Lua Programming Help Thread

[Merick]

Is there a way to us c/c++ code in a lua script? For instance would it be possible to modify some of the functions from Zettablade's vlib to to let them be used with the lua player, or would they have to compiled into the player itself?

[Yongobongo]

You either have to compile it into luaplayer or load it as an lrx

[Merick]

Sorry, but I'm still a newbie, what's an lrx?

[Yongobongo]

It's an extra library that lets you add more functions to your script
Ive used sysext lrx, for example that adds the ability to play .ogg, overclock the cpu, exit the application, launch static elf's etc.

[Merick]

Is an lrx a pre-compiled library, or is it like a script that can be edited?

[Access_Denied]

Is an lrx a pre-compiled library, or is it like a script that can be edited?

It's a pre-compiled library. It's basically a .prx, with the L from LuaPlayer. :|

[Ba11in13]

hey can i just have a menu coded in lua so i can learn from it and study cause i am learning lua now and want a menu thank you

[Anti-QuickJay]

Look in the code snippets thread, Its sticked in this forum.

[Ba11in13]

ok but is there one that will help me with this type of menu
where there are 3 menu bgs with 3 options in them start credits and quit this is designed in

and the three images are
the first one is with the arrow pionting to start second one to credits and 3rd one to quit designed in not coded is there a menu in the snippets like that

[Anti-QuickJay]

So when you highlight an option, It will display the arrow picture next to it?

[Ba11in13]

kinda if you want i can post the pics

[Anti-QuickJay]

Guess what i found in the snippets thread?
Just with some minor indention ;)

Spoiler for Keep guessing...:

-- Menu code
-- Lua Snippets thread @ QJ

black = Color.new(0, 0, 0)
white = Color.new(255, 255, 255)
index = 1
xIcon = 0
yIcon = 0
offscreen = Image.createEmpty(480, 272)
offscreen:clear(black)
function menuCode()
screen:clear(white)

if index == 1 then
	screen:print(0, 0, "You have chosen 'Play'.", black)
		elseif index == 2 then
			screen:print(0, 0, "You have chosen 'Options'.", black)
				elseif index == 3 then
					screen:print(0, 0, "You have chosen 'Exit'.", black)
end
		end
					end
screen.flip()
end

function printMenu ()
	for i = 0, table.getn(menu)-1 do
	offscreen:print(10, i*15, menu[i+1], white)
	end
end

function moveIcon (direction)
screen:clear(black) -- reset/clear the screen every time the icon moves
screen:blit(0, 0, offscreen, false)
	if direction == 1 and index > 1 and index <= table.getn(menu) then
		index = index - 1
		yIcon = yIcon - 15
		else if direction == 2 and index >= 1 and index < table.getn(menu) then
			index = index + 1
			yIcon = yIcon + 15
		end
end

screen:fillRect (xIcon, yIcon, 5, 5, white)
screen.waitVblankStart(4) 
screen.flip()
end

menu = {}
menu[1] = "Play"
menu[2] = "Options"
menu[3] = "Exit"

printMenu()

screen:blit(0, 0, offscreen, false)
screen:fillRect(xIcon, yIcon, 5, 5, white)
screen.flip()

while true do
pad = Controls.read()
if pad:start() then
	System.Quit()
	end
	elseif pad:down() then
		moveIcon(2)
		end
		elseif pad:up() then
			moveIcon(1)
			end
			elseif pad:cross() then
				menuCode()
				end

screen.waitVblankStart()
end

[Yongobongo]

A basic menu is not hard to make, just simply declare the amount of menu items and make something like this:

 if pad:up() then
menu = menu - 1
end

if pad:down() then
menu = menu + 1
end

if menu > 5 then -- if menu is over the maximum amount
menu = 1
end

if menu == 1 then -- if the menu is number 1
screen:blit(0,0,arrow)
end

if menu == 2 then -- if menu is number 2
screen:blit(0,10,arrow)
end

and so on.

[Ba11in13]

ok these are the images please no one copy these
menu1


menu2


menu3

[SuperBatXS]

A basic menu is not hard to make, just simply declare the amount of menu items and make something like this:

 if pad:up() then
menu = menu - 1
end

if pad:down() then
menu = menu + 1
end

if menu > 5 then -- if menu is over the maximum amount
menu = 1
end

if menu == 1 then -- if the menu is number 1
screen:blit(0,0,arrow)
end

if menu == 2 then -- if menu is number 2
screen:blit(0,10,arrow)
end

and so on.

I think that could should be:

 if pad:up() then
menu = menu - 1
end

if pad:down() then
menu = menu + 1
end

if menu > 5 then -- if menu is over the maximum amount
menu = 5
end

if menu < 1 then -- if menu is below the minimum amount
menu = 1
end

if menu == 1 then -- if the menu is number 1
screen:blit(0,0,arrow)
end

if menu == 2 then -- if menu is number 2
screen:blit(0,10,arrow)
end

I just changed some things in it. In your code, if you go above of the 5th option in the menu, the code resets to the 1st option. It should be 5th option if the menu goes above the 5th option. Vice versa for the minimum option.

[Anti-QuickJay]

Just edit the code I posted to display your arrow instead of the arrow it makes.
Also edit it to blit the arrow on both sides.
Should be very simple, I just don't want to give you the code cause i would rather have you learn something ;)

[Ba11in13]

ok thanks
-= Double Post =-
would it look something like this

code-
blue = Color.new(0, 153, 255)
orange = Color.new(155, 102, 0)
gray = Color.new(153, 153, 153)
black = Color.new(0 , 0, 0)

---Variables---

Select = 1

MaxSelect = 3

WOC1 = Image.load("images/WoC1.jpg")
WOC2 = Image.load("images/WoC2.png")
WOC3 = Image.load("images/WoC3.png")

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

--Player decision---
if pad:down()
Select = Select + 1
end

if pad:up() then
Select = Select - 1
end

--Menu Options---

if Select == 1 then
screen:blit(0,0,WOC1)
screen:flip()
end
if Select == 2 then
screen:blit(0,0,WOC2)
screen:flip()
end
if Select == 3 then
screen:blit(0,0,WOC3)
screen:flip()
end
if Select < 1 then
screen:blit(0,0,WOC3)
screen:flip()
end
if Select > 3 then
screen:blit(0,0,WOC1)
end
screen:flip()
screen.waitVblankStart()
end

[Anti-QuickJay]

I think that could should be:

 if pad:up() then
menu = menu - 1
end

if pad:down() then
menu = menu + 1
end

if menu > 5 then -- if menu is over the maximum amount
menu = 5
end

if menu < 1 then -- if menu is below the minimum amount
menu = 1
end

if menu == 1 then -- if the menu is number 1
screen:blit(0,0,arrow)
end

if menu == 2 then -- if menu is number 2
screen:blit(0,10,arrow)
end

I think it should be:

if pad:up() then
menu = menu - 1
end
elseif pad:down() then
menu = menu + 1
end
elseif menu => 4 then
menu = 1
end
elseif menu <= 0 then
menu = 3
end
elseif menu == 1 then
screen:blit(0,0,arrow)
end
elseif menu == 2 then
screen:blit(0,10,arrow)
end
elseif menu == 3 then
screen:blit(0,20,arrow)
end

[Ba11in13]

ok thanks
-= Double Post =-
would it look something like this

code-
blue = Color.new(0, 153, 255)
orange = Color.new(155, 102, 0)
gray = Color.new(153, 153, 153)
black = Color.new(0 , 0, 0)

---Variables---

Select = 1

MaxSelect = 3

WOC1 = Image.load("images/WoC1.png")
WOC2 = Image.load("images/WoC2.png")
WOC3 = Image.load("images/WoC3.png")

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

--Player decision---
if pad:down()
Select = Select + 1
end

if pad:up() then
Select = Select - 1
end

--Menu Options---

if Select == 1 then
screen:blit(0,0,WOC1)
screen:flip()
end
if Select == 2 then
screen:blit(0,0,WOC2)
screen:flip()
end
if Select == 3 then
screen:blit(0,0,WOC3)
screen:flip()
end
if Select < 1 then
screen:blit(0,0,WOC3)
screen:flip()
end
if Select > 3 then
screen:blit(0,0,WOC1)
end
screen:flip()
screen.waitVblankStart()
end

does that look ok or needs work

[SuperBatXS]

I think it should be:

elseif menu =>4 then
menu = 1
end

So if a menu option is more than 4, make the menu option 1? Or if a menu option is equal to 4, make the menu option 1? It depends on the user. You can have a menu either way. Btw, I was talking about 5 menu options. Also, you don't have to have that. Instead of

elseif menu =>4 then
menu = 1
end

you can put

if menu > 3 then
menu = 1
end

Btw, i am not sure if it needs an else if....you can just if alone.

--Double post--

--Variables

Select = 1
MaxSelect = 3
WOC1 = Image.load("images/WoC1.png")
WOC2 = Image.load("images/WoC2.png")
WOC3 = Image.load("images/WoC3.png")

---Loop----
while true do
pad = Controls.read()

--Player decision---
if pad:down()
Select = Select + 1
end

if pad:up() then
Select = Select - 1
end

--Menu Options---

if Select == 1 then
screen:blit(0,0,WOC1)
screen:flip()
end
if Select == 2 then 
screen:blit(0,0,WOC2)
screen:flip()
end
if Select == 3 then
screen:blit(0,0,WOC3)
screen:flip()
end
if Select > 3 then
Select == 1
end
if Select < 1 then
Select == 3
end
screen.waitVblankStart()
end

Just a simple code cleanup. Yea, that could work. Btw, you don't need the colors, unless you use them later.

[Anti-QuickJay]

blue = Color.new(0, 153, 255)
orange = Color.new(155, 102, 0)
gray = Color.new(153, 153, 153)
black = Color.new(0 , 0, 0)

---Variables---

Select = 1

MaxSelect = 3

WOC1 = Image.load("images/WoC1.png")
WOC2 = Image.load("images/WoC2.png")
WOC3 = Image.load("images/WoC3.png")

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

--Player decision---
if pad:down()
Select = Select + 1
end

if pad:up() then
Select = Select - 1
end

--Menu Options---

if Select == 1 then
screen:blit(0,0,WOC1)
screen:flip()
end
elseif Select == 2 then
screen:blit(0,0,WOC2)
screen:flip()
end
elseif Select == 3 then
screen:blit(0,0,WOC3)
screen:flip()
end
if Select <= 0 then
screen:blit(0,0,WOC3)
screen:flip()
end
elseif Select => 4 then
screen:blit(0,0,WOC1)
end
screen:flip()
screen.waitVblankStart()
end

You need to had a statement where if X is press it will do this, You can do that...
-= Double Post =-

So if a menu option is more than 4, make the menu option 1? Or if a menu option is equal to 4, make the menu option 1? It depends on the user. You can have a menu either way. Btw, I was talking about 5 menu options. Also, you don't have to have that. Instead of

elseif menu =>4 then
menu = 1
end

you can put

if menu > 3 then
menu = 1
end

Btw, i am not sure if it needs an else if....you can just if alone.

=> means "equal" or "greater than"
<= means "equal" or less than"

"elseif" is a good idea when you have alot of if statements.

[SuperBatXS]

=> means "equal" or "greater than"
<= means "equal" or less than"

"elseif" is a good idea when you have alot of if statements.

Lol, you can use either ways. I was just saying that you don't have to have "elseif", you can just put "if".

Edit:
Anti-Qj, in your code

if Select <= 0 then
screen:blit(0,0,WOC3)
screen:flip()
end
elseif Select => 4 then
screen:blit(0,0,WOC1)
screen:flip()
end

What if you keep pressing up? What if you are at Select == -1? If you keep press up, and when you eventually try to go above the 1st option, you will get the 3rd option. But if you keep pressing up, it will stay as the third option. Here is what should work:

if Select < 1 then
Select == 1
end
elseif Select > 3 then
Select == 3
end

[Anti-QuickJay]

Lol, you can use either ways. I was just saying that you don't have to have "elseif", you can just put "if".

But if you have alot of if statements, a elseif is a good idea.

Bad

if blah then
blah
end
if blah then
blah
end
if blah then 
blah
end

Good

if blah then
blah
end
elseif blah then
blah
end
elseif blah then 
blah
end

[SuperBatXS]

But if you have alot of if statements, a elseif is a good idea.

Bad

if blah then
blah
end
if blah then
blah
end
if blah then 
blah
end

Good

if blah then
blah
end
elseif blah then
blah
end
elseif blah then 
blah
end

Edited previous post*
Also, doesn't matter to me.....both do the same thing. In fact, "if" is less code than "elseif".

[Anti-QuickJay]

In fact, "if" is less code than "elseif".

....:Argh:
-= Double Post =-

Lol, you can use either ways. I was just saying that you don't have to have "elseif", you can just put "if".

Edit:
Anti-Qj, in your code

if Select <= 0 then
screen:blit(0,0,WOC3)
screen:flip()
end
elseif Select => 4 then
screen:blit(0,0,WOC1)
screen:flip()
end

What if you keep pressing up? What if you are at Select == -1? If you keep press up, and when you eventually try to go above the 1st option, you will get the 3rd option. But if you keep pressing up, it will stay as the third option. Here is what should work:

if Select < 1 then
Select == 1
end
elseif Select > 3 then
Select == 3
end

As mentioned before, I dont want to give him the full code, He jsut wanted to know how to use an arrow as a selector.;)

[ClearTranquil]

I should point out that there's a mistake there....and that multiple Ifs are longer than Elseifs.

if blah then
something
elseif blah then
something
end

--AS OPPOSED TO--

if blah then
something
end
if blah then
something
end

Elseifs basically allow you to skip the "end" until you've finished putting in Elseifs.

[Anti-QuickJay]

Thats what i have been saying...

Look, Say you have a program that has this snippet in it...

if x == 2 then
	blah
		end
			if x == 3 then
	blah	
		end
			if x == 4 then
	blah
end

Well, it will check if x is equal to 2, if it is then it will run but it will still check if x is equal to 3 and 4 which is wasting time.

Now if you put...

if x == 2 then
	blah
		end
			elseif x == 3 then
	blah	
		end
			elseif x == 4 then
	blah
end

It will check and if 2 is equal to x it will run whatever the blah is, but now since you have a elseif statement it will(as mentioned before0 ignore the other two if statements because we already know what x is, x = 5

It basically saves some time.

PS. Sorry about the indention if you cant read it, I just am use to indention now.

[Grimfate126]

Edited previous post*
Also, doesn't matter to me.....both do the same thing. In fact, "if" is less code than "elseif".

your ignorance scares me. if they both do the same thing, why in the world would lua even have it? as aint-qj explained, using else/elseif's saves many cpu cycles, which you desperately need when working with a console such as the psp.

[Anti-QuickJay]

I just didn't like how he said " "if" is less code then "elseif" "
That just seems like something a nub would say.

BTW, Doesn't this look nice?

if x == 2 then
	blah
		end
			elseif x == 3 then
	blah	
		end
			elseif x == 4 then
	blah
end

Why in the world did i say that?
Because i think super should learn how to indent.

[SuperBatXS]

your ignorance scares me. if they both do the same thing, why in the world would lua even have it? as aint-qj explained, using else/elseif's saves many cpu cycles, which you desperately need when working with a console such as the psp.

Sorry, i have to be honest. I wasn't thinking properly....just typing while i was doing my math homework (or was I.....?). Honestly, i do use "else if" in my menu code in C.