(******************************************************************************
                           A3D nGine 2003
                    a3d.intelligentdevelopment.sk
                   kollar@intelligentdevelopment.sk

                    Open Source 3D Graphics Engine

 ******************************************************************************
 *                                                                            *
 * This program is distributed in the hope that it will be useful,            *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of             *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the              *
 * GNU General Public License for more details.                               *
 *                                                                            *
 ******************************************************************************)
unit A3D_GAMMA;

interface
uses math, windows;

type

  TGammaRamp = packed record
    R, G, B: array[0..255] of Word;
  end;

procedure A3D_StoreOriginalGamma(dc: HDC);
procedure A3D_SetNewGamma(dc: HDC; val: single);
procedure A3D_RestoreGamma(dc: HDC);

var
  originalRamp, adjustedRamp: TGammaRamp;

implementation

procedure A3D_StoreOriginalGamma(dc: HDC);
begin

  // Get the system's current gamma ramp, so we can restore later.
  FillChar(originalRamp, SizeOf(originalRamp), 0);
  GetDeviceGammaRamp(dc, originalRamp);
  adjustedRamp := originalRamp;


end;

procedure A3D_SetNewGamma(dc: HDC; val: single);
var i, v            : integer;
begin
  for i := 0 to 255 do
  begin
    v := Round(255 * Power(i / 255, val));
    if v > 255 then v := 255;
    // You can adjust each curve separately, but you usually shouldn't need to.
    adjustedRamp.R[i] := v shl 8;
    adjustedRamp.G[i] := v shl 8;
    adjustedRamp.B[i] := v shl 8;
  end;

  // Send the adjusted gamma ramp to the video card.
  SetDeviceGammaRamp(dc, adjustedRamp);


end;

procedure A3D_RestoreGamma(dc: HDC);
begin
  SetDeviceGammaRamp(dc, originalRamp);
end;
end.