//
// The graphics engine GLScene
//
unit Formats.DDSImage;
(*
    Alternative for DDS unit with more supported formats of flat image:
    Alpha8, Luminance8, R3G3B2, RGB5A1, RGBA4, Alpha8Luminance8, Luminance16, R5G6B5,
    RGB8, R10G10B10A2, RGBA8, RGBA16, R16F, RGBA16F, R32F, RGBA32F, GR16, GR16F, GR32F,
    Compressed RGB S3TC DXT1, Compressed RGBA S3TC DXT1, Compressed RGBA S3TC DXT3,
    Compressed RGBA S3TC DXT5
    But it down color to RGBA8 because becomes to TBitmap
    Good for preview picture in OpenDialog,
    so you may include both DDSImage (preview) and GLFileDDS (loading)
*)
interface

{$I Stage.Defines.inc}

uses
  Winapi.Windows,
  System.Classes,
  System.SysUtils,
  Vcl.Graphics,

  Stage.VectorTypes,
  Stage.OpenGLTokens,
  Stage.VectorGeometry,
  GLS.Graphics,
  GLS.Context,
  GLS.FileDDS,
  Stage.TextureFormat;

type
  TDDSImage = class(TBitmap)
  public
    procedure LoadFromStream(stream: TStream); override;
    procedure SaveToStream(stream: TStream); override;
  end;

  EDDSException = class(Exception);

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

uses
  Formats.DXTC;

// ------------------
// ------------------ TDDSImage ------------------
// ------------------

procedure TDDSImage.LoadFromStream(stream: TStream);
var
  FullDDS: TGLDDSImage;
  bCubeMap: Boolean;
  src, dst: PGLubyte;
  y: integer;
begin
  FullDDS := TGLDDSImage.Create;
  try
    FullDDS.LoadFromStream(stream);
  except
    FullDDS.Free;
    raise;
  end;

  bCubeMap := FullDDS.CubeMap;
  FullDDS.Narrow;

  PixelFormat := pf32bit;
  Transparent := True;
  Width := FullDDS.LevelWidth[0];
  Height := FullDDS.LevelHeight[0];

  src := PGLubyte(FullDDS.Data);
  if bCubeMap then
    for y := 0 to Height - 1 do
    begin
      dst := ScanLine[y];
      BGRA32ToRGBA32(src, dst, Width);
      Inc(src, Width * 4);
    end
  else
    for y := 0 to Height - 1 do
    begin
      dst := ScanLine[Height - 1 - y];
      BGRA32ToRGBA32(src, dst, Width);
      Inc(src, Width * 4);
    end;
  FullDDS.Free;
end;

procedure TDDSImage.SaveToStream(stream: TStream);
const
  Magic: array[0..3] of AnsiChar = 'DDS ';
var
  header: TDDSHeader;
  rowSize: integer;
  i: Integer;

begin
  FillChar(header, SizeOf(TDDSHeader), 0);
  header.magic := cardinal(Magic);
  with header.SurfaceFormat do
  begin
    dwSize := sizeof(TDDSURFACEDESC2);
    dwFlags := DDSD_CAPS + DDSD_PIXELFORMAT + DDSD_WIDTH + DDSD_HEIGHT + DDSD_PITCH;
    dwWidth := Width;
    dwHeight := Height;
    ddpf.dwSize := sizeof(TDDPIXELFORMAT);
    case PixelFormat of
{$IFDEF MSWINDOWS}
      pf24bit:
        begin
          ddpf.dwFlags := DDPF_RGB;
          ddpf.dwRGBBitCount := 24;
          ddpf.dwRBitMask := $00FF0000;
          ddpf.dwGBitMask := $0000FF00;
          ddpf.dwBBitMask := $000000FF;
        end;
{$ENDIF}
      pf32bit:
        begin
          ddpf.dwFlags := DDPF_RGB;
          ddpf.dwRGBBitCount := 32;
          ddpf.dwRBitMask := $00FF0000;
          ddpf.dwGBitMask := $0000FF00;
          ddpf.dwBBitMask := $000000FF;
          if Transparent then
          begin
            ddpf.dwFlags := ddpf.dwFlags + DDPF_ALPHAPIXELS;
            ddpf.dwRGBAlphaBitMask := $FF000000;
          end;
        end;
    else
      raise EDDSException.Create('Unsupported pixel format');
    end;
    rowSize := (ddpf.dwRGBBitCount div 8) * dwWidth;
    dwPitchOrLinearSize := dwHeight * cardinal(rowSize);
    dwCaps := DDSCAPS_TEXTURE;
    stream.Write(header, SizeOf(TDDSHeader));
    for i := 0 to Height - 1 do
      stream.Write(ScanLine[i]^, rowSize);
  end;
end;

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

  TPicture.RegisterFileFormat(
    'dds', 'Microsoft DirectDraw Surface', TDDSImage);

// ------------------------------------------------------------------
finalization
// ------------------------------------------------------------------

  TPicture.UnregisterGraphicClass(TDDSImage);

end.