Lua Programming Help Thread

[cwirsing]

What is a nil value in LUA.
Sorry I am still learning LUA

[cwirsing]

Can someone also give me an example of how to load a ttf font and display it also.

[Predator04]

im trying to make a maze in lua.. like a oldschool one.. like this
http://sinai.critter.net/gallery/blakat-maze.gif

i would like to have the joystick be a image.. and i would like to make it detect when i hit a black line on the maze.. whats the best way to go about that? thanks for your help!

[EminentJonFrost]

function check(dummy)
if dummybb[1].x + 49 >= house1x and dummybb[1].x + 49 <= house1x + 21 and dummybb[1].y + 20 >= house1y and dummybb[1].y <= house1y + 20 and tile1show1a == 1 then
dummybb[1].go = false
tile1show1a = 2
end
if tile1show1a >= 2 then
screen:fillRect(house1x, house1y, 21, 21, blue)
screen:blit(house1x, house1y, house1R)
end

I think its either one of two things.

function check(dummy) -- nowhere in your function does it mention "dummy" again

and/or

tile1show1a = 2
end
if tile1show1a >= 2 then -- turn ">=" into "=="
screen:fillRect(house1x, house1y, 21, 21, blue)
screen:blit(house1x, house1y, house1R)

[montrob]

function check(dummy)
if dummybb[1].x + 49 >= house1x and dummybb[1].x + 49 <= house1x + 21 and dummybb[1].y + 20 >= house1y and dummybb[1].y <= house1y + 20 and tile1show1a == 1 then
dummybb[1].go = false
tile1show1a = 2
end
if tile1show1a >= 2 then
screen:fillRect(house1x, house1y, 21, 21, blue)
screen:blit(house1x, house1y, house1R)
end

I think its either one of two things.

function check(dummy) -- nowhere in your function does it mention "dummy" again

and/or

tile1show1a = 2
end
if tile1show1a >= 2 then -- turn ">=" into "=="
screen:fillRect(house1x, house1y, 21, 21, blue)
screen:blit(house1x, house1y, house1R)

Its def. not the second part.

I tried something and now i get

error:attempt to index field '?' <a nil value>

anyone know what that means?

[PSPduh]

What is a nil value in LUA.
Sorry I am still learning LUA

A nil value is a variable that you haven't declared yet. Example:

red = Color.new(255,0,0)

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

if pad:up() then 
bob = bob + 1 --This would return an error saying that the program is trying --to execute an arthimetic function on a nil value.
end

screen.waitVblankStart()
screen.flip()
end

You haven't declared bob yet, if you put bob = 1 above while true do, you declared it and the program can perform functions on it.
--PSPduh

[Altair]

Also, nil means that is has no value at all, nothing.

[PopcOrn DeVil]

Who unstickied this?

[HaxxBlaster]

Who unstickied this?

As you might see, there is a thread called "Programming help" which is stickied, the "Lua help thread" is linked from there.
New Developers! *READ*

[Bronx]

Who unstickied this?

yeah, this is all serideths doing ;)

[EminentJonFrost]

why un-sticky this? its used so often it just doesnt make sense to me to make it harder to find.

[HaxxBlaster]

Read what i wrote.

[PopcOrn DeVil]

I prefer it just being up the top than just clicking on a thread then getting the link to go here...

[montrob]

Its def. not the second part.

I tried something and now i get

error:attempt to index field '?' <a nil value>

anyone know what that means?

answer please

[emericaska8r]

if its not stickied, you can just add it to your favorites, yet i think it should have stayed stickied, so other people can directly see this thread.

[Electro]

how can you flip an image
(preferbly in v16)

[DeMoN X]

I was wondering if you could use LUA Player to calculate the TOTAL space on the memory stick? , If so could someone post the code for it. Thanks.

[emericaska8r]

I was wondering if you could use LUA Player to calculate the TOTAL space on the memory stick? , If so could someone post the code for it. Thanks.

mem = System.getFreeMemory() -- gets free memory at least.

i'm not sure if thats what you wanted since you said TOTAL space, but maybe that will help anyways.

[DeMoN X]

mem = System.getFreeMemory() -- gets free memory at least.

i'm not sure if thats what you wanted since you said TOTAL space, but maybe that will help anyways.

Well I tried getfreememory(), heres the code :

mem = System.getFreeMemory()
screen:print(200, 100, mem)
screen.flip()

while true do
screen.waitVblankStart()

end

It gives me the wrong values when I do it.. :Argh:

[PSPduh]

Well I tried getfreememory(), heres the code :

mem = System.getFreeMemory()
screen:print(200, 100, mem)
screen.flip()

while true do
screen.waitVblankStart()

end

It gives me the wrong values when I do it.. :Argh:

Wouldn't the code be:

white = Color.new(255,255,255)

mem = System.getFreeMemory()

while true do
screen:clear()
screen:print(100,100,"Free Memory = " .. mem, white)

screen.waitVblankStart()
screen.flip()
end

Try that instead.
--PSPduh

[DeMoN X]

I get 'Free Memory = 8399608' , Erm.. 8MB? Lol.. It should say 111MB..

[SG57]

PSPduh - It doesnt really matter... The System.getfreeMemory() returns an integer, which means you cant use a number as a string, although a string is just a bunch of ASCII number values... But ohwell, it desnt really matter, you just need to have that '.. mem' then a color to get it working...

[PSPduh]

I get 'Free Memory = 8399608' , Erm.. 8MB? Lol.. It should say 111MB..

Here is what it says at http://wiki.ps2dev.org/psp:lua_player:functions

number System.getFreeMemory()

Gets the available free memory. You can use it like this:

print("about " .. System.getFreeMemory() / 1024 / 1024 .. " megabytes free memory available")

That's what it says over at the website.
--PSPduh

[emericaska8r]

so are you saying that you just divide the number you get by 1024 twice then to get the memory in mb?

[Altair]

thats what the wiki says yes.

[DeMoN X]

thats what the wiki says yes.

I think that code only works on older versions of LUA Player.

[Altair]

Hmm I wouldn't know, I use 0.16. But why wouldn't it work on newer versions? It doesn't say that these commands are for any specific version, or am I missing something?

[emericaska8r]

Hmm I wouldn't know, I use 0.16. But why wouldn't it work on newer versions? It doesn't say that these commands are for any specific version, or am I missing something?

true dat

[HaxxBlaster]

I have seen that some of the newer LuaPlayer versions are slower, that's not good at all.
I tried "Graphic Creator" with 0.20 i think, and when choosing a BGcolor it lagged alot more then it did on the previous LuaPlayer versions.

[Mast3r_Shak3]

OKay I REALLY need help. This is the basic engine (minus jump script which im workin on) But whenever I try it on windowsluaplayer I get the stackdump thing. and when i try it on my PSP it freezes and shuts off. I dont see any problems with my code and anyone PLEASE HELP??

black = Color.new(0,0,0)

--VARIABLES/ARRAYS--
player = {}
player.x = 20
player.y = 212

enemy = {}
enemy.x = 420
enemy.y = 212

poox = nil
pooy = nil   
poo2x = nil   
poo2y = nil 
z = 0

--IMAGES--
browndashleft = Image.load("brown/monkey1dashl.png")
browndashright = Image.load("brown/monkey1dashr.png")
brownhitleft = Image.load("brown/monkey1hitl.png")
brownhitright = Image.load("brown/monkey1hitr.png")
brownjumpleft = Image.load("brown/monkey1jumpl.png")
brownjumpright = Image.load("brown/monkey1jumpr.png")
brownstandleft = Image.load("brown/monkey1standl.png")
brownstandright = Image.load("brown/monkey1standr.png")

bluedashleft = Image.load("blue/monkey2dashl.png")
bluedashright = Image.load("blue/monkey2dashr.png")
bluehitleft = Image.load("blue/monkey2hitl.png")
bluejumpleft = Image.load("blue/monkey2jumpl.png")
bluejumpright = Image.load("blue/monkey2jumpr.png")
bluestandleft = Image.load("blue/monkey2standl.png")
bluestandright = Image.load("blue/monkey2standr.png")

bg = Image.load("lv1.png")

while true do

screen:clear()
screen:blit(0,0, bg, false)
screen:print(6,2, "[WIP]", black)

pad = Controls.read() 

if pad:left() then
     z = 1
         if player.x > 0 then
            player.x = player.x - 5
         end
      end
   
if pad:right() then
     z = 0
         if player.x < 456 then
            player.x = player.x + 5
         end
      end

if z == 1 then 
screen:blit(player.x, player.y, browndashleft)
else
screen:blit(player.x, player.y, browndashright)
end

if pad:start() then 
	break
end

screen:blit(player.x, player.y, monkeystandright)

screen.flip()
screen.waitVblankStart()
end