Lua Programming Help Thread

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
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 =-

Zitat:

---

Zitat von superbatxs

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

Code:

---

elseif menu =>4 then
menu = 1
end

---

you can put

Code:

---

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.

Zitat:

---

Zitat von Anti-QJ

=> 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

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:

Code:

---

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

---

Zitat:

---

Zitat von superbatxs

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

Code:

---

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

---

Good

Code:

---

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

---

Zitat:

---

Zitat von Anti-QJ

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

Bad

Code:

---

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

---

Good

Code:

---

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".

Zitat:

---

Zitat von superbatxs

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

---

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

Zitat:

---

Zitat von superbatxs

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

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:

Code:

---

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.;)

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

Code:

---

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.

Thats what i have been saying...

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

Code:

---

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...

Code:

---

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.

Zitat:

---

Zitat von superbatxs

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.

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?

Code:

---

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.

Zitat:

---

Zitat von Grimfate126

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.

Zitat:

---

Zitat von superbatxs

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.

---

if you say so. But your excuse seems a little shabby. bah.

Zitat:

---

Zitat von Anti-QJ

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?

Code:

---

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.

---

Uhm, i hope you realize you have like 5 indeitations for the if statement, than 2 for the code to execure, then 1 for hte end... That is quite random (to me) and will be unreadable in any semi-large project.

Personally, my indentations are 2-5 spaces.

Code:

---

int main() {
  for(;;) {
      if(condtion is true) {
        break;
      }
  }
  return 0;
}

---

Zitat:

---

Zitat von SG57

Uhm, i hope you realize you have like 5 indeitations for the if statement, than 2 for the code to execure, then 1 for hte end... That is quite random (to me) and will be unreadable in any semi-large project.

Personally, my indentations are 2-5 spaces.

Code:

---

int main() {
  for(;;) {
      if(condtion is true) {
        break;
      }
  }
  return 0;
}

---

---

Yea, the code that you just posted ( for(;;) { ) is exactly what i am using for the G-Pack's credit loading screens. It works very very well, and i greatly thank psp-programming for that. Lol, i didn't know they had that in lua because i never actually coded in lua well enough to use it. :(

Hi... I am a noob at LUA and just beginning to learn it...

Could someone tell me how to make a program wait for a certain amount of time?

Zitat:

---

Zitat von blotus21

Hi... I am a noob at LUA and just beginning to learn it...

Could someone tell me how to make a program wait for a certain amount of time?

---

Either make your own timer or use this:

Code:

---

screen.waitVblankStart(60)

---

I put 60 there, which is a second. Every 60 is a second. For example, if i use 300 instead, it would be 5 seconds.

Use this to learn lua in an easy way:

http://www.psp-programming.com/tutor...a/lesson02.htm

ah, thanks very much... I'll try to do it that way ^_^

Zitat:

---

Zitat von SG57

Uhm, i hope you realize you have like 5 indeitations for the if statement, than 2 for the code to execure, then 1 for hte end... That is quite random (to me) and will be unreadable in any semi-large project.

Personally, my indentations are 2-5 spaces.

Code:

---

int main() {
  for(;;) {
      if(condtion is true) {
        break;
      }
  }
  return 0;
}

---

---

To ME its real easy to read, When i have alot of lines of code, Its still easy for ME, I guess people just shave different preferences.

Code:

---

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

---

That is definitely non-standard.

Code:

---

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

---

This is more common place.

http://astyle.sourceforge.net/

How would I rotate an image? For example, to be able to turn an image (or twist, I guess) in order to shoot different things all around you? Thanks.

Zitat:

---

Zitat von andyauff

How would I rotate an image? For example, to be able to turn an image (or twist, I guess) in order to shoot different things all around you? Thanks.

---

use the GU.

How would i do that? I thought it was for 3d. Sorry if I'm wrong, just trying to figure things out.

Zitat:

---

Zitat von superbatxs

Either make your own timer or use this:

Code:

---

screen.waitVblankStart(60)

---

I put 60 there, which is a second. Every 60 is a second. For example, if i use 300 instead, it would be 5 seconds.

Use this to learn lua in an easy way:

http://www.psp-programming.com/tutor...a/lesson02.htm

---

I thought it was a millasecond timer. and arent thier 100 milliseconds in a second?

EDIT_____!!!!
NVM its vblanks and there are 60 vblanks in a second. so ur right.

Zitat:

---

Zitat von andyauff

How would i do that? I thought it was for 3d. Sorry if I'm wrong, just trying to figure things out.

---

everything software wise is based on the GU. (on the PSP) tactical penguin wrote a tutorial here:

http://forums.qj.net/f-psp-developme...ive-89527.html

how do you add a thing so if you are at the main menu and you press credits it goes to credits what is the code for that and i would like it to be x that selects it

if pad:cross() then

btw, pspdude10594 = pspdude 10/5/94 = pspdude October 5th, 1994?

Zitat:

---

Zitat von youresam

if pad:cross() then

btw, pspdude10594 = pspdude 10/5/94 = pspdude October 5th, 1994?

---

Haha.......lol. Youresam, you are my hero....:ROFL:

Zitat:

---

Zitat von youresam

if pad:cross() then

btw, pspdude10594 = pspdude 10/5/94 = pspdude October 5th, 1994?

---

sure whatever you want to think

Zitat:

---

Zitat von pspdude10594

sure whatever you want to think

---

Uh, ok? Im assuming it was just random pounding on the keyboard. Nevermind then.

How come os.exit( ) freezes my PSP when I use it? I used the same method as the tutorial. It was something along the lines of this:

I'm looking to return to the XMB from an EBOOT compiled in Game Maker.

Code:

---

if pressing X then
    do nothing
elseif pressing O then
    os.exit( )
end

---

The command is slightly different in different versions of the player. Try using System.Quit() and see if that works

yeah System.Quit() works in Cools mod

when I use this piece of code:

for line in songindex:lines() do

song[songlineread] = line
songlineread = songlineread + 1

end

It always adds a weird character (i'm assuming its a line end) to the end of each line, any way of removing it or stopping it from happening?

Thanks

Hey guys i am learning lua right now and i did some tutorials. Now i am trying to combine some to make a simple game like AOTM. Can you tell me why my guy won't shoot. It encounters an error everytime u try to shoot.

Code:

---

green=Color.new(0,255,0)
grass=Image.load("grass.png")
player=Image.load("player.png")
tree=Image.load("tree.png")
bullet = Image.createEmpty(4,4)
bullet:clear(green)

screenwidth=480-player:width()
screenheight=272-player:width()

Player={}
Player[1]={x=200, y=50}

oldpad = Controls.read()
currentBullet = 0
direction = "right"

BulletInfo = {}
for a = 1,800 do
        BulletInfo[a] = { pic = bullet , firing = false, direction = "right", x = Player[1].x + 32,
        y = Player[1].y + 16 }
end

function bulletSetup()
        if currentBullet < 800 then
                currentBullet = currentBullet + 1
        else
                currentBullet = 1
        end
if direction == "left" then
BulletInfo[currentBullet].x = Player[1].x
BulletInfo[currentBullet].y = Player[1].y + 16
end
if direction == "right" then
BulletInfo[currentBullet].x = Player[1].x + 32
BulletInfo[currentBullet].y = Player[1].y + 16
end
if direction == "up" then
BulletInfo[currentBullet].x = Player[1].x + 16
BulletInfo[currentBullet].y = Player[1].y
end
if direction == "down" then
BulletInfo[currentBullet].x = Player[1].x + 16
BulletInfo[currentBullet].y = Player[1].y + 32
end
BulletInfo[currentBullet].direction = direction
BulletInfo[currentBullet].firing = false
end
function bulletFire()
        for i = 1,800 do
                if BulletInfo[i].firing == true then
                        screen:blit(BulletInfo[i].x,BulletInfo[i].y,BulletInfo[i].pic)
                end
                if BulletInfo[i].x < 0 or BulletInfo[i].x > 480 or BulletInfo[i].y < 0 or BulletInfo[i].y > 272 then
                        BulletInfo[i].firing = false
                end
        end
end

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

        bulletSetup()

        for a=0, 14 do
                for b=0, 8 do
                        screen:blit(32 * a, 32 * b, grass)
                end
        end

        screen:blit(100,100,tree)
        screen:blit(300,220,tree)
        screen:blit(87,46,tree)
        screen:blit(400,150,tree)
        screen:blit(Player[1].x,Player[1].y,player)

        if pad:left() and Player[1].x>0 then
                Player[1].x=Player[1].x-3
        end

        if pad:right() and Player[1].x<screenwidth then
                Player[1].x=Player[1].x+3
        end

        if pad:up() and Player[1].y>0 then
                Player[1].y=Player[1].y-3
        end

        if pad:down() and Player[1].y<screenheight then
                Player[1].y=Player[1].y+3
        end

        if pad:triangle() then
                if BulletInfo[i].direction == "up" then
                        BulletInfo[i].y = BulletInfo[i].y - 10
                end
        end
        if pad:circle() then
                if BulletInfo[i].direction == "right" then
                        BulletInfo[i].x = BulletInfo[i].x + 10
                end
        end
        if pad:cross() then
                if BulletInfo[i].direction == "down" then
                        BulletInfo[i].y = BulletInfo[i].y + 10
                end
        end
        if pad:square() then
                if BulletInfo[i].direction == "left" then
                        BulletInfo[i].x = BulletInfo[i].x - 10
                end
        end

        bulletFire()

        screen.waitVblankStart()
        screen.flip()
end

---

post your error please

GAME.LUA:105:attempt to index field '?' (a nil value)

There you go. Not sure what is wrong.
Thanks

screenwidth=480-player:width()
screenheight=272-player:width()

shouldn't it be:
screenwidth=480-Player:width()
screenheight=272-Player:width()

Not sure but the error is in line 105
-= Double Post =-
It has to do with something when i hit the button to shoot it encounters that error. I need this because next i am going to add enemies and collision hopefully.

Thanks to anyone that helps me out.

well in

Code:

---

BulletInfo = {}
for a = 1,800 do
        BulletInfo[a] = { pic = bullet , firing = false, direction = "right", x = Player[1].x + 32,
        y = Player[1].y + 16 }
end

---

you stated direction="right" but right above that line you stated direction="right"

maybe that has something to do with it, also dont blame me when i say this cause im new at Lua also, but where did "right" come from?

Well i just started so to start i am combing tutorials to make my first game then will write my next game from my head. In the bullet one it said to shoot right.

so tha character moves right? not right in the direction i mean right is in right