README.md

libtess2 for Pascal

This is a port of libtess2 library to Free Pascal. The purpose of the library is to reduce the complexity of using libtess2 in Free Pascal applications. No need to link with external library, no need to use C compiler.

I've tried to keep the interface and behaviour as similar as possible, so using the library in pascal code is pretty similar to using it in C code:

uses
  libtess2_tesselator; // tesselator.h


const
  CONTOUR1: array[0 .. 5] of TESSreal = (
    185.28, 455.91,
    143.93, 270.04,
    608.54, 489.26
  );
  CONTOUR2: array[0 .. 5] of TESSreal = (
    167.59, 256.50,
    217.29, 556.70,
    363.79, 668.17
  );



var
  tess: PTESStesselator;

  I, Count: LongInt;
  Indices: PTESSindex;
  Vertices: PTESSreal;



begin
  tess := tessNewTess(nil);
  if tess = nil then begin
    Writeln(stderr, 'Out of memory');
    Halt(1);
  end;

  tessAddContour(tess, 2, @CONTOUR1[0], 2 * SizeOf(TESSreal), 3);
  tessAddContour(tess, 2, @CONTOUR2[0], 2 * SizeOf(TESSreal), 3);

  if not tessTesselate(tess, TESS_WINDING_ODD, TESS_POLYGONS, 3, 2, nil) then begin
    Writeln(stderr, 'Tesselation failed');
    Halt(1);
  end;

  Count    := tessGetElementCount(tess);
  Indices  := tessGetElements(tess);
  Vertices := tessGetVertices(tess);
  Writeln('Triangulation (', Count, ' triangles):');
  for I := 0 to Count - 1 do begin
    Writeln( I:2, Vertices[2 * Indices[3 * I + 0]], ' ', Vertices[2 * Indices[3 * I + 0] + 1]);
    Writeln('  ', Vertices[2 * Indices[3 * I + 1]], ' ', Vertices[2 * Indices[3 * I + 2] + 1]);
    Writeln('  ', Vertices[2 * Indices[3 * I + 2]], ' ', Vertices[2 * Indices[3 * I + 2] + 1]);
  end;

  tessDeleteTess(tess);
end.

I've tried to keep the implementation as similar as possible as well to simplify side-by-side comparison and debugging, although it was necessary to change the names of some types to avoid ambiguities, and their placement to avoid circular unit dependencies.