Difference between revisions of "LuaWML"
(Filled a few sections of the Lua page) |
(Added a WML event and its Lua translation) |
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code = << wesnoth.message "Hello World!" >> | code = << wesnoth.message "Hello World!" >> | ||
[/lua] | [/lua] | ||
+ | |||
+ | The '''[args]''' tag can be used to pass a WML object to the script via its variadic local variable. | ||
== Examples == | == Examples == | ||
+ | |||
+ | The following WML event is taken from Wesnoth' tutorial. It will serve as an example to present how Lua scripts are embedded into Wesnoth. The event is fired whenever a unit from side 1 (that is, the hero controlled by the user) moves to a tile that is not the one set in the WML variable ''target_hex''. | ||
+ | |||
+ | # General catch for them moving to the wrong place. | ||
+ | [event] | ||
+ | name=moveto | ||
+ | first_time_only=no | ||
+ | [allow_undo][/allow_undo] | ||
+ | [filter] | ||
+ | side=1 | ||
+ | [/filter] | ||
+ | |||
+ | [if] | ||
+ | [variable] | ||
+ | name=target_hex.is_set | ||
+ | equals=yes | ||
+ | [/variable] | ||
+ | [then] | ||
+ | [if] | ||
+ | [variable] | ||
+ | name=x1 | ||
+ | equals=$target_hex.x | ||
+ | [/variable] | ||
+ | [variable] | ||
+ | name=y1 | ||
+ | equals=$target_hex.y | ||
+ | [/variable] | ||
+ | [then] | ||
+ | [/then] | ||
+ | [else] | ||
+ | [redraw][/redraw] | ||
+ | [message] | ||
+ | speaker=narrator | ||
+ | message=_ "*Oops! | ||
+ | You moved to the wrong place! After this message, you can press 'u' to undo, then try again." + | ||
+ | _ " | ||
+ | *Left click or press spacebar to continue..." | ||
+ | [/message] | ||
+ | [/else] | ||
+ | [/if] | ||
+ | [/then] | ||
+ | [/if] | ||
+ | [/event] | ||
+ | |||
+ | A Lua script that performs the same action is presented below. | ||
+ | |||
+ | [event] | ||
+ | name=moveto | ||
+ | first_time_only=no | ||
+ | [allow_undo][/allow_undo] | ||
+ | [filter] | ||
+ | side=1 | ||
+ | [/filter] | ||
+ | |||
+ | [lua] | ||
+ | code = << | ||
+ | local args = ... | ||
+ | if target_hex.is_set and | ||
+ | (args.x1 ~= target_hex.x or args.y1 ~= target_hex.y) | ||
+ | then | ||
+ | W.redraw() | ||
+ | narrator_says(_ "*Oops!\nYou moved to the wrong place! After this message, you can press 'u' to undo, then try again.") | ||
+ | end | ||
+ | >> | ||
+ | [/lua] | ||
+ | [/event] | ||
== Environment == | == Environment == | ||
Line 20: | Line 88: | ||
The global environment is preloaded with the following modules: [http://www.lua.org/manual/5.1/manual.html#5.1 basic] (no name), [http://www.lua.org/manual/5.1/manual.html#5.4 string], [http://www.lua.org/manual/5.1/manual.html#5.5 table], and [http://www.lua.org/manual/5.1/manual.html#5.6 math]. A '''wesnoth''' module is also available, see below. | The global environment is preloaded with the following modules: [http://www.lua.org/manual/5.1/manual.html#5.1 basic] (no name), [http://www.lua.org/manual/5.1/manual.html#5.4 string], [http://www.lua.org/manual/5.1/manual.html#5.5 table], and [http://www.lua.org/manual/5.1/manual.html#5.6 math]. A '''wesnoth''' module is also available, see below. | ||
+ | |||
+ | At the start of the script, the variadic local variable '''...''' (three dots) contains a table. It contains the content of the [args] sub-tag of the [lua] tag. The table also contains (if they make sense for the current event) the fields '''x1''', '''y1''', '''x2''', and '''y2''', containing map locations, and the the sub-tables '''weapon''' and '''second_weapon''' containing attacks. | ||
== Interface to the C++ engine == | == Interface to the C++ engine == | ||
+ | |||
+ | == Encoding WML object in Lua == | ||
== Helper functions == | == Helper functions == | ||
==== set_wml_meta_var ==== | ==== set_wml_meta_var ==== |
Revision as of 15:48, 22 March 2009
Contents
The [lua] tag
This tag is a subtag of the [event]. It makes it possible to write actions with the Lua 5.1 language.
The tag supports only the code key, which is a string containing the Lua scripts. Since Lua makes usage of the quotes and the { and } symbols, it is certainly wise to enclose the script between stronger quotes, as they prevent the preprocessor from performing macro expansion and tokenization.
[lua] code = << wesnoth.message "Hello World!" >> [/lua]
The [args] tag can be used to pass a WML object to the script via its variadic local variable.
Examples
The following WML event is taken from Wesnoth' tutorial. It will serve as an example to present how Lua scripts are embedded into Wesnoth. The event is fired whenever a unit from side 1 (that is, the hero controlled by the user) moves to a tile that is not the one set in the WML variable target_hex.
# General catch for them moving to the wrong place. [event] name=moveto first_time_only=no [allow_undo][/allow_undo] [filter] side=1 [/filter] [if] [variable] name=target_hex.is_set equals=yes [/variable] [then] [if] [variable] name=x1 equals=$target_hex.x [/variable] [variable] name=y1 equals=$target_hex.y [/variable] [then] [/then] [else] [redraw][/redraw] [message] speaker=narrator message=_ "*Oops! You moved to the wrong place! After this message, you can press 'u' to undo, then try again." + _ " *Left click or press spacebar to continue..." [/message] [/else] [/if] [/then] [/if] [/event]
A Lua script that performs the same action is presented below.
[event] name=moveto first_time_only=no [allow_undo][/allow_undo] [filter] side=1 [/filter] [lua] code = << local args = ... if target_hex.is_set and (args.x1 ~= target_hex.x or args.y1 ~= target_hex.y) then W.redraw() narrator_says(_ "*Oops!\nYou moved to the wrong place! After this message, you can press 'u' to undo, then try again.") end >> [/lua] [/event]
Environment
All the Lua scripts of a scenario shares the same global environment (aka Lua state). This environment is not preserved over save/load cycles. Therefore, storing values in the global environment is a generally a bad idea (unless it has been redirected to WML variables, see set_wml_meta_var). The only time it makes sense to assign global variables is during a preload event, as this event is always run. Therefore, helper functions defined at that time will be available to all the later scripts.
The global environment is preloaded with the following modules: basic (no name), string, table, and math. A wesnoth module is also available, see below.
At the start of the script, the variadic local variable ... (three dots) contains a table. It contains the content of the [args] sub-tag of the [lua] tag. The table also contains (if they make sense for the current event) the fields x1, y1, x2, and y2, containing map locations, and the the sub-tables weapon and second_weapon containing attacks.