unit fHeightField;

interface

uses
  Winapi.OpenGL,
  System.SysUtils,
  System.Classes,
  System.Math,
  System.Types,
  Vcl.Graphics,
  Vcl.Controls,
  Vcl.Forms,
  Vcl.StdCtrls,
  Vcl.ComCtrls,
  Vcl.ExtCtrls,

  GLS.Scene,
  GLS.Graph,
  GLS.Objects,
  GLS.Texture,
  GLS.Cadencer,
  GLS.VectorGeometry,
  GLS.VectorTypes,
  GLS.SceneViewer,
  GLS.Color,
  GLS.Coordinates,
  GLS.BaseClasses;

type
  TFormHeightField = class(TForm)
    GLScene1: TGLScene;
    GLSceneViewer1: TGLSceneViewer;
    GLCamera1: TGLCamera;
    GLLightSource1: TGLLightSource;
    HeightField1: TGLHeightField;
    Timer1: TTimer;
    Sphere1: TGLSphere;
    GLCadencer1: TGLCadencer;
    Lines1: TGLLines;
    Panel1: TPanel;
    Label1: TLabel;
    TrackBar1: TTrackBar;
    Label2: TLabel;
    TrackBar2: TTrackBar;
    Label3: TLabel;
    TrackBar3: TTrackBar;
    RadioGroup1: TRadioGroup;
    CheckBox1: TCheckBox;
    Label4: TLabel;
    ComboBox1: TComboBox;
    CheckBox2: TCheckBox;
    LabelFPS: TLabel;
    procedure GLSceneViewer1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure GLSceneViewer1MouseMove(Sender: TObject; Shift: TShiftState;
      X, Y: Integer);
    procedure CheckBox1Click(Sender: TObject);
    procedure TrackBar1Change(Sender: TObject);
    procedure TrackBar2Change(Sender: TObject);
    procedure TrackBar3Change(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure RadioGroup1Click(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
    procedure ComboBox1Change(Sender: TObject);
    procedure Sphere1Progress(Sender: TObject;
      const deltaTime, newTime: Double);
    procedure CheckBox2Click(Sender: TObject);
    procedure FormMouseWheel(Sender: TObject; Shift: TShiftState;
      WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
  private

    procedure Formula1(const X, Y: Single; var z: Single;
      var Color: TColorVector; var texPoint: TTexPoint);
    procedure Formula2(const X, Y: Single; var z: Single;
      var Color: TColorVector; var texPoint: TTexPoint);
    procedure Formula3(const X, Y: Single; var z: Single;
      var Color: TColorVector; var texPoint: TTexPoint);
  public
    mx, my: Integer;
  end;

var
  FormHeightField: TFormHeightField;

implementation

{$R *.DFM}

procedure TFormHeightField.FormCreate(Sender: TObject);
begin
  // start with first formula
  HeightField1.OnGetHeight := Formula1;
  // no per-vertex coloring
  ComboBox1.ItemIndex := 1; // emission
  ComboBox1Change(Sender);
end;

procedure TFormHeightField.Formula1(const X, Y: Single; var z: Single;
  var Color: TColorVector; var texPoint: TTexPoint);
begin
  // first formula
  z := VectorNorm(X, Y);
  z := cos(z * 12) / (2 * (z * 6.28 + 1));
  VectorLerp(clrBlue, clrRed, (z + 1) / 2, Color);
end;

procedure TFormHeightField.Formula2(const X, Y: Single; var z: Single;
  var Color: TColorVector; var texPoint: TTexPoint);
begin
  // 2nd formula
  z := 0.5 * cos(X * 6.28) * sin(Sqrt(abs(Y)) * 6.28);
  VectorLerp(clrBlue, clrRed, (z + 1) / 2, Color);
end;

procedure TFormHeightField.Formula3(const X, Y: Single; var z: Single;
  var Color: TColorVector; var texPoint: TTexPoint);
begin
  // 3rd formula, dynamic
  z := 1 / (1 + VectorNorm(Sphere1.position.X - X, Sphere1.position.Y - Y));
  if ((Round(X * 4) + Round(Y * 4)) and 1) = 1 then
    Color := clrBlue
  else
    Color := clrYellow;
end;

procedure TFormHeightField.RadioGroup1Click(Sender: TObject);
begin
  Sphere1.Visible := False;
  // switch between formulas
  case RadioGroup1.ItemIndex of
    0:
      HeightField1.OnGetHeight := Formula1;
    1:
      HeightField1.OnGetHeight := Formula2;
    2:
      begin
        HeightField1.OnGetHeight := Formula3;
        Sphere1.Visible := True;
      end;
  end;
end;

procedure TFormHeightField.Sphere1Progress(Sender: TObject;
  const deltaTime, newTime: Double);
begin
  // move our little sphere around
  if Sphere1.Visible then
  begin
    Sphere1.position.SetPoint(cos(newTime * 2.3), sin(newTime), 1.5);
    HeightField1.StructureChanged;
  end;
end;

procedure TFormHeightField.CheckBox1Click(Sender: TObject);
begin
  // enable two sided surface
  if CheckBox1.Checked then
    HeightField1.Options := HeightField1.Options + [hfoTwoSided]
  else
    HeightField1.Options := HeightField1.Options - [hfoTwoSided];
end;

procedure TFormHeightField.ComboBox1Change(Sender: TObject);
begin
  // change per vertex color mode
  case ComboBox1.ItemIndex of
    0:
      HeightField1.ColorMode := hfcmNone;
    1:
      HeightField1.ColorMode := hfcmEmission;
    2:
      HeightField1.ColorMode := hfcmDiffuse;
  end;
end;

procedure TFormHeightField.CheckBox2Click(Sender: TObject);
begin
  GLLightSource1.Shining := CheckBox2.Checked;
end;

procedure TFormHeightField.TrackBar1Change(Sender: TObject);
begin
  // adjust X extents
  with HeightField1.XSamplingScale do
  begin
    Min := -TrackBar1.position / 10;
    Max := TrackBar1.position / 10;
  end;
end;

procedure TFormHeightField.TrackBar2Change(Sender: TObject);
begin
  // adjust Y extents
  with HeightField1.YSamplingScale do
  begin
    Min := -TrackBar2.position / 10;
    Max := TrackBar2.position / 10;
  end;
end;

procedure TFormHeightField.TrackBar3Change(Sender: TObject);
begin
  // adjust grid steps (resolution)
  with HeightField1 do
  begin
    XSamplingScale.Step := TrackBar3.position / 1000;
    YSamplingScale.Step := TrackBar3.position / 1000;
  end;
end;

procedure TFormHeightField.Timer1Timer(Sender: TObject);
begin
  // Display number of triangles used in the mesh
  // You will note that this number quickly gets out of hand if you are
  // using large high-resolution grids
  LabelFPS.Caption := Format('%d Triangles - %.2f FPS',
    [HeightField1.TriangleCount, GLSceneViewer1.FramesPerSecond]);
  GLSceneViewer1.ResetPerformanceMonitor;
end;

// following code takes care of camera movement, see camera & movement demos
// for explanations and more samples

procedure TFormHeightField.GLSceneViewer1MouseDown(Sender: TObject;
  Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
  mx := X;
  my := Y;
end;

procedure TFormHeightField.GLSceneViewer1MouseMove(Sender: TObject;
  Shift: TShiftState; X, Y: Integer);
begin
  if Shift <> [] then
  begin
    GLCamera1.MoveAroundTarget(my - Y, mx - X);
    mx := X;
    my := Y;
  end;
end;

procedure TFormHeightField.FormMouseWheel(Sender: TObject; Shift: TShiftState;
  WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
begin
  GLCamera1 := GLSceneViewer1.Camera;
  GLCamera1.AdjustDistanceToTarget(Power(1.1, WheelDelta / 150));
end;

end.