Lua Programming Help Thread

Don't make a tile engine more complex than it is - it's just a table with a bunch of tables inside it and each entry (tile) has some properties.

i need i tiny bit of help!!!

I have a variable like this
enemy.health = 100
and another one for the player

i would like to know where to put this if statement

if enemy.health = 0 then
dofile("Story2.lua)
end

do i put it in the main loop or outside of it and also is that the correct if statement to use :?

Zitat:

---

Zitat von dan369

i need i tiny bit of help!!!

I have a variable like this
enemy.health = 100
and another one for the player

i would like to know where to put this if statement

if enemy.health = 0 then
dofile("Story2.lua)
end

do i put it in the main loop or outside of it and also is that the correct if statement to use :?

---

requires tables

Code:

---

player = { health = 100 }
enemy = { health = 100 }

while  true do

-- game stuff for shooting or whatever

if enemy.health == 0 then
dofile("story2.lua")
end

end -- end of while loop

---

my code was messed up although right i just edited it to give it popper line formatting

Dang it. I had a great post all typed up and I lost it. Oh well; I'll try again.

Where you put the if statement depends on the complexity of your script and what you need the if statement to do. If the script is not very complex or the if statement is a big part of the game or application you are making, you can put it in the main loop. However, if you might need to only do the if statement under certain conditions, or if you would need to be able to have more control over the if statement, I would put it in a function outside of the main loop. Then, if need be, you can put that function inside of the main loop; you'll have more control over the if statement and all of your code.

Secondly, the if statement script you provided is incorrect.

Code:

---

if enemy.health = 0 then
dofile("Story2.lua)
end

---

It should be:

Code:

---

if enemy.health == 0 then
dofile("Story2.lua)
end

---

Here's why:

In lua, "=" and "==" have completely different meanings and uses. "=" is used to set a variable equal to something, such as in "red = Color.new(255,0,0)", or in "gamestate = 1". The symbol "==", however, is used to compare a variable to something, such as in your code, "if enemy.health == 0 then", or "if gamestate == 1 then".

I remember this difference in the way I say (or rather think) the names of the symbols. For "=" I think "equals", and for "==" I think "is equal to". This helps me keep them separated in my mind.

As for comparison symbols, there are others besides "==". In lua there are "<, >, <=, >=, and ~=. In order, these are "less than", "greater than", "less than or equal to", "greater than or equal to", and "not equal to". You can use these to compare variables to other variables or to numbers. For instance, "if enemy.health <= 0 then" would allow you to do the action even if the enemy has less than 0 health, as if he was "overkilled". Another example, "if gamestate ~= 1 then", would execute the code only if the variable gamestate is not equal to 1. For a final example, you can use these when using timers, such as in "if timer < 0 then", where timer is the variable connected to the timer in the script. The code would then only execute if the the timer has run below 0.

I hope this has helped you and others! I know you aren't the only one who didn't understand this concept; I see it being used incorrectly fairly often.

thanks i get it know

No problem. :)

And there was no second quote in the dofile.
You wrote:

Code:

---

dofile("Story2.lua)

---

when it should be:

Code:

---

dofile("Story2.lua")

---

Ah, nice catch. Didn't see that.

This may be a dumb question, but is there an easy way to restart my script? (Eg. Game Over! Press O to play a new game").

Or is the best thing to do just reset all the variables and things in a function.

littlevish - A typical 'restructure program flow or screw good practice' scenario.

Bad practice would be unloading all used resources then dofile("thisscript.lua"). One method of good practice would be creating a program that flows via 'game state's so restarting your script would be as easy as settingthe game state to the initial game state and initialize it. ('main menu' or 'intro' typically).

Zitat:

---

Zitat von littlevish

This may be a dumb question, but is there an easy way to restart my script? (Eg. Game Over! Press O to play a new game").

Or is the best thing to do just reset all the variables and things in a function.

---

Zitat:

---

Zitat von SG57

littlevish - A typical 'restructure program flow or screw good practice' scenario.

Bad practice would be unloading all used resources then dofile("thisscript.lua"). One method of good practice would be creating a program that flows via 'game state's so restarting your script would be as easy as settingthe game state to the initial game state and initialize it. ('main menu' or 'intro' typically).

---

look at the lua snippets i posted a good game state system there, thanks to sg57 who gave me the idea by posting his and then i made my own

LINK

thanks

ok i have an error message which i have never seen before!!
THE ERROR:
581: attempt to perform arithmetic on global 'Moving' ( a boolean value) WAT does this mean and how would u fix it??

Zitat:

---

Zitat von dan369

ok i have an error message which i have never seen before!!
THE ERROR:
581: attempt to perform arithmetic on global 'Moving' ( a boolean value) WAT does this mean and how would u fix it??

---

Show us the few lines before and after 581. Also, a boolen value is a value that holds either 'true' or 'false'.

i know wat i did wrong i but

Code:

---

if Moving-Left == true then

---

where it should be

Code:

---


if Moving_Left == true then

---

at least i know wat boolean error means thanks!!!
-= Double Post =-
since that it has been working fine!! but there is one promblem when it loads up the menu the backgroung image doesn't change, it loads up the menu-image but it doesn't load up the level image is there a way to clear the screen when X is pressed on menu = 1 so that it would load up the other backgroung image

screen:clear()

use game states aswell and at the beginning of each state put

screen:clear()

if you want something to show in every state put it outside of the states

when you press X the game state changes to "Game"

Should it be like this

Code:

---

if pad:cross() and gamestate = "Game" then
screen:clear()
Load_First_level()
end

---

Zitat:

---

Zitat von dan369

when you press X the game state changes to "Game"

Should it be like this

Code:

---

if pad:cross() and gamestate = "Game" then
screen:clear()
Load_First_level()
end

---

---

i would use this method

here is what i posted in the snippets not so long ago

Code:

---

white = Color.new(255, 255, 255)
black = Color.new(0, 0, 0)
red = Color.new(255, 0, 0)
green = Color.new(0, 255, 0)
blue = Color.new(0, 0, 255)
orange = Color.new(235, 115, 0)
yellow = Color.new(255, 255, 0)

state = { loading = 1, menu = 2, game = 3 }

current_state = state.loading

function Set_State(state_to_change_to)
current_state = state_to_change_to
end

function Get_State()
return current_state
end

function Start_States()
if Get_State() == state.loading then
-- do loading stuff
screen:clear()
screen:print(10, 10, "loading state", white)
if pad:cross() and oldpad:cross() ~= pad:cross() then
Set_State(state.menu)
end
elseif Get_State() == state.menu then
-- do menu stuff
screen:clear()
screen:print(10, 10, "menu state", white)
if pad:cross() and oldpad:cross() ~= pad:cross() then
Set_State(state.game)
end
elseif Get_State() == state.game then
-- do game stuff
screen:clear()
screen:print(10, 10, "game state", white)
if pad:cross() and oldpad:cross() ~= pad:cross() then
Set_State(state.loading)
end
end
end

oldpad = Controls.read()

while true do

pad = Controls.read()

screen:clear()

-- main

Start_States()

-- main

if Controls.read():start() then
break
end

screen.flip()
screen.waitVblankStart()

oldpad = pad

end

---

so say i have 3 scripts, index(starting one), menu( menu) game(game) how would u incorporate that with this???

it is better to have 3 scripts in most projects and structure them to fit your needs but if you want to keep your separate files then i would do this

in each of your files, make the information inside them a function

so go into game.lua and on the first line type function Game(), and on the last line another end - do this for menu.lua aswell, then have this file structure,

index.lua

Code:

---

dofile("main.lua")

---

main.lua

Code:

---

white = Color.new(255, 255, 255)
black = Color.new(0, 0, 0)
red = Color.new(255, 0, 0)
green = Color.new(0, 255, 0)
blue = Color.new(0, 0, 255)
orange = Color.new(235, 115, 0)
yellow = Color.new(255, 255, 0)

dofile("game.lua")
dofile("menu.lua")

state = { menu = 1, game = 2 }

current_state = state.loading

function Set_State(state_to_change_to)
current_state = state_to_change_to
end

function Get_State()
return current_state
end

function Start_States()
if Get_State() == state.menu then
-- do menu stuff
Menu()
if pad:cross() and oldpad:cross() ~= pad:cross() then
Set_State(state.game)
end
elseif Get_State() == state.game then
-- do game stuff
Game
if pad:cross() and oldpad:cross() ~= pad:cross() then
Set_State(state.menu)
end
end
end

oldpad = Controls.read()

while true do

pad = Controls.read()

screen:clear()

-- main

Start_States()

-- main

if Controls.read():start() then
break
end

screen.flip()
screen.waitVblankStart()

oldpad = pad

end

---

then use the Get_State() and Set_State(state) commands to swap through each

i get this know in the script file i'll put the dofile command in the script
is there possibly an easy way the actual promblem is that when i press X on start(selected 1) it doesn't chande the background img to the actual one i want it keeps the menu image, is there a way when X is pressed on selected 1 that it will clear the screen black and the blit the other image??
-= Double Post =-
i have FIXEDDD IT Turns out i was that image was blitting underneath DUHHHH since i have fix that i have only one little tweak to do thanks

omg ive been looking all over the internet on how to load tiles from a tile sheet then input them into a table so then i can use them in my tile engine and blit them to the screen with the corrosponding number.

how the hell can i do it?
ive been looking at like zelda demo/LUMM all those things with tile engines in and i have no idea on how to mod it to my game.
can some one please give me a code snippet or a link to a tutorial or site on how to load 32x32 tiles from a tile sheet and input them into a table.

thxz for any replys
Luke

animlib

http://dl.qj.net/AnimLib-v4.5-PSP-De...3704/catid/202

Can't find where I went wrong...

It returns nil when I do showEnemy()

Code:

---


--vars
enemies = 0
test = 1
enemyImg = Image.load("enemy.png")
screenColor = Color.new(255,255,255)

--tables
player = {x=200, y=100, width=25, height=25, speed=10, img = Image.load("player.png")}
block = {x=0, y=0, width=20, height=20, img = Image.load("block.png")}
enemy = { }

function newEnemy()
        enemies = enemies + 1
        new = enemies + 1
        enemy[enemies] = {x=math.random(0,460), Y=math.random(0,252), width=25, height=25, speed=5, direction=math.random(1,4)}
        showEnemies()
end

function showEnemies()
--directions: 1 up, 2 right, 3 down, 4 left
        for i=1, enemies do
                screen:blit(enemy[i].x, enemy[i].y, enemyImg)
                if enemy[i].direction == 1 then
                        if enemy[i].y >= 0 then
                                enemy[i].direction = 3
                        else
                                enemy[i].y = enemy[i].y - enemy[i].speed
                        end
                elseif enemy[i].direction == 2 then
                        if enemy[i].x >= 480 - enemy[i].width then
                                enemy[i].direction = 4
                        else
                                enemy[i].x = enemy[i].x + enemy[i].speed
                        end
                elseif enemy[i].direction == 3 then
                        if enemy[i].y >= 272-enemy[i].width then
                                enemy[i].direction = 1
                        else
                                enemy[i].y = enemy[i].y + enemy[i].speed
                        end
                elseif enemy[i].direction == 4 then
                        if enemy[i].x >= 0 then
                                enemy[i].direction = 1
                        else
                                enemy[i].y = enemy[i].y - enemy[i].speed
                        end
                end
        end
end

while true do
pad = Controls.read()
screen:clear(screenColor)
        if pad:up() then
                player.y = player.y - player.speed
        elseif pad:down() then
                player.y = player.y + player.speed
        elseif pad:left() then
                player.x = player.x - player.speed
        elseif pad:right() then
                player.x = player.x + player.speed
        end
       
        if pad:start() then break end
       
        if enemies < 1 then
                newEnemy()
        else
                showEnemies()
        end
       
        screen:blit(player.x,player.y,player.img)
        screen:blit(block.x,block.y,block.img)
        screen.flip()
        screen.waitVblankStart()
end

---

littlevish - Lua player interprets scripts as it runs through it, not all at once then runs through it - your calling showEnemies in yoiur newEnemy function, and to newEnemy's scope, there's no such thing as showEnemies.

Basically - just move the showEnemies function above the newEnemy.

Zitat:

---

Zitat von FaT3oYCG

animlib

http://dl.qj.net/AnimLib-v4.5-PSP-De...3704/catid/202

---

and please excuse what i said on that. those were my n00b days.

Zitat:

---

* Found a major flaw in sprite sheet animation blitting. The problem was, the lib calculated the width to height ratio in the blit function, when it should have been done in the loading function. It works both ways, but doing it the the blitting function meant that the lib was dividing (with is a costly calculation) every frame unnecessarily. I fixed it so that it calculates only once, in the loading function. This should provide a MASSIVE speed-up when using sprite sheets.

---

not entirely true. the speedup is not nearly as much as i make it sound.

Zitat:

---

Zitat von Grimfate126

and please excuse what i said on that. those were my n00b days.


not entirely true. the speedup is not nearly as much as i make it sound.

---

ahhhh...
http://lh5.google.com/LastNYCHero/Rr...ibhOQ/n00b.JPG
First milestone to success is admitting it...

Zitat:

---

Zitat von SG57

ahhhh...
http://lh5.google.com/LastNYCHero/Rr...ibhOQ/n00b.JPG
First milestone to success is admitting it...

---

lol. truth hurts :(

if only vista let me code again...

edit: nvm, it was a case-sensitive problem

did somebody help me correctly delete some files from flash1?
i cant assign flash 1 to delete custom ptf theme :( with my script...

i thought you could copy paste delete files from flash with lua player anyway ?, but if you can't use luaplayer hm or another version that has flash assign and un assign and then use the remove file option

System.removeFile(path)

can you write example, how can i correctly assign flash1?

Code:

---

System.assign(flash1:)
System.removeFile(flash1:/some.file)
System.unassign(flash1:)

---

???

you have to un assign first, there was some example scripts that came with sg57's mod, search for the download on dl.qj.net, or pm him

Zitat:

---

Zitat von lps

can you write example, how can i correctly assign flash1?

Code:

---

System.assign(flash1:)
System.removeFile(flash1:/some.file)
System.unassign(flash1:)

---

???

---

Last time I checked, the flash1 is in write mode to begin with.

Zitat:

---

Zitat von Judas

Last time I checked, the flash1 is in write mode to begin with.

---

so how i can to delete the file?

System.removeFile("flash1 :/folder/file.ext")

hmmmmm...
you dont understand((
how can i correctly mount f1, delete file, unmount f1 ?

Zitat:

---

Zitat von lps

hmmmmm...
you dont understand((
how can i correctly mount f1, delete file, unmount f1 ?

---

so basically you want me to do it for you

Zitat:

---

Zitat von FaT3oYCG

so basically you want me to do it for you

---

How ironic.

Zitat:

---

Zitat von lps

hmmmmm...
you dont understand((
how can i correctly mount f1, delete file, unmount f1 ?

---

Why do you need to un-mount the flash1? Delete the file, and be done with it, that's it. No more work required.

Zitat:

---

Zitat von Judas

Last time I checked, the flash1 is in write mode to begin with.

---

if you do need to mount it i dont know the specific commands, as i have said there are examples in the mod that was made

if you do just mount it and delete then unmount

it is probably something like

System.assign("flash0:")
and
System.unassign("flash0:" )

and then do what i said