LZScene

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//
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// This unit is part of the GLScene Engine https://github.com/glscene
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//
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{
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   TIN (Triangular Irregular Network) vector file format implementation.
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   History : 
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       08/04/13 - PW - Fixed a bug in VertArr: decremented element numbers by one
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       17/11/05 - PW - Added support for ascii TIN files with materials
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       05/06/03 - SG - Separated from GLVectorFileObjects.pas
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}
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unit GLFileTIN;
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interface
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{$I GLScene.inc}
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uses
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  Classes, SysUtils,
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  GLVectorFileObjects, GLApplicationFileIO;
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type
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   // TGLTINVectorFile
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   //
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   { The TIN vector file (triangle irregular network).
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      It is a simple text format, with one triangle record per line, no materials,
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      no texturing (there may be more, but I never saw anything in this files).
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      This format is encountered in the DEM/DTED world and used in place of grids. }
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   TGLTINVectorFile = class(TGLVectorFile)
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      public
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         class function Capabilities : TGLDataFileCapabilities; override;
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         procedure LoadFromStream(aStream : TStream); override;
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   end;
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// ------------------------------------------------------------------
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// ------------------------------------------------------------------
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// ------------------------------------------------------------------
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implementation
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// ------------------------------------------------------------------
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// ------------------------------------------------------------------
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// ------------------------------------------------------------------
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uses
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  GLVectorGeometry, GLUtils, GLTypes;
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// ------------------
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// ------------------ TGLTINVectorFile ------------------
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// ------------------
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// Capabilities
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//
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class function TGLTINVectorFile.Capabilities : TGLDataFileCapabilities;
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begin
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   Result:=[dfcRead];
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end;
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// LoadFromStream
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//
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procedure TGLTINVectorFile.LoadFromStream(aStream : TStream);
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var
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   i, j : Integer;
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   sl, tl : TStringList;
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   mesh : TGLMeshObject;
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   v1, v2, v3, n : TAffineVector;
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   ActiveTin : Boolean;
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   Id_Tin : Integer;
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   Tnam, S : string;
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   Id_Mat, NVert, NTri : Integer;
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   VertArr :  TGLPoint3DArray;
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   n1, n2, n3 : Integer;
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begin
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  sl := TStringList.Create;
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  tl := TStringList.Create;
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  try
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    sl.LoadFromStream(aStream);
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    mesh      := TGLMeshObject.CreateOwned(Owner.MeshObjects);
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    mesh.Mode := momTriangles;
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    if sl[0]<>'TIN' then    // the file with single TIN described by vertices only
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    begin
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      for i := 0 to sl.Count - 1 do
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      begin
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        tl.CommaText := Copy(sl[i], 0, MaxInt);
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        Trim(tl.CommaText);
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        if tl.Count = 9 then
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        begin
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            SetVector(v1, GLUtils.StrToFloatDef(tl[0],0), GLUtils.StrToFloatDef(tl[1],0), GLUtils.StrToFloatDef(tl[2],0));
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            SetVector(v2, GLUtils.StrToFloatDef(tl[3],0), GLUtils.StrToFloatDef(tl[4],0), GLUtils.StrToFloatDef(tl[5],0));
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            SetVector(v3, GLUtils.StrToFloatDef(tl[6],0), GLUtils.StrToFloatDef(tl[7],0), GLUtils.StrToFloatDef(tl[8],0));
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            mesh.Vertices.Add(v1, v2, v3);
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            n := CalcPlaneNormal(v1, v2, v3);
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            mesh.Normals.Add(n, n, n);
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        end;
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      end
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    end
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    else  // the file with multiple TINs described by triangles and materials
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    while i < sl.Count - 1  do
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    begin
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      Inc(i);
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      tl.DelimitedText := sl[i];
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      if (tl.CommaText = 'BEGT') then // the beginning of new tin
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      begin
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        repeat
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          Inc(i); tl.DelimitedText := sl[i];
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          if (tl[0] = 'ACTIVETIN') then
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            ActiveTin := True;
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          if (tl[0] = 'ID') then
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            Id_Tin := StrToInt(tl[1]);
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          if (tl[0] = 'TNAM') then
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            Tnam := tl[1];
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          if (tl[0] = 'MAT') then
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            Id_Mat := StrToInt(tl[1]);
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          if (tl[0] = 'VERT') then
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            NVert := StrToInt(tl[1]);
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        until tl[0]='VERT';
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        SetLength(VertArr, NVert);
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        j := 0;
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        repeat
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          Inc(i);
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          tl.DelimitedText := sl[i];
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          VertArr[j].X := StrToFloat(tl[0]);
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          VertArr[j].Y := StrToFloat(tl[1]);
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          VertArr[j].Z := StrToFloat(tl[2]);
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          Inc(j);
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        until (j = NVert);
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        Inc(i);  tl.DelimitedText := sl[i];
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        NTri := StrToInt(tl[1]);
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        j := 0;
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        repeat
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          Inc(i); Inc(j);
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          tl.DelimitedText := sl[i];
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          n1 := StrToInt(tl[0]); n2 := StrToInt(tl[1]); n3 := StrToInt(tl[2]);
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          SetVector(v1, VertArr[n1-1].X, VertArr[n1-1].Y, VertArr[n1-1].Z);
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          SetVector(v2, VertArr[n2-1].X, VertArr[n2-1].Y, VertArr[n2-1].Z);
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          SetVector(v3, VertArr[n3-1].X, VertArr[n3-1].Y, VertArr[n3-1].Z);
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          mesh.Vertices.Add(v1, v2, v3);
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          n := CalcPlaneNormal(v1, v2, v3);
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          mesh.Normals.Add(n, n, n);
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        until (j = NTri);
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        Inc(i); tl.DelimitedText := sl[i]; //tl.DelimitedText = 'ENDT';
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      end;
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    end;
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  finally
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    tl.Free;
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    sl.Free;
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  end;
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end;
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// ------------------------------------------------------------------
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// ------------------------------------------------------------------
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// ------------------------------------------------------------------
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initialization
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// ------------------------------------------------------------------
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// ------------------------------------------------------------------
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// ------------------------------------------------------------------
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   RegisterVectorFileFormat('tin', 'Triangular Irregular Network', TGLTINVectorFile);
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end.
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