Lua Programming Help Thread

[TacticalPenguin]

I wonder if your image load portion needs fixed! Anyways, anyone ko whats wrong with my script?

[Grimfate126]

Oh, ok. It says:

Error: index.lua :6: function arguments expected near 'scree'

Press start to restart

you write screen clear like this:

screen:clear

it SHOULD be:

screen:clear()

[TacticalPenguin]

OH I FORGOT THE LITTLE PARENTHESES THINGIES!!!!!!!!!!!!!!!!! !!!!!!

Do I also need to do that on screen.flip?

[LMelior]

Do I also need to do that on screen.flip?

Yep.

It's nice that these problems are working themselves out. :) The error descriptions are quite good, aren't they?

[-Marshall-]

lol now i feel more dumb i cant fix my image problem and it works fine on my computer so im confused
-= Double Post =-
never mind i figured it out

[TacticalPenguin]

Ok, it shows the text up to where it should display the background pic then it shows this:

Error: index.lua:14: Image.load: Error loading image.

Press start to restart

My code now is:

blue = Color.new(0, 0, 255)
screen:print(0, 0, "Loading: 30%", blue)
screen.flip()
screen.waitVblankStart(120)
screen:clear()
screen:print(0, 0, "Loading: 70%", blue)
screen.flip()
screen.waitVblankStart(120)
screen:clear()
screen:print(0,0, "Loading Complete", blue)
screen.flip()
screen.waitVblankStart(120)
screen:clear()
background = Image.load("background.jpg")
screen:print(0, 0, "Tux says hello!", blue)
screen.flip()
screen.waitVblankStart(240)
screen:clear()
background = Image.load("background.jpg")
screen:print(0, 0, "Tux says goodbye!", blue)
screen.flip()
screen.waitVblankStart(180)
while true do
screen.waitVblankStart()
end

The pic is named background.jpg and is in the same directory as index.lua

[-Marshall-]

ok i have 2 new problems now
1. how do i make the car move faster and smoother (if you need to look at my code its in the last page
2.how do i make a button to return to the lua player

[ZereoX]

how can i do this:

if timerD > 120 and < 140 then characterL = Run_L[7] end

where "and" is writin i dont know what to put to do:

if timer D is > then 120 but < then 140

My part of code:

if timerL == 140 then timerL = 0 end
if timerL >= 120 < 140 then characterL = Run_L[7] end
if timerL >= 100 < 120 then characterL = Run_L[6] end
if timerL >= 80  < 100 then characterL = Run_L[5] end
if timerL >= 60  < 80 then characterL = Run_L[4] end
if timerL >= 40  < 60 then characterL = Run_L[3] end
if timerL >= 20  < 40 then characterL = Run_L[2] end
if timerL >= 0   < 20 then characterL = Run_L[1] end

[SG57]

ZeroX, you must do:

if timerL >= 0 and timerL < 20 then characterL = Run_L[1] end

But for all of them...

[ZereoX]

Tkz SG57 tomorow when im done jumping and shooting and maybe a part of the level collision il send you a demo.TKZ i whas to tired to find it out TKZ

[LMelior]

@ Tactical Penguin

I never use jpegs, always pngs, and I've never had a problem. How big in pixels is background.jpg? Make sure the capitalization and spelling is correct. Also, you load it twice, which you obviously don't need to do.


@ iamcanadian

1. These kinds of problems are ones where you have to do trial and error, because there's hardly ever just one way to do things. Faster is easy, just make it move more pixels per loop. However, it generally makes the movement seem less smooth when you make it faster.

2. When the interpreter reaches the end of the code, it goes back to luaplayer. So all you have to do is "break" out of the main loop.


@ ZereoX

It is far more efficient to use elseif's when you are testing the same variable, because it only runs through the if statements until it finds a satisfied condition.

SG57 posted the easiest way since I started, so I'll post another way, which is probably less efficient time-wise, but it does condense the two conditions into one (I suppose that makes it more efficient space-wise):

if math.abs(timerL-9.5) < 10 then characterL = Run_L[1] end

and to use elseif's:

if math.abs(timerL-9.5) < 10 then 
   characterL = Run_L[1] 
elseif math.abs(timerL-29.5) < 10 then 
   characterL = Run_L[2] 
end

[TacticalPenguin]

Ok guys, I got mine all fixed! Thanks for the help!

[-Marshall-]

ok i got the break code to work but my whole script is slow for some reason

[ZereoX]

My works perfect thanks guys.


PS.Im participating in the Dream coding compo sponsor by DCemu also Zion's compo sponsor by him hope you vote for me when im done.
Cheers,ZereoX

[Access_Denied]

It's pretty nice because since it returns an integer, you don't have to do an if statement (in the simplest case, at least).

player.x=player.x+math.floor(pad:analogX()/32)
player.y=player.y-math.floor(pad:analogY()/32)

You'll have to mess with the signs a bit to get it right, but that takes care of movement in almost all directions.


@ Tactical Penguin and iamcanadian:

Post errors.

I did try that, but I keep getting some error that has nothing to do with those two lines. I put this in:

mx=mx+math.floor(pad:analogX()/32)
my=my+math.floor(pad:analogY()/32)

But I get some stupid error. Could somone maybe post a working example?

[LMelior]

I did try that, but I keep getting some error that has nothing to do with those two lines. I put this in:

mx=mx+math.floor(pad:analogX()/32)
my=my+math.floor(pad:analogY()/32)

But I get some stupid error. Could somone maybe post a working example?

This is from one of my projects; you should be able to tell what it does and why I did it this way. It works for me and it's not that different from what you posted, so I don't know what's wrong with your code.

-- Allow player to change map offset with analog
if pad:analogX()<0 then
	mapoffset.x=mapoffset.x-math.floor(pad:analogX()^2/2500)
elseif pad:analogX()>0 then
	mapoffset.x=mapoffset.x+math.floor(pad:analogX()^2/2500)
end
if pad:analogY()<0 then
	mapoffset.y=mapoffset.y-math.floor(pad:analogY()^2/2500)
elseif pad:analogY()>0 then
	mapoffset.y=mapoffset.y+math.floor(pad:analogY()^2/2500)
end

[Grimfate126]

This is from one of my projects; you should be able to tell what it does and why I did it this way. It works for me and it's not that different from what you posted, so I don't know what's wrong with your code.

-- Allow player to change map offset with analog
if pad:analogX()<0 then
	mapoffset.x=mapoffset.x-math.floor(pad:analogX()^2/2500)
elseif pad:analogX()>0 then
	mapoffset.x=mapoffset.x+math.floor(pad:analogX()^2/2500)
end
if pad:analogY()<0 then
	mapoffset.y=mapoffset.y-math.floor(pad:analogY()^2/2500)
elseif pad:analogY()>0 then
	mapoffset.y=mapoffset.y+math.floor(pad:analogY()^2/2500)
end

sry for the n00bish question, but what DOES math.floor do??

[LMelior]

Surely a pro in 2D Lua would know to check the Lua Reference Manual. ;) I'll give you a hint, you don't need a separate rounding function because math.floor(x + 0.5) does the exact same thing.

[Grimfate126]

Surely a pro in 2D Lua would know to check the Lua Reference Manual. ;) I'll give you a hint, you don't need a separate rounding function because math.floor(x + 0.5) does the exact same thing.

i got burned... so let me guess, it removes the decimal off of any number?

and the reference is just too boring for me. sad how i know metatables, but not this..:Cry:

[Aphonia]

it removes the decimal off of any number?

Yeah. It rounds down (or, returns the largest integer <= a specific number), and is antonymous with math.ceiling.

I usually don't check for things I don't know exist, either. It's just too bad you had to learn something so important on the streets.

[Grimfate126]

Yeah. It rounds down (or, returns the largest integer <= a specific number), and is antonymous with math.ceiling.

I usually don't check for things I don't know exist, either. It's just too bad you had to learn something so important on the streets.

i get it! floor - down, ceiling - up! corny, but it works!
-= Double Post =-

I did try that, but I keep getting some error that has nothing to do with those two lines. I put this in:

mx=mx+math.floor(pad:analogX()/32)
my=my+math.floor(pad:analogY()/32)

But I get some stupid error. Could somone maybe post a working example?

here is some code that *should* work. havent tested it, but it should.

sentivity = 32 -- the higher you put this, the slower it will move--


mx = mx + (pad:analogX()/sentivity)
my = my + (pad:analogX()/sentivity)

[myschoo]

hello i have 3 questions:

1. i found this timer on evilmana.com site:

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

counter = Timer.new()
counter:start()
while true do
screen:clear()

currentTime = counter:time()

screen:print(10,10,"Counter Time: " .. currentTime,white)

if currentTime < 1000 then
screen:print(100,100,"Less than 1000",white)
end

if currentTime > 1000 and currentTime < 2000 then
screen:print(100,100,"Greater than 1000",white)
end

if currentTime > 2000 then
counter:reset(0)
counter:start()
end

screen.waitVblankStart()
screen.flip()
end

its really good BUT...its TOO FAST! ... its moving maybe 50-100 numbers/second...
so HOW do i set it to 1 number in 1 sec???

2. Question:

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

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

screen:print(190,100,"Autor: myschoo",white)
screen:print(110,110,"Podakovanie: QJ forum a EvilMana.com",white)
screen:print(140,120,"Stlac X pre navrat do menu",white)

if pad:cross() then
break
end

screen.waitVblankStart()
screen.flip()
end

this is simple code for info...i want it so when i press X it throw me back in Main Menu...it works but only sometimes...normally a i have to tap the button and then it randomly close and im back in menu...sometimes i pres X once...sometimes 20 times... i dont know whats the problem :/

3. question is similar to 1st question:

Music.playFile("music.xm", true)

when i use this code i can hear only maybe 0.5 sec from music then it plays from start..again and again and again...how to STOP this???

THX 4 answers!

[yaustar]

1. The timer is in milliseconds which is why it seems so fast. If you want seconds then simply divide it by 1000.

currentTimeInSecs = currentTime / 1000

(You may want to floor it to get a whole number)

2. You need to store the state of the button in the previous frame so you can tell the difference between a button press and a when you hold down the button.

[myschoo]

head_54us:

thx mate 1st. thing sorted...i will try the second one

edit. sorted :)

so my last question again:

"Music.playFile("music.xm ", true)"

when i use this code, i dont know what to add so the music plays correctly...

[AndyMosh]

Well atleast someone sorted your problem out

[myschoo]

yeeh well good thread!!

[-Marshall-]

System.usbDiskModeActivate()
line = Image.load("line.png")
player = Image.load("player.png")
linee = Image.load("line1.png")

--Colisions
function collisionCheck(object)
if (Player.x + playerWidth > object.x) and (Player.x < object.x + object.width) and (Player.y + playerHeight > object.y) and (Player.y < object.y + object.height) then
Player.x = oldx
Player.y = oldy
end
end



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

Player = { }
Player[1] = { x = 10, y = 75 }
playerHeight = 60
playerWidth = 66
oldx = Player.x
oldy = Player.y



 
line = { }
line[1] = { x = 0, y = 150 }

while true do

pad = Controls.read()
screen:clear()

screen:blit(0,50,linee)

screen:blit(0,150,line)


--check collision for line
collisionCheck(line[1])



screen:blit(Player[1].x,Player[1].y,player)

if pad:left() and Player[1].x > 0 then
Player[1].x = Player[1].x - 4
end

if pad:right() and Player[1].x < screenwidth then
Player[1].x = Player[1].x + 4
end

if pad:up() and Player[1].y > 0 then
Player[1].y = Player[1].y - 4
end

if pad:down() and Player[1].y < screenheight then
Player[1].y = Player[1].y + 4
end

if pad:start() then break end
screen.waitVblankStart()
screen.flip()
end

im just trying to ad collisions what am i doing wrong here?

[Grimfate126]

System.usbDiskModeActivate()
line = Image.load("line.png")
player = Image.load("player.png")
linee = Image.load("line1.png")

--Colisions
function collisionCheck(object)
if (Player.x + playerWidth > object.x) and (Player.x < object.x + object.width) and (Player.y + playerHeight > object.y) and (Player.y < object.y + object.height) then
Player.x = oldx
Player.y = oldy
end
end



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

Player = { }
Player[1] = { x = 10, y = 75 }
playerHeight = 60
playerWidth = 66
oldx = Player.x
oldy = Player.y



 
line = { }
line[1] = { x = 0, y = 150 }

while true do

pad = Controls.read()
screen:clear()

screen:blit(0,50,linee)

screen:blit(0,150,line)


--check collision for line
collisionCheck(line[1])



screen:blit(Player[1].x,Player[1].y,player)

if pad:left() and Player[1].x > 0 then
Player[1].x = Player[1].x - 4
end

if pad:right() and Player[1].x < screenwidth then
Player[1].x = Player[1].x + 4
end

if pad:up() and Player[1].y > 0 then
Player[1].y = Player[1].y - 4
end

if pad:down() and Player[1].y < screenheight then
Player[1].y = Player[1].y + 4
end

if pad:start() then break end
screen.waitVblankStart()
screen.flip()
end

im just trying to ad collisions what am i doing wrong here?

whats your error?

[-Marshall-]

bad argument #2 'blit' (image expected, got table) but that dosent make sence beacuse it never had problems eith any blit's intill i added the collision script???

[PSPMillionaire]

its because you created a table named line after you had already created line for an image.
Change the name of one of the two.