//
// The graphics engine GLScene
//
unit GLS.SceneForm;

(*  GLScene form loader *)

interface

{$I Stage.Defines.inc}

uses
  Winapi.Windows,
  Winapi.Messages,
  System.Classes,
  VCL.Controls,
  VCL.Forms,
  GLS.Scene,
  GLS.Context,
  GLS.Screen,
  GLS.SceneViewer;

const
  lcl_major = 0;
  lcl_minor = 0;
  lcl_release = 0;

type

  TGLSceneForm = class;

  (* Defines how GLSceneForm will handle fullscreen request
     fcWindowMaximize: Use current resolution (just maximize form and hide OS bars)
     fcNearestResolution: Change to nearest valid resolution from current window size
     fcManualResolution: Use FFullScreenVideoMode settings *)
  TGLFullScreenResolution = (
    fcUseCurrent,
    fcNearestResolution,
    fcManualResolution);

  // Screen mode settings
  TGLFullScreenVideoMode = class(TPersistent)
  private
    FOwner: TGLSceneForm;
    FEnabled: Boolean;
    FAltTabSupportEnable: Boolean;
    FWidth: Integer;
    FHeight: Integer;
    FColorDepth: Integer;
    FFrequency: Integer;
    FResolutionMode: TGLFullScreenResolution;
    procedure SetEnabled(aValue: Boolean);
    procedure SetAltTabSupportEnable(aValue: Boolean);
  public
    constructor Create(AOwner: TGLSceneForm);
  published
    property Enabled: Boolean read FEnabled write SetEnabled default False;
    property AltTabSupportEnable: Boolean read FAltTabSupportEnable
      write SetAltTabSupportEnable default False;
    property ResolutionMode: TGLFullScreenResolution read FResolutionMode
      write FResolutionMode default fcUseCurrent;
    property Width: Integer read FWidth write FWidth;
    property Height: Integer read FHeight write FHeight;
    property ColorDepth: Integer read FColorDepth write FColorDepth;
    property Frequency: Integer read FFrequency write FFrequency;
  end;

  TGLSceneForm = class(TForm)
  private
    FBuffer: TGLSceneBuffer;
    FVSync: TGLVSyncMode;
    FOwnDC: HDC;
    FFullScreenVideoMode: TGLFullScreenVideoMode;
    procedure SetBeforeRender(const val: TNotifyEvent);
    function GetBeforeRender: TNotifyEvent;
    procedure SetPostRender(const val: TNotifyEvent);
    function GetPostRender: TNotifyEvent;
    procedure SetAfterRender(const val: TNotifyEvent);
    function GetAfterRender: TNotifyEvent;
    procedure SetCamera(const val: TGLCamera);
    function GetCamera: TGLCamera;
    procedure SetBuffer(const val: TGLSceneBuffer);
    function GetFieldOfView: single;
    procedure SetFieldOfView(const Value: single);
    function GetIsRenderingContextAvailable: Boolean;
    procedure WMEraseBkgnd(var Message: TWMEraseBkgnd); message WM_ERASEBKGND;
    procedure WMPaint(var Message: TWMPaint); message WM_PAINT;
    procedure WMSize(var Message: TWMSize); message WM_SIZE;
    procedure WMDestroy(var Message: TWMDestroy); message WM_DESTROY;
    procedure LastFocus(var Mess: TMessage); message WM_ACTIVATE;
    procedure SetFullScreenVideoMode(AValue: TGLFullScreenVideoMode);
    procedure StartupFS;
    procedure ShutdownFS;
  protected
    procedure Notification(AComponent: TComponent; Operation: TOperation);
      override;
    procedure CreateWnd; override;
    procedure Loaded; override;
    procedure DoBeforeRender(Sender: TObject); virtual;
    procedure DoBufferChange(Sender: TObject); virtual;
    procedure DoBufferStructuralChange(Sender: TObject); virtual;
    procedure MouseMove(Shift: TShiftState; X, Y: Integer); override;
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
    procedure DestroyWnd; override;
    property IsRenderingContextAvailable: Boolean read
      GetIsRenderingContextAvailable;
    property RenderDC: HDC read FOwnDC;
  published
    // Camera from which the scene is rendered.
    property Camera: TGLCamera read GetCamera write SetCamera;
    (* Specifies if the refresh should be synchronized with the VSync signal.
      If the underlying OpenGL ICD does not support the WGL_EXT_swap_control
      extension, this property is ignored. *)
    property VSync: TGLVSyncMode read FVSync write FVSync default vsmNoSync;
    (* Triggered before the scene's objects get rendered.
      You may use this event to execute your own OpenGL rendering. *)
    property BeforeRender: TNotifyEvent read GetBeforeRender write
      SetBeforeRender;
    (*  Triggered just after all the scene's objects have been rendered.
      The OpenGL context is still active in this event, and you may use it
      to execute your own OpenGL rendering.  *)
    property PostRender: TNotifyEvent read GetPostRender write SetPostRender;
    (* Called after rendering.
      You cannot issue OpenGL calls in this event, if you want to do your own
      OpenGL stuff, use the PostRender event. *)
    property AfterRender: TNotifyEvent read GetAfterRender write SetAfterRender;
    // Access to buffer properties.
    property Buffer: TGLSceneBuffer read FBuffer write SetBuffer;
    (* Returns or sets the field of view for the viewer, in degrees.
      This value depends on the camera and the width and height of the scene.
      The value isn't persisted, if the width/height or camera.focallength is
      changed, FieldOfView is changed also. *)
    property FieldOfView: single read GetFieldOfView write SetFieldOfView;
    property FullScreenVideoMode: TGLFullScreenVideoMode read
      FFullScreenVideoMode
      write SetFullScreenVideoMode;
  end;

//-----------------------------------------------------------------
implementation
//-----------------------------------------------------------------

constructor TGLSceneForm.Create(AOwner: TComponent);
begin
  FBuffer := TGLSceneBuffer.Create(Self);
  FVSync := vsmNoSync;
  FBuffer.ViewerBeforeRender := DoBeforeRender;
  FBuffer.OnChange := DoBufferChange;
  FBuffer.OnStructuralChange := DoBufferStructuralChange;
  FFullScreenVideoMode := TGLFullScreenVideoMode.Create(Self);
  inherited Create(AOwner);
end;

destructor TGLSceneForm.Destroy;
begin
  FBuffer.Free;
  FBuffer := nil;
  FFullScreenVideoMode.Destroy;
  inherited Destroy;
end;


procedure TGLSceneForm.Notification(AComponent: TComponent; Operation:
  TOperation);
begin
  if (Operation = opRemove) and (FBuffer <> nil) then
  begin
    if (AComponent = FBuffer.Camera) then
      FBuffer.Camera := nil;
  end;
  inherited;
end;

procedure TGLSceneForm.CreateWnd;
begin
  inherited CreateWnd;
  // initialize and activate the OpenGL rendering context
  // need to do this only once per window creation as we have a private DC
  FBuffer.Resize(0, 0, Self.Width, Self.Height);
  FOwnDC := GetDC(Handle);
  FBuffer.CreateRC(FOwnDC, false);
end;

procedure TGLSceneForm.DestroyWnd;
begin
  if Assigned(FBuffer) then
  begin
    FBuffer.DestroyRC;
    if FOwnDC <> 0 then
    begin
      ReleaseDC(Handle, FOwnDC);
      FOwnDC := 0;
    end;
  end;
  inherited;
end;

procedure TGLSceneForm.Loaded;
begin
  inherited Loaded;
  // initiate window creation
  HandleNeeded;
  if not (csDesigning in ComponentState) then
  begin
    if FFullScreenVideoMode.FEnabled then
      StartupFS;
  end;
end;

procedure TGLSceneForm.WMEraseBkgnd(var Message: TWMEraseBkgnd);
begin
  if GetIsRenderingContextAvailable then
    Message.Result := 1
  else
    inherited;
end;

procedure TGLSceneForm.WMSize(var Message: TWMSize);
begin
  inherited;
  if Assigned(FBuffer) then
    FBuffer.Resize(0, 0, Message.Width, Message.Height);
end;

procedure TGLSceneForm.WMPaint(var Message: TWMPaint);
var
  PS: TPaintStruct;
begin
  BeginPaint(Handle, PS);
  try
    if GetIsRenderingContextAvailable and (Width > 0) and (Height > 0) then
      FBuffer.Render;
  finally
    EndPaint(Handle, PS);
    Message.Result := 0;
  end;
end;

procedure TGLSceneForm.WMDestroy(var Message: TWMDestroy);
begin
  if Assigned(FBuffer) then
  begin
    FBuffer.DestroyRC;
    if FOwnDC <> 0 then
    begin
      ReleaseDC(Handle, FOwnDC);
      FOwnDC := 0;
    end;
  end;
  inherited;
end;

procedure TGLSceneForm.LastFocus(var Mess: TMessage);
begin
  if not (csDesigning in ComponentState)
    and FFullScreenVideoMode.FEnabled
    and FFullScreenVideoMode.FAltTabSupportEnable then
    begin
      if Mess.wParam = WA_INACTIVE then
      begin
        ShutdownFS;
      end
      else
      begin
        StartupFS;
      end;
    end;
  inherited;
end;

procedure TGLFullScreenVideoMode.SetEnabled(aValue: Boolean);
begin
  if FEnabled <> aValue then
  begin
    FEnabled := aValue;
    if not ((csDesigning in FOwner.ComponentState)
      or (csLoading in FOwner.ComponentState)) then
    begin
      if FEnabled then
        FOwner.StartupFS
      else
        FOwner.ShutdownFS;
    end;
  end;
end;

constructor TGLFullScreenVideoMode.Create(AOwner: TGLSceneForm);
begin
  inherited Create;
  FOwner := AOwner;
  FEnabled := False;
  FAltTabSupportEnable := False;
  ReadVideoModes;
{$IFDEF MSWINDOWS}
  FWidth := vVideoModes[0].Width;
  FHeight := vVideoModes[0].Height;
  FColorDepth := vVideoModes[0].ColorDepth;
  FFrequency := vVideoModes[0].MaxFrequency;
{$ENDIF}
  if FFrequency = 0 then
    FFrequency := 50;
  FResolutionMode := fcUseCurrent;
end;

procedure TGLFullScreenVideoMode.SetAltTabSupportEnable(aValue: Boolean);
begin
  if FAltTabSupportEnable <> aValue then
    FAltTabSupportEnable := aValue;
end;

procedure TGLSceneForm.StartupFS;
begin
  case FFullScreenVideoMode.FResolutionMode of
    fcNearestResolution:
      begin
        SetFullscreenMode(GetIndexFromResolution(ClientWidth, ClientHeight,
{$IFDEF MSWINDOWS}
        vVideoModes[0].ColorDepth));
{$ELSE}
        32));
{$ENDIF}
      end;
    fcManualResolution:
      begin
        SetFullscreenMode(GetIndexFromResolution(FFullScreenVideoMode.Width , FFullScreenVideoMode.Height, FFullScreenVideoMode.ColorDepth), FFullScreenVideoMode.Frequency);
      end;
  end;

  Left := 0;
  Top := 0;
  BorderStyle := bsNone;
  FormStyle := fsStayOnTop;
  BringToFront;
  WindowState := wsMaximized;

  Application.MainFormOnTaskBar := True;
end;

procedure TGLSceneForm.ShutdownFS;
begin
  RestoreDefaultMode;
  SendToBack;
  WindowState := wsNormal;
  BorderStyle := bsSingle;
  FormStyle := fsNormal;
  Left := (Screen.Width div 2) - (Width div 2);
  Top := (Screen.Height div 2) - (Height div 2);
end;

procedure TGLSceneForm.DoBeforeRender(Sender: TObject);
begin
  SetupVSync(VSync);
end;

procedure TGLSceneForm.DoBufferChange(Sender: TObject);
begin
  if (not Buffer.Rendering) and (not Buffer.Freezed) then
    Invalidate;
end;


procedure TGLSceneForm.DoBufferStructuralChange(Sender: TObject);
begin
  RecreateWnd;
end;

procedure TGLSceneForm.MouseMove(Shift: TShiftState; X, Y: Integer);
begin
  inherited;
  if csDesignInteractive in ControlStyle then
    FBuffer.NotifyMouseMove(Shift, X, Y);
end;


procedure TGLSceneForm.SetBeforeRender(const val: TNotifyEvent);
begin
  FBuffer.BeforeRender := val;
end;


function TGLSceneForm.GetBeforeRender: TNotifyEvent;
begin
  Result := FBuffer.BeforeRender;
end;


procedure TGLSceneForm.SetPostRender(const val: TNotifyEvent);
begin
  FBuffer.PostRender := val;
end;

function TGLSceneForm.GetPostRender: TNotifyEvent;
begin
  Result := FBuffer.PostRender;
end;


procedure TGLSceneForm.SetAfterRender(const val: TNotifyEvent);
begin
  FBuffer.AfterRender := val;
end;

function TGLSceneForm.GetAfterRender: TNotifyEvent;
begin
  Result := FBuffer.AfterRender;
end;

procedure TGLSceneForm.SetCamera(const val: TGLCamera);
begin
  FBuffer.Camera := val;
end;

function TGLSceneForm.GetCamera: TGLCamera;
begin
  Result := FBuffer.Camera;
end;

procedure TGLSceneForm.SetBuffer(const val: TGLSceneBuffer);
begin
  FBuffer.Assign(val);
end;

function TGLSceneForm.GetFieldOfView: single;
begin
  if not Assigned(Camera) then
    Result := 0
  else if Width < Height then
    Result := Camera.GetFieldOfView(Width)
  else
    Result := Camera.GetFieldOfView(Height);
end;

procedure TGLSceneForm.SetFieldOfView(const Value: single);
begin
  if Assigned(Camera) then
  begin
    if Width < Height then
      Camera.SetFieldOfView(Value, Width)
    else
      Camera.SetFieldOfView(Value, Height);
  end;
end;

procedure TGLSceneForm.SetFullScreenVideoMode(AValue: TGLFullScreenVideoMode);
begin
end;

function TGLSceneForm.GetIsRenderingContextAvailable: Boolean;
begin
  Result := FBuffer.RCInstantiated and FBuffer.RenderingContext.IsValid;
end;

// ------------------------------------------------------------------
initialization
// ------------------------------------------------------------------

  RegisterClass(TGLSceneForm);

end.