Load a series of 3D models using OpenGL (Streaming 3D model?)

Question

My application produces a stream of 3D models, say in .obj format. Each model is a 3D mesh with texture. I wonder how I can display/visualize a stream of 3D models using OpenGL. My thought is just to load the 3D models sequentially, but I am not sure how to achieve that.

Answer 1

1. You will need code for loading a 3D model from obj file. Either write it yourself, or find an implementation online. Search for e.g. "obj model parsing c++".

   For the specification of the obj format you can have a look here: https://en.wikipedia.org/wiki/Wavefront_.obj_file

2. Each model should probably be loaded into an instance of a class like this:

class Model
{
public:
  bool LoadObj(std::string const & filename);

  using VertexPosition = std::array<float, 3>;
  std::vector<VertexPosition> const &  GetVerticesPositions();

  using VertexColor = std::array<unsigned char, 4>;
  std::vector<VertexColor> const & GetVerticesColors();

  using FaceIndices = std::array<int, 3>;
  std::vector<FaceIndices> const & GetFacesIndices();

  using VertexUV = std::array<float, 2>;
  std::vector<VertexUV> const & GetVerticesUVs();

  int GetTextureWidth();
  int GetTextureHeight();
  unsigned char const * GetTextureData();

  // etc...
};

3. All the models can be stored in a std::vector<Model>.

4. Your application should have a timer for rendering. Each time you need to render a frame you need to determine which model to render, based on the time passed and frames-per-second. When you pick a model, you can render it using the interface of Model.

5. If you have many models and do not want to require too much memory, you can do a delay load (load from file only when yo need it). This technique requires to load some frames in advance, on a separate thread (i.e. buffering). Otherwise your playing will not be smooth as you will need to wait to load the obj file which can take some time.