View source for Player-World Interaction

{{Incomplete}}

== Digging a node ==

Preconditions are a node somewhere in the map.<br/>
This node is pointable, has a selection box and can be dug by the hand or the tool the player is wielding.<br/>
The player has interact priv and the tool has a tool range that the node can be pointed.<br/>
The node is not stuck somewhere the player can't point it.

* First look at the node, it becomes pointed_thing.
: Note that on android the node is pointed without looking (referring to the cross position) at it.
* Then LMB is pressed down while holding an item which does not have on_use.
: If LMB wasn't released before, a click happens, which causes a punch event.
:: The client send a punch event (client->interact(4, pointed), see game.cpp:3657 (28.02.2017)).
:: On server side the punch event is passed to mods, see on_punch and the deprecated register_on_punchnode.
: Then the client sends the digging start event to the server (interact(0, pointed), game.cpp:3948).
:: The server uses this information for anticheat measurements.
* Now continue looking at the node, i.e. keep pointing it, and hold down LMB.
: Periodically client-side: Crack animation is updated, digging particles are spawned (if not disabled in the settings) and the node dig sound is played.
:: The dig sound is either the "dig" field in the "sounds" table in the nodedef
:: or, if it's not present, the client uses the sound "default_dig_${groupname}" (file name extension omitted here), where $groupname is one of the groups the node has, see (game.cpp:4001), and gain is set to 0.5.
:: The default_dig_ thing should be banned from source code in my opinion.
* Some time later, when the digging time elapsed,
: the client sends a digging completion event to the server (interact(2, pointed), game.cpp:4018),
: the node disappears client-side,
: more particles are spawned (if enabled) and
: the dug sound is played.
* Now the server recieves the digging completion event.
: Anticheat probably, e.g due to lag, thinks the player dug the node too fast.
:: dug_too_fast cheat is passed to mods, see register_on_cheat, and digging aborts.
: If the nodedef has a can_dig function, it's executed and probably stops the digging.
: The on_dig function in the nodedef is called now.
:: The default on_dig function problably removes the node:
::: The on_destruct is executed, air is set and after_destruct is executed.
:: And probably (the same probably as before) it then calls the after_dig_node function in the nodedef if present.

[[Category:Core Engine]]