Lua Programming Help Thread

[montrob]

on lua for windows, it doesnt report an error, but nothing pops up on the screen.

background = Image.load("Cursor/background.png")
mouse = Image.load("Cursor/mouse1.png")
blood = Image.load("Cursor/blood.png")
enemy = Image.load("Cursor/enemy1.png")

mousex = 100
mousey = 172

while true do
screen:clear()
end


pad = Controls.read()

screen:blit(0, 0, background, false)
screen:blit(mousex, mousey, mouse)

if pad:up() then
mousey = mousey - 5
end

if pad:down() then
mousey = mousey + 5
end

if pad:left() then
mousex = mousex - 5
end

if pad:right() then
mousex = mousex + 5
end

if pad:r() then
if mousex == 135 and mousey == 151 then
screen:blit(135, 151, blood)
end

screen.waitVblankStart()
screen.flip()
end

[Grimfate126]

montrob: try this:

background = Image.load("Cursor/background.png")
mouse = Image.load("Cursor/mouse1.png")
blood = Image.load("Cursor/blood.png")
enemy = Image.load("Cursor/enemy1.png")

mousex = 100
mousey = 172


while true do

screen:clear()

pad = Controls.read()

screen:blit(0, 0, background, false)
screen:blit(mousex, mousey, mouse)

if pad:up() then
mousey = mousey - 5
end

if pad:down() then
mousey = mousey + 5
end

if pad:left() then
mousex = mousex - 5
end

if pad:right() then
mousex = mousex + 5
end

if pad:r() and mousex > 130 and mousex < 140 then
if mousey > 146 and mousey < 156 then
screen:blit(135, 151, blood)
end
end

screen.waitVblankStart()
screen.flip()
end

[Mast3r_Shak3]

(at the very end of the code)

[slicer4ever]

or just take out screen:clear() it just is constantly clearing the screen

[montrob]

For my new game, WildSniper , i am going to have bullets shooting from the enemies guns. I need to know how to detect a collision when they moving bullet hits my aimer that is moving.

[Grimfate126]

For my new game, WildSniper , i am going to have bullets shooting from the enemies guns. I need to know how to detect a collision when they moving bullet hits my aimer that is moving.

well if you have ur aimer x and y like theis:

aimerx = 100
amiery=  130

and u have the bullets x and y like this:

enemyBulletx = 30
enemyBullety = 50

this u just do this:

if enemyBulletx > aimerrx - 5 and enemyBulletx < aimerx + 5 then
if enemyBullety > aimerry - 5 and enemyBullety < aimery + 5 then 
-- the rest of ur code

this means that if the bullet comes within 5 pixels of the aimer, then it will do what u want it to do.

hope i helped!! good luck!

EDIT- 600th post!! w00t!!!!!!!

[PSPHax0r9]

Does anyone know how to check what the last number is in a table? For example, if I have LUA automatically make a table like this:

folders=System.listDirectory()

is there a way LUA can find the number of the last entry in that table, for example, folders[4] ? Thanks to anyone who can answer my question.

[Psilocybeing]

Had a look on google, and I found this :)

We can find the size of a table using the standard
table library function table.getn() (i.e. get
number of elements)

table.getn(t)

So you would want folders.getn(t), and then I presume t will hold the number of entries.

Source: http://lua-users.org/wiki/TablesTutorial

[PSPHax0r9]

Had a look on google, and I found this :)

We can find the size of a table using the standard
table library function table.getn() (i.e. get
number of elements)

table.getn(t)

So you would want folders.getn(t), and then I presume t will hold the number of entrys.

Source: http://lua-users.org/wiki/TablesTutorial

Thank you very much! I checked the wiki and but never saw that part of it. Thanks again, Psilocybeing, now custom characters will be easy to implement in my game by just placing in the folder. :icon_smil

[PSPHax0r9]

One other question. Is there a way that I can quote a variable? Like say I wanted to concatenate a variable, but it needed quotes around it to work. For example:

folders=System.listDirectory()

screen:blit(0,0,"images/"..folders[1].name.."/pic.png")

doesn't work because the folder names don't have quotes around them.

Because the table is created by LUA, I can't manually add quotes around each entry, so is there a way I could do this when blitting to the screen? Thanks again.

[Psilocybeing]

It looks like in LUA the function lua_pushfstring works the same way that sprintf does in C, so you can construct your path variable before passing it to blit. I.e.

otherString = "and so is this"
lua_pushfstring(newString , "This is my string: %s", otherString)
newString = "This is my string: and so is this"

This is just pseudo code, as I've not used LUA before, just trying to be helpfull :)

[PSPHax0r9]

It looks like in LUA the function lua_pushfstring works the same way that sprintf does in C, so you can construct your path variable before passing it to blit. I.e.

otherString = "and so is this"
lua_pushfstring(newString , "This is my string: %s", otherString)
newString = "This is my string: and so is this"

This is just pseudo code, as I've not used LUA before, just trying to be helpfull :)

Hmmm...I actually understand that lol. I'll try something like that right now and see if it works, thanks a lot.

[PSPHax0r9]

No go. It's telling me that lua_pushfstring is a nil value.

[ro0kie42]

how do you get windows lua to report errors? whenever i have an error, the screen just pops up and closes real quick.

[PSPHax0r9]

One other question. Is there a way that I can quote a variable? Like say I wanted to concatenate a variable, but it needed quotes around it to work. For example:

folders=System.listDirectory()

screen:blit(0,0,"images/"..folders[1].name.."/pic.png")

doesn't work because the folder names don't have quotes around them.

Because the table is created by LUA, I can't manually add quotes around each entry, so is there a way I could do this when blitting to the screen? Thanks again.

[slicer4ever]

hello ever1 well if havent seen i've been working on a game: pspaintball and recently released v 0.1 so i want to implement wifi within the next few versions and i remeber a while back seeing sometin about lua wifi libary's now then heres my question:

A: fanjita got wifi for lua to work in 2.1+ correctly?
B:are there any tut's yet made for how to implement wifi into lua
C: if so where
D:anyway to check if it works or not as of i don't have a wifi connection spot
E: thats about it=-)

[dragaron]

how do you get windows lua to report errors? whenever i have an error, the screen just pops up and closes real quick.

Send (open) "test.cmd" in a text editor. Add a 2nd line with the text "pause". Save file. It will look like this:

luaplayer index.lua
pause

[youresam]

PSPhax09, that code *should* work, but maybe the first index value of the directory isnt what you think it is. I remember when I was making LUA OS and my card became corrupted. After that, the files in the directory were literally in a random order each time. Because of this, i almost gave up because my code didnt work for it anymore. But, yeah, I got it fixed.

Anyhoo, the first 2 index values are:
.
..

The . means current directory, the .. means back 1 directory. Also, check what folder you are trying to open. (maybe print(folders[3])).
Either that, or add a space like: .. folders[3] ..

[Greenskull]

how do you randomize something?

[montrob]

how do you randomize something?

number = math.random(1,4) -- ""number is the variable you want to randomize, 1 and 4 are the numbers you want the random number to be between""
if number >= 2 then....
-more code here-

[ro0kie42]

Send (open) "test.cmd" in a text editor. Add a 2nd line with the text "pause". Save file. It will look like this:

luaplayer index.lua
pause

thanks d00d

[Electro]

number = math.random(1,4) -- ""number is the variable you want to randomize, 1 and 4 are the numbers you want the random number to be between""
if number >= 2 then....
-more code here-

and you have to add
math.randomseed(os.time() )

at the beginning, outside the loop

[slicer4ever]

have you guys just gone right pass my question??

[Greenskull]

ok how do i start the randomization?

[youresam]

math.randomseed(os.time() ) makes it so the numbers are TRULY random based on the time. If you didnt do this, every time you started luaplayer, the 'random' numbers generated would be the same. You call this at the begining of your program.

math.random(low,high) returns an integer between low and high. It's that simple.

[slicer4ever]

or you can just define the high one and lua well auto set low to 1

[Grimfate126]

my code:

pad = Controls.read()
dx = pad:analogX()
dy = pad:analogY()

        if math.abs(dx) > 32 then
		cursorx = cursorx + dx / 64
                          height = height +1
	end
	if math.abs(dy) > 32 then
		cursory = cursory + dy / 64
        end

how can i make it so that if the analog stik goes down, height decreases by 1?right now, if you go up or down, the height increases.

[Mundaka Inc.]

Ok, here goes...

I've been coding Lua for over three months now, and somewhere I got stuck. I'm trying to move multiple objects around my screen, using the same function. Something like a rack of balls on a pool table. Here it is:

function moving()
a = speed / 500
if a >= 0 then
if ball.x <= 6 or ball.x >= 460 then
angle = pi - angle
end
if ball.y <= 5 or ball.y >= 252 then
angle = angle * (-1)
end
ball.x = ball.x + math.cos(angle) * a
ball.y = ball.y + math.sin(angle) * a
speed = speed - 10
end
screen:blit(ball.x,ball.y ,BallNumber,true)
end

This function moves the object in a given "angle" for "a" pixels, untill "speed / a" reaches zero.
I would like to enter some variables when running the function, like so:

function moving(speed, angle, ball.x, ball.y, BallNumber)

Now comes my problem: if call this function inside my mainloop, it gets repeated over and over, ball.x and ball.y would get resetted every time. How could I get this to work?

[Altair]

you have to make a table where there are n balls. Then in that function make a for loop so that it happens for all the balls.

[Mundaka Inc.]

Hey Altair,

could you give me an example of how that table would look like?