unit fGrassD;

interface

uses
  Winapi.Windows,
  Winapi.Messages,
  Winapi.OpenGL,
  System.SysUtils,
  System.Variants,
  System.Classes,
  Vcl.Graphics,
  Vcl.Controls,
  Vcl.Forms,
  Vcl.Dialogs,
  Vcl.StdCtrls,
  Vcl.Imaging.Jpeg,
  Vcl.ComCtrls,
  Vcl.ExtCtrls,
  GLS.Scene,
  GLS.Objects,
  GLS.Cadencer,
  GLS.SceneViewer,
  GLS.Navigator,
  Stage.VectorGeometry,
  GLS.Texture,
  GLS.HeightData,
  GLS.TerrainRenderer,
  GLS.AsyncTimer,
  GLS.Material,
  GLS.Coordinates,
  GLS.XCollection,
  GLS.BaseClasses,
  GLS.RenderContextInfo,
  Stage.TextureFormat,
  Stage.Keyboard,
  Stage.Utils
  ;

type
  TFormGrass = class(TForm)
    GLScene: TGLScene;
    GLSceneViewer: TGLSceneViewer;
    GLCadencer: TGLCadencer;
    Camera: TGLCamera;
    GLNavigator: TGLNavigator;
    GLUserInterface: TGLUserInterface;
    Wind1: TGLDummyCube;
    DirectOpenGL: TGLDirectOpenGL;
    Terrain: TGLTerrainRenderer;
    GLBitmapHDS: TGLBitmapHDS;
    GLAsyncTimer: TGLAsyncTimer;
    MatLib: TGLMaterialLibrary;
    Wind2: TGLDummyCube;
    Wind3: TGLDummyCube;
    Panel: TPanel;
    Leafbar: TTrackBar;
    AnimateBox: TCheckBox;
    LeafLabel: TLabel;
    NodeCountLabel: TLabel;
    NodeCountBar: TTrackBar;
    NodeHLabel: TLabel;
    NodeHBar: TTrackBar;
    NodeAngleLabel: TLabel;
    NodeAngleBar: TTrackBar;
    Label1: TLabel;
    WindRangeBar: TTrackBar;
    WindRangeLabel: TLabel;
    WindPowerLabel: TLabel;
    WindPowerBar: TTrackBar;
    procedure FormCreate(Sender: TObject);
    procedure GLCadencerProgress(Sender: TObject; const deltaTime,
      newTime: Double);
    procedure DirectOpenGLRender(Sender: TObject;
      var rci: TGLRenderContextInfo);
    procedure AsyncTimer1Timer(Sender: TObject);
    procedure LeafbarChange(Sender: TObject);
    procedure GLSceneViewerClick(Sender: TObject);
  private
    Path: TFileName;
    procedure MakeGrass;
    procedure UpdateGrass;
  end;

  TLine = record
    pos: TAffineVector;
    org: TAffineVector;
  end;

  TLines = record
    n: array of TLine;
    dir: TAffineVector;
  end;

var
  FormGrass: TFormGrass;

  org: TAffineVector;
  Lines: array of TLines;
  WindPower: single = 2;
  WindRange: single = 20;
  NodeCount: integer = 3;
  NodeH: single = 1;
  NodeAngle: single = 1;
  // Size: integer=40;
  LeafNum: integer = 1000;
  S: single = 0.3;

//===================================
implementation
//===================================

{$R *.dfm}

procedure TFormGrass.FormCreate(Sender: TObject);
begin
  Path := GetCurrentAssetPath();
  SetCurrentDir(Path  + '\texture');

   GLBitmapHDS.Picture.LoadFromFile('terrain.bmp');
   MatLib.AddTextureMaterial('grass', 'grass.bmp');
   Terrain.Material.Texture.Image.LoadFromFile('clover.jpg');
   UpdateGrass;
   Label1.Caption:='Click on viewer to'#13#10'toggle mouse look +'#13#10'(W,S,A,D)';
end;

procedure TFormGrass.MakeGrass;
var
   n, l: integer;
   opos, ndir: TAffineVector;
   h, xx, yy: single;
   new: boolean;
begin
  if Length(Lines) = LeafNum then
    new := False
  else
    new := True;
  SetLength(Lines, LeafNum);
  for l := 0 to LeafNum - 1 do
  begin
    SetLength(Lines[l].n, NodeCount);
    Lines[l].dir := AffineVectorMake(1, 0, 0);
    Lines[l].dir := VectorRotateAroundY(Lines[l].dir, l / LeafNum * pi * 2);
    Lines[l].dir := VectorNormalize(Lines[l].dir);
    ndir := VectorRotateAroundY(Lines[l].dir, pi / 2);
    if new then
    begin
      xx := Random * 40 - 20;
      yy := Random * 40 - 20;
    end
    else
    begin
      xx := Lines[l].n[0].pos.V[0];
      yy := Lines[l].n[0].pos.V[2];
    end;

    h := Terrain.InterpolatedHeight(VectorMake(xx + 26, 0, yy - 26));
    opos := AffineVectorMake(xx, h + 0.1, yy);
    for n := 0 to Length(Lines[l].n) - 1 do
    begin
      Lines[l].n[n].pos := opos;
      Lines[l].n[n].org := opos;
      Lines[l].n[n].org.V[0] := opos.V[0] + (n / Length(Lines[l].n)) *
        ndir.V[0] * NodeAngle;
      Lines[l].n[n].org.V[1] := opos.V[1] + NodeH;
      Lines[l].n[n].org.V[2] := opos.V[2] + (n / Length(Lines[l].n)) *
        ndir.V[2] * NodeAngle;
      opos := Lines[l].n[n].org;
    end;
  end;
end;

procedure TFormGrass.UpdateGrass;
begin
  with FormGrass do
  begin
    LeafNum := Leafbar.Position;
    NodeCount := NodeCountBar.Position;
    NodeH := NodeHBar.Position / 10;
    NodeAngle := NodeAngleBar.Position / 90 * pi * NodeCount;
    WindRange := WindRangeBar.Position / 10;
    WindPower := WindPowerBar.Position / 10;
    LeafLabel.Caption := 'Leaf count: ' + IntToStr(LeafNum);
    NodeCountLabel.Caption := 'Node count: ' + IntToStr(NodeCount);
    NodeHLabel.Caption := 'Node height: ' + Format('%f', [NodeH]);
    NodeAngleLabel.Caption := 'Node angle: ' + IntToStr(NodeAngleBar.Position);
    WindRangeLabel.Caption := 'Wind range: ' + Format('%f', [WindRange]);
    WindPowerLabel.Caption := 'Wind power: ' + Format('%f', [WindPower]);
    MakeGrass;
  end;
end;

procedure TFormGrass.GLCadencerProgress(Sender: TObject; const deltaTime,
  newTime: Double);
var
   speed: double;
begin
  GLUserInterface.MouseUpdate;
  GLUserInterface.MouseLook;

  speed := 20 * deltaTime;
  if IsKeyDown('W') then
    Camera.Move(speed);
  if IsKeyDown('S') then
    Camera.Move(-speed);
  if IsKeyDown('A') then
    Camera.Slide(-speed);
  if IsKeyDown('D') then
    Camera.Slide(speed);

  if AnimateBox.Checked then
  begin
    Wind1.Position.X := sin(newTime * 4) * 10;
    Wind1.Position.Z := cos(newTime) * 10;
    Wind2.Position.X := sin(newTime) * 10;
    Wind2.Position.Z := cos(newTime * 4) * 10;
    Wind3.Position.X := sin(newTime * 2) * 20;
    Wind3.Position.Z := cos(newTime * 2) * 20;

    Wind1.Position.Y := 2 + Terrain.InterpolatedHeight
      (VectorMake(Wind1.Position.X + 26, 0, Wind1.Position.Z - 26));
    Wind2.Position.Y := 2 + Terrain.InterpolatedHeight
      (VectorMake(Wind2.Position.X + 26, 0, Wind2.Position.Z - 26));
    Wind3.Position.Y := 2 + Terrain.InterpolatedHeight
      (VectorMake(Wind3.Position.X + 26, 0, Wind3.Position.Z - 26));
  end;
end;

procedure TFormGrass.DirectOpenGLRender(Sender: TObject;
  var rci: TGLRenderContextInfo);
var
   i, n, ln, w: integer;
   v, pos, new, w1, w2, tmp: TAffineVector;
   d, ws1, ws2: single;
   Wind: TGLDummyCube;
begin
  glDisable(GL_CULL_FACE);
  glColor3f(1, 1, 1);
  glLineWidth(1);
  MatLib.ApplyMaterial('grass', rci);
  glBegin(GL_TRIANGLES);
  for i := 0 to Length(Lines) - 1 do
  begin
    ws2 := NodeCount * 0.05 + 0.05;
    ws1 := ws2 + 0.05;
    for n := 0 to Length(Lines[i].n) - 1 do
    begin
      tmp := AffineVectorMake(0, 0, 0);
      for w := 1 to 3 do
      begin
        if w = 1 then
          Wind := Wind1
        else if w = 2 then
          Wind := Wind2
        else
          Wind := Wind3;

        V := VectorSubtract(Lines[i].n[n].org, Wind.Position.AsAffineVector);
        d := VectorLength(V);
        if d > WindRange then
          new := Lines[i].n[n].org
        else
        begin
          NormalizeVector(V);
          ScaleVector(V, (1 - d / WindRange) * WindPower);
          new := VectorAdd(Lines[i].n[n].org, V);
        end;
        tmp := VectorAdd(tmp, new);
      end;
      ScaleVector(tmp, 1 / 3);

      new := tmp;
      d := VectorDistance(Lines[i].n[n].pos, new);
      if d > NodeH then
        new.V[1] := new.V[1] - (d - NodeH);
      if new.V[1] < Lines[i].n[n].pos.V[1] then
        new.V[1] := Lines[i].n[n].pos.V[1];
      d := VectorDistance(Lines[i].n[n].pos, new);
      if d > NodeH then
      begin
        V := VectorSubtract(new, Lines[i].n[n].pos);
        NormalizeVector(V);
        ScaleVector(V, NodeH);
        new := VectorAdd(Lines[i].n[n].pos, V);
      end;

      if n < Length(Lines[i].n) - 1 then
      begin
        V := VectorSubtract(new, Lines[i].n[n + 1].pos);
        Lines[i].n[n + 1].pos := new;
        Lines[i].n[n + 1].org := VectorAdd(Lines[i].n[n + 1].org, V);
      end;
      ln := Length(Lines[i].n);

      pos := Lines[i].n[n].pos;
      w1.V[0] := ws1 * Lines[i].dir.V[0];
      w1.V[1] := ws1 * Lines[i].dir.V[1];
      w1.V[2] := ws1 * Lines[i].dir.V[2];
      w2.V[0] := ws2 * Lines[i].dir.V[0];
      w2.V[1] := ws2 * Lines[i].dir.V[1];
      w2.V[2] := ws2 * Lines[i].dir.V[2];

      if n < ln - 1 then
      begin
        glTexCoord2f(0, n / ln);
        glVertex3f(pos.V[0] - w1.V[0], pos.V[1] - w1.V[1], pos.V[2] - w1.V[2]);
        glTexCoord2f(0, (n + 1) / ln);
        glVertex3f(new.V[0] - w2.V[0], new.V[1] - w2.V[1], new.V[2] - w2.V[2]);
        glTexCoord2f(1, n / ln);
        glVertex3f(pos.V[0] + w1.V[0], pos.V[1] + w1.V[1], pos.V[2] + w1.V[2]);

        glTexCoord2f(1, n / ln);
        glVertex3f(pos.V[0] + w1.V[0], pos.V[1] + w1.V[1], pos.V[2] + w1.V[2]);
        glTexCoord2f(0, (n + 1) / ln);
        glVertex3f(new.V[0] - w2.V[0], new.V[1] - w2.V[1], new.V[2] - w2.V[2]);
        glTexCoord2f(1, (n + 1) / ln);
        glVertex3f(new.V[0] + w2.V[0], new.V[1] + w2.V[1], new.V[2] + w2.V[2]);
      end
      else
      begin
        glTexCoord2f(0, n / ln);
        glVertex3f(pos.V[0] - w1.V[0], pos.V[1] - w1.V[1], pos.V[2] - w1.V[2]);
        glTexCoord2f(0.5, n / ln);
        glVertex3f(new.V[0], new.V[1], new.V[2]);
        glTexCoord2f(1, (n + 1) / ln);
        glVertex3f(pos.V[0] + w1.V[0], pos.V[1] + w1.V[1], pos.V[2] + w1.V[2]);
      end;
      ws1 := ws1 - 0.05;
      ws2 := ws2 - 0.05;
    end;
  end;
  glEnd;
  MatLib.UnApplyMaterial(rci);
  glEnable(GL_CULL_FACE);
end;

procedure TFormGrass.AsyncTimer1Timer(Sender: TObject);
begin
   Caption:=Format('Grass with '+'%d faces at %f FPS', [(2*(NodeCount-1)+1)*LeafNum, GLSceneViewer.FramesPerSecond]);
   GLSceneViewer.ResetPerformanceMonitor;
end;

procedure TFormGrass.LeafbarChange(Sender: TObject);
begin
   UpdateGrass;
end;

procedure TFormGrass.GLSceneViewerClick(Sender: TObject);
begin
   GLUserInterface.MouseLookActive:=not GLUserInterface.MouseLookActive;
end;

end.