diff --git a/lazarus/magic-marker/project1.ico b/lazarus/magic-marker/project1.ico
new file mode 100644
index 0000000..0341321
Binary files /dev/null and b/lazarus/magic-marker/project1.ico differ
diff --git a/lazarus/magic-marker/project1.lpi b/lazarus/magic-marker/project1.lpi
new file mode 100644
index 0000000..3afe492
--- /dev/null
+++ b/lazarus/magic-marker/project1.lpi
@@ -0,0 +1,79 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<CONFIG>
+ <ProjectOptions>
+ <Version Value="9"/>
+ <General>
+ <SessionStorage Value="InProjectDir"/>
+ <MainUnit Value="0"/>
+ <Title Value="project1"/>
+ <ResourceType Value="res"/>
+ <UseXPManifest Value="True"/>
+ <Icon Value="0"/>
+ </General>
+ <i18n>
+ <EnableI18N LFM="False"/>
+ </i18n>
+ <VersionInfo>
+ <StringTable ProductVersion=""/>
+ </VersionInfo>
+ <BuildModes Count="1">
+ <Item1 Name="Default" Default="True"/>
+ </BuildModes>
+ <PublishOptions>
+ <Version Value="2"/>
+ </PublishOptions>
+ <RunParams>
+ <local>
+ <FormatVersion Value="1"/>
+ </local>
+ </RunParams>
+ <RequiredPackages Count="1">
+ <Item1>
+ <PackageName Value="LCL"/>
+ </Item1>
+ </RequiredPackages>
+ <Units Count="2">
+ <Unit0>
+ <Filename Value="project1.lpr"/>
+ <IsPartOfProject Value="True"/>
+ </Unit0>
+ <Unit1>
+ <Filename Value="unit1.pas"/>
+ <IsPartOfProject Value="True"/>
+ <ComponentName Value="Form1"/>
+ <ResourceBaseClass Value="Form"/>
+ <UnitName Value="Unit1"/>
+ </Unit1>
+ </Units>
+ </ProjectOptions>
+ <CompilerOptions>
+ <Version Value="11"/>
+ <Target>
+ <Filename Value="project1"/>
+ </Target>
+ <SearchPaths>
+ <IncludeFiles Value="$(ProjOutDir)"/>
+ <UnitOutputDirectory Value="lib/$(TargetCPU)-$(TargetOS)"/>
+ </SearchPaths>
+ <Linking>
+ <Options>
+ <Win32>
+ <GraphicApplication Value="True"/>
+ </Win32>
+ </Options>
+ </Linking>
+ </CompilerOptions>
+ <Debugging>
+ <Exceptions Count="3">
+ <Item1>
+ <Name Value="EAbort"/>
+ </Item1>
+ <Item2>
+ <Name Value="ECodetoolError"/>
+ </Item2>
+ <Item3>
+ <Name Value="EFOpenError"/>
+ </Item3>
+ </Exceptions>
+ </Debugging>
+</CONFIG>
diff --git a/lazarus/magic-marker/project1.lpr b/lazarus/magic-marker/project1.lpr
new file mode 100644
index 0000000..58c35dc
--- /dev/null
+++ b/lazarus/magic-marker/project1.lpr
@@ -0,0 +1,21 @@
+program project1;
+
+{$mode objfpc}{$H+}
+
+uses
+ {$IFDEF UNIX}{$IFDEF UseCThreads}
+ cthreads,
+ {$ENDIF}{$ENDIF}
+ Interfaces, // this includes the LCL widgetset
+ Forms, Unit1
+ { you can add units after this };
+
+{$R *.res}
+
+begin
+ RequireDerivedFormResource:=True;
+ Application.Initialize;
+ Application.CreateForm(TForm1, Form1);
+ Application.Run;
+end.
+
diff --git a/lazarus/magic-marker/project1.res b/lazarus/magic-marker/project1.res
new file mode 100644
index 0000000..e994dfa
Binary files /dev/null and b/lazarus/magic-marker/project1.res differ
diff --git a/lazarus/magic-marker/unit1.lfm b/lazarus/magic-marker/unit1.lfm
new file mode 100644
index 0000000..daa8436
--- /dev/null
+++ b/lazarus/magic-marker/unit1.lfm
@@ -0,0 +1,23 @@
+object Form1: TForm1
+ Left = 324
+ Height = 431
+ Top = 277
+ Width = 451
+ Caption = 'Form1'
+ OnCreate = FormCreate
+ OnMouseMove = FormMouseMove
+ OnPaint = FormPaint
+ LCLVersion = '1.6.2.0'
+ object Timer1: TTimer
+ Interval = 1
+ OnTimer = Timer1Timer
+ left = 18
+ top = 9
+ end
+ object Timer2: TTimer
+ Interval = 50
+ OnTimer = Timer2Timer
+ left = 57
+ top = 10
+ end
+end
diff --git a/lazarus/magic-marker/unit1.pas b/lazarus/magic-marker/unit1.pas
new file mode 100644
index 0000000..02c8d4e
--- /dev/null
+++ b/lazarus/magic-marker/unit1.pas
@@ -0,0 +1,137 @@
+unit Unit1;
+
+{$mode objfpc}{$H+}
+
+interface
+
+uses
+ Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, ExtCtrls;
+
+type
+
+ { TForm1 }
+
+ TForm1 = class(TForm)
+ Timer1: TTimer;
+ Timer2: TTimer;
+ procedure FormCreate(Sender: TObject);
+ procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
+ procedure FormPaint(Sender: TObject);
+ procedure Timer1Timer(Sender: TObject);
+ procedure Timer2Timer(Sender: TObject);
+ private
+ { private declarations }
+ public
+ { public declarations }
+ end;
+
+const
+ pointR = 5;
+ ballR = 40;
+ g = 0.002;
+
+var
+ Form1: TForm1;
+ maxPoints: integer = 100;
+ points: array of TPoint;
+ bx, by, vx, vy: single;
+
+implementation
+
+{$R *.lfm}
+
+procedure addPoint(x, y: integer);
+var
+ i, l: integer;
+begin
+ if maxPoints <= 0 then exit;
+ l := Length(points);
+ if l < maxPoints then begin
+ SetLength(points, l+1);
+ points[l].X := x;
+ points[l].Y := y;
+ end else begin
+ for i:=1 to l-1 do begin
+ points[i-1] := points[i];
+ end;
+ points[l-1].X := x;
+ points[l-1].Y := y;
+ end;
+end;
+
+procedure TForm1.FormCreate(Sender: TObject);
+begin
+ bx := 200;
+ by := 100;
+ vx := 0.1;
+ vy := 0;
+end;
+
+procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
+ Y: Integer);
+begin
+ if ssLeft in Shift then begin
+ addPoint(x, y);
+ // todo: addPointChain
+ end;
+end;
+
+procedure TForm1.FormPaint(Sender: TObject);
+var
+ i: integer;
+begin
+ Canvas.Pen.Color := clBlack;
+ Canvas.Pen.Width := pointR * 2;
+ for i:=0 to length(points)-1 do begin
+ Canvas.MoveTo(points[i].x, points[i].y);
+ Canvas.LineTo(points[i].x, points[i].y);
+ end;
+
+ Canvas.Pen.Color := clBlue;
+ Canvas.Pen.Width := ballR * 2;
+ Canvas.MoveTo(round(bx), round(by));
+ Canvas.LineTo(round(bx), round(by));
+end;
+
+procedure TForm1.Timer1Timer(Sender: TObject);
+var
+ i: integer;
+ dx, dy, sqlen, minSqlen, dv: single;
+ collision: boolean;
+begin
+ collision := false;
+
+ bx := bx + vx;
+ by := by + vy;
+
+ if bx > ClientWidth - ballR then begin vx := -abs(vx); collision := true; end;
+ if by > ClientHeight - ballR then begin vy := -abs(vy); collision := true; end;
+ if bx < ballR then begin vx := abs(vx); collision := true; end;
+ if by < ballR then begin vy := abs(vy); collision := true; end;
+
+ minSqlen := sqr(ballR + pointR);
+ for i := 0 to length(points)-1 do begin
+ dx := points[i].X-bx;
+ dy := points[i].Y-by;
+ sqlen := sqr(dx) + sqr(dy);
+ if (sqlen > 0.1*minSqlen) and (minSqlen > sqlen) then begin
+ dv := -2*(dx*vx + dy*vy)/sqlen;
+ if dv < 0 then begin
+ vx := vx + dv*dx;
+ vy := vy + dv*dy;
+ collision := true;
+ end;
+ end;
+ end;
+
+ if not collision then vy := vy + g;
+ if collision then refresh;
+end;
+
+procedure TForm1.Timer2Timer(Sender: TObject);
+begin
+ Refresh;
+end;
+
+end.
+