Lua Programming Help Thread

[alatnet]

TP - Have you considered using a OO approach to your programming? Nothing's wrong with what you currently do, but I highly recommend it (that doesnt mean much though, as ive yet to release anything decent using it (anything actually :P) but that will change soon)

youresam: For something as simple as a filebrowser, implementing OOP would be both useless and a waste of time.

Did this for youresam, for reasons that you have to ask him yourself.

[SG57]

Well, relay this to youresam:

When did i tell him to make a filebrowser OO? your implying just because the quetsion he answered, when really, it was an 'in-general' type of thing, as I believe OO programming is 'better' then any other type (given the project is suitable for it).

[Urameshi]

he said:

youresam: OOP is a better programming style, but only for certain things. Simple things dont need OOP, and it should be avoided, whereas most other things, OOP is a good thing. And learn the rule of the square bracket.

[KINGOFNOOBS]

Holy crap, I actually understand the code now that I'm almost done with Java class. I need to start developing again. Jeez.

[SG57]

Best of luck, however, i recommend using C as, from what i hear, Java has heavy (a lot of) syntax that must be followed, so it wouldnt be that difficult using C knowing you must follow some strict syntax (all from what i hear, is Java closer to Lua or C?)

[Joel Van]

Java is closer to C,

As the guys who created JAVA based JAVA's Syntax on C-ish style.

[PSPJunkie_]

OO is a great design flow to follow and it is good to get into it early. Whether or not it is a large project, it is always good to keep an OO approach to things.

Before youresam gets another person to flame me, yes, this is opinon based.

[SG57]

Either use OO programming all the time, or none of the time... You cant get experience and improve by object orienting only projects you feel are big enough for it.

PSPJunkie - i think you mean 'bias'...

[ahrimanes]

To make it more portable, here's a function for what you want:

function randomFloatFromOrigin(center,range)
     return ( math.random( (center-range), (center+range) )+math.random() )
end

I believe that will work, however, i havent tested it.

function math.randfloat(low, high)
   x=math.random()*(high-low)+low
   return x
end

That might work.

well if you take my version and just use a range in the first section like this:

var = math.random(-10, 10)+math.random()

you will get a float between -10 and 10

if you want to set the range based on your original value, then do it like this:

var = math.random( (orig-10), (orig+10) )+math.random()

goodd thaks you all guys, i will be testhig this stuff as sson as in have some more free time and a pc thks

[trex6662k5]

By using gsub, how can I extract only the file name from the path?

Example
C:\somepath\somefile.tmp

Results in "somefile"

Cant get my head around the patterns.

[hallo007]

filepath = "C:\somepath\somefile.tmp";
for loop = 0 , sizeof(filepath) do
      if(filepath[loop] == '\') then 
                currentPosition = 0;
       end
      else if filepath[loop] == '.' then
                currentPosition = -1;
       end
      else if currentPosition != -1 then
           filename[currentPosition] = filepath[loop];
           currentPosition++;
       end
end

k , this will be probebly horrible LUA

[trex6662k5]

imageName = string.gsub(string.gsub(s tring.gsub(currentlyPlayi ng.values["Thumb"],"(.*\\)([^\\]+)$","%2"),";;",";"),".tb n","")

Thats what I got now
Except it relies on the file being a .tbn which is making things harder for me.
Too many string.gsubs IMO.

Thanks for the effort though...

[Merick]

I've got a partially working function for that using string.sub instead of gsub. It doesn't quite work though because I'm having trouble figuring out how to compare a character from the string to the \ . Anyway, what I have so far:

function find_name(text)

for i = text:len(), 1, -1 do
	if string.sub(text, i, i) == "." then
		local name_end = i-1
	end
	if string.sub(text, i, i) == "\" then
		local name_start = i+1
	end
end

return string.sub(text, name_start, name_end)

end

if you could figure out how to get this line to work:

if string.sub(text, i, i) == "\"

then with this:

filename = find_name(""C:\somepath\s omefile.tmp")

filename would be "somefile"

[trex6662k5]

In lua "\\" means "\"
You cant use "\"

if string.sub(text, i, i) == "\\"

That should work

I'll give it a go...
Thanks!

[Merick]

well, I tried to use "\\" but that didn't work either. now that I think about it, it's probably because the text string with the file path only has single \'s in it, so lua probably skips over it. If you change all the \ over to / it will work, however I don't know how that will effect the rest of your program

anyway, I looked at my code again and re-wrote it a little:

function find_name(text)
	for i = 1, text:len() do
		if string.sub(text, i, i) == "\\" then
			name_start = i+1
		elseif string.sub(text, i, i) == "." then
			name_end = i-1
		end
	end
	return string.sub(text, name_start, name_end)
end

[PSPJunkie_]

filepath = "C:\somepath\somefile.tmp";
for loop = 0 , sizeof(filepath) do
      if(filepath[loop] == '\') then 
                currentPosition = 0;
       end
      else if filepath[loop] == '.' then
                currentPosition = -1;
       end
      else if currentPosition != -1 then
           filename[currentPosition] = filepath[loop];
           currentPosition++;
       end
end

k , this will be probebly horrible LUA

What language is that?

[trex6662k5]

Certainly isn't lua
-= Double Post =-

imageName = string.gsub(string.gsub(currentlyPlaying.values["Thumb"],"(.*\\)([^\\]+)$","%2"),"%.[^%.]*$","")

Got it

[Merick]

lol, and I just figured it out with my function too

if you use double square brackets [[]] instead of "", then lua will not parse the escape sequences in the text:

filepath = [[C:\somepath\somefile.tmp]]
white=Color.new(255,255,255)

function find_name(text)
	for i = 1, text:len() do
		if string.sub(text, i, i) == [[\]] then
			name_start = i+1
		elseif string.sub(text, i, i) == "." then
			name_end = i-1
		end
	end
	return string.sub(text, name_start, name_end)
end
 
filename = find_name(filepath)
screen:clear()
screen:print(10,10, filename, white)
screen:flip()

pad = Controls.read()

while not pad:cross() do
	pad = Controls.read()
end

[trex6662k5]

I'll keep that in mind

[cruisx]

i kno i am doing something wrong, gives me an error ( i am a nooob at LUA)

--Load images into a table
Images = {
    Image.load("images/background.jpg"),
    Image.load("epic.png"),
    Image.load("img_3.png"),
    Image.load("img_4.png"),
    Image.load("img_5.png"),
    Image.load("img_6.png"),
    Image.load("img_7.png")
}

currentImageToDisplay = 1;  

while true do
    screen:clear()
    pad = Controls.read()
    
    if pad:r() and currentImageToDisplay < table.getn(Images) then
        currentImageToDisplay = currentImageToDisplay + 1;
    end
    
    if pad:l() and currentImageToDisplay > 0 then
        currentImageToDisplay = currentImageToDisplay - 1;
    end

    screen:blit(0, 0, Images[background]);
    
    screen.waitVblankStart() 
    screen.flip()
end 

EDIT

--Load images into a table
Images = {
    Image.load("images/background.jpg"),
    Image.load("images/epic.png"),
    
}

currentImageToDisplay = 1;  

while true do
    screen:clear()
    pad = Controls.read()
    
    if pad:r() and currentImageToDisplay < table.getn(Images) then
        currentImageToDisplay = currentImageToDisplay + 1;
    end
    
    if pad:l() and currentImageToDisplay > 0 then
        currentImageToDisplay = currentImageToDisplay - 1;
    end

    screen:blit(0, 0, Images[currentImageToDisplay]);
    
    screen.waitVblankStart() 
    screen.flip()
end 

ok i can get the images to load but when i try to go back to an image it says

index.lua :22: bad argument #2 to /blit/ (image expected, got nil)
Error: no script file found

[Merick]

in lua, tables start at 1, so here:

if pad:l() and currentImageToDisplay > 0

you need to change the 0 to a 1

[Urameshi]

i have one question, when i try to redefine Player.x and Player.y, how come when i run the game Player's moves are limited but not only that but the Player moves in like a invisible box, and then it just resets back to the middle of the invisible box

[cruisx]

really sorry for the doubble post but i have a prob

--Load images into a table
Images = {
    Image.load("images/background.jpg"),
    Image.load("images/epic.png"),
    Image.load("images/test2.jpg"),
    Image.load("images/work2.jpg")
    
}

currentImageToDisplay = 1;  

while true do
    screen:clear()
    pad = Controls.read()
    
    if pad:r() and currentImageToDisplay < table.getn(Images) then
        currentImageToDisplay = currentImageToDisplay + 1;
    end
    
    if pad:l() and currentImageToDisplay > 1 then
        currentImageToDisplay = currentImageToDisplay - 1;
    end

    screen:blit(0, 0, Images[currentImageToDisplay]);
    
    screen.waitVblankStart() 
    screen.flip()
end

when i try to run it, it skips rlly fast from pic 1 to pic 2. The pics in between load for like 0.1 secconds lol. can someone pls help =)

[Merick]

Urameshi: can't be sure without seeing the code, but to me it sounds like instead of adding the analog x,y to the screen position you are using the analog position as the actual screen position

cruisx: right after you flip the screen, add this line: "oldpad = pad"
then, add this to your if statments: "and pad ~= oldpad"

[Urameshi]

can't be sure without seeing the code, but to me it sounds like instead of adding the analog x,y to the screen position you are using the analog position as the actual screen position

there ya go

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

ball=Image.load("./Images/ball.png")
Sball=Image.load("./Images/Spike Ball.png")
square=Image.load("./Images/10x10.jpg")
bigSquare=Image.load("./Images/30x30.jpg")
stick=Image.load("./Images/190x23.jpg")
lvl=Image.load("./Images/backgrounds/silkwave black.png")
menu=Image.load("./Images/menu.png")
next=Image.load("./Images/next level.png")
stick2=Image.load("./Images/23x190.png")

ball:width()
ball:height()

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

Player={x=40,y=25,w=40,h=40,img=ball,oldimg=Sball}

Enemy={x=0,y=0,w=30,h=30,img=bigSquare,}
Square={x=0,y=0,w=10,h=10,img=square}
Stick={x=0,y=0,w=190,h=23,img=stick}
Stick2={x=0,y=0,w=23,h=190,img=stick2}

enemylist = {}
enemylist[1] = Stick1
enemylist[2] = Stick2
--------------------------------------------------------------------------functions
function menu1()
pad=Controls.read()	
screen:blit(0,0,menu)

if pad:cross() then
level1()
end
end
------------------------------------------------------lvl1
function level1()
	while true do
	screen:clear()
Enemy.x=100
Enemy.y=100

if collision(Player,Enemy) then
screen:blit(0,0,next)
screen.flip()
screen.waitVblankStart(90)
level2()
end

movePlayer()
screen:blit(0,0,lvl,true)
screen:blit(Player.x,Player.y,Player.img)
screen:blit(Enemy.x,Enemy.y,Enemy.img)

screen.waitVblankStart()
screen.flip()
end
end
---------------------------------------------------lvl2
function level2()
	while true do
	screen:clear()
Enemy.x=300
Enemy.y=50

if collision(Player,Enemy) then
screen:blit(0,0,next)
screen.flip()
screen.waitVblankStart(90)
level3()
end

movePlayer()
screen:blit(0,0,lvl,true)
screen:blit(Player.x,Player.y,Player.img)
screen:blit(Enemy.x,Enemy.y,Enemy.img)

screen.waitVblankStart()
screen.flip()
end
end
---------------------------------------------------lvl3
function level3()
nbc=0
ncc=2
	while true do
	screen:clear()
Enemy.x=400
Enemy.y=50
Stick.x=117
Stick.y=234
Stick2.x=230
Stick2.y=0

if collision(Player,Enemy) then
screen:blit(0,0,next)
screen.flip()
screen.waitVblankStart(90)
level4()
end

movePlayer()
screen:blit(0,0,lvl,true)
screen:blit(Player.x,Player.y,Player.img)
screen:blit(Enemy.x,Enemy.y,Enemy.img)
screen:blit(Stick.x,Stick.y,Stick.img)
screen:blit(Stick2.x,Stick2.y,Stick2.img)
screen.waitVblankStart()
screen.flip()
end
end
-------------------------------------------------------------------------level4
function level4()
run=false
nbc=0
ncc=1
	while true do
	screen:clear()
Enemy.x=40
Enemy.y=50
Stick.x=117
Stick.y=234
Stick2.x=230
Stick2.y=0
Square.x=470
Square.y=45

if collision(Player,Stick2) and Player.img==Player.oldimg then 
nbc=nbc-1 
else if collision(Player,Stick2) then
nbc=nbc+1
end
end

if nbc>ncc then
dofile("br.lua")
end

if collision(Player,Square) then
Player.img = Player.oldimg
end

if collision(Player,Enemy) then
screen:blit(0,0,next)
screen.flip()
screen.waitVblankStart(90)
level5()
end

screen:blit(Stick2.x,Stick2.y,Stick2.img)

movePlayer()
screen:blit(0,0,lvl,true)
screen:blit(Player.x,Player.y,Player.img)
screen:blit(Enemy.x,Enemy.y,Enemy.img)
screen:blit(Stick.x,Stick.y,Stick.img)
screen:blit(Square.x,Square.y,Square.img)
screen.waitVblankStart()
screen.flip()
end
end

----------------------------------------------------------------------Level 5
function level5()
run=false
nbc=0
ncc=1
	while true do
	screen:clear()
Enemy.x=378
Enemy.y=49
Stick.x=384
Stick.y=79
Stick2.x=280
Stick2.y=90
Square.x=22
Square.y=236
Player.x=14
Player.y=17

if collision(Player,Stick2) and Player.img==Player.oldimg then 
nbc=nbc-1 
else if collision(Player,Stick2) then
nbc=nbc+1
end
end

if nbc>ncc then
dofile("br.lua")
end

if collision(Player,Square) then
Player.img = Player.oldimg
end

screen:blit(Stick2.x,Stick2.y,Stick2.img)

movePlayer()
screen:blit(0,0,lvl,true)
screen:blit(Player.x,Player.y,Player.img)
screen:blit(Enemy.x,Enemy.y,Enemy.img)
screen:blit(Stick.x,Stick.y,Stick.img)
screen:blit(Square.x,Square.y,Square.img)
screen.waitVblankStart()
screen.flip()
end
end

--------------------------------------------------------------------------Other Function
function collision(ob1_,ob2_) 
     if (ob1_.x + ob1_.w > ob2_.x) and (ob1_.x < ob2_.x + ob2_.w) and (ob1_.y + ob1_.h > 

ob2_.y) and (ob1_.y < ob2_.y + ob2_.h) then 
          return true 
     else 
          return false 
     end 
end

function movePlayer()
pad=Controls.read()

if pad:right() and Player.x < screenwidth then
Player.x=Player.x + 5
end

if pad:left() and Player.x>0 then
Player.x=Player.x - 5
end

if pad:down() and Player.x < screenheight then
Player.y=Player.y + 5
end

if pad:up() and Player.y>0 then
Player.y=Player.y - 5 else if not pad:up() then
Player.y=Player.y + 8
end
end
end

falling=false

------------------------------------------------------------------------Main loop
while true do
screen:clear()

menu1()

screen.waitVblankStart()
screen.flip()
end

[Merick]

first, at the beginning of your script you've got this:

ball:width()
ball:height()

there are no operations on these, so what are you trying to do there?

as for the movement problem, I can't really see anything that would cause the behavior you described

[Urameshi]

idk why those
ball:width()
ball:height()
are there either i just have alot of useless stuff in there

[emericaska8r]

really sorry for the doubble post but i have a prob

--Load images into a table
Images = {
    Image.load("images/background.jpg"),
    Image.load("images/epic.png"),
    Image.load("images/test2.jpg"),
    Image.load("images/work2.jpg")
    
}

currentImageToDisplay = 1;  

while true do
    screen:clear()
    pad = Controls.read()
    
    if pad:r() and currentImageToDisplay < table.getn(Images) then
        currentImageToDisplay = currentImageToDisplay + 1;
    end
    
    if pad:l() and currentImageToDisplay > 1 then
        currentImageToDisplay = currentImageToDisplay - 1;
    end

    screen:blit(0, 0, Images[currentImageToDisplay]);
    
    screen.waitVblankStart() 
    screen.flip()
end

when i try to run it, it skips rlly fast from pic 1 to pic 2. The pics in between load for like 0.1 secconds lol. can someone pls help =)

you can use an oldpad type thing:

oldpad = Controls.read()
while true do
pad = Controls.read()
if pad:cross() and oldpad:cross() ~= pad:cross() then
     --do something
end
oldpad = pad
end

here, if you hold cross, it will only execute the "do something" once. It waits for you to lift off the button, and press it again before it re-executes.
-= Double Post =-
@ Urameshi:

i think your problem is that you define your players x and y values in the main loop. Therefor once you move, you are just moved back once the loop restarts again.

[Urameshi]

thanks dude that worked

[emericaska8r]

no problem