Lua Programming Help Thread

[Bob Hoil]

Thanks

[pspfreak101]

Ok I added animation to my game on start up and it works fine on the pc but when run it on my psp I get this error "Libpng warning: Incomplete compressed datastream in iCCP chunk Libpng warning: profile size field missing from iCCP chunk

[myschoo]

is it possible to make color with half opacity???

i thought lowering RGBA element would make it half transparent, but that doesnt seem to work :/

[TacticalPenguin]

transparentred = Color.new(255,0,0,127)

[pspfreak101]

Ok I added animation to my game on start up and it works fine on the pc but when run it on my psp I get this error "Libpng warning: Incomplete compressed datastream in iCCP chunk Libpng warning: profile size field missing from iCCP chunk

any body know whats wrong

[youresam]

any body know whats wrong

Yeah, youre using the windows port of lua player

[pspfreak101]

But it works fine on the pc

[TacticalPenguin]

But windows luaplayer ftl

[Bob Hoil]

Hey guys i was wondereing if there is a tutorial for making an digital clock anywhere. Or if someone could just help me out.

Thanks Bob Hoil

[Urameshi]

couldn't you just use the screen.waitVblankStart() to your advantage, all you'll need is the set of numbers

[Bob Hoil]

I have a question can you get the time that is set on the psp and use that and have it print to the screen some how so that would be the clock?
-= Double Post =-
That way you don't have to code an entire clock.

[TacticalPenguin]

Go to the lua snippets thread and theres a clock snippet i have in there just look for it

[Bob Hoil]

I just found it before you posted it thanks.:)

[youresam]

Hey guys i was wondereing if there is a tutorial for making an digital clock anywhere. Or if someone could just help me out.

Thanks Bob Hoil

Its...in...the... luaplayer....build....
-= Double Post =-

But it works fine on the pc

It does? I thought you had a problem with it?

[Urameshi]

that's what i thought too

[SG57]

pspfreak - Try opening and re-saving your image giving you the problem as PNG using MSPaint. Other than that, i dont know what to suggest you try.

[xmex]

Hello, Ive just started to learn Lua

Ive made a small script which im trying to run in luaplayerwindows, and i get an error that in line ten "then" expected near " ="

heres the code:

red = Color.new(255, 0, 0)
blue = Color.new(0, 0, 255)
green = Color.new(0, 255, 0)
color = red
while true do
screen:print(0, 0, "This text is red. Press 'X' to change the color.", color)
screen.flip()
end
if pad:cross() then
if color = red then
color = blue
end
if color = blue then
color = green
end
if color = green then
color = red
end
end
while true do
screen.waitVblankStart()
end

Now I know it's something in the syntax of if statements, and dont flame me for being a Luan00b. Please just say the problem and leave me alone.

[Merick]

when using if statements, you need to use "==" instead of"="

[xmex]

Ok, thanks. Another problemo in another script:

--variables
easy=1
med=1
hard=1
enemy1={}
enemy2={}
enemy3={}
bullet={}

--Load images

bulletimg=Image.load("bullet.png")
planeimg=Image.load("blob.png")

--TIMERS
easytimer=0
medtimer=0
hardtimer=0

--Collision script
function Death(obj)
if (obj.x+obj.width>bullet.x) and (obj.x<bullet.x+16) and (obj.y+obj.height>bullet.y) and (obj.y<bullet.y+16) then
score=score+20
obj.x=1000000000
end
end

--Increase the timers
easytimer=easytimer+1
medtimer=medtimer+1
hardtimer=hardtimer+1

--reset them
if easytimer>300 then
easytimer=0
enemy1[easy]={x=math.random(480-32), y=0, width=32, height=32}
easy=easy+1
end

if medtimer>450 then
medtimer=0
enemy2[med]={x=math.random(480-32), y=0, width=32, height=32}
med=med+1
end

if hardtimer>600 then
hardtimer=0
enemy3[hard]={x=math.random(480-32), y=0, width=32, height=32}
hard=hard+1
end

--Draw the planes
while true do
for a=1,easy do
screen:blit(enemy1[a].x, enemy1[a].y, planeimg, false)
end
for b=1,med do
screen:blit(enemy1[b].x, enemy1[b].y, planeimg, false)
end
for c=1,hard do
screen:blit(enemy1[c].x, enemy1[c].y, planeimg, false)
end
end

At line 55 (the first for) attempting to index "?"

Is this because the for statement is wrong, or that I cant use easy?

[Urameshi]

did you try it without using easy

[myschoo]

transparentred = Color.new(255,0,0,127)

thx, thats what i was doing... but i didnt know it doesnt work in windows lua player

[yumCOOKIEZZ]

whats wrong with this line?
pad = Controls.read()

I get an error "Attempt to index global 'controls' (a nil value)"

[xmex]

weird that seems odd...check capitals.

on another note:

alarm={}
red=Color.new(255, 0, 0)
b=1
for a=1, 6400 do
alarm[a]=0
end
alarm[0]=60
block={}
block[1]={x=math.random(440), y=math.random(240), width=32, height=32}
blockimg=Image.load("circle.png")
while true do
for a=1, 6400 do
if alarm[a]>0 then
alarm[a]=alarm[a]-1
end
end
if alarm[0]<=1 then
block[b+1]={x=math.random(440), y=math.random(240), width=32, height=32}
alarm[0]=60
end
for f=1, b do
screen:clear()
screen:print(0, 0, alarm[0], red)
screen:blit(block[f].x, block[f].y, blockimg, false)
screen.flip()
screen.waitVblankStart()
block[f].y=block[f].y+1
end
end

should act as an alarm - only the alarm never goes down. it is always 60. shouldnt

for a=1, 6400 do
if alarm[a]>0 then
alarm[a]=alarm[a]-1
end
end

make it go down?

[myschoo]

nothing

question: is it possible to draw circle ??? i looked in SGs transmutation script but i want to draw it without that "animation"

[yumCOOKIEZZ]

weird that seems odd...check capitals.

Nope. I tried upper and lowercase. Same problem.

[LMelior]

whats wrong with this line?
pad = Controls.read()

I get an error "Attempt to index global 'controls' (a nil value)"

That's not the line the error is referring to.

for a=1, 6400 do
alarm[a]=0
end
alarm[0]=60
while true do
for a=1, 6400 do
if alarm[a]>0 then
alarm[a]=alarm[a]-1
end
end

you are setting alarm[1-6400]==0, and then you say alarm[0]=60, and then you loop from 1 to 6400 checking if it's greater than zero.

I really don't know how you're not getting an error, because table indices do not begin at zero in Lua. Even if they did, that if statement would never be true since you don't check the zeroth entry of the table in the while loop, whatever that means. On top of that, it only decrements the current entry, so even if it did what you seem to be trying to make it do, the table would just be {59,0,0,0,0,0,........}.

[yumCOOKIEZZ]

That's not the line the error is referring to.

for a=1, 6400 do
alarm[a]=0
end
alarm[0]=60
while true do
for a=1, 6400 do
if alarm[a]>0 then
alarm[a]=alarm[a]-1
end
end

you are setting alarm[1-6400]==0, and then you say alarm[0]=60, and then you loop from 1 to 6400 checking if it's greater than zero.

I really don't know how you're not getting an error, because table indices do not begin at zero in Lua. Even if they did, that if statement would never be true since you don't check the zeroth entry of the table in the while loop, whatever that means. On top of that, it only decrements the current entry, so even if it did what you seem to be trying to make it do, the table would just be {59,0,0,0,0,0,........}.

It said line 54 and...that was line 54 o.o

[xmex]

okok, i see fixed it. But now a new problem:

I have a variable called direction, which is 0 - 360. If i hold left it goes up, and right it goes down. How can I calculate the correct x and y increments to use this to move around? as in if it was 0, which i want to be right, it would be x=x+2. And if it was 45 it would be x=x+1 y=y-1. The thing is, I cant have 360 if statements. Is the an algorithm for this?

[matriculated]

okok, i see fixed it. But now a new problem:

I have a variable called direction, which is 0 - 360. If i hold left it goes up, and right it goes down. How can I calculate the correct x and y increments to use this to move around? as in if it was 0, which i want to be right, it would be x=x+2. And if it was 45 it would be x=x+1 y=y-1. The thing is, I cant have 360 if statements. Is the an algorithm for this?

You can use basic trigonometry: SOHCAHTOA

You have an angle, and a distance, you can calculate the x and y by applying knowledge from the above link.

[xmex]

Well that sort of is the idea but i'm not quite into Sin Cosine i cant really understand it. In Game Maker there was a function which returned the x and y componenets of a length and direction, which would help, except i doubt Lua has that.