Загрузка модели через ASSIMP

type
//3 дробных числа
  T3f = record
    x, y, z: single;
  end;
//массив вершин
  TVertexArray = array of T3f;
 
procedure LoadObj(var VertexArray: TVertexArray; var NormalArray: TVertexArray; const fname: string);
var
  s: PaiScene = nil;
  i, j: integer;
  MaxCoord, Min_x, Min_y, Min_z, Max_x, Max_y, Max_z: single;
  delta_x, delta_y, delta_z: single;
begin
  s := aiImportFile(PChar(fname), aiProcess_Triangulate + aiProcess_GenNormals);
  for i := 0 to s^.mNumMeshes - 1 do
    for j := 0 to s^.mMeshes[i]^.mNumVertices - 1 do
    begin
      SetLength(VertexArray, Length(VertexArray) + 1);
      VertexArray[High(VertexArray)].x := s^.mMeshes[i]^.mVertices[j].x;
      VertexArray[High(VertexArray)].y := s^.mMeshes[i]^.mVertices[j].y;
      VertexArray[High(VertexArray)].z := s^.mMeshes[i]^.mVertices[j].z;
    end;
  for i := 0 to s^.mNumMeshes - 1 do
    for j := 0 to s^.mMeshes[i]^.mNumVertices - 1 do
      if s^.mMeshes[i]^.mNormals <> nil then
      begin
        SetLength(NormalArray, Length(NormalArray) + 1);
        NormalArray[High(NormalArray)].x := s^.mMeshes[i]^.mNormals[j].x;
        NormalArray[High(NormalArray)].y := s^.mMeshes[i]^.mNormals[j].y;
        NormalArray[High(NormalArray)].z := s^.mMeshes[i]^.mNormals[j].z;
      end;
  aiReleaseImport(s);
  //нормализация нормалей
  if (Length(NormalArray) > 0) then
  begin
    MaxCoord := NormalArray[0].x;
    for i := 0 to High(NormalArray) do
    begin
      MaxCoord := Max(MaxCoord, Abs(NormalArray[i].x));
      MaxCoord := Max(MaxCoord, Abs(NormalArray[i].y));
      MaxCoord := Max(MaxCoord, Abs(NormalArray[i].z));
    end;
    if MaxCoord <> 0 then
    begin
      for i := 0 to High(NormalArray) do
      begin
        NormalArray[i].x := NormalArray[i].x / MaxCoord;
        NormalArray[i].y := NormalArray[i].y / MaxCoord;
        NormalArray[i].z := NormalArray[i].z / MaxCoord;
      end;
    end;
  end;
  //сдвиг центра модели в центр системы координат
  if (Length(VertexArray) > 0) then
  begin
    Min_x := VertexArray[0].x;
    Min_y := VertexArray[0].y;
    Min_z := VertexArray[0].z;
    Max_x := VertexArray[0].x;
    Max_y := VertexArray[0].y;
    Max_z := VertexArray[0].z;
    for i := 0 to High(VertexArray) do
    begin
      Min_x := Min(Min_x, VertexArray[i].x);
      Min_y := Min(Min_y, VertexArray[i].y);
      Min_z := Min(Min_z, VertexArray[i].z);
      Max_x := Max(Max_x, VertexArray[i].x);
      Max_y := Max(Max_y, VertexArray[i].y);
      Max_z := Max(Max_z, VertexArray[i].z);
    end;
    delta_x := (Min_x + Max_x) / 2;
    delta_y := (Min_y + Max_y) / 2;
    delta_z := (Min_z + Max_z) / 2;
    for i := 0 to High(VertexArray) do
    begin
      VertexArray[i].x := VertexArray[i].x - delta_x;
      VertexArray[i].y := VertexArray[i].y - delta_y;
      VertexArray[i].z := VertexArray[i].z - delta_z;
    end;
    Min_x := Min_x - delta_x;
    Min_y := Min_y - delta_y;
    Min_z := Min_z - delta_z;
    Max_x := Max_x - delta_x;
    Max_y := Max_y - delta_y;
    Max_z := Max_z - delta_z;
  end;
  //нормализация вершин
  if (Length(VertexArray) > 0) then
  begin
    MaxCoord := Abs(Min_x);
    MaxCoord := Max(MaxCoord, Abs(Min_y));
    MaxCoord := Max(MaxCoord, Abs(Min_z));
    MaxCoord := Max(MaxCoord, Abs(Max_x));
    MaxCoord := Max(MaxCoord, Abs(Max_y));
    MaxCoord := Max(MaxCoord, Abs(Max_z));
    if MaxCoord = 0 then
      MaxCoord := 1
    else
      for i := 0 to High(VertexArray) do
      begin
        VertexArray[i].x := VertexArray[i].x / MaxCoord;
        VertexArray[i].y := VertexArray[i].y / MaxCoord;
        VertexArray[i].z := VertexArray[i].z / MaxCoord;
      end;
  end;
 
end;

procedure LoadObj(var VertexArray: TVertexArray; var NormalArray: TVertexArray; const fname: string);
 
  procedure AddVertexAndNormal(const s: PaiScene; const i, j, k: longword);
  begin
    SetLength(VertexArray, Length(VertexArray) + 1);
    with s^.mMeshes[i]^.mVertices[s^.mMeshes[i]^.mFaces[j].mIndices[k]] do
    begin
      VertexArray[High(VertexArray)].x := x;
      VertexArray[High(VertexArray)].y := y;
      VertexArray[High(VertexArray)].z := z;
    end;
    if s^.mMeshes[i]^.mNormals <> nil then
    begin
      SetLength(NormalArray, Length(NormalArray) + 1);
      with s^.mMeshes[i]^.mNormals[s^.mMeshes[i]^.mFaces[j].mIndices[k]] do
      begin
        NormalArray[High(NormalArray)].x := x;
        NormalArray[High(NormalArray)].y := y;
        NormalArray[High(NormalArray)].z := z;
      end;
    end;
  end;
 
 var
  s: PaiScene = nil;
  i, j, k: longword;
begin
  s := aiImportFile(PChar(fname), 0);
  if s = nil then
    exit;
  for i := 0 to s^.mNumMeshes - 1 do
    for j := 0 to s^.mMeshes[i]^.mNumFaces - 1 do
      for k := 0 to s^.mMeshes[i]^.mFaces[j].mNumIndices - 3 do
      begin
        AddVertexAndNormal(s, i, j, k);
        AddVertexAndNormal(s, i, j, k + 1);
        AddVertexAndNormal(s, i, j, s^.mMeshes[i]^.mFaces[j].mNumIndices - 1);
      end;
  aiReleaseImport(s);
end;