add doc/en/scripting/events.md

doc/en/scripting/events.md

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+# Engine events
+
+## Block events
+
+Callbacks specified in block script.
+
+```lua
+function on_placed(x, y, z, playerid)
+```
+
+Called on block placed by player
+
+```lua
+function on_broken(x, y, z, playerid)
+```
+
+Called on block broken by player
+
+```lua
+function on_interact(x, y, z, playerid) -> bool
+```
+
+Called on block RMB click interaction. Prevents block placing if **true** returned.
+
+```lua
+function on_update(x, y, z)
+```
+
+Called on block update (near block changed)
+
+```lua
+function on_random_update(x, y, z)
+```
+
+Called on random block update (grass growth)
+
+```lua
+function on_blocks_tick(tps: int)
+```
+
+Called tps (20) times per second.
+
+## Item events
+
+Callbacks specified in item script.
+
+```lua
+function on_use(playerid: int)
+```
+
+Called on RMB click out of a block.
+
+```lua
+function on_use_on_block(x: int, y: int, z: int, playerid: int)
+```
+
+Called on block RMB click. Prevents block **placing-block** placing if returns **true**
+
+```lua
+function on_block_break_by(x: int, y: int, z: int, playerid: int)
+```
+
+Called on block LMB click (unbreakable blocks included).  Prevents block destruction if returns **true**.
+
+## World events
+
+Callbacks specified in *world.lua* script.
+
+```lua
+function on_world_open()
+```
+
+Called on world open.
+
+```lua
+function on_world_save()
+```
+
+Called before world save.
+
+```lua
+function on_world_tick()
+```
+
+Called 20 times per second
+
+```lua
+function on_world_quit()
+```
+
+Called on world close (after saving)
+
+## Layout events
+
+Script *layouts/layout_name.xml.lua* events.
+
+```lua
+function on_open(invid: int, x: int, y: int, z: int)
+```
+
+Called on element added to the screen.
+invid=0 if no inventory bound
+x,y,z=0 if no block bound
+
+```lua
+function on_close(invid: int)
+```
+
+Called on element removed from the screen.
+
+## HUD events
+
+Callbacks specified in *hud.lua* script.
+
+
+```lua
+function on_hud_open(playerid: int)
+```
+
+Called after world open.
+
+```lua
+function on_hud_close(playerid: int)
+```
+
+Called on world close (before saving)