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OVERVIEW.md

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Code overview

DFPlex adds multiplayer into Dwarf mode by using the following simple algorithm every frame for each player (see dfplex.cpp:dfplex_update()):

  1. (state.cpp:restore_state()) Restore the player's UI state (where they are looking, their cursor position, current menu, etc.) primarily through two different means:
  • Applying a sequence of key commands that were previously entered by this client. For example, the command sequence D_NOBLES, STANDARDSCROLL_DOWN, STANDARDSCROLL_DOWN will open up the [n]obles menu and scroll down twice. (See state.cpp:apply_restore_key())
  • Directly editing dwarf fortress memory -- the cursor position and view position are restored this way, and a few other things as well. This editing occurs before, after, or even during the application of the keypress sequence above. (See state.cpp's restore_cursor(), restore_data(), restore_post_state(), etc.)
  1. (command.cpp:apply_command()) Apply any new key commands the player has entered this frame. If the command changes the current menu (see hackutil.cpp:get_current_menu_id()), it is stored and added to the key command sequence.
  • If we return to a previous menu, instead of adding the key to the sequence, we remove some keys.
  • Certain keys in certain menus are special cased, as the general-purpose logic doesn't work for those keys. See command.cpp:apply_special_case(). This is quite a meaty function!
  • Scrolling and typing keys are special cased so that they are always saved (except in certain special cases where they are not).
  1. screenbuf.cpp:perform_render() Render and store the contents of the screen.
  2. screenbuf.cpp:transfer_screenbuf_client() Copy the new screen to the client. (To save bandwidth, only the CURSES character information is sent, rather than pixels, and delta-encoding is used.)
  3. hackutil.cpp:return_to_root() Return to the main dwarfmode screen.
  4. (server.cpp:tock()) Later, when the client requests an update, the screen information is sent.

Finally, after all player updates have occurred, we set the pause state and return from the plugin dfplex_update() so that DF may advance a frame on its own.