I'm working on a game in a 3D world with 2D sprites only (like Don't Starve game). (OpenGL ES2 with C++)

Currently, I'm ordering elements back to front before drawing them without batch (so 1 element = 1 drawcall). I would like to implement batching in my framework to decrease draw calls.

Here is what I've got for the moment:

• Order all elements of my scene back to front.
• Send order list of elements to the Renderer.

• Renderer look in his batch manager if a batch exist for the given element with his Material.

  • Batch didn't exist: create a new one.
  • Batch exist for element with this Material: Add sprite to the batch.

• Compute big mesh with all sprite for each batch (1 material type = 1 batch).

• When all batches are ok, the batch manager compute draw commands for the renderer.

• Renderer process draw commands (bind shader, bind textures, bind buffers, draw element)

Image with my problem here: Explication here

But I've got some problems because objects can be behind another objects inside another batch.

How can I do something like that?

Thanks!