata&#41;.keydown&#40;DIK_SPACE&#41; then begin
    s&#58;= 'space';
  end;
  if tkeyboarddata&#40;di_key.didata&#41;.keydown&#40;DIK_ESCAPE&#41; then begin
    s&#58;= 'escape';
    fgamestate&#58;= pfs_quit;
  end;

  if tkeyboarddata&#40;di_key.didata&#41;.keydown&#40;DIK_UPARROW&#41; then begin
    s&#58;= 'UP';
    temp_dir_y&#58;= -1;
  end;
  if tkeyboarddata&#40;di_key.didata&#41;.keydown&#40;DIK_DOWNARROW&#41; then begin
    s&#58;= 'DOWN';
    temp_dir_y&#58;= +1;
  end;
  if tkeyboarddata&#40;di_key.didata&#41;.keydown&#40;DIK_LEFTARROW&#41; then begin
    s&#58;= 'LEFT';
    temp_dir_x&#58;= -1;
  end;
  if tkeyboarddata&#40;di_key.didata&#41;.keydown&#40;DIK_RIGHTARROW&#41; then begin
    s&#58;= 'RIGHT';
    temp_dir_x&#58;= +1;
  end;

  //move_player&#40;temp_dir_x, temp_dir_y&#41;;
  vx&#58;= temp_dir_x;
  vy&#58;= temp_dir_y;
end;

function tpf_simplegame_2.getplayerpos&#58; tpoint;
begin
  result.X&#58;= fsimpleplayer.x;
  result.Y&#58;= fsimpleplayer.y;
end;

procedure tpf_simplegame_2.load_textmap&#40;const filename&#58; string&#41;;
begin
  fsimplemap.loadfromtextfile&#40;filename&#41;;
end;

function tpf_simplegame_2.map_gettilepos&#40;const pos_x, pos_y&#58; single&#41;&#58; tpoint;
var p&#58; tpoint;
    temp_x,
    temp_y&#58; integer;
begin
  p.X&#58;= -1;
  p.Y&#58;= -1;

  //***
  temp_x&#58;= round&#40;pos_x/ fsimplemap.tile_width&#41;;
  temp_y&#58;= round&#40;pos_y/ fsimplemap.tile_height&#41;;

  temp_x&#58;= trunc&#40;pos_x/ fsimplemap.tile_width&#41;;
  temp_y&#58;= trunc&#40;pos_y/ fsimplemap.tile_height&#41;;
  //***

  if &#40;temp_x>= low&#40;fsimplemap.pattern&#91;0&#93;&#41;&#41;and &#40;temp_x<high>= low&#40;fsimplemap.pattern&#41;&#41;and &#40;temp_y<high> -1&#41;and &#40;p.Y> -1&#41; then begin
    result&#58;= fsimplemap.pattern&#91;p.y, p.x&#93;.walkable;
  end
  else begin
    result&#58;= false;
  end;
end;

procedure tpf_simplegame_2.player_corners&#40;const x, y&#58; single; out corners&#58; tpf_corners&#41;;
var temp_left,
    temp_right,
    temp_up,
    temp_down&#58; single;
    outofmap&#58; boolean;
begin
  temp_left&#58;= x- &#40;fsimpleplayer.width/ 2&#41;;
  temp_right&#58;= x+ &#40;fsimpleplayer.width/ 2&#41;;
  temp_up&#58;= y- &#40;fsimpleplayer.height/ 2&#41;;
  temp_down&#58;= y+ &#40;fsimpleplayer.height/ 2&#41;;

  corners.upperleft&#58;= map_getwalkable&#40;temp_left, temp_up&#41;;
  corners.upperright&#58;= map_getwalkable&#40;temp_right, temp_up&#41;;
  corners.lowerleft&#58;= map_getwalkable&#40;temp_left, temp_down&#41;;
  corners.lowerright&#58;= map_getwalkable&#40;temp_right, temp_down&#41;;
end;

procedure tpf_simplegame_2.move_player&#40;const dir_x, dir_y&#58; integer&#41;;
var corners&#58; tpf_corners;
    temp_dir_x,
    temp_dir_y&#58; integer;
begin
  player_corners&#40;fsimpleplayer.pos_x+ dir_x, fsimpleplayer.pos_y+ dir_x, corners&#41;;

  temp_dir_x&#58;= 0;
  temp_dir_y&#58;= 0;

  if dir_x= -1 then begin
    if corners.upperleft and corners.lowerleft then begin
      temp_dir_x&#58;= dir_x;
    end
    else begin
      temp_dir_x&#58;= 0;
    end;
  end;

  if dir_x= +1 then begin
    if corners.upperright and corners.lowerright then begin
      temp_dir_x&#58;= dir_x;
    end
    else begin
      temp_dir_x&#58;= 0;
    end;
  end;

  if dir_y= -1 then begin
    if corners.upperleft and corners.upperright then begin
      temp_dir_y&#58;= dir_y;
    end
    else begin
      temp_dir_y&#58;= 0;
    end;
  end;

  if dir_y= +1 then begin
    if corners.lowerleft and corners.lowerright then begin
      temp_dir_y&#58;= dir_y;
    end
    else begin
      temp_dir_y&#58;= 0;
    end;
  end;

  fsimpleplayer.pos_x&#58;= fsimpleplayer.pos_x+ temp_dir_x;
  fsimpleplayer.pos_y&#58;= fsimpleplayer.pos_y+ temp_dir_y;
end;

procedure tpf_simplegame_2.process;
begin
  //per gettickcount abfragen, abstand ca 10 ms oder was
  //****
  di_keydown;

  update&#40;1&#41;;
end;

procedure tpf_simplegame_2.render;
begin
  fsimplemap.render;
  fsimpleplayer.render;
end;

procedure tpf_simplegame_2.setdjx&#40;const value&#58; tdanjetx&#41;;
begin
  fdjx&#58;= value;

  fsimplemap.djx&#58;= fdjx;
  fsimpleplayer.djx&#58;= fdjx;
end;

procedure tpf_simplegame_2.setstretch_x&#40;const value&#58; single&#41;;
begin
  fstretch_x&#58;= value;

  fsimplemap.stretch_x&#58;= fstretch_x;
  fsimpleplayer.stretch_x&#58;= fstretch_x;
end;

procedure tpf_simplegame_2.setstretch_y&#40;const value&#58; single&#41;;
begin
  fstretch_y&#58;= value;

  fsimplemap.stretch_y&#58;= fstretch_y;
  fsimpleplayer.stretch_y&#58;= fstretch_y;
end;

procedure tpf_simplegame_2.settm&#40;const value&#58; tdxtexturemanager&#41;;
begin
  ftm&#58;= value;

  fsimplemap.texturemanager&#58;= ftm;
  fsimpleplayer.texturemanager&#58;= ftm;
end;

function tpf_simplegame_2.TileIsWalkable&#40;const tx, ty&#58; Integer&#41;&#58; boolean;
begin
  result&#58;= false;
  
  If tx < 0           Then Exit;
  If ty <0>= fsimplemap.width  Then Exit;
  If ty >= fsimplemap.height Then Exit;

  if &#40;tx> -1&#41;and &#40;ty> -1&#41; then begin
    result&#58;= fsimplemap.pattern&#91;ty, tx&#93;.walkable;
  end
  else begin
    result&#58;= false;
  end;
end;

function tpf_simplegame_2.ClampValue&#40;const n, l, u &#58; integer&#41;&#58; integer;
begin
    Result &#58;= n;
    If Result <l> u Then Result &#58;= u; 
end;

function tpf_simplegame_2.Floor&#40;X&#58; extended&#41;&#58; integer;
begin
  Result &#58;= Integer&#40;Trunc&#40;X&#41;&#41;; 
  If Frac&#40;X&#41; < 0 Then Dec&#40;Result&#41;;
end;

procedure tpf_simplegame_2.GetCornersAt&#40;const ax, ay&#58; single&#41;;
&#123; 
           | 
           | 
     -,-   |   +,- 

    -------|------- 

     -,+   |   +,+ 
           | 
           | 
&#125; 
begin
    CnrUL.x &#58;= Floor&#40;&#40;ax - fsimpleplayer.width/2&#41; / fsimplemap.tile_width&#41;;
    CnrUL.y &#58;= Floor&#40;&#40;ay - fsimpleplayer.height/2&#41; / fsimplemap.tile_height&#41;;

    CnrUR.x &#58;= Floor&#40;&#40;ax + fsimpleplayer.width/2&#41; / fsimplemap.tile_width&#41;;
    CnrUR.y &#58;= Floor&#40;&#40;ay - fsimpleplayer.height/2&#41; / fsimplemap.tile_height&#41;;

    CnrLR.x &#58;= Floor&#40;&#40;ax + fsimpleplayer.width/2&#41; / fsimplemap.tile_width&#41;;
    CnrLR.y &#58;= Floor&#40;&#40;ay + fsimpleplayer.height/2&#41; / fsimplemap.tile_height&#41;;

    CnrLL.x &#58;= Floor&#40;&#40;ax - fsimpleplayer.width/2&#41; / fsimplemap.tile_width&#41;;
    CnrLL.y &#58;= Floor&#40;&#40;ay + fsimpleplayer.height/2&#41; / fsimplemap.tile_height&#41;;

    CnrUL.x &#58;= ClampValue&#40;CnrUL.x,0,fsimplemap.width - 1&#41;;
    CnrUR.x &#58;= ClampValue&#40;CnrUR.x,0,fsimplemap.width - 1&#41;;
    CnrLR.x &#58;= ClampValue&#40;CnrLR.x,0,fsimplemap.width - 1&#41;;
    CnrLL.x &#58;= ClampValue&#40;CnrLL.x,0,fsimplemap.width - 1&#41;;

    CnrUL.y &#58;= ClampValue&#40;CnrUL.y,0,fsimplemap.height - 1&#41;;
    CnrUR.y &#58;= ClampValue&#40;CnrUR.y,0,fsimplemap.height - 1&#41;;
    CnrLR.y &#58;= ClampValue&#40;CnrLR.y,0,fsimplemap.height - 1&#41;;
    CnrLL.y &#58;= ClampValue&#40;CnrLL.y,0,fsimplemap.height - 1&#41;; 
end;

procedure tpf_simplegame_2.update&#40;const ATimeSlice &#58; single&#41;;
var TileIsWalkableUL &#58; Boolean; // upper left  player corner tile is walkable
    TileIsWalkableUR &#58; Boolean; // upper right player corner tile is walkable 
    TileIsWalkableLL &#58; Boolean; // lower left  player corner tile is walkable 
    TileIsWalkableLR &#58; Boolean; // lower right player corner tile is walkable 
Begin 
    GetCornersAt&#40;fsimpleplayer.pos_x,fsimpleplayer.pos_y + vy * ATimeSlice&#41;;
    If vy <0> 0 Then 
    //moving down 
    Begin 
        TileIsWalkableLL &#58;= TileIsWalkable&#40;CnrLL.x,CnrLL.y&#41;;
        TileIsWalkableLR &#58;= TileIsWalkable&#40;CnrLR.x,CnrLR.y&#41;;
        If TileIsWalkableLL And TileIsWalkableLR Then 
            fsimpleplayer.pos_y &#58;= fsimpleplayer.pos_y + vy * ATimeSlice
        Else 
            // move player to sit on tile&#40;s&#41; below 
            fsimpleplayer.pos_y  &#58;= CnrLR.y * fsimplemap.tile_height - fsimpleplayer.height/2 - 0.01;
    End; 

    GetCornersAt&#40;fsimpleplayer.pos_x + vx * ATimeSlice,fsimpleplayer.pos_y&#41;;
    If vx <0> 0 Then 
    //moving right 
    Begin 
        TileIsWalkableUR &#58;= TileIsWalkable&#40;CnrUR.x,CnrUR.y&#41;;
        TileIsWalkableLR &#58;= TileIsWalkable&#40;CnrLR.x,CnrLR.y&#41;;
        If TileIsWalkableUR And TileIsWalkableLR Then 
            fsimpleplayer.pos_x &#58;= fsimpleplayer.pos_x + vx * ATimeSlice
        Else 
            // move player to touch tile&#40;s&#41; on right 
            fsimpleplayer.pos_x  &#58;= CnrUR.x * fsimplemap.tile_width - fsimpleplayer.width/2 - 0.01;
    End; 
    // add gravity to vy here and cap to max velocity so not faster than tile height; 
End;

end.