//
// The graphics engine GXScene https://github.com/glscene
//
unit GXS.FileVRML;

(* Preliminary VRML vector file support *)

interface

uses
  System.Classes,
  System.SysUtils,
  System.Math,

  Stage.VectorTypes,
  Stage.VectorGeometry,
  GXS.VectorLists,

  GXS.ApplicationFileIO,
  GXS.VectorFileObjects,
  GXS.Material,
  GXS.MeshUtils,

  Formatx.VRML;

type

  TgxVRMLVectorFile = class(TgxVectorFile)
  public
    class function Capabilities: TDataFileCapabilities; override;
    procedure LoadFromStream(aStream: TStream); override;
  end;

  // ------------------------------------------------------------------
implementation

// ------------------------------------------------------------------

procedure TessellatePolygon(PolyVerts: TgxAffineVectorList;
  PolyIndices, TriIndices: TgxIntegerList);

  function IsPolyClockWise: Boolean;
  var
    i, j: Integer;
    det: Single;
    mat: TAffineMatrix;
  begin
    det := 0;
    for i := 0 to PolyIndices.Count - 1 do
    begin
      for j := 0 to 2 do
        if (i + j) >= PolyIndices.Count then
          mat.V[j] := PolyVerts[PolyIndices[i + j - PolyIndices.Count]]
        else
          mat.V[j] := PolyVerts[PolyIndices[i + j]];
      det := det + MatrixDeterminant(mat);
    end;
    Result := (det < 0);
  end;

  function IsTriClockWise(v0, v1, v2: TAffineVector): Boolean;
  var
    mat: TAffineMatrix;
  begin
    mat.X := v0;
    mat.Y := v1;
    mat.Z := v2;
    Result := (MatrixDeterminant(mat) < 0);
  end;

  function PointInTriangle(p, v0, v1, v2: TAffineVector;
    IsClockWise: Boolean = False): Boolean;
  begin
    Result := not((IsTriClockWise(v1, v0, p) = IsClockWise) or
      (IsTriClockWise(v0, v2, p) = IsClockWise) or
      (IsTriClockWise(v2, v1, p) = IsClockWise));
  end;

var
  i, j, prev, next, min_vert, min_prev, min_next: Integer;
  PolyCW, NoPointsInTriangle: Boolean;
  V: TAffineMatrix;
  temp: TgxIntegerList;
  min_dist, d, area: Single;
begin
  temp := TgxIntegerList.Create;
  try
    PolyCW := IsPolyClockWise;
    temp.Assign(PolyIndices);
    while temp.Count > 3 do
    begin
      min_dist := 10E7;
      min_vert := -1;
      min_prev := -1;
      min_next := -1;
      for i := 0 to temp.Count - 1 do
      begin
        prev := i - 1;
        next := i + 1;
        if prev < 0 then
          prev := temp.Count - 1;
        if next > temp.Count - 1 then
          next := 0;
        V.X := PolyVerts[temp[prev]];
        V.Y := PolyVerts[temp[i]];
        V.Z := PolyVerts[temp[next]];
        if IsTriClockWise(V.X, V.Y, V.Z) = PolyCW then
        begin
          NoPointsInTriangle := True;
          for j := 0 to temp.Count - 1 do
          begin
            if (j <> i) and (j <> prev) and (j <> next) then
            begin
              if PointInTriangle(PolyVerts[temp[j]], V.X, V.Y, V.Z, PolyCW) then
              begin
                NoPointsInTriangle := False;
                Break;
              end;
            end;
          end;

          area := TriangleArea(V.X, V.Y, V.Z);

          if NoPointsInTriangle and (area > 0) then
          begin
            d := VectorDistance2(V.X, V.Z);
            if d < min_dist then
            begin
              min_dist := d;
              min_prev := prev;
              min_vert := i;
              min_next := next;
            end;
          end;
        end;
      end;
      if min_vert = -1 then
      begin
        raise Exception.Create('Failed to tessellate polygon.');
      end
      else
      begin
        TriIndices.Add(temp[min_prev], temp[min_vert], temp[min_next]);
        temp.Delete(min_vert);
      end;
    end;
    TriIndices.Add(temp[0], temp[1], temp[2]);
  finally
    temp.Free;
  end;
end;


// ------------------
// ------------------ TgxVRMLVectorFile ------------------
// ------------------

class function TgxVRMLVectorFile.Capabilities: TDataFileCapabilities;
begin
  Result := [dfcRead];
end;

procedure TgxVRMLVectorFile.LoadFromStream(aStream: TStream);
var
  mesh: TgxMeshObject;
  uniqueMatID: Integer;
  currentMaterial: TgxLibMaterial;
  currentTransform: TMatrix4f;
  creaseAngle: Single;

  function GetUniqueMaterialName: String;
  var
    libMat: TgxLibMaterial;
  begin
    repeat
      Result := 'UntitledMaterial' + IntToStr(uniqueMatID);
      Inc(uniqueMatID);
      libMat := Owner.MaterialLibrary.Materials.GetLibMaterialByName(Result);
    until not Assigned(libMat);
  end;

  function AddMaterialToLibrary(VRMLMaterial: TVRMLMaterial): TgxLibMaterial;
  var
    matname: String;
  begin
    Result := nil;
    if not Assigned(Owner.MaterialLibrary) then
      Exit;

    if VRMLMaterial.DefName = '' then
      matname := GetUniqueMaterialName
    else
      matname := VRMLMaterial.DefName;

    Result := Owner.MaterialLibrary.Materials.GetLibMaterialByName(matname);
    if not Assigned(Result) then
    begin
      Result := Owner.MaterialLibrary.Materials.Add;
      Result.Name := matname;
    end;

    // Assign values from the current material
    if Assigned(currentMaterial) then
      Result.Material.FrontProperties.Assign
        (currentMaterial.Material.FrontProperties);

    with Result.Material.FrontProperties do
    begin
      if VRMLMaterial.HasDiffuse then
        Diffuse.Color := VectorMake(VRMLMaterial.DiffuseColor, Diffuse.Color.W);
      if VRMLMaterial.HasAmbient then
        Ambient.Color := VectorMake(VRMLMaterial.AmbientColor, Ambient.Color.W);
      if VRMLMaterial.HasSpecular then
        Specular.Color := VectorMake(VRMLMaterial.SpecularColor,
          Specular.Color.W);
      if VRMLMaterial.HasEmissive then
        Emission.Color := VectorMake(VRMLMaterial.EmissiveColor,
          Emission.Color.W);
      if Shininess = 0 then
        Shininess := 16;
      if VRMLMaterial.HasShininess then
        Shininess := Floor(128 * VRMLMaterial.Shininess);
      if VRMLMaterial.HasTransparency then
      begin
        Diffuse.Color := VectorMake(AffineVectorMake(Diffuse.Color),
          1 - VRMLMaterial.Transparency);
        Ambient.Color := VectorMake(AffineVectorMake(Ambient.Color),
          1 - VRMLMaterial.Transparency);
        Specular.Color := VectorMake(AffineVectorMake(Specular.Color),
          1 - VRMLMaterial.Transparency);
        Emission.Color := VectorMake(AffineVectorMake(Emission.Color),
          1 - VRMLMaterial.Transparency);
      end;
    end;
    if VRMLMaterial.HasTransparency then
      Result.Material.BlendingMode := bmTransparency;
  end;

  procedure RebuildMesh;
  var
    i, j, k, l: Integer;
    newfg: TgxFGVertexIndexList;
    fg: TFGVertexNormalTexIndexList;
    vertices, normals, texcoords, triNormals, newVertices, newNormals,
      newTexCoords: TgxAffineVectorList;
    optimized: TgxIntegerList;
    cosAngle: Single;
    normal: TAffineVector;
    s, t: array [0 .. 2] of Integer;
    n: array [0 .. 2] of TgxIntegerList;
    smooth, hasVertices, hasNormals, hasNormalIndices, hasTexCoords,
      hasTexCoordIndices: Boolean;
  begin
    if not Assigned(mesh) then
      Exit;

    hasVertices := mesh.vertices.Count > 0;
    hasNormals := mesh.normals.Count > 0;
    hasTexCoords := mesh.texcoords.Count > 0;

    if not hasVertices then
      Exit;

    vertices := TgxAffineVectorList.Create;
    normals := TgxAffineVectorList.Create;
    texcoords := TgxAffineVectorList.Create;
    newVertices := TgxAffineVectorList.Create;
    newNormals := TgxAffineVectorList.Create;
    newTexCoords := TgxAffineVectorList.Create;
    triNormals := TgxAffineVectorList.Create;
    n[0] := TgxIntegerList.Create;
    n[1] := TgxIntegerList.Create;
    n[2] := TgxIntegerList.Create;
    for i := 0 to mesh.FaceGroups.Count - 1 do
    begin
      fg := TFGVertexNormalTexIndexList(mesh.FaceGroups[i]);

      hasNormalIndices := fg.NormalIndices.Count > 0;
      hasTexCoordIndices := fg.TexCoordIndices.Count > 0;

      vertices.Clear;
      normals.Clear;
      texcoords.Clear;
      triNormals.Clear;

      if not hasNormals then
      begin
        for j := 0 to (fg.VertexIndices.Count div 3) - 1 do
        begin
          normal := VectorCrossProduct
            (VectorNormalize(VectorSubtract(mesh.vertices[fg.VertexIndices[3 * j
            + 1]], mesh.vertices[fg.VertexIndices[3 * j]])),
            VectorNormalize(VectorSubtract(mesh.vertices[fg.VertexIndices[3 * j
            + 2]], mesh.vertices[fg.VertexIndices[3 * j]])));
          triNormals.Add(VectorNormalize(normal));
        end;
      end;

      for j := 0 to (fg.VertexIndices.Count div 3) - 1 do
      begin
        vertices.Add(mesh.vertices[fg.VertexIndices[3 * j]],
          mesh.vertices[fg.VertexIndices[3 * j + 1]],
          mesh.vertices[fg.VertexIndices[3 * j + 2]]);

        if hasNormals then
        begin
          if hasNormalIndices then
          begin
            normals.Add(mesh.normals[fg.NormalIndices[3 * j]],
              mesh.normals[fg.NormalIndices[3 * j + 1]],
              mesh.normals[fg.NormalIndices[3 * j + 2]]);
          end
          else
          begin
            normals.Add(mesh.normals[fg.VertexIndices[3 * j]],
              mesh.normals[fg.VertexIndices[3 * j + 1]],
              mesh.normals[fg.VertexIndices[3 * j + 2]]);
          end;
        end
        else
        begin
          // No normal data, generate the normals
          n[0].Clear;
          n[1].Clear;
          n[2].Clear;
          s[0] := fg.VertexIndices[3 * j];
          s[1] := fg.VertexIndices[3 * j + 1];
          s[2] := fg.VertexIndices[3 * j + 2];
          for k := 0 to (fg.VertexIndices.Count div 3) - 1 do
            if j <> k then
            begin
              t[0] := fg.VertexIndices[3 * k];
              t[1] := fg.VertexIndices[3 * k + 1];
              t[2] := fg.VertexIndices[3 * k + 2];
              if (s[0] = t[0]) or (s[0] = t[1]) or (s[0] = t[2]) then
                n[0].Add(k);
              if (s[1] = t[0]) or (s[1] = t[1]) or (s[1] = t[2]) then
                n[1].Add(k);
              if (s[2] = t[0]) or (s[2] = t[1]) or (s[2] = t[2]) then
                n[2].Add(k);
            end;

          for k := 0 to 2 do
          begin
            if n[k].Count > 0 then
            begin
              smooth := True;
              for l := 0 to n[k].Count - 1 do
              begin
                cosAngle := VectorAngleCosine(triNormals[j],
                  triNormals[n[k][l]]);
                smooth := smooth and (cosAngle > Cos(creaseAngle));
                if not smooth then
                  Break;
              end;
              if smooth then
              begin
                normal := triNormals[j];
                for l := 0 to n[k].Count - 1 do
                  AddVector(normal, triNormals[n[k][l]]);
                ScaleVector(normal, 1 / (n[k].Count + 1));
                normals.Add(VectorNormalize(normal));
              end
              else
                normals.Add(triNormals[j]);
            end
            else
            begin
              normals.Add(triNormals[j]);
            end;
          end;
        end;

        if hasTexCoords then
        begin
          if hasTexCoordIndices then
          begin
            texcoords.Add(mesh.texcoords[fg.TexCoordIndices[3 * j]],
              mesh.texcoords[fg.TexCoordIndices[3 * j + 1]],
              mesh.texcoords[fg.TexCoordIndices[3 * j + 2]]);
          end
          else
          begin
            texcoords.Add(mesh.texcoords[fg.VertexIndices[3 * j]],
              mesh.texcoords[fg.VertexIndices[3 * j + 1]],
              mesh.texcoords[fg.VertexIndices[3 * j + 2]]);
          end;
        end;

      end;

      // Optimize the mesh
      if hasTexCoords then
      begin
        optimized := BuildVectorCountOptimizedIndices(vertices, normals,
          texcoords);
        RemapReferences(texcoords, optimized);
      end
      else
        optimized := BuildVectorCountOptimizedIndices(vertices, normals);
      RemapReferences(normals, optimized);
      RemapAndCleanupReferences(vertices, optimized);
      optimized.Offset(newVertices.Count);

      // Replace the facegroup with a vertex-only index list
      newfg := TgxFGVertexIndexList.Create;
      newfg.Owner := mesh.FaceGroups;
      newfg.Mode := fg.Mode;
      newfg.MaterialName := fg.MaterialName;
      newfg.VertexIndices.Assign(optimized);
      mesh.FaceGroups.Insert(i, newfg);
      mesh.FaceGroups.RemoveAndFree(fg);
      optimized.Free;

      newVertices.Add(vertices);
      newNormals.Add(normals);
      newTexCoords.Add(texcoords);
    end;
    vertices.Free;
    normals.Free;
    texcoords.Free;
    n[0].Free;
    n[1].Free;
    n[2].Free;
    triNormals.Free;

    if newVertices.Count > 0 then
      mesh.vertices.Assign(newVertices);
    if newNormals.Count > 0 then
      mesh.normals.Assign(newNormals);
    if newTexCoords.Count > 0 then
      mesh.texcoords.Assign(newTexCoords);

    newVertices.Free;
    newNormals.Free;
    newTexCoords.Free;
  end;

  procedure RecursNodes(node: TVRMLNode);
  var
    i, j, n: Integer;
    points: TgxSingleList;
    indices, fgindices: TgxIntegerList;
    fg: TFGVertexNormalTexIndexList;
    face: TgxIntegerList;
    tempLibMat: TgxLibMaterial;
    saveTransform, mat: TMatrix4f;
    saveMaterial: TgxLibMaterial;
    axis: TAffineVector;
    angle: Single;
  begin
    // Store current transform and material
    saveTransform := currentTransform;
    saveMaterial := currentMaterial;

    // Look for a child node data (transforms and materials)
    for i := 0 to node.Count - 1 do
      if node[i] is TVRMLTransform then
      begin
        if not VectorEquals(TVRMLTransform(node[i]).Rotation, NullHMGVector)
        then
        begin
          axis := AffineVectorMake(TVRMLTransform(node[i]).Rotation);
          angle := TVRMLTransform(node[i]).Rotation.W;
          mat := MatrixMultiply(CreateRotationMatrix(axis, angle),
            CreateRotationMatrixZ(Pi / 2));
        end
        else
          mat := IdentityHMGMatrix;
        for j := 0 to 2 do
          mat.V[j] := VectorScale(mat.V[j], TVRMLTransform(node[i])
            .ScaleFactor.V[j]);
        mat.W := PointMake(TVRMLTransform(node[i]).Center);
        currentTransform := MatrixMultiply(mat, currentTransform);
      end
      else if node[i] is TVRMLMaterial then
      begin
        currentMaterial := AddMaterialToLibrary(TVRMLMaterial(node[i]));
      end
      else if node[i] is TVRMLShapeHints then
      begin
        creaseAngle := TVRMLShapeHints(node[i]).creaseAngle;
      end
      else if node[i] is TVRMLUse then
      begin
        if Assigned(Owner.MaterialLibrary) then
        begin
          tempLibMat := Owner.MaterialLibrary.Materials.GetLibMaterialByName
            (TVRMLUse(node[i]).Value);
          if Assigned(tempLibMat) then
            currentMaterial := tempLibMat;
        end;
      end;

    // Read node data
    if (node.Name = 'Coordinate3') and (node.Count > 0) then
    begin
      RebuildMesh;
      mesh := TgxMeshObject.CreateOwned(Owner.MeshObjects);
      points := TVRMLSingleArray(node[0]).Values;
      for i := 0 to (points.Count div 3) - 1 do
        mesh.vertices.Add(points[3 * i], points[3 * i + 1], points[3 * i + 2]);
      mesh.vertices.TransformAsPoints(currentTransform);

    end
    else if (node.Name = 'Normal') and (node.Count > 0) and Assigned(mesh) then
    begin
      points := TVRMLSingleArray(node[0]).Values;
      for i := 0 to (points.Count div 3) - 1 do
        mesh.normals.Add(points[3 * i], points[3 * i + 1], points[3 * i + 2]);
      mesh.normals.TransformAsVectors(currentTransform);

    end
    else if (node.Name = 'TextureCoordinate2') and (node.Count > 0) and
      Assigned(mesh) then
    begin
      points := TVRMLSingleArray(node[0]).Values;
      for i := 0 to (points.Count div 2) - 1 do
        mesh.texcoords.Add(points[2 * i], points[2 * i + 1], 0);

    end
    else if (node.Name = 'IndexedFaceSet') and (node.Count > 0) and
      Assigned(mesh) then
    begin
      fg := TFGVertexNormalTexIndexList.CreateOwned(mesh.FaceGroups);
      mesh.Mode := momFaceGroups;
      face := TgxIntegerList.Create;
      if Assigned(currentMaterial) then
        fg.MaterialName := currentMaterial.Name;
      for n := 0 to node.Count - 1 do
      begin
        if node[n].Name = 'CoordIndexArray' then
          fgindices := fg.VertexIndices
        else if node[n].Name = 'NormalIndexArray' then
          fgindices := fg.NormalIndices
        else if node[n].Name = 'TextureCoordIndexArray' then
          fgindices := fg.TexCoordIndices
        else
          fgindices := nil;

        if not Assigned(fgindices) then
          Continue;

        indices := TVRMLIntegerArray(node[n]).Values;
        i := 0;
        while i < indices.Count do
        begin
          if indices[i] = -1 then
          begin
            if face.Count <= 4 then
            begin
              for j := 0 to face.Count - 3 do
                fgindices.Add(face[0], face[j + 1], face[j + 2]);
            end
            else
            begin
              TessellatePolygon(mesh.vertices, face, fgindices);
            end;
            face.Clear;
          end
          else
          begin
            face.Add(indices[i]);
          end;
          i := i + 1;
        end;
      end;

      face.Free;

    end
    else
    begin
      // Continue recursion through child nodes
      for i := 0 to node.Count - 1 do
        RecursNodes(node[i]);
    end;

    // Load transform and material from stored values
    currentTransform := saveTransform;
    currentMaterial := saveMaterial;
  end;

var
  str: TStringList;
  parser: TVRMLParser;
begin
  str := TStringList.Create;
  parser := TVRMLParser.Create;
  currentMaterial := nil;
  currentTransform := IdentityHMGMatrix;
  creaseAngle := 0.5;
  mesh := nil;
  uniqueMatID := 0;
  try
    str.LoadFromStream(aStream);
    parser.Parse(str.Text);
    currentMaterial := nil;
    RecursNodes(parser.RootNode);
    RebuildMesh;
  finally
    str.Free;
    parser.Free;
  end;
end;

// ------------------------------------------------------------------
initialization

// ------------------------------------------------------------------

RegisterVectorFileFormat('wrl', 'VRML files', TgxVRMLVectorFile);

end.