Blur Image

[wagenheimer]

Hi!

I need to blur a texture using ZenGL. It does not need to be very fast because I need to blur it once and I will use it for several frames (I want to blur everything bellow a Game Dialog).

Andrey converted this code of a BoxBlur to me, it works very well, but it does have two side-effects!

- To works well I need to use it twice (or the blur will be very weak).
- The blurred image seems to be some pixels off, so I get a strange effect, it seems the background was moved.

procedure BoxBlur(var Texture: zglPTexture);
  var
    X, Y: Integer;
    yLine, xLine: PByteArray;
    data : PByteArray;
    realWidth : Integer;
    realHeight : Integer;
begin
  realWidth := Round( Texture.Width / Texture.U );
  realHeight := Round( Texture.Height / Texture.V );
  tex_GetData(Texture, data);
  for Y := 1 to realHeight - 2 do
  begin
    yLine := @data[ realWidth * ( Y - 1 ) * 4 ];
    xLine := @data[ realWidth * Y * 4 ];
    for X := 1 to realWidth - 2 do
    begin
      xLine^[X * 4    ] := (xLine^[X * 4 - 4] + xLine^[X * 4 + 4] + yLine^[X * 4 - 4] + yLine^[X * 4 + 4] + yLine^[X * 4    ] + xLine^[X * 4 - 4] + xLine^[X * 4 + 4] + xLine^[X * 4]) div 8;
      xLine^[X * 4 + 1] := (xLine^[X * 4 - 3] + xLine^[X * 4 + 5] + yLine^[X * 4 - 3] + yLine^[X * 4 + 5] + yLine^[X * 4 + 1] + xLine^[X * 4 - 3] + xLine^[X * 4 + 5] + xLine^[X * 4 + 1]) div 8;
      xLine^[X * 4 + 2] := (xLine^[X * 4 - 2] + xLine^[X * 4 + 6] + yLine^[X * 4 - 2] + yLine^[X * 4 + 6] + yLine^[X * 4 + 2] + xLine^[X * 4 - 2] + xLine^[X * 4 + 6] + xLine^[X * 4 + 2]) div 8;
    end;
  end;
  tex_SetData(Texture, data, 0, 0, realWidth, Texture.Height);
  zgl_FreeMem( data );
end;

Anybody have to suggest some alternative blurring routine? A Gaussian Blur seems to be ideal, but I wasn't able to convert it to ZenGL after some tries.

Thanks