LUA CPP bindings "how to" tutorial 1/7
Thnigs i will cover:
1) How to get objects created on the editor from Cpp
2) How to send objects created by Cpp code to LUA
3) How to call an entity's script LUA function easely (without parameters)
4) How to call an entity's script LUA function passing parameters
5) How to receive returned parameters from LUA functions (yes one or more)
6) How to expose a Cpp Class to LUA using tolua++
I will split this post acordingly to the items listed above for easy referencing/reading
Here a complete Leadwerks app: cpp source, map and scripts of a working example of the all above.
//no longer valid!
https://dl.dropboxusercontent.com/u/78894295/leadwerks/cppLuaBindings.zip
//2021/12/14 update
https://drive.google.com/file/d/1JdewNls8joRJygZ5zkNnuHrnCqNqDl_S/view?usp=sharing
(see description of what executable does and how to operate it on a note at the end of this post)
I'm not English native, so apologies if i do linguistic mistakes, and i'm not a so experienced cpp programmer (ok i'm not a programmer, I'm a technician in electronics, so for any inconsistency or semantic error/mistake pm me and i'll edit/modify the post, thank's)
This site has many topics about this subject but for someone like me many of them has almost all, but normally there are some or too much details which are not exposed. Normally it takes a while to get to the point:
do
try, pray, try again, reread
until ok OR tooLate
My intention is to give "allincluded" for new Leadwerks cpp users which is asumed that if they are
cpp programmers normally are advanced ones, but being new to Leadwerks normally the learning
curve is shorten with material like i'll expose.
Here some interesting links on the subject (not all of them)
http://www.leadwerks.com/werkspace/topic/7548-access-cpp-global-via-lua/page__hl__tolua#entry60531
http://www.leadwerks.com/werkspace/topic/8802-tolua-exposure-problems/
http://www.leadwerks.com/werkspace/topic/7866-lua-version-in-30/
http://www.leadwerks.com/werkspace/blog/138/entry-1288-pushing-complex-lua-tables-from-c/
there are many references to:
http://www.leadwerks.com/werkspace/files/file/216-tolua/
but this just display: sorry we couldn't find that!
so, here is the tolua++ source
https://github.com/LuaDist/toluapp
documentation
https://www8.cs.umu.se/kurser/TDBD12/VT04/lab/lua/tolua%2B%2B.html
precompiled
(note, the link addressed by autors to download:
tolua++ can be downloaded from the sites below:
http://www.codenix.com/~tolua/ is broken! )
How hard is to get all the links up to date! isn't it?
Items coming soon...
jio
---------------------------------------------------------------
Notes about the executable:
In the terminal window, each Lua function and cpp method throws some info, so
move the main window a little to the right, so you can see the terminal window.
You'll se something like that, without my comments in italic:
app.lua start //things that happens LUA side App.lua Start
c2luaTest not nil //instance of object form c created and not nil
lua is calling me! //calling an object's method from lua OK
3.3561e+008 //calling average: (10+35+15)/3 :(WRONG! see bellow)
start scanning.... //this is cpp side on App.cpp, App::Start
//list of objets from the map (world)
Directional Light 4
EditorCamera
findMe //objet searched
found entity findMe !!! // find OK, set a pointer to it for future use.
Directional Light 4
EditorCamera //now searching only for cameras
found editor camera //found editor camera, got camera from editor!
now, put manin window on focus.
Press a, s, d, f
a: calls average(10, 15, 25) and print the results on the terminal window
s: calls average( 5, 10, 4) and print the results on the terminal window
d: calls turnMe(vec3) with a default value of: turn.x=10; turn.y = 20; turn.z = 30;
if ok, you see the red cube turn this amount per axis on each keyhit.
f: calls noParams() and print "executing noParams"
As you press each letter, new messages appear on the terminal window confirming functions of lua
correctly called from c++ code.
if you press a, s, d, f in this sequence, you should see
entity has script
average defined
executing average
16.6667
entity has script
average defined
executing average
6.33333
entity has script
turnMe defined
calling me from C
executin noParams
WRONG display in calling average cpp method from LUA, guess what? a bug.
in Start function inside App.lua i do:
c2luaTest.intA = 10
c2luaTest.intA = 35
c2luaTest.intA = 15
System:Print(c2luaTest:average())
so I only initialize intA, leaving intB and intC with garbage, so, expect to see any number
on each run!
Please edit the App.lua for me!
Edited by Charrua
dropbox link is no longer valid
-
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