Lua Programming Help Thread

[slicer4ever]

lui you are the best that helped me so much=-)(cmd thing)

new question is there a duplication feature like laser:duplicate(laser+i)
i'll do a little searching

[Mast3r_Shak3]

What code would I use to make something fall down the screen?

@slicer4ever. You could make a function with x and y variables and call the function with the coordinates you want, maybe something like...

function duplicate()
screen:blit(x, y, image)
screen.flip()
end

Where "image" is the image you want to duplicate

[slicer4ever]

would this reset the thing if used a second time?

[Mast3r_Shak3]

No, you can call the function over and over again. The purpose is to call the same things over and over again without having to keep on typing it out. You can write the function in or outside of your main loop

[slicer4ever]

k i'll try it and thanks=-)

[Mast3r_Shak3]

Depending on the nature of the duplication you might want to put differnt variables, but thats up to you.

[slicer4ever]

hmm...how do you call the function i tried:

if pad:cross() then duplicate()
end

but it doesn't seem to wanna work

edit: nvm i forgot: if pad:cross() then duplicate()

[Mast3r_Shak3]

You have to do it like this.

function duplicate()
if pad:cross() then 
screen:blit(x,y, image)

So when you want that to happen just type duplicate() in the code

Click me for a tut on functions

[slicer4ever]

k thanks=-)

[lui2603]

Earlier I asked how I would read from a .txt file in lua and display some of it on screen...
someone said the function would be io.read or something like that

could someone explain more how to use this? Like if I wanted to write a score to a text file, would it be io.write?
and what would I have to put after that for it to write a number to a text file

[Altair]

That was me. But the thing is it wasn't in the list of all the commands, so im not sure if it will work. The command was: io.input(”file.txt”) where file.txt is your file.
To write maybe io.output("...") works. You will have to try it out.

@ PSPHax0r9
Sure you can send it to me. Ill give it a look.

[Glynnder]

@Altair - yes start and select do, why?

[Vaza]

can somebody give me a sample code for a timer?

[PSPHax0r9]

One comes included with luaplayer.

@Altair - I PM'ed you.

[Glynnder]

EDIT: Sorted it out, just need to do click function!

[slicer4ever]

hey i have a problem so here it is:

i am using a function to blit something to the screen when i press x but now it won't stay on the screen heres my function:

function duplicatetoplaser()
screen:blit(playerx+10,playery-31, playerlasertop)
screen.flip()
screen:waitVblankStart()
end

thanks in advance

[Altair]

thats because you only call the function when you press "X". So what happens is, you press X, then it goes through the function ones and then the next loop it makes its gone again.

BTW 100th post W000T!!! Im a Journeyman, im a Journeyman!

[slicer4ever]

so what would i do then to make it stay there permently?

[Greenskull]

Hi everyone! I have an idea for a game but I'm just learning Lua so can someone give me a bit of code to get me started? I want a simple little game that there are 3 constantly bouncing balls that when you press a trigger, you can select one and move it right or left. I need some help. How do you make it so you can switch between them and how can you make them bounce constantly. Those are my main issues. Help would be appreciated. Thank you!

[soadnation]

im trying to get highscore working in my game but it always gives me an error

attempt to compare nil with a number

these are my functions

save function

function saveHighscore()
	file = io.open(highscoreFile, "w")
	if file then
		file:write(high)
		file:close()
	end
end

load function

function loadHighscore()
	file = io.open(highscoreFile, "r")
	if file then
		high = file:read("*n")
		file:close()
	end
end

this is how i call the funtion in my game(the write variable is to make sure it only saves once)

	if write==1 then
		loadHighscore()
		if high<score then
			high=score
			saveHighscore()
			write=2
		end
	end

i know the save funtion works because if i get rid of the part where i compare the highscore variable to your score(and just save the score) it saves it.

i know the load funtion is fine because in my menu script i have an option to view highscore.

function loadHighscore()
	file = io.open(highscoreFile, "r")
	if file then
		high = file:read("*n")
		file:close()
	end
end

then i just have it print the high variable and it works fine. but when i combined the two i get the error and i dont know why.

[Mast3r_Shak3]

What does the "function argument expected near 'blah blah'" mean? And what code would I use to make 'script.lua' (My loading screen) read 'game.lua'? (The actual game code)

[PSPHax0r9]

What does the "function argument expected near 'blah blah'" mean? And what code would I use to make 'script.lua' (My loading screen) read 'game.lua'? (The actual game code)

Why not just make your entire loading screen file a function? Then you could condense it into one LUA file. If you can't do that for some reason, the comand would be dofile("game.lua")

[Mast3r_Shak3]

Good idea... But I need to know what the error means before I can get anyhere =/

[PSPHax0r9]

Give the exact error.

[Mast3r_Shak3]

Well im on my PSP but it was

Function argument expected near 'while'

[PSPMillionaire]

whats your while command look like..an example could be...

while something == something do
code here
end

make sure you just dont have something like

while do

whereas ..

while true do ... would work

[Altair]

Soadnation, what line is the error in?
Also, do you get the error when you leave in the comparisation of the highscore and your score, or only when you put in the save and load function?

[lui2603]

could someone please explain how io.input and io.output are used?
I've got io.output("highscore.txt" ) ... what do I need to put to make it write a variable (score) to the text file?
then what would I have to put after io.input in order to read the score from the text file and display it on screen/

[Greenskull]

hey PSPHax0r9, I have an idea for a game but I'm just learning Lua so can you give me a bit of code to get me started? I want a simple little game that there are 3 constantly bouncing balls that when you press a trigger, you can select one and move it right or left. I need some help. How do you make it so you can switch between them and how can you make them bounce constantly. Those are my main issues. Help would be appreciated. Thank you!

[Mast3r_Shak3]

whats your while command look like..an example could be...

while something == something do
code here
end

make sure you just dont have something like

while do

whereas ..

while true do ... would work

Heres my code so far (besides the loading screen, combining scripts later)

black=Color.new(0, 0, 0)

player={}
player[1]={x=240, y=250}

screenwidth=480 - player:width

while true do

screen:blit(0, 0, background, false)
screen:blit(player[1].x,player[1].y,player)

for a=0,10 do
for b=0,0 do
screen:blit(45*a, 45*b, spike)
end
end

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

if pad:left() then
player[1].x = player.x - 2
end
if pad:right() then
player[1].x = player.x + 2
end

screen.waitVblankStart()
screen.flip()
end