MathgeomGLS

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unit fDelaunayPick;
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interface
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uses
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  Winapi.Windows,
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  Winapi.Messages,
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  System.Types,
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  System.SysUtils,
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  System.Variants,
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  System.Classes,
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  Vcl.Graphics,
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  Vcl.Controls,
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  Vcl.Forms,
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  Vcl.Dialogs,
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  Vcl.StdCtrls,
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  GLS.Triangulation,
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  GLS.SceneViewer,
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  GLS.BaseClasses,
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  GLS.Scene;
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type
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  TFormDelaunayPick = class(TForm)
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    GLScene1: TGLScene;
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    GLSceneViewer1: TGLSceneViewer;
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    procedure FormCreate(Sender: TObject);
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    procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
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      Shift: TShiftState; X, Y: Integer);
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  private
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    Z, U, V : Single;
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    MatIndex : Integer;
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    TempBuffer: TBitmap;
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    procedure ClearBackPage;
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    procedure FlipBackPage;
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  public
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    TheMesh: TGLDelaunay2D;
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    procedure Draw;
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  end;
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var
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  FormDelaunayPick: TFormDelaunayPick;
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implementation
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{$R *.dfm}
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procedure TFormDelaunayPick.FormCreate(Sender: TObject);
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begin
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  TheMesh := TGLDelaunay2D.Create;
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  TempBuffer := TBitmap.Create;
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  FormDelaunayPick.Caption := 'Click on the form!';
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end;
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procedure TFormDelaunayPick.ClearBackPage;
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begin
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  TempBuffer.Height := FormDelaunayPick.Height;
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  TempBuffer.Width := FormDelaunayPick.Width;
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  TempBuffer.Canvas.Brush.Color := clSilver;
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  TempBuffer.Canvas.FillRect(Rect(0, 0,
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    FormDelaunayPick.Width, FormDelaunayPick.Height));
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end;
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procedure TFormDelaunayPick.FlipBackPage;
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var
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  ARect: TRect;
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begin
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  ARect := Rect(0, 0, FormDelaunayPick.Width, FormDelaunayPick.Height);
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  FormDelaunayPick.Canvas.CopyRect(ARect, TempBuffer.Canvas, ARect);
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end;
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procedure TFormDelaunayPick.Draw;
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var
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  // variable to hold how many triangles are created by the triangulate function
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  i: Integer;
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begin
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  // Clear the form canvas
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  ClearBackPage;
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  TempBuffer.Canvas.Brush.Color := clTeal;
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  // Draw the created triangles
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  with TheMesh do
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  begin
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    if (TheMesh.HowMany > 0) then
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    begin
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      for i := 1 To TheMesh.HowMany do
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      begin
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        TempBuffer.Canvas.Polygon([Point(Trunc(Vertex[Triangle[i].vv0].x),
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          Trunc(Vertex[Triangle[i].vv0].y)),
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          Point(Trunc(Vertex[Triangle[i].vv1].x),
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          Trunc(Vertex[Triangle[i].vv1].y)),
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          Point(Trunc(Vertex[Triangle[i].vv2].x),
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          Trunc(Vertex[Triangle[i].vv2].y))]);
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      end;
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    end;
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  end;
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  FlipBackPage;
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end;
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procedure TFormDelaunayPick.FormMouseDown(Sender: TObject; Button: TMouseButton;
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  Shift: TShiftState; X, Y: Integer);
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begin
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  TheMesh.AddPoint(X, Y, Z, U, V, MatIndex); // add a point to the mesh
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  TheMesh.Mesh(True); // triangulate the mesh
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  Draw; // draw the mesh on the forms canvas
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  FormDelaunayPick.Caption := 'Points: ' + IntToStr(TheMesh.tPoints - 1) +
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    '  Triangles: ' + IntToStr(TheMesh.HowMany);
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end;
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end.
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