Lua Programming Help Thread

[eldiablov]

Judas is right. It is already in write mode.

[dan369]

ok i need some help with reading and writing files, so far i have got it to write out the player's X andY values and read it but nothing else, how would u do it so that when i come out of a pause screen it will read that file and using those X and Y values???
instead off starting again.

[FaT3oYCG]

writing:

file_variable = io.open(filepath)
file_variable:write("x = " .. x_coordinate)
file_variable:write("x = " .. x_coordinate)
file_variable:close()

reading:

dofile(filepath)
x_coordinate = x
y_coordinate = y

untested but looks like it will work to me

[Nielkie]

ok i need some help with reading and writing files, so far i have got it to write out the player's X andY values and read it but nothing else, how would u do it so that when i come out of a pause screen it will read that file and using those X and Y values???
instead off starting again.

Having to write variables to a file is a clear sign of bad program structure. You can go on and do what FatBoy suggests, but I am warning you, it is considered bad practice. You should rather consider re-organizing your program (Use some kind of state system).

[sanctifi3d]

is there a command to shutdown or standby?

thanks in advance.

[FaT3oYCG]

Having to write variables to a file is a clear sign of bad program structure. You can go on and do what FatBoy suggests, but I am warning you, it is considered bad practice. You should rather consider re-organizing your program (Use some kind of state system).

he asked how using files so i answered i dint say it was ant good, i do agree with you and to do it a better way you could set some more variables up that hold the x and y values while you change the state or, set up a second state system, which is the best way for a pause menu or inventory, so you would have something like ss1.a ss1.b ss1.c where ss.b is your game or something and set up another state system inside of that like this ss1.a ss1.b ss2.a ss2.b ss1.c where ss2.a is the game and ss2.b is the pause menu or inventory, this way any data held in the main state system is kept while entering the second level state system

[dan369]

i have got state's!!!
good idea but how would u store the players X and Y ???
would u use something like an btw my variable is Link.x and .y
i use this

Link.x = oldx 
Link.y = oldy

[eldiablov]

I dont see what that achieves.

[FaT3oYCG]

i have got state's!!!
good idea but how would u store the players X and Y ???
would u use something like an btw my variable is Link.x and .y
i use this

Link.x = oldx 
Link.y = oldy

to make it easy you can use two state tables one inside another state, so you have your main file with all of your states and stuff in

e.g.

if game_state == state.game then

-- -*-
link.x = ?
link.y = ?

state_table_for_in_game = { in_game = 1, in_pause = 2}

in_game_state = state_table_for_in_game.in_game

if  in_game_state == state_table_for_in_game.in_game then
-- whatever the controlls and screen display for the game is

if pad:up() then
link.y = link.y - 1
end
-- and so on
-- this will change the link.x and link.y outside of the states -*-

if pad:start() then
in_game_state = state_table_for_in_game.in_pause
end

elseif in_game_state == state_table_for_in_game.in_pause then

-- whatever you have in your pause

if pad:start() then
in_game_state = state_table_for_in_game.in_game
end

-- when you retun to the game the x and y should stay

end

end

I dont see what that achieves.

keeping link in his correct x and y positions after the game has been paused

[dan369]

ok i'm on my ps3 using an wirless keyboard!!!!
so i have states like this:

state = "Game"
state = "Credits"
state = "Inventory"

like that i've tried writing files to hold the players x and y values in my case Link.x and .y
i also have a statement that holds the players x and y values and stores them into an variable that holds them during collisions etc.
like this

Link.x = oldx
Link.y = oldy

like that it stores it's previous x and y postition useful for collisions like i said, anyway the game starts and you have to press START to load the Inventory screen
so then when i exit it will load the file which is the first level but of course it has the same starting postition so it would start from where u began!!!
I would like to know how to make the store the player's X and Y values and when you want to return from the Inventory menu and the place where u pressed start that would be where u would be placed when you exit the Inventory screen????????????????

[_df_]

do you loose state all the time that you need to save variables like that? I'm not sure why you would loose the interpreter state, but I dont use luaplayer, i just embed my own modified lua interpreter (no doubles/floats for speed, and other patches).

if they are global vars, you should be ok, unless your code is really bad and you clobber your global vars in functions that shouldnt be touching them... (this is why local exists!)..

you could always do state inside lua's _G[] table.

I assume your doing loadfile/loadstring/dofile etc.. but I dont see why lua player would be killing your lua_State* that you need to write out links x/y position..

something very wrong here if you need to be doing that just to show a pause screen.

also since you've limited memory (its a good practice) to not use strings if you dont really need to, you could define state modes as; even tho the global string table holds only 1 copy of a string.. waste not want not.

state_Game = 1
state_Credits = 2
state_Inventory = 3

state = state_Game

something sounds totally wrong with your code based on your above statements.... or you are correct and my knowledge of lua is wrong in its implementation in luaplayer...

[FaT3oYCG]

as i said you need states inside states and it is not good practice to use dofiles that is why people like me created state snippets so you dont have to, and files dont have to be loaded

so now to tell you what i said before

you need to have a main state system

containing

game
credits

and inside the game state of the fist state system you need another

containing

main_game
inventory

then it will be set out something like this

- game
-- main_game
-- inventory
- credits

which is what my example before showed

then the variables for links x and y positions need to be inside the first state system under game but outside of the other state system, like so

- game
- links x and y variables
-- main_game
-- inventory
- credits

this way when you enter game you have links x and y co ordinates
when you enter main_game you also have links x and y co ordinates
and finally when you enter inventory you have links x and y co ordinates

now seen as you should only be changing links x and y co ordinates inside main_game if you swap to and from inventory the x and y co ordinates will be kept and when you actually do exit from the inventory link will be in the same position at the same point in the game

if you still dont understand it will be because of one or more of these three reasons

1. you are relatively new to coding
2. the structure of your game is just plain bad
3. you do not understand how states work properly

[dan369]

so i have to do some IF statements????
i am relatively new
all i would link to know is how to store Link's X and Y when START is pressed then use the numbers given to be used AS the players X and Y???

[FaT3oYCG]

out side of all game states above while true do make two new variables,

link_x_store = 0
link_y_store = 0

then inside the state that you swap to, save them to that

so when in the game state

if pad:start() then
link_x_store = link.x
link_y_store = link.y
-- swap state to inventory state
end

-- inside inventory state

if pad:start() then
-- swap to game state
link.x = link_x_store
link.y = link_y_store
end

[dan369]

i understand
thanks 4 being patient with me i do understand it now

[eldiablov]

Rotating a 2d image using the gu ? Is it possible?

[andyauff]

Check out this:

http://www.forums.evilmana.com/index.php?topic=676.0

Haven't tried it, but looks good enough.

[JOY6679]

Hi to all, I am using LUA for this homebrew. Im trying to play music on a homebrew game so I am using this command:

Music.playFile(”music.it” , true), the music file is 12.5 MB in size, so when I try to load the game calling the music the PSP shows the MS light then it stops and hangs and then turns off the PSP. How do I add some music to the homebrew?

Thanks to all in advance!

[SG57]

JOY - you don't think 12.5mb worth of compressed music + anyother of your resources could maybe exceed the 24mb RAM limit? (especially in Lua as it takes away atleast 3mb of RAM alone...)

[JOY6679]

Ok, well I got it to be 1.57 MB in size but still cant find the way to make the music play .

Ok, is there a limit in size for the music files? I still get the same hang on the PSP.

[FaT3oYCG]

1. .wav files are better
2. it needs a low kbps rate and bit rate to work
3. if you send me a copy in .wav form ill convert it 4 u

if it still doesn't work it is because the file is still too big, or is corrupted or something else that we dont know the reason for

[nickdagamer]

how do i run an eboot.pbp file??? i've used luaplayer HM but nothing happens! plz help

[FaT3oYCG]

how do i run an eboot.pbp file??? i've used luaplayer HM but nothing happens! plz help

because of the kernel the function used has some problems loading eboot files, its trying to be fixed

[nickdagamer]

oh ok! i hope it is fixed quickly!

[matsuda]

Nielkie-san help me no need for this post :P

[Nielkie]

Short answer: You need to use "==" instead of "=". "=" sets a value, while "==" reads a value. You are also assigning your page values as both a image and a booleen.

Long answer: You need to change your coding style. Use indenting and tables, and do not repeat code. Here is what I think your code should look more like:

--learn japanese
white = Color.new(255,255,255)

graphics = {}
graphics.page = {Image.load("images/lesson1/page1.png"),
	Image.load("images/lesson1/page2.png"),
	Image.load("images/lesson1/page3.png"),
	Image.load("images/lesson1/page4.png"),
	Image.load("images/lesson1/page5.png"),
	Image.load("images/lesson1/page6.png"),
	etc...}

graphics.menu = Image.load("images/menu.png")
graphics.lesson1menu = Image.load("images/lesson1menu.png")
graphics.lessoncomplete = Image.load("images/lessoncompletedefault.png ")

states = {}

states.page = {}
states.page.n = 1

states.menuon = true
states.lessondone = false

while true do
	screen:clear(white)
	pad = Controls.read()

	if states.menuon then
		if pad:cross() and states.menuon then
			screen:clear(white)
			states.menuon = false
		end
	elseif states.lessondone then
		if pad:cross() then dofile quiz1.lua() end
		if pad:circle() then dofile menu.lua() end
	else
		if pad:r() then
			screen:clear(white)
			states.page.n = states.page.n + 1
		end

		if pad:l() then
			screen:clear(white)
			states.page.n = app.states.page.n - 1
		end
		if states.page.n < 1 then
			states.page.n = 1
		elseif states.page.n > table.getn(graphics.page) then
			states.page.n = table.getn(graphics.page)
		end
		screen:blit(0,0,graphics.page[states.page.n])
	end

	screen:blit(0,0,graphics.menu)
	screen:blit(183,88,graphics.lesson1menu)

	screen.waitVblankStart()
	screen.flip()
end

[matsuda]

thank you very much Nielkie-san! i am very glad you helped me.
I have learned more functions thanks to you! This style is much cleaner. thank you!

[Nielkie]

No problem, if you want to know more (e.g. functions, usage, etc) There are some great resources around.

For Library definitions, I greatly recommend http://lua-users.org/wiki/TutorialDirectory

[SG57]

Just throwing this out there - Nielkie - '==' doesn't 'read' a value, it's a comparing operator ;)

[ifiwere1337]

hey everyone, i am working on a lua project, and i would like to add support to play mp3 music from the memorystick, i do not know how to do this, can i get some help, also which version of lua player hm will i need