vector fonts? (freetype for pascal?)

[noeska]

Is it possible to use vector fonts with opengl? I know of wgl, but that is windows only.
Now there is also freetype2. It is supposed to be able to give access to the vector data of the glyph. That give me 3 questions:
1. Is there a delphi/pascal unit for freetype2?
2. How does rendering a glyph work? Bezier->Polygon->Triangulate?
3. Has someone else already done the hard work?

With knowing how point 2 works. The font can also be save in like a milkshape ascii format. So the original font is not needed.

[JernejL]

Is it possible to use vector fonts with opengl? I know of wgl, but that is windows only.
Now there is also freetype2. It is supposed to be able to give access to the vector data of the glyph. That give me 3 questions:
1. Is there a delphi/pascal unit for freetype2?
2. How does rendering a glyph work? Bezier->Polygon->Triangulate?
3. Has someone else already done the hard work?

With knowing how point 2 works. The font can also be save in like a milkshape ascii format. So the original font is not needed.

1. no
2. yes
3. no

I was considering doing this a while ago, but i did experiments (using WGL font outlines and converting them to mesh using feedback buffer), but the renderings were, well let me put it simply, the renderings looked like crap at low scale without AA, and you can't force users to use AA.. so they weren't useable for anything else but large text (it was totally unsuitable for hud text etc..).

[Brainer]

Maybe this could be of any help: http://nopaste.info/51922ec7d4.html.

[noeska]

As always torry is verry helpful as it provides a ttf2vector component. Now this solutions is also windows only. But gives access to the font coords. And allowed me to render with GL_LINES.
http://www.torry.net/quicksearchd.ph...ctor&Title=Yes
so with this i should also be able to extrude etc. I have yet to test it with my experimental 2dpolygon render to see if it can render it solid also, but i expect no problems there. It just needs a good cleanup.
And more importantly it is possible to save the font coords. So it is possible to render a font that is not available on the end user system. The ony thing to worry about is precission.

Only the font generator application would only run on windows only.

But for linux support freetype(2) is really needed.

Example:

Init

  TTF2Vector := TTTFToVectorConverter.Create(DGLForm);
  TTF2Vector.Font := TFont.Create();
  TTF2Vector.Font.Name := 'Arial';
  // Setup spline precision (1 min, 100 max)
  TTF2Vector.Precision := 1;

Render

  // Get glyphs' strokes
    glyphs := TTF2Vector.GetCharacterGlyphs( ord('m') );
    if glyphs = nil then // May be a "empty" glyph !!!!
      beep;
    // Get character bounds
    cbounds := glyphs.Bounds;
    xm := (cbounds.Right-cbounds.Left+1) div 2;
    ym := (cbounds.Bottom-cbounds.Top+1) div 2;
    // Compute the scaling factors
    sx := 0.5;//(PaintBox.Width-20)/(cbounds.Right-cbounds.Left+1);
    sy := 0.5;//(PaintBox.Height-20)/(cbounds.Bottom-cbounds.Top+1);

    for i := 0 to glyphs.Count-1 do
    begin
      // Get a stroke
      stroke := glyphs.Stroke[i];

        x1 := 10 + round( (stroke.Pt1.X-cbounds.Left) * sx );
        x2 := 10 + round( (stroke.Pt2.X-cbounds.Left) * sx );
        y1 := 10 + round( (stroke.Pt1.Y-cbounds.Top) * sy );
        y2 := 10 + round( (stroke.Pt2.Y-cbounds.Top) * sy );

      // Draw the stroke
      glBegin(GL_LINES);
        glVertex3f(x1/1000, (y1-1)/1000, 0);
        glVertex3f(x2/1000, (y2-1)/1000,0);
      glEnd();

    end;
    // Free the glyphs
    glyphs.Free;

[JernejL]

Any pictures of how the font looks rendered?

[noeska]

for the moment not as good as expected:


But that is due to my polygon tesselation that goes haywire on the i character.

[chronozphere]

You might want to triangulate the polygon's yourself using earclipping. As far as i can tell, it's not that hard to do.

It looks good so far. Great efforts.

[noeska]

I am using glu tesselation now. And with good results. Only how do i implement it as part of an class?

gluTessCallback(tess, GLU_TESS_BEGIN, @tessBeginCB);

@tessBeginCB cannot be part of the class and has to be an real procedure with stdcall.

[JernejL]

I am using glu tesselation now. And with good results. Only how do i implement it as part of an class?

gluTessCallback(tess, GLU_TESS_BEGIN, @tessBeginCB);

@tessBeginCB cannot be part of the class and has to be an real procedure with stdcall.

sort of userdata pointer and global function?

[noeska]

My TPolygon Class: (MPL license)

unit Polygon;

interface

uses DGLOpenGL;

type
TPoint = packed record
  x: single;
  y: single;
  z: single;
  r: single;
  g: single;
  b: single;
  a: single;
end;

TPolygon = class
private
  FPoints: array of TPoint; //polygon point
  FVertex: array of TPoint; //triangulated data
  FColor: TPoint;
  FCount: integer;
  FVertexCount: integer;
  FTesselated: boolean;
  procedure SetPoint(I: integer; Value: TPoint);
  procedure AddVertex(x: single; y: single; z: single; r: single; g: single; b: single; a:single);
  function GetPoint(I: integer): TPoint;
  function GetCount(): integer;
  procedure tessBegin(which: GLenum);
  procedure tessEnd();
  procedure tessVertex(x: single; y: single; z: single; r: single; g: single; b: single; a:single);
public
  constructor Create();
  destructor Destroy();
  procedure SetColor(R: single; G: single; B: single;A: single);
  procedure Add(X: single; Y: single); overload;
  procedure Add(X: single; Y: single; Z: single); overload;
  procedure Add(X: single; Y: single; Z: single; R: single; G: single; B: single; A: single); overload;
  procedure Render();
  procedure Tesselate();
  property Points[I: integer]: TPoint read GetPoint write SetPoint;
  property Count: integer read GetCount;
end;

implementation

type
     TGLArrayd6 = array[0..5] of GLDouble;
     PGLArrayd6 = ^TGLArrayd6;
     TGLArrayvertex4 = array[0..3] of PGLArrayd6;
     PGLArrayvertex4 = ^TGLArrayvertex4;
     PGLArrayf4 = ^TGLArrayf4;

threadvar
  PolygonClass: TPolygon;

procedure TPolygon.SetColor(R: single; G: single; B: single;A: single);
begin
  FColor.r := R;
  FColor.g := G;
  FColor.b := B;
  FColor.a := A;
end;

procedure TPolygon.tessBegin(which: GLenum);
begin
    glBegin(which);
end;

procedure TPolygon.tessEnd();
begin
    glEnd();
end;

procedure TPolygon.tessVertex(x: single; y: single; z: single; r: single; g: single; b: single; a:single);
begin
    glcolor3f(r,g,b);
    glVertex3f(x,y,z);
end;

procedure TPolygon.AddVertex(x: single; y: single; z: single; r: single; g: single; b: single; a:single);
begin
    FVertexCount := FVertexCount + 1;
    SetLength(FVertex, FVertexCount);

    FVertex[FVertexCount-1].R := R;
    FVertex[FVertexCount-1].G := G;
    FVertex[FVertexCount-1].B := B;

    FVertex[FVertexCount-1].X := X;
    FVertex[FVertexCount-1].Y := Y;
    FVertex[FVertexCount-1].Z := Z;
end;

constructor TPolygon.Create();
begin
  inherited Create();
  FCount := 0;
  FVertexCount := 0;
  FTesselated := false;
  FColor.R := 0.0;
  FColor.G := 0.0;
  FColor.B := 0.0;
  FColor.A := 0.0;
end;

destructor TPolygon.Destroy();
begin
  FTesselated := false;
  FCount := 0;
  FVertexCount := 0;
  SetLength(FPoints, FCount);
  SetLength(FVertex, FVertexCount);
  inherited Destroy;
end;

procedure TPolygon.SetPoint(I: integer; Value: TPoint);
begin
  FTesselated := false; //check first on changed values
  FPoints[I] := Value;
end;

function TPolygon.GetPoint(I: integer): TPoint;
begin
  result := FPoints[I];
end;

function TPolygon.GetCount(): integer;
begin
  result := FCount;
end;

procedure TPolygon.Add(X: single; Y: single);
begin
  FTesselated := false;
  FCount := FCount + 1;
  SetLength(FPoints, FCount);
  FPoints[FCount-1].X := X;
  FPoints[FCount-1].Y := Y;
  FPoints[FCount-1].Z := 0.0;
  FPoints[FCount-1].R := FColor.R;
  FPoints[FCount-1].G := FColor.G;
  FPoints[FCount-1].B := FColor.B;
  FPoints[FCount-1].A := FColor.A;
end;

procedure TPolygon.Add(X: single; Y: single; Z: single);
begin
  FTesselated := false;
  FCount := FCount + 1;
  SetLength(FPoints, FCount);
  FPoints[FCount-1].X := X;
  FPoints[FCount-1].Y := Y;
  FPoints[FCount-1].Z := Z;
  FPoints[FCount-1].R := FColor.R;
  FPoints[FCount-1].G := FColor.G;
  FPoints[FCount-1].B := FColor.B;
  FPoints[FCount-1].A := FColor.A;
end;

procedure TPolygon.Add(X: single; Y: single; Z: single; R: single; G: single; B: single; A: single);
begin
  FTesselated := false;
  FCount := FCount + 1;
  SetLength(FPoints, FCount);
  FPoints[FCount-1].X := X;
  FPoints[FCount-1].Y := Y;
  FPoints[FCount-1].Z := Z;
  FPoints[FCount-1].R := R;
  FPoints[FCount-1].G := G;
  FPoints[FCount-1].B := B;
  FPoints[FCount-1].A := A;
end;

Procedure TPolygon.Render();
var
  loop: integer;
begin
  if FTesselated = false then Tesselate;

  glbegin(GL_TRIANGLES);
  for loop:=0 to FVertexCount-1 do
  begin
    glcolor3f(FVertex[loop].R,FVertex[loop].G,FVertex[loop].B);
    glvertex3f(FVertex[loop].X,FVertex[loop].Y,FVertex[loop].Z);
  end;
  glend;
end;

procedure TPolygon.Tesselate();
var
  loop: integer;
  tess: pointer;
  test: TGLArrayd3;
  pol: PGLArrayd6;

  MyTest: string;

procedure iTessBeginCB(which: GLenum); {$IFDEF Win32}stdcall; {$ELSE}cdecl; {$ENDIF}
begin
  //PolygonClass.tessBegin(which);
end;

procedure iTessEndCB(); {$IFDEF Win32}stdcall; {$ELSE}cdecl; {$ENDIF}
begin
  //PolygonClass.tessEnd();
end;

procedure iTessEdgeCB(flag: GLboolean; lpContext: pointer); {$IFDEF Win32}stdcall; {$ELSE}cdecl; {$ENDIF}
begin
      //just do nothing to force GL_TRIANGLES !!!
end;

procedure iTessVertexCB(data: PGLArrayd6); {$IFDEF Win32}stdcall; {$ELSE}cdecl; {$ENDIF}
begin
  //PolygonClass.tessVertex(data[0], data[1], data[2], data[3], data[4], data[5],0);
  PolygonClass.AddVertex(data[0], data[1], data[2], data[3], data[4], data[5],0);
end;


procedure iTessCombineCB(newVertex : PGLArrayd6; neighborVertex : Pointer;
                      neighborWeight : Pointer; var outData : Pointer); {$IFDEF Win32}stdcall; {$ELSE}cdecl; {$ENDIF}
var
  vertex: PGLArrayd6;
  loop: integer;
  colorloop: integer;
  color: double;
begin
  new(vertex);

  vertex[0] := newVertex^[0];
  vertex[1] := newVertex^[1];
  vertex[2] := newVertex^[2];

  for colorloop := 3 to 5 do
  begin
    vertex[colorloop] := 0.0;
    for loop:=0 to 3 do
    begin
      if PGLArrayf4&#40;neighborWeight&#41;^&#91;loop&#93; <> 0 then
      begin
        vertex&#91;colorloop&#93; &#58;= vertex&#91;colorloop&#93; +
             PGLArrayf4&#40;neighborWeight&#41;^&#91;loop&#93; *
             PGLArrayvertex4&#40;neighborVertex&#41;^&#91;loop&#93;&#91;colorloop&#93;
      end;
    end;
  end;

  // return output data &#40;vertex coords and others&#41;
  outData&#58;= vertex;
end;

begin
  PolygonClass &#58;= Self;

  tess &#58;= gluNewTess&#40;&#41;;

  gluTessCallback&#40;tess, GLU_TESS_BEGIN, @iTessBeginCB &#41;;
  gluTessCallback&#40;tess, GLU_TESS_END, @iTessEndCB&#41;;
  gluTessCallback&#40;tess, GLU_TESS_VERTEX, @iTessVertexCB&#41;;
  gluTessCallback&#40;tess, GLU_TESS_COMBINE, @iTessCombineCB&#41;;  //does not work for font?
  gluTessCallback&#40;tess, GLU_TESS_EDGE_FLAG_DATA, @iTessEdgeCB&#41;; //force triangles

  gluTessProperty&#40;tess, GLU_TESS_WINDING_RULE, GLU_TESS_WINDING_NONZERO &#41;;

  gluTessBeginPolygon&#40;tess, nil&#41;;                   // with NULL data
  gluTessBeginContour&#40;tess&#41;;

  for loop &#58;= 0 to FCount-1 do
  begin
      new&#40;pol&#41;;
      pol&#91;3&#93;&#58;=FPoints&#91;loop&#93;.R; //color
      pol&#91;4&#93;&#58;=FPoints&#91;loop&#93;.G;
      pol&#91;5&#93;&#58;=FPoints&#91;loop&#93;.B;

      pol&#91;0&#93;&#58;=FPoints&#91;loop&#93;.X;
      pol&#91;1&#93;&#58;=FPoints&#91;loop&#93;.Y;
      pol&#91;2&#93;&#58;=0;

      test&#91;0&#93; &#58;= pol&#91;0&#93;;
      test&#91;1&#93; &#58;= pol&#91;1&#93;;
      test&#91;2&#93; &#58;= pol&#91;2&#93;;
      gluTessVertex&#40;tess, test, pol&#41;;
  end;

  gluTessEndContour&#40;tess&#41;;
  gluTessEndPolygon&#40;tess&#41;;
  gluDeleteTess&#40;tess&#41;;        // delete after tessellation

  PolygonClass &#58;= nil;
  FTesselated &#58;= true;
end;

end.