Lua Programming Help Thread

[Gutya]

my break command works fine on windows, but not in PSP.

??? :icon_sad:

[TPTaylor]

no worries altair, luckily, i just worked around the error. copied and pasted the stuff i had done into an older version of the app, so it works just fine! only took like 3 mins in the end.
i'll have to keep thinking on it i think. i will try out some sounds in lua and see they lose quality if i hold them down.

[Electro]

if you find it out, please tell me, since i have the same problem

[suckerr70]

Well. I'm preaty new to lua but have teh basics down. I want to make an rpg of some sort and right now I am trying to figure out how I would make the world (background?) from a tile sheet. I've seen some people do it that way so I figure its the best.

I have looked at a bunch of tuorials and came across: "http://wiki.ps2dev.org/psp:lua_player:tutorial" Which at the bottom tells me about tiles and how to use them.

now, I don't really get what is going on in the script. I could copy and past it and just use it but I would REALLY apriciate it if someone could tell me what each part means like:

"screen:blit(16 * x, 16 * y, tiles, 17 * tileX + 1, 17 * tileY + 1, 16, 16, false)"

screen:blit = prints picture to screen

16 * x = first cordinate of something something -- 16 = number of pixels of "image.png", *=multiply, x = bla bla bla...

or something like that. I dont know what Im talking about in the example but I hope you get what I mean. Thanks!

P.S. If this has been answered then Im really sorry. Its just that 103 pages is alot!

[califrag]

basically it's dynamically setting up the image locations and where they will appear on the screen..

imagine your PSP screen is like a cartoon animation.. you have different layers.. for example your background, main character, foreground, etc..

They all stack on top of each other in the order that you draw them.. so first things first you want to draw your background... in your case you will be using tiles to create the background.

A table is created to store the information for the background and where to draw each tile. A function would then read the information from the table and get the variables which tell lua where to put the image.

You should copy the tutorial script and images and get it working yourself. Once you have a working version of the tutorial, you can modify it by substituting your own images and adjusting the values to get it to work for your application. This will help you learn the small fine-tuning skills you will need to develop a bug-free application.

Hope I've helped answer your question and good luck!

[Gutya]

I'm trying to blit a random image, i'm using this:

screen:blit(enemy.x,enemy.y,enemysprite[math.random(1,2)])

and my array looks like this:

enemysprite = {}
enemysprite.a = Image.load("Images/enemy1.png")
enemysprite.b = Image.load("Images/enemy2.png")

But i get this error:

error: Jumper.lua:93: bad argument #2 to `blit' (Image expected, got nil)

Can you not blit from an array?

Is there another way to do this?

[Altair]

hmm i think you can, but you can always just use variables. And say if var==1 then image1 end etc. But using a table would be more convenient ofcourse.

[Altair]

BTW what is the line where the error occurs?

[Gutya]

The error occours on the blit.

[Altair]

Ok i got it: You haven't got it stored in enemysprite[number] but in enemysprite.a en .b which will never be generated by math.random obviously.

So what you should do is:

enemysprite = {Image.load("Images/enemy1.png"),Image.load("Images/enemy2.png")}

[mokong]

can i ask some here??? guys if ever i update my psp to 2.6 version, can i still use my iso?

[Gutya]

Well that is not the kind of question to ask here. This thread is for LUA help only.

But no you cannot use ISOs on 2.0+

[Altair]

--deleted

[Gutya]

Yeah i saw it, thanks Altair.

Most of my problems seem to be stupid mistakes, but at least you put me right.

[Altair]

No prob and this way we get more games so i do it gladly.

[Gutya]

Yeah more games!

As i start to get more experienced i will help here as much as i can.

[Gutya]

Is it possible to make it so that a press only counts once each time?

For example, on my menu i have to tap left for one milisecond otherwise it zooms across, how can i make it so one press equals one move.

[Gutya]

Is there anyway to blit an image, wait a set amount of time, then blit another?

[Glynnder]

err gutya, do something like:

oldpad = controls.read
pad = controls.read

if pad ~= oldpad then
code goes here...
oldpad = pad
end

At least i think its this

[Gutya]

No, that does not work.

[Altair]

its like this:

while true do
pad=controls.read
if pad~=oldpad then

put your control code here

end -- end of the if pad~=oldpad loop
oldpad=pad

end --end of while loop

[Altair]

Is there anyway to blit an image, wait a set amount of time, then blit another?

Yes. OR use a timer (this way you still have functionality, i.e. the loop continues), OR use screen.waitVblanck() (this way the loop will pause for a given amount of time (60=1 second))

[Gutya]

Thanks, but now i get this error, what on earth does is mean?

error: index.lua:131: <eof> expected near `end'

[Altair]

You have to much ends, maybe it can also mean that you have to few. Anyway, check your ends.

[Gutya]

The oldpad thing doesnt work, heres what i have in my main loop:

--Main Loop
while true do
pad = Controls.read()
if pad~=oldpad then

if pad:down() then
menustatus = 2
end

if pad:up() then
menustatus = 1
end

if pad:cross() and menustatus == 1 then
score = 0
dofile("Jumper.lua")
end

if pad:cross() and menustatus == 2 then
break
end

if pad:right() then
dificulty = dificulty + 1
end

if pad:left() then
dificulty = dificulty - 1
end

if dificulty > 3 then
dificulty = 3
end

if dificulty < 1 then
dificulty = 1
end

if menustatus == 1 then
screen:print(200,248,"Play",green)
screen:print(200,258,"Quit",white)
end

if menustatus == 2 then
screen:print(200,248,"Play",white)
screen:print(200,258,"Quit",green)
end

if dificulty == 1 then
screen:print(160,208,"Easy",green)
screen:print(200,208,"Medium",white)
screen:print(250,208,"Hard",white)
end

if dificulty == 2 then
screen:print(160,208,"Easy",white)
screen:print(200,208,"Medium",green)
screen:print(250,208,"Hard",white)
end

if dificulty == 3 then
screen:print(160,208,"Easy",white)
screen:print(200,208,"Medium",white)
screen:print(250,208,"Hard",green)
end
screen.flip()
screen.waitVblankStart()
end

if pad:right() then
dificulty = dificulty + 1
end

if pad:left() then
dificulty = dificulty - 1
end

if dificulty > 3 then
dificulty = 3
end

if dificulty < 1 then
dificulty = 1
end

if menustatus == 1 then
screen:print(200,248,"Play",green)
screen:print(200,258,"Quit",white)
end

if menustatus == 2 then
screen:print(200,248,"Play",white)
screen:print(200,258,"Quit",green)
end

if dificulty == 1 then
screen:print(160,208,"Easy",green)
screen:print(200,208,"Medium",white)
screen:print(250,208,"Hard",white)
end

if dificulty == 2 then
screen:print(160,208,"Easy",white)
screen:print(200,208,"Medium",green)
screen:print(250,208,"Hard",white)
end

if dificulty == 3 then
screen:print(160,208,"Easy",white)
screen:print(200,208,"Medium",white)
screen:print(250,208,"Hard",green)
end

screen.flip()
screen.waitVblankStart()
oldpad=pad
end

[Altair]

look closer at my post. Anyway, the controls that you want to do something only ones if pressed should be in the "if pad~=oldpad then" and "end" commands. Now you have exactly those outside of them.

[Gutya]

I don't understand. :Argh:

[TPTaylor]

you have added the right bits to the controls.

if pad:------directional button-------() and
oldpad:------directional button-------() ~= pad:------directional button-------() then
(-------sound here-----)lay()
end
end

obviously delete the spaces i created there. it's just to show you where to put them. make sure oldpad = pad is at the end, before you have the ends. so in the loop. and make sure you have

oldpad = Controls.read()

out of the loop at the beginning and finaly, make sure you have

pad = Controls.read()

at the beginning of the loop.


obviously, change it from the sound play, to whatever you want it to do.

[Gutya]

So this would be correct?:

if pad:right() and 
oldpad:right() ~= pad:right() then
dificulty = dificulty + 1
end

if pad:left() and
oldpad:left() ~= pad:right() then
dificulty = dificulty - 1
end

if so it doesnt work

[TPTaylor]

you spelt dificulty wrong, don't know if that makes a difference. it's difficulty.
i'll take a look at the script if you want.