Lua Programming Help Thread

[Anti-QuickJay]

load sound

if pad cross then
play sound1
elseif pad circle then
play sound2
end

[Nielkie]

ehh... I usually don't help people who ask for code as basic as this, but it was just too easy to mash up...

sound1 = Sound.load("sound1.wav",false)
sound2 = Sound.load("sound2.wav",false)
oldpad = Controls.read()
while true do
	pad = Controls.read()
	screen:print(10,10,"Press X for first sound, and O for the second")
	if ((pad:cross() ~= oldpad:cross()) and pad:cross()) then sound1:play() end
	if ((pad:circle() ~= oldpad:circle()) and pad:circle()) then sound2:play() end
	oldpad = pad
	screen.waitVblankStart()
	screen.flip()
end

[j3r3mie]

Tanks a lot.

[HaxxBlaster]

ehh... I usually don't help people who ask for code as basic as this, but it was just too easy to mash up...

sound1 = Sound.load("sound1.wav",false)
sound2 = Sound.load("sound2.wav",false)
oldpad = Controls.read()
while true do
	pad = Controls.read()
	screen:print(10,10,"Press X for first sound, and O for the second")
	if ((pad:cross() ~= oldpad:cross()) and pad:cross()) then sound1:play end
	if ((pad:circle() ~= oldpad:circle()) and pad:circle()) then sound2:play end
	oldpad = pad
	screen.waitVblankStart()
	screen.flip()
end

Does "sound1:play" really work? I made a cleaner alternative, removed unnecessary "(" and ")"s.

sound1 = Sound.load("sound1.wav",false)
sound2 = Sound.load("sound2.wav",false)
oldpad = Controls.read()
while true do
	pad = Controls.read()
	screen:print(10,10,"Press X for first sound, and O for the second")
	if pad:cross() ~= oldpad:cross() and pad:cross() then sound1:play() end
	if pad:circle() ~= oldpad:circle() and pad:circle() then sound2:play() end
	oldpad = pad
	screen.waitVblankStart()
	screen.flip()
end

I may not have to be this way, but i think it's a cleaner alternative, since LUA don't need the highlighted ones "if (something) then"
Also the "sound1:play", it may not need the "sound1:play()" but i think it's a lot less confusing.

[Nielkie]

Sorry, I have got a habit of over-bracketing my code. Oh, and yeah, it is : play().

[Highsight]

Does anyone here have any experience with the 3D lighting functions?

[drag_93]

ive been working on a horizontal scrolling shooting for a couple of days now and have run into a problem. i want to create another enemy after 1-2 seconds. ive looked at the timer tutorials at evilmana.com but cant get them to work. anyone know what to do?

[Nielkie]

ive been working on a horizontal scrolling shooting for a couple of days now and have run into a problem. i want to create another enemy after 1-2 seconds. ive looked at the timer tutorials at evilmana.com but cant get them to work. anyone know what to do?

A basic timer goes like this:


yourtimer = timer.new(0)
This creates a new timer.

Next, you must create a variable to hold the current time.
yourtime = yourtimer:time()
This must be put in your main loop - to update every frame.

Next, you must start the timer.
yourtimer:start()

To stop the timer you have:
yourtimer:stop()

And you can reset the timer to 0 like this:
yourtimer:reset(0)



Now, you can do this:
If yourtime >= 1000 then
enemy.new()
yourtimer:reset(0)
end

[drag_93]

thanks

[FaT3oYCG]

could someone help me figure out why this doesnt work please

i dont have much time to work on things at the moment and this is taking too long to work out

ALL help appreciated thanks

-- image resizer

-- either the file name or variable that holds file name
origpic = Image.load(browserbg.png)
-- either the file name or variable that holds file name

-- creates an empty variable that holds the values that need to be resized
resize = ""
-- creates an empty variable that holds the values that need to be resized

-- creates an empty variable that stores the picture to be used
pictouse = ""
-- creates an empty variable that  stores the picture to be used

-- will check if the image needs to be resized
-- if not it will skip the resize process
-- if it does it will check the height, width or both height and width
function sizecheck()
if
origpic:height() > 240 -- set to the largest x value wanted
or
origpic:width() > 230 -- set to the largest y value wanted
then
resizecheck()
else
pictouse = screen:blit(244, 37, origpic)
end
end
-- end of size check function

rvx = 0
rvy = 0

-- resize check value - checks which values need to be resized
-- for example if the x is bigger than the y then the x will be
-- the value to be checked to see if the new image is small enough
-- and vice versa if they are the same then the x valuse will be used
function resizecheck()
if
origpic:height() > origpic:width()
then
resize = y
elseif
origpic:width() > origpic:height()
then
resize = x
elseif
origpic:height() == origpic:width()
then
resize = x
end
resizevalues()
end
-- end of resizecheck function


-- stores the new x and y values
function resizevalues()
if
resize == x
then
rvx = origpic:width() / 2
rvy = origpic:height() / 2
until
rvx <  240 -- set to the largest x value wanted
elseif
resize == y
then
rvx = origpic:width() / 2
rvy = origpic:height() / 2
until
rvy <  230 -- set to the largest y value wanted
end
end
end
resizepicture(rvx, rvy, origpic)
end
-- stores the new x and y values

-- creates a new version or the image that you have resized
function resizepicture(newx, newy, theimage)

newpicture = Image.createEmpty(newx, newy)

for
thex = 1, newx
do
for
they = 1, newy
do
newpicture:blit(thex, they , theimage, math.floor(thex * (theimage:width() / newx)), math.floor(they * (theImage:height() / newy)), 1, 1)
end
end
return pictouse = newpicture
end
-- creates a new version or the image that you have resized

function blitpic()
pictouse
end

while true do

blitpic()

i know i have a few extra ends in there at the moment but the main error araises before that

the error message is

line 64 'end' expected (to close 'if' at line 59) near 'until' but if you look i dont want to end it there

thanks

[Nielkie]

You know, you will get more help if you're code is actually readable. (Indenting, not one-word-per-line)

Anyway, what are you trying to accomplish with that "until"? "until" is used like this:
repeat block until exp
It's basically a reverse "while" loop

[michaelp]

origpic = Image.load(browserbg.png)
resize = ""
pictouse = ""
function sizecheck()
if origpic:height() > 240 or origpic:width() > 230 then
resizecheck()
else
pictouse = screen:blit(244, 37, origpic)
end
end
rvx = 0
rvy = 0
function resizecheck()
if origpic:height() > origpic:width() then
resize = y
elseif origpic:width() > origpic:height() then
resize = x
elseif origpic:height() == origpic:width()
then
resize = x
end
resizevalues()
end
function resizevalues()
if resize == x then
rvx = origpic:width() / 2
rvy = origpic:height() / 2
until
rvx <  240 
elseif
resize == y
then
rvx = origpic:width() / 2
rvy = origpic:height() / 2
until
rvy <  230 
end
end
end
resizepicture(rvx, rvy, origpic)
end
function resizepicture(newx, newy, theimage)
newpicture = Image.createEmpty(newx, newy)
for thex = 1, newx do
for they = 1, newy do
newpicture:blit(thex, they , theimage, math.floor(thex * (theimage:width() / newx)), math.floor(they * (theImage:height() / newy)), 1, 1)
end
end
return pictouse = newpicture
end
function blitpic()
pictouse
end
while true do
blitpic()

Your code is horrible. I took out all the comments and made things on the same line here. A couple of things which I'm not sure where they are, but these are the problems:
1. One of your functions is "pictouse". That means absolutely nothing. Putting a random variable in a functions is... WTF?
2.

pictouse = screen:blit(244, 37, origpic)

???? You are trying to assign something to "pictouse" using screen:blit? Does screen:blit even return anything?
3. As Nielkie said, why is there a random until in the middle of nowhere?
4.

return pictuose = newpicture

I'm pretty sure that is not how return statements work...

There are an unbelievable amount of problems with your code.

[FaT3oYCG]

ok maybe if i explain what i was wanting to do it is hard to know what i am doing wrong when i dont have much time and have to work on it in little bits so as i said earlier it was taking too long so i came to ask for some help

the code is meant to take an image either predefined or defined from a file browser

then when it has loaded the file see if it needs resizeing or not

if it doesnt skip the whole resize process to save time

if it does then do the resize function (which is very messed up i know) (i just explained why above)

then it checks the x and y and sees which is larger

then it makes both x and y untill the larger is smaller than the defined value

then it resizes using the defined values and blits the image to the screen


well thats what ti is supposed to do but it doesnt

so i am asking for some help pleas for example some revised code or a propper explanation of how to fix the problems that you have apparently found

thanks

[Judas]

ok maybe if i explain what i was wanting to do it is hard to know what i am doing wrong when i dont have much time and have to work on it in little bits so as i said earlier it was taking too long so i came to ask for some help

the code is meant to take an image either predefined or defined from a file browser

then when it has loaded the file see if it needs resizeing or not

if it doesnt skip the whole resize process to save time

if it does then do the resize function (which is very messed up i know) (i just explained why above)

then it checks the x and y and sees which is larger

then it makes both x and y untill the larger is smaller than the defined value

then it resizes using the defined values and blits the image to the screen


well thats what ti is supposed to do but it doesnt

so i am asking for some help pleas for example some revised code or a propper explanation of how to fix the problems that you have apparently found

thanks

This is where you get help with your code. Not where others code for you. Post the code you have, and we'll help you fix it.

[michaelp]

He did post his code. Check a couple posts back. My last post takes out all of the comments and organizes it a bit.

First of all, you pretty much need to take out that until. For sure, unless you know how to use this:

repeat 
block of code
until expression

http://lua-users.org/wiki/ControlStructureTutorial

You did not end your main loop, "while true do". Put an end at the end of it.
Try making the variable names more descriptive so you don't need so many comments. Instead of rvy and rvx, make them what they mean.
Indent!!!! So you know where to put "end"s.

[Nielkie]

Untested, but this is basically what you're code is trying to do in a condensed forum.

function load_img_scaled(image,width,height)
	local retimg;
	local img = Image.load(image)
	local aspect = img:width / img:height

	local function scaleimg(theImage,newX,newY)
		resizedImage = Image.createEmpty(newX, newY) 
		for x = 1, newX do 
			for y = 1, newY do 
				resizedImage:blit(x,y , theImage, math.floor(x*(theImage:width()/newX)), math.floor(y*(theImage:height()/newY)),1,1) 
			end
		end
		return resizedImage 
	end

	if img:width > width and img:height > height then
		if img:width > img:height then
			local heightA = width / aspect
			retimg = scaleimg(img,width, heightA)
		else
			local widthA = height * aspect
			retimg = scaleimg(img,widthA, height)
		end
	elseif img:width > width then
		local heightA = width / aspect
		retimg = scaleimg(img,width, heightA)
	elseif img:height > height then
		local widthA = height * aspect
		retimg = scaleimg(img,widthA, height)
	else
		retimg = img
	end

	return retimg
end

usage: load_img_scaled("path/to/file.png",maxwidth,maxhei ght)

e.g:
resized_image = load_img_scaled("pic_that _is_bigger_than_480x272.p ng",480,272)

[michaelp]

You put a semi-colon at the end of your second line.

function load_img_scaled(image,width,height)
	local retimg;

[FaT3oYCG]

thanks a load i modified it slightly to make it work but thanks

here is the finished and working code

function load_img_scaled(image,width,height)
	local retimg;
	local img = Image.load(image)
	local aspect = img:width() / img:height()

	local function scaleimg(theImage,newX,newY)
		resizedImage = Image.createEmpty(newX, newY) 
		for x = 1, newX do 
			for y = 1, newY do 
				resizedImage:blit(x,y , theImage, math.floor(x*(theImage:width()/newX)), math.floor(y*(theImage:height()/newY)),1,1) 
			end
		end
		return resizedImage 
	end

	if img:width() > width and img:height() > height then
		if img:width() > img:height() then
			local heightA = width / aspect
			retimg = scaleimg(img,width, heightA)
		else
			local widthA = height * aspect
			retimg = scaleimg(img,widthA, height)
		end
	elseif img:width() > width then
		local heightA = width / aspect
		retimg = scaleimg(img,width, heightA)
	elseif img:height() > height then
		local widthA = height * aspect
		retimg = scaleimg(img,widthA, height)
	else
		retimg = img
	end

	return retimg
end

resized_image = load_img_scaled("image.png",230,136)

while true do

screen:blit(244, 37, resized_image)


screen.flip()
screen.waitVblankStart()

end

thank you so much neilkie

[emericaska8r]

You put a semi-colon at the end of your second line.

function load_img_scaled(image,width,height)
	local retimg;

you are allowed to do that so it won't mess anything up

[nobodyimportant]

I need a better way to select a random line from a file.

I'm trying to write a name generator for the PSP. I have a file with a list of names in it, one per line.

My code works perfectly for small files (under about 1000 lines), but for larger ones (like 300Kb), it gives me the error "No space left on device". Seems there isn't enough memory to load the entire file into memory.

Any suggestions on a more memory efficient way to do this? My existing code is below. It opens the file into a table and returns 5 randomly selected names.

function getname()
	firstnamefile = "names-first.txt"

	local count = 0
	local lines = {}
	for line in io.lines(firstnamefile) do
		table.insert(lines, line)
	end

	-- Figure out how many there are
	count = table.maxn(lines)

	-- Select 5 random names
	first1 = lines[math.random(1,count)]
	first2 = lines[math.random(1,count)]
	first3 = lines[math.random(1,count)]
	first4 = lines[math.random(1,count)]
	first5 = lines[math.random(1,count)]

        return first1, first2, first3, first4, first5

end

[Merick]

Instead of reading the entire file into memory, you can use file:seek() to change the current position in the file, then read from that point:

http://pgl.yoyo.org/luai/i/file%3Aseek

[nobodyimportant]

Is there a way to seek by line instead of by byte?

Or would I just have to seek to a random location and read in two lines (one possibly partial line, one full line)?

[drag_93]

i've been reading the collision tutorial on evilmana.com but dont understand any of it. what i'm trying to do is in a horizontal scrolling shooter i want the enemy to collide with the bullet, be replaced with an explosion animation, the explosion disappears and the enemy goes to 500(x) and a random position between 20 and 232(y). anyone know how to do this?

[Nielkie]

Is there a way to seek by line instead of by byte?

Or would I just have to seek to a random location and read in two lines (one possibly partial line, one full line)?

I don't think so, but you could do this:

local ranline = math.random(1,io.lines("wordlist.txt"))
local ranword;
local count = 0
for lines in io.lines("wordlist.txt") do
	count = count + 1
	if count == ranline then
		ranword = line
		break --Not sure, can you break out of a for loop? I've never tried.
	end
end

[nobodyimportant]

Thanks Nielkie. math.random doesn't like me putting io.lines in its parameters...says it was expecting a number but got a function.

But it did get me thinking.

My new function looks like this. It works, even on my 37000 line file. Wish there was a more efficient way, but it'll do for now:

function getname()
        filename = "names-first.txt"
	-- Count lines in the file
	local namelines = 0
	for line in io.lines(lastnamefile) do
		namelines = namelines + 1
	end
		
	-- Select 5 random lines
	local name1num = math.random(1,namelines)
	local name2num = math.random(1,namelines)
	local name3num = math.random(1,namelines)
	local name4num = math.random(1,namelines)
	local name5num = math.random(1,namelines)


	local name1found, name2found, name3found, name4found, name5found = false,false,false,false,false
	local curline = 0
	
	-- Go through the entire file, 
        -- selecting the lines as we encounter them.
	-- When all the needed lines are found, exit
	for line in io.lines(lastnamefile) do
		curline = curline + 1
		if curline == name1num then
			name1 = line
			name1found = true
		end
		if curline == name2num then
			name2 = line
			name2found = true
		end
		if curline == name3num then
			name3 = line
			name3found = true
		end
		if curline == name4num then
			name4 = line
			name4found = true
		end
		if curline == name5num then
			name5 = line
			name5found = true
		end
		if name1found and name2found and name3found and name4found and name5found then
			break
		end
	end

The full script actually saves the number of lines in the file, so it doesn't have to repeat that step each time. It takes about 5 seconds the first time I run it, and about 3-4 for subsequent runs.

[FaT3oYCG]

I don't think so, but you could do this:

local ranline = math.random(1,io.lines("wordlist.txt"))
local ranword;
local count = 0
for lines in io.lines("wordlist.txt") do
    count = count + 1
    if count = ranline then
        ranword = line
        break --Not sure, can you break out of a for loop? I've never tried.
    end
end

making a slight change to the way nielkie set out the code would make i work

by changing this code to

endline = io.lines("wordlist.txt")

local ranline = math.random(1, endline)
local ranword;
local count = 0
for lines in io.lines("wordlist.txt") do
    count = count + 1
    if count = ranline then
        ranword = line
        break --Not sure, can you break out of a for loop? I've never tried.
    end
end

as you cannot use a function as a paramete or inside another function as the error you got explained

try that and tell me what happens, there might be another error with nielkie's code near the end as also i dont know weather you can break a for loop.

anyway repot back and im sure either myself or nielkie will be able to help, unless someone else wants a pop at it

thanks

[Merick]

Why not just use something like this:

function getname()
	filename = "names.txt"
	file = io.open(filename)
	filesize = file:seek("end")	-- get the size of the file

	names = {}
	
	for i = 1, 5 do
		local pos = math.random(filesize - maxnamesize - 1)
		if pos < 1 then pos  = 1 end
		file:seek("set", pos )
		file:read()
		names[i] = file:read()
	end
	file:close()
	return names
end

This works, and since you are only reading from the file 10 times, it'll be much faster than using io.lines to read through the file until you find five matches, especially if it's a file with 37000 lines

[Nielkie]

Just a quick question, could anyone give me an example of the usage of Font:getTextSize(string) ? I can't seem to get it working.

(using:

 width = myfont:getTextSize(text)["width"]

) (from here)

EDIT: I see in the luaplayer 0.20 release notes:
- Font:getTextSize fixed.
Is it broken in 0.16?
If yes, is there any work-around?

[emericaska8r]

why not just use the .20 version?

[Anti-QuickJay]

.16 is better than .20 IMO.