Lua Programming Help Thread

[EminentJonFrost]

@ EminentJonFrost, you DO NOT need spaces between your ='s, <'s, or >',s. although they do make your code easier to read.

oh, i thought it was only inside parantheses () that spaces didnt matter.

[montrob]

I have absolutley no clue on how to do this.. but how do you make a scrolling background..

[SG57]

I have an question: how can i make trigger R to do multiple, Triple Things like an example below

if pad:r() and screen:blit(3,0, color) then screen:blit(3,50, color)
end

But i get error =/

Well, your problem is that the screenblit function does not return an integer/anything bresides the image to tell if its true or not after blitting. Therefore, we must make it return something. If i am not mistakin,, you want to display an image while R and the image color at the co-ordinates 3,0 are all true. well,i do not know if this is orrect, but does the luaplayer currently have the screen:blit function return anything? besides the image? But i dunno, So if the screen:blit function/prototype does return an integer, then u can do, if screen:blit(blahcX, blahY, blah)==1 then ... That is a guess, casue usually functions/prototypes return 1 for completion/a pointer to the newly created obect/memory allocated, or return NULL for an error.

@montorb - A sidescrolling backround is nothng short of a simple backround, blitted usingthe co-ordsinates of a variabel you can change. Yet another mini-tut by SG57 lol:

SsBg = Image.load("side
_scrolling_bg.png")
bgX = 0
bgY = 0
bg2X = 479
ScrollingSpeed = 5
while true do 
	screen:blit(bgX, bgY, SsBg)
	screen:blit(bg2X, bgY, SsBg)
	bgX=bgX+ScrollingSpeed
	bg2X=bg2X+ScrollingSpeed
	if bgX<-475 then
		bgX=0
		bg2X=479
	end
end

Just a basic sidescrolling backround. There is a way to do this via either Lumo's tut, or using the offsets of the image to keep verlapping after off the screeen, but thats a little too advanced for new comers to understand So ya, all this is doing is blitting the backround 2 times, making there X Co-ordinates move via bgX and bg2X, and once bgX is almost offscreen, itll reset back to the start/right of the screen and keep going. Also, in C, you can declare your image's dimensions, and if the dimensions are too big, they just blit the image again until it fills those dimensions, so in C i use only have to blit my image once, use only 1 variable to change/move, etc.

Hope this gives someone a basic un derstanding.

[PSPduh]

Yes it's me again! I have had another problem. This time, I'm trying to code a game/useful tool to release, and I am having a problems. One, how would you print the result from a function? Like:

function duh()
[some code]
end

screenrint(x, y, "duh: " .. duh(), color)

would that be it? Also, I am getting the error: script.lua:11: '=' expected near *
that line of code is:

function caf()
r*r*3.14 < line #11
end

then later I want to:

screenrint(x, y, "caf: " .. caf(), color)
Is that the right way?

If you get the kind of useful tool that I am trying to make, please don't steal it or post it.
And no, I tryed it spacing the *'s out, but it still doesn't work.
Thanks in advance!

[EminentJonFrost]

Yes it's me again! I have had another problem. This time, I'm trying to code a game/useful tool to release, and I am having a problems. One, how would you print the result from a function? Like:

function duh()
[some code]
end

screenrint(x, y, "duh: " .. duh(), color)

would that be it? Also, I am getting the error: script.lua:11: '=' expected near *
that line of code is:

function caf()
r*r*3.14 < line #11
end

If you get the kind of useful tool that I am trying to make, please don't steal it or post it.
And no, I tryed it spacing the *'s out, but it still doesn't work.
Thanks in advance!

you have to say

something = r*r*3.14 -- the mathematical sentence equals 'something'

i cant really tell what your app is by what your showing. but i think its a *a***l*t*r. (lol)

[PSPduh]

LOL. Sort of, but not really. How would I print that result out?

function caf()
x = r*r*3.14
end

then later...

screenrint(x, y, "caf: " .. x, color)

If i do that then it gives me an error of: attempt to concatenate global 'x' (a nil value) On line 48. That screenrint line is line 48.

And also, how do I make something happen when a button is held down for a certain amount of time?
Thanks again! (Once I release this, should be in a couple of days, I'll mention you, PSPmillionare, and whitehawk in the credits!)

[EminentJonFrost]

LOL. Sort of, but not really. How would I print that result out?

function caf()
x = r*r*3.14
end

then later...

screenrint(x, y, "caf: " .. x, color)

If i do that then it gives me an error of: attempt to concatenate global 'x' (a nil value) On line 48. That screenrint line is line 48.

And also, how do I make something happen when a button is held down for a certain amount of time?
Thanks again! (Once I release this, should be in a couple of days, I'll mention you, PSPmillionare, and whitehawk in the credits!)

screen:print(#, #, x, color) -- no parantheses, just 'x'

thanks! (for the credit)

[PSPduh]

Ughhh, another problem...I got everything to load, the background and the r = 0 part, so now the screen is green and R = 0 appears, but when I press up, down, left, or right, it still stays the same:
This is the whole code:

red = Color.new(255,0,0)
yellow = Color.new(255, 255, 0)
blue = Color.new(0, 0, 255)
orange = Color.new(223, 88, 6)
grey = Color.new(94, 97, 111)
black = Color.new(0, 0, 0)
white = Color.new(255, 255, 255)
green = Color.new(0,255,0)

r = 0

function caf()
x = r*r*3.14
end

while true do

screen:clear(green)

pad = Controls.read()
oldpad = Controls.read()

if pad:up() and oldpad:up() ~= pad:up() then
r = r + 1
end

if pad:down() and oldpad:down() ~= pad:down() then
r = r + 5
end

if pad:right() and oldpad:right() ~= pad:right() then
r = r + 20
end

if pad:left() and oldpad:left() ~= pad:left() then
r = r + 10
end

if r > 500 then
r = 0
end

if pad:cross() then
caf() 
screen:print(50, 10, 'x', black)
end


screen:print(10,10,"R = " .. r, black)


oldpad = pad

screen.waitVblankStart()
screen.flip()
end

Now you are probably guessing what it is, but I'll never say until its done. :icon_razz
Thanks a bunch again!

[EminentJonFrost]

Ughhh, another problem...I got everything to load, the background and the r = 0 part, so now the screen is green and R = 0 appears, but when I press up, down, left, or right, it still stays the same:
This is the whole code:

red = Color.new(255,0,0)
yellow = Color.new(255, 255, 0)
blue = Color.new(0, 0, 255)
orange = Color.new(223, 88, 6)
grey = Color.new(94, 97, 111)
black = Color.new(0, 0, 0)
white = Color.new(255, 255, 255)
green = Color.new(0,255,0)

r = 0

function caf()
x = r*r*3.14
end

while true do

screen:clear(green)

pad = Controls.read()
oldpad = Controls.read()

if pad:up() and oldpad:up() ~= pad:up() then
r = r + 1
end

if pad:down() and oldpad:down() ~= pad:down() then
r = r + 5
end

if pad:right() and oldpad:right() ~= pad:right() then
r = r + 20
end

if pad:left() and oldpad:left() ~= pad:left() then
r = r + 10
end

if r > 500 then
r = 0
end

if pad:cross() then
caf() 
screen:print(50, 10, 'x', black)
end


screen:print(10,10,"R = " .. r, black)


oldpad = pad

screen.waitVblankStart()
screen.flip()
end

Now you are probably guessing what it is, but I'll never say until its done. :icon_razz
Thanks a bunch again!

Try taking out the part that I put in bold letters.
edit - oh, and you dont need these marks: ' '

[PSPduh]

Now that I did, it works, but it goes up WAY to fast. That was the point of that oldpad. But now that its out, it works...Anyway to make it go slower without the oldpad, or a way to work it with the oldpad? Because besides that, my app does not have any other problems. Once that's worked out, then all I have to do is some more coding.
It just printed x without the ' ' marks. That line works now; it is:
screenrint(100, 100, 'caf = ' .. x, black)
Thanks.

[EminentJonFrost]

Now that I did, it works, but it goes up WAY to fast. That was the point of that oldpad. But now that its out, it works...Anyway to make it go slower without the oldpad, or a way to work it with the oldpad? Because besides that, my app does not have any other problems. Once that's worked out, then all I have to do is some more coding.

just before (in other words RIGHT ABOVE) the 'end' for each of your 'if' loops. put a "screen.waitVblankStart(5 )".

put a small number in the parantheses, whichever you want. that should slow things down to how you want.

[EminentJonFrost]

so it would look like this:

if pad:up() then
r = r + 1
screen.waitVblankStart(5)
end

if pad:down() then
r = r + 5
screen.waitVblankStart(5)
end

if pad:right() then
r = r + 20
screen.waitVblankStart(5)
end

if pad:left() then
r = r + 10
screen.waitVblankStart(5)
end

[PSPduh]

SO MUCH THANKS! And also, another problem. (I never stop having problems) This should be the last one. In my code I have:

r = 0
d = r*2

function caf()
x = r*r*3.14
end

function cac()
y = d*3.14
end

Yet as r increases, d stays the same. If i set r as 1, d would show up as d = 2, and never go up no matter how much r goes up. THis is the final problem, (I hope!)
THANKS again.

[EminentJonFrost]

SO MUCH THANKS! And also, another problem. (I never stop having problems) This should be the last one. In my code I have:

r = 0
d = r*2

function caf()
x = r*r*3.14
end

function cac()
y = d*3.14
end

Yet as r increases, d stays the same. If i set r as 1, d would show up as d = 2, and never go up no matter how much r goes up. THis is the final problem, (I hope!)
THANKS again.

can you post all the code again, i need to see it all in one place as it is. (its confusing going back and forth between posts to see where we are)

[PSPduh]

Whoops, here is the whole code:

red = Color.new(255,0,0)
yellow = Color.new(255, 255, 0)
blue = Color.new(0, 0, 255)
orange = Color.new(223, 88, 6)
grey = Color.new(94, 97, 111)
black = Color.new(0, 0, 0)
white = Color.new(255, 255, 255)
green = Color.new(0,255,0)

r = 0
d = r*2

function caf()
x = r*r*3.14
end

function cac()
y = d*3.14
end

while true do

screen:clear(green)

pad = Controls.read()

if pad:up() then
r = r + 1
screen.waitVblankStart(7)
end

if pad:down() then
r = r + 5
screen.waitVblankStart(7)
end

if pad:right() then
r = r + 20
screen.waitVblankStart(7)
end

if pad:left() then
r = r + 10
screen.waitVblankStart(7)
end

if r > 500 then
r = 0
end

if pad:cross() then
caf() 
screen:print(100, 100, 'Circles area = ' .. x, black)
end

if pad:square() then
cac()
screen:print(10,10,'Circles circumfence = ' .. y, black)
end

screen:print(10,20,"Diameter = " .. d, black)
screen:print(10,10,"Radius = " .. r, black)

oldpad = pad

screen.waitVblankStart()
screen.flip()
end

Now you can kinda see what I am trying to make.

[EminentJonFrost]

Whoops, here is the whole code:

red = Color.new(255,0,0)
yellow = Color.new(255, 255, 0)
blue = Color.new(0, 0, 255)
orange = Color.new(223, 88, 6)
grey = Color.new(94, 97, 111)
black = Color.new(0, 0, 0)
white = Color.new(255, 255, 255)
green = Color.new(0,255,0)

r = 0
d = r*2

function caf()
x = r*r*3.14
end

function cac()
y = d*3.14
end

while true do

screen:clear(green)

pad = Controls.read()

if pad:up() then
r = r + 1
screen.waitVblankStart(7)
end

if pad:down() then
r = r + 5
screen.waitVblankStart(7)
end

if pad:right() then
r = r + 20
screen.waitVblankStart(7)
end

if pad:left() then
r = r + 10
screen.waitVblankStart(7)
end

if r > 500 then
r = 0
end

if pad:cross() then
caf() 
screen:print(100, 100, 'Circles area = ' .. x, black)
end

if pad:square() then
cac()
screen:print(10,10,'Circles circumfence = ' .. y, black)
end

screen:print(10,20,"Diameter = " .. d, black)
screen:print(10,10,"Radius = " .. r, black)

oldpad = pad

screen.waitVblankStart()
screen.flip()
end

Now you can kinda see what I am trying to make.

do the circle's diameter and circumference show correctly? (i cant find my PSP's usb wire so i cant test it)

[PSPduh]

Yeah, both of them show correctly. It's just that I would like them to d to increase as r is. It would make the app much simpler.

[EminentJonFrost]

I really dont know..all the coding looks fine. dont know why it doesnt work.

[PSPduh]

Meh, then thanks anyway. I could work around that...Do you know how to code menus? Because if you do, then just PM me, because I could use you for this app.

[kozine]

JW, In LUA is it possible to find out the PSP Username?

[EminentJonFrost]

JW, In LUA is it possible to find out the PSP Username?

dont think so...

[natan333]

1 hour ago i found out how to change the pixels of the paint =PP
when i finish i will release my 2nd verson
=PPP

[Grimfate126]

Meh, then thanks anyway. I could work around that...Do you know how to code menus? Because if you do, then just PM me, because I could use you for this app.

i could help. i have just written a guide on menus. search "menus in lua" and youll see it. or i can do it for you.

[PSPMillionaire]

SO MUCH THANKS! And also, another problem. (I never stop having problems) This should be the last one. In my code I have:

r = 0
d = r*2

function caf()
x = r*r*3.14
end

function cac()
y = d*3.14
end

Yet as r increases, d stays the same. If i set r as 1, d would show up as d = 2, and never go up no matter how much r goes up. THis is the final problem, (I hope!)
THANKS again.

This is because you only defined "d" in the top of your code.
It isn't anywhere in your loop so it can't be updated. It's only created at the top of your code. You need to either put it somewhere in your loop to update the variable, or into a function that gets called.

[Electro]

how would you 'refresh' a randomly chosen number,
so when i tell it to, it will randomize again,(pick a new number)

[PSPMillionaire]

how would you 'refresh' a randomly chosen number,
so when i tell it to, it will randomize again,(pick a new number)

Do it the same way you made the first number.

If you did

number = math.random(1,10)

to get the first number then just call that command again wherever you want a new random number.

I would also recommend at the top of your code before your loop to "seed" your random numbers so that the same ones arent generated each time you run your app.Here's a good way to do that.

math.randomseed(os.time))

That's a good way

[Electro]

thanks,,

and is there a way turn rotate/ or zoom in on an image,

[natan333]

guys. i put a qustion in a page but no one answered

if pad:l() and pad:triangle() then screen:save("PortablePaint.tga") end

what do i change so the tga picture will go to root of the memory stick or in another location ?

[dragaron]

guys. i put a qustion in a page but no one answered

if pad:l() and pad:triangle() then screen:save("PortablePaint.tga") end

what do i change so the tga picture will go to root of the memory stick or in another location ?

screen:save("ms0:/PortablePaint.tga") to save to root of ms, or
screen:save("ms0:/PSP/SCREENIES/PortablePaint.tga") to save in "screenies" folder within the "psp" folder on the ms.

[natan333]

thank you so much dragon
dragaron