GLU Tesselation problem

[JSoftware]

You have the code already. It only varies on this line:
gluTessBeginPolygon(tess,nil);

if i import the procedure without the second parameter it'll give me an accessviolation.

glu32.dll you mean? i'm using ver 5.1.2600.2180 from microsoft. The one that came with sp2

edit: try yourself www.graesdal.dk/Project3.zip

[JernejL]

omg, you are right! must be the bug-ridden and outdated delphi 4 opengl header i used works perfectly now!

[JSoftware]

I'm surprised too mine actually works, as i just copied the one supplied with delphi 5

[JernejL]

Cool, it works perfectly now, i also implemented callback for adding new vertices, so self intresecting polygons work now! (tested! ) so make use of this code as much as you need, i'm posting this so that google bots find it and if anybody has problems with this it is here to help

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, Buttons, opengl;

type

DVector = packed record
x, y, z: double;
end;

PDVector = ^DVector;

Tweight = array[0..3] of single;
Tvertexdata = array[0..3] of longword;

  TForm1 = class(TForm)
    BitBtn1: TBitBtn;
    output: TMemo;
    procedure BitBtn1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  poly: array of DVector;

const
  GLU_TESS_VERTEX_DATA    = 100107;
  GLU_TESS_BEGIN_DATA     = 100106;
  GLU_TESS_EDGE_FLAG_DATA = 100110;
  GLU_TESS_COMBINE_DATA   = 100111;

procedure gluTessBeginPolygon( tess: GLUtesselator; gon_data: Pointer ); stdcall; external glu32;

implementation

{$R *.DFM}

procedure TForm1.BitBtn1Click(Sender: TObject);
var
tess: GLUtesselator;
i: integer;

   procedure tessError(errno : GLEnum); stdcall;
   begin
   showmessage('error, ERROR! ' + inttostr(errno));
   end;

   procedure ElementBegin (mode: GLenum); stdcall;
   begin
   unit1.Form1.output.lines.add('BEGIN ' + inttostr(mode));
   end;

   procedure ElementEnd; stdcall;
   begin
   unit1.Form1.output.lines.add('END');
   end;

   Procedure PrimitiveCombine (coords: PDVector; vertex_data: pointer; weight: pointer; var outData: pointer; UserData: Pointer); stdcall;
   begin
   setlength(poly, length(poly)+1);
   move(coords^, poly[length(poly)-1].x, sizeof(dvector));
   outData:= @poly[length(poly)-1].x;
   end;

   Procedure EdgeFlagNull(flag: glboolean; lpContext: pointer); stdcall;
   begin

   end;

   procedure ElementPrimitiveV2(vertexData : Pointer; polygonData : Pointer); stdcall;
   var
     pv: DVector;
   begin

   move(vertexData^, pv, sizeof(dvector));

   unit1.Form1.
   output.lines.add(
     format('%f %f %f', [
     pv.x,
     pv.y,
     pv.z])
   );

  end;

begin
tess:= gluNewTess;

gluTessCallback(tess, GLU_TESS_BEGIN, @ElementBegin);
gluTessCallback(tess, GLU_TESS_VERTEX_DATA, @ElementPrimitiveV2);
//gluTessCallback(tess, GLU_TESS_EDGE_FLAG_DATA, @EdgeFlagNull); // uncomment and you'll get only GL_TRIANGLES!
gluTessCallback(tess, GLU_TESS_COMBINE_DATA, @PrimitiveCombine);
gluTessCallback(tess, GLU_TESS_END, @ElementEnd);
gluTessCallback(tess, GLU_TESS_ERROR, @tessError);

gluTessBeginPolygon(tess, nil);
gluTessBeginContour(tess);

setlength(poly, 4);
poly[0].x:= 0;
poly[0].y:= 0;
poly[0].z:= 0;

poly[1].x:= 1;
poly[1].y:= 0; // set to 1 to test self intresecting polygons
poly[1].z:= 0;

poly[2].x:= 1;
poly[2].y:= 1; // set to 0 to test self intresecting polygons
poly[2].z:= 0;

poly[3].x:= 0;
poly[3].y:= 1;
poly[3].z:= 0;


for i:= 0 to high(poly) do begin
gluTessVertex(tess, @poly[i].x, @poly[i].x);
end;

gluTessEndContour(tess);
gluTessEndPolygon(tess);

gluDeleteTess(tess);

end;

end.