Font wglUseFontOutlines Anti-aliasing

[WhatJac3]

Hello,

I have a problem with anti-aliasing the font that I use in my application. I have seen that more people had that problem but when trying does implementations they don't seem to work for me. When I set my anti-aliasing from my graphics card (ATI control panel) from application managed to 4x the fonts look smooth like they should. But I can't let everyone who uses my application have to change their anti aliasing settings on the graphics card. I know it can be done in the application, but I cant seem to get it work.

Here is my current code:

procedure GLInit();
begin
 glClearColor(1.0, 1.0, 1.0, 1.0); 	  // White Background
 glDisable(Gl_DEPTH_TEST);
 glEnable (GL_POLYGON_SMOOTH);
 glEnable(GL_BLEND);
 glDisable(GL_CULL_FACE);
 glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 glHint (GL_POLYGON_SMOOTH_HINT, GL_NICEST);	
 BuildFont;
end;

procedure BuildFont();
var
 font:HFont;
begin
 fontOffset := glGenLists (256);
 font := CreateFont(-cFontHeight, 0, 0, 0, 0, 0, 0, 0,
     ANSI_CHARSET, OUT_TT_PRECIS,
     CLIP_DEFAULT_PRECIS, ANTIALIASED_QUALITY,
     FF_DONTCARE or DEFAULT_PITCH, cFont);
 SelectObject(DC, font);
 wglUseFontOutlines(DC, 0, 255, fontOffSet, 0.0, 0.0, WGL_FONT_POLYGONS, @gmf);
end;

And my pixel format:

procedure GLFormCreate(AHandle: HWND);
var pfd : TPIXELFORMATDESCRIPTOR;
  pf : Integer;
begin
 dc:=GetDC(AHandle);

 // PixelFormat
 pfd.nSize:=sizeof(pfd);
 pfd.nVersion:=1;
 pfd.dwFlags:=PFD_DRAW_TO_WINDOW or PFD_SUPPORT_OPENGL or PFD_DOUBLEBUFFER;
 pfd.iPixelType:=PFD_TYPE_RGBA;  
 pfd.cColorBits:=24;

 pf :=ChoosePixelFormat(dc, @pfd); 
 SetPixelFormat(dc, pf, @pfd);

 rc :=wglCreateContext(dc);
 wglMakeCurrent(dc,rc);  

 // Initialist GL environment variables
 glInit;
 GLResize();  // sets up the perspective
end;

If I change everything to GL_Line, so:

WGL_FONT_POLYGONS = WGL_FONT_LINES
GL_POLYGON_SMOOTH = GL_LINE_SMOOTH
GL_POLYGON_SMOOTH_HINT = GL_LINE_SMOOTH_HINT

I get nice smooth fonts, but only the outlines of the fonts. They are not filled. Anyone has any idea what I am doing wrong?

[VilleK]

The kind of antialiasing that you set in the GPU control panel is actually called "multisample" and requires quite a bit of code to initialize yourself.

See this NeHe-tutorial:

http://nehe.gamedev.net/data/lessons....asp?lesson=46

[WhatJac3]

Thanks for your reply. I have downloaded the example and had to change one thing (added the red part):

wglGetExtString: function(hdc: HDC): PAnsiChar; stdcall;


Now when I go debugging wglChoosePixelFormatARB returns false both times (bit either 4 and 2). My videocard (ATI control panel) gives me 8x, 4x and 2x anti-aliasing options. So I can't believe that OpenGL tells me it is not supported. Anyone has any idea what is wrong here?

If I open the OpenGL Extension Viewer it tells met that WGL_ARB_Multisample is a correct extension.

If I list the pixel formats it tell me for instance that pixel format 30 has:
WGL_DOUBLE_BUFFER_ARB = TRUE
WG_ACCELERATION_ARB = TRUE
WGL_PIXEL_TYPE_ARB = 0
WGL_SAMPLES_ARB = 8

Any idea why it doesn't work? Even if I use the options from a correct pixelformat (nr 14 accoring to OpenGL Extensions Viewer), I still get a false as return value.

[WhatJac3]

Or does anyone know how to list all pixelformats? If I choose one myself from OpenGL Extensions Viewer with Anti-aliasing, it works perfect. So if I could list all options I would be able to pick the most appropriate, since the example from NeHe does not work.

[User137]

Did you purposefully disable anti-aliasing from graphics card settings or are they set on "application-control"? Those settings can lock anything from using it... ofc depends on manufacturer etc.

[WhatJac3]

It is set on application-control.

I am now iterating through the pixelformats with:

 K := DescribePixelFormat(dc, 1, L , pfd);
 while K do
 begin
  K := DescribePixelFormat(dc, J, L , pfd);
  J := J + 1;
 end;

Now I only need to find a way to check the value of WGL_SAMPLES_ARB from pfd to find the best possible pixelformat.

[WhatJac3]

I fixed the NeHe example. It has one problem. This is what should be done.

In ARB_multisample add:

type
 TGLLongArray = array[0..21] of GLInt;
 PGLLongArray = ^TGLLongArray;

change wglChoosePixelFormatARB into:

 wglChoosePixelFormatARB: function(hdc: HDC; piAttribIList: PGLLongArray; pfAttribFList: PGLfloat; nMaxFormats: GLuint; piFormats: PGLint; nNumFormats: PGLuint): BOOL; stdcall;

Add after the iAttributes[21] := 0;

tmp := @iAttributes;

Change valid := wglChoosePixelFormatARB into

valid := wglChoosePixelFormatARB(h_dc,tmp,@fattributes,1,@pixelFormat,@numFormats);

Now the example works. Enjoy!