Lua Programming Help Thread

[SuperBatXS]

hey sorry for being off topic here, but how do you change what it says under your picture when you post? because mine just says novice, and thats gay.

lol, you need dev status. Funny thing is mine said "Neophyte" (even though i think it still should for now).

Also, about that, i am pming a moderator or administrator about that to get it removed...

[emericaska8r]

oh, yea and like i just deposited all my points to the bank, and now it says i don't have enough points to enter the bank anymore. thats so gay

[Anti-QuickJay]

Yea, You need to have 50 to enter it.

[SuperBatXS]

Ahem.......Sorry it was my fault to start this off topic; this is a lua help thread. Lol....

[%chrono trigger%]

i fixed my other error and now am wondering a question i defined player width and player height like this:

player:width()
player:height()

but in the collision function i need to use player width also how do i call the variables if they look like the above code? or do i need to assign new varibales and assign them the dimensions of the image?

--edit--
also i calls other variables such as (variable name).width how do I need to assign those as well?

[Grimfate126]

i fixed my other error and now am wondering a question i defined player width and player height like this:

player:width()
player:height()

but in the collision function i need to use player width also how do i call the variables if they look like the above code? or do i need to assign new varibales and assign them the dimensions of the image?

--edit--
also i calls other variables such as (variable name).width how do I need to assign those as well?

you could do this:

if (player.x + player:width() > whatever) etc.

but, its more efficient to do this:

pW = player:width()

--in your collision function--

if (player.x + pW > whatever) etc.

that way, the psp doesnt spend time each frame checking the width of the player over and over again.

[%chrono trigger%]

--edit--
ok im moving rather smoothly now except when i added this to my code:

Jewel = {}
Jewel[1] = {x=350,y=150,height = Jewel:height(), width = Jewel:width() }
Jewel[2] = {x=150,y=100,height = Jewel:height(), width = Jewel:width() }
Jewel[3] = {x=200,y=250,height = Jewel:height(), width = Jewel:width() }
Jewel[4] = {x=300,y=120,height = Jewel:height(), width = Jewel:width() }
Jewel[5] = {x=100,y=225,height = Jewel:height(), width = Jewel:width() }

it gives me an error saying attemtp to call method 'height' (a nil value)

[SG57]

Well, seems to me like you don't have a 'Jewel' image created. Whether it be loaded via Image.load as an example, or created, via Image.createEmpty(n,n).

[EminentJonFrost]

does anyone know a lua game with scrolling? i have scrolling down, its that in my game i create objects that i want for to STAY on the scrolling background. (example, throw a ...rock or something, it lands and stays, i move character, screen scrolls, rock disappears from screen, go back, rock reappears in the place it was thrown.) i just need to know if someone else has done this so i can get an idea of how to do it myself.

so basically, does anyone know a game with scrolling and has newly created objects scroll with the map too?

[HaxxBlaster]

does anyone know a lua game with scrolling? i have scrolling down, its that in my game i create objects that i want for to STAY on the scrolling background. (example, throw a ...rock or something, it lands and stays, i move character, screen scrolls, rock disappears from screen, go back, rock reappears in the place it was thrown.) i just need to know if someone else has done this so i can get an idea of how to do it myself.

so basically, does anyone know a game with scrolling and has newly created objects scroll with the map too?

You got to have two main axis, x and y.
For example:

Screen.x = 0
Screen.y = 0

screen:blit(x+Screen.x,y+Screen.y,image) -- You can make this a function so you don't have to write the "+Screen.x" stuff over and over again.

Now you make Screen.x and Screen.y togglable, then you can start to place out your sprites and stuff. Simple enugh?

[EminentJonFrost]

i'm afraid not...whats making this difficult in my case is that, not only does the screen scroll, but the player can move (in a limited box, you can say) around too. so my object appears around my character and it moves how it should on-screen (like if my character goes up, it doesnt). but i want for it to stop, and be part of the background, which scrolls, so now my object must change from player-screen-based coordinates to map coordinates. its complicated...

oh yes, my view is top-down.

[HaxxBlaster]

i'm afraid not...whats making this difficult in my case is that, not only does the screen scroll, but the player can move (in a limited box, you can say) around too. so my object appears around my character and it moves how it should on-screen (like if my character goes up, it doesnt). but i want for it to stop, and be part of the background, which scrolls, so now my object must change from player-screen-based coordinates to map coordinates. its complicated...

oh yes, my view is top-down.

Yeah, i guessed your game was in a top-down view. I got a unfinnished game with sidescrolling, not top-down view, but it's nearly the same. I think you might want to have a look at it.
MSN: [email protected]

[EminentJonFrost]

um, ok sure!

edit - i added you. sorry for the delayed response, my internet acted wierd....

[%chrono trigger%]

well this collision is really throwing me off. Can i create a empty image and then paste a .png file on it?

[EminentJonFrost]

well this collision is really throwing me off. Can i create a empty image and then paste a .png file on it?

that wouldnt do anything different. theres no point (that i know of) to blitting an image, in an image, when all you want is...the first image. post some code up, i'll see if i can be of assistance! :)

[%chrono trigger%]

jeres the first half of my code:

red = Color.new(255,0,0)
background = Image.load("b.png") 
player = Image.load("a.png")
jewel = Image.load("c.png")

playerWidth = 50 
playerHeight = 50

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

Player = {}
Player[1] = {x=10,y=10}
Background = {}
Background[1] = {x=0,y=0}
Jewel = {}
Jewel[1] = {x=350,y=150, height = jewel:height(), width = jewel:width() }
Jewel[2] = {x=150,y=100, height = jewel:height(), width = jewel:width() }
Jewel[3] = {x=200,y=250, height = jewel:height(), width = jewel:width() }
Jewel[4] = {x=300,y=120, height = jewel:height(), width = jewel:width() }
Jewel[5] = {x=100,y=225, height = jewel:height(), width = jewel:width() }

Jewel:height()
Jewel:width()

function collisionCheck(Jewel)
if (Player[1].x + playerWidth > Jewel[1].x) and (Player[1].x < Jewel[1].x + Jewel[1].width) and (Player[1].y + playerHeight > Jewel[1].y) and (Player[1].y < Jewel[1].y + Jewel[1].height) then
Player.x = oldx
Player.y = oldy
end 
end

function collisionCheck(Jewel)
if (Player[1].x + playerWidth > Jewel[2].x) and (Player[1].x < Jewel[2].x + Jewel[2].width) and (Player[1].y + playerHeight > Jewel[2].y) and (Player[1].y < Jewel[2].y + Jewel[2].height) then
Player.x = oldx
Player.y = oldy
end 
end

function collisionCheck(Jewel)
if (Player[1].x + playerWidth > Jewel[3].x) and (Player[1].x < Jewel[3].x + Jewel[3].width) and (Player[1].y + playerHeight > Jewel[3].y) and (Player[1].y < Jewel[3].y + Jewel[3].height) then
Player.x = oldx
Player.y = oldy
end 
end

function collisionCheck(Jewel)
if (Player[1].x + playerWidth > Jewel[4].x) and (Player[1].x < Jewel[4].x + Jewel[4].width) and (Player[1].y + playerHeight > Jewel[4].y) and (Player[1].y < Jewel[4].y + Jewel[4].height) then
Player.x = oldx
Player.y = oldy
end 
end

function collisionCheck(Jewel)
if (Player[1].x + playerWidth > Jewel[5].x) and (Player[1].x < Jewel[5].x + Jewel[5].width) and (Player[1].y + playerHeight > Jewel[5].y) and (Player[1].y < Jewel[5].y + Jewel[5].height) then
Player.x = oldx
Player.y = oldy
end 
end

[EminentJonFrost]

screenwidth = 480 - player:width() --did you MEAN to do this?
screenheight = 272 - player:width()

you put player:width twice..

also, it could be confusing to have an image and an array both called 'player'. i know one is capitalized, and that it should work fine, but it could lead to problems later.

i shortened this:

Jewel = {}
for a = 1, 5 do
Jewel[a] = {x=350,y=150, height = jewel:height(), width = jewel:width() }
end

in place of this:

Jewel = {}
Jewel[1] = {x=350,y=150, height = jewel:height(), width = jewel:width() }
Jewel[2] = {x=150,y=100, height = jewel:height(), width = jewel:width() }
Jewel[3] = {x=200,y=250, height = jewel:height(), width = jewel:width() }
Jewel[4] = {x=300,y=120, height = jewel:height(), width = jewel:width() }
Jewel[5] = {x=100,y=225, height = jewel:height(), width = jewel:width() }

[%chrono trigger%]

yes i did thats not the problem and disregard Jewel:height() and the width one they shouldnt be there

[EminentJonFrost]

yes i did thats not the problem

HERES the problem:

function collisionCheck(Jewel)
if (Player[1].x + playerWidth > Jewel[1].x) and (Player[1].x < Jewel[1].x + Jewel[1].width) and (Player[1].y + playerHeight > Jewel[1].y) and (Player[1].y < Jewel[1].y + Jewel[1].height) then
Player.x = oldx
Player.y = oldy
end 
end

remember how i shortened the part before? you announced the SAME function 5 times, so it only affected 1 jewel, since you kept changing which jewel number each time you defined it.

try this:

function collisionCheck(Jewel)
for a = 1, 5 do
if (Player[a].x + playerWidth > Jewel[a].x) and (Player[a].x < Jewel[a].x + Jewel[a].width) and (Player[a].y + playerHeight > Jewel[a].y) and (Player[a].y < Jewel[a].y + Jewel[a].height) then
Player.x = oldx
Player.y = oldy
end
end 
end

[jamz1825]

ok I wasnt sure if i should post this in this thread or not but here it is:

For school im doing a long term project on developing a program for the psp in c/c++.

I thought i had longer than i had so i cant learn the amount of info i need in time.

Basically is there a way that i can imbed a lua file in an eboot so that even if you open up the eboot you couldnt tell that its a lua file or w/e inside. This way i could just pretend its in c and i could make it better and get a better grade since im pretty good at lua

[EminentJonFrost]

ok I wasnt sure if i should post this in this thread or not but here it is:

For school im doing a long term project on developing a program for the psp in c/c++.

I thought i had longer than i had so i cant learn the amount of info i need in time.

Basically is there a way that i can imbed a lua file in an eboot so that even if you open up the eboot you couldnt tell that its a lua file or w/e inside. This way i could just pretend its in c and i could make it better and get a better grade since im pretty good at lua

i dont think so...but i dont know about eboots, so you'll want a second opinion.

[%chrono trigger%]

function collisionCheck(Jewel)
    local i = 1
    while i <=5 do
        if (Player[1].x + playerWidth > Jewel[i].x) and (Player[1].x < Jewel[i].x + Jewel[i].width) and (Player[1].y + playerHeight > Jewel[i].y) and (Player[1].y < Jewel[i].y + Jewel[i].height) then
            Player.x = oldx
            Player.y = oldy
        end 
        i = i +1
    end
end

therers my new optimized code so i dont have to many if statements but it gives me the error attempt to index field '?' (a nil value)

[EminentJonFrost]

function collisionCheck(Jewel)
    local i = 1
    while i <=5 do
        if (Player[1].x + playerWidth > Jewel[i].x) and (Player[1].x < Jewel[i].x + Jewel[i].width) and (Player[1].y + playerHeight > Jewel[i].y) and (Player[1].y < Jewel[i].y + Jewel[i].height) then
            Player.x = oldx
            Player.y = oldy
        end 
        i = i +1
    end
end

therers my new optimized code so i dont have to many if statements but it gives me the error attempt to index field '?' (a nil value)

change every '1' in a these: [ ] to an 'i'. and it should work.
also, put this: for i = 1, 5 do
instead of: while i <=5 do
it cycles the code with 'i' changing its values, therefore, affecting 5 jewels. it basically works the same, but you can code how you want. :)

[%chrono trigger%]

function collisionCheck(Jewel)
    local i = i
for i = 1, 5 do
while i <=5 do
        if (Player[1].x + playerWidth > Jewel[i].x) and (Player[1].x < Jewel[i].x + Jewel[i].width) and (Player[1].y + playerHeight > Jewel[i].y) and (Player[1].y < Jewel[i].y + Jewel[i].height) then
            Player.x = oldx
            Player.y = oldy
        end 
        i = i +i
    end
end

like that?
-edit-
i guess i did something wrong as i am getting another error

[EminentJonFrost]

like this:

function collisionCheck(Jewel)
for i = 1, 5 do
        if (Player[i].x + playerWidth > Jewel[i].x) and (Player[i].x < Jewel[i].x + Jewel[i].width) and (Player[i].y + playerHeight > Jewel[i].y) and (Player[i].y < Jewel[i].y + Jewel[i].height) then
            Player.x = oldx
            Player.y = oldy
        end 
    end
end

:)

[emericaska8r]

what does the:

local i = 1

do?

[Grimfate126]

what does the:

local i = 1

do?

'local' means that only the function you called it in can access the variable. for example, if i did this:

function BOB()

local joe = 0

end


while true do

joe = joe + 1

end

that would result in an error. but this:

function BOB()

local joe = 0
joe = joe + 1

end


while true do

BOB()

end

that would work perfectly.

[BlackShark]

got a problem ( a stupid one at that), for some reason, in my 2d side scroller, when my charactor moves right and hits the midde of the screen, the background scrolls AND my character still moves forward, yet, when he goes left it works Perfectly, i dont understand, it was working good before, but I must have been stupid and put something in the code to make it stop working, i copied the left movement code to the right and configured it to the right animation but still no good, here is my movement code,

Spoiler for code:

if pad:right() and santaX >= 200 and bg4.x > 0 then
    scroll = "true"
	santaState = "runningR"
    santaDirection = "right"
	bg1.x = bg1.x - 3
	bg2.x = bg2.x - 3
	bg3.x = bg3.x - 3
	bg4.x = bg4.x - 3
	else
	scroll = "false"
	end	

	
if pad:left() and santaX <= 155 and bg1.x < 0 then
    scroll = "true"
	santaState = "runningL"
    santaDirection = "left"
	bg1.x = bg1.x + 3
	bg2.x = bg2.x + 3
	bg3.x = bg3.x + 3
	bg4.x = bg4.x + 3
	else
	scroll = "false"
	end	

	
	
if pad:right()  and santaX <= rightWall and scroll == "false" then
	santaState = "runningR"
	santaDirection = "right"
	santaX = santaX + 4
	end
				
if pad:left()  and santaX >= leftWall and scroll == "false" then
	santaState = "runningL"
	santaDirection = "left"
	santaX = santaX - 4
	end

the 2 blocks of code in front are for when the player reaches the middle of the screen, he is "supposedly" stops going forward 4 pixels and the background starts to scroll, (supposedly cuz this doesn't happen for when you press right) the other two code is for when he reaches the end of the screens, it stops scrolling and he starts to walk normally and make sures to stop when he reaches the end of the screen. Help for this would be great, if you need the full code + resources then PM me, I am absilutly sure this is a really simple problem that i just cant find.

thanks in advance, Later!

-Jaws-

[SG57]

Im too busy to look into that deeply, but give this try for your FIRST to if's there...

if pad:right() and santaX >= 200 and bg4.x > 0 then
scroll = "true"
santaState = "runningR"
santaDirection = "right"
santaX = 200
bg1.x = bg1.x - 3
bg2.x = bg2.x - 3
bg3.x = bg3.x - 3
bg4.x = bg4.x - 3
else
scroll = "false"
end


if pad:left() and santaX <= 155 and bg1.x < 0 then
scroll = "true"
santaState = "runningL"
santaDirection = "left"
santaX = 155
bg1.x = bg1.x + 3
bg2.x = bg2.x + 3
bg3.x = bg3.x + 3
bg4.x = bg4.x + 3
else
scroll = "false"
end

[BlackShark]

Ahhh yup, that did , thanks again! (another reason to credit you:) )
thanks man
y i didn't think to simply state santa's X value is beyond me...

thanks again :)