Lua Programming Help Thread

[psp11]

System.usbDiskModeActivate()
blue = Color.new(0,0,255)
green = Color.new(0,255,0)
red = Color.new(255, 0, 0)

player = {x = 1, y = 1, image = Image.createEmpty(32,32)}
enemy = {x = 448, y = 240, image = Image.createEmpty(5,5)}
player.image:clear(blue)
enemyimg = enemy.image:clear(green)

function movement()
if pad:up() then
player.y = player.y - 5
end
if pad:down() then
player.y = player.y + 5
end
if pad:right() then
player.x = player.x + 5
end
if pad:left() then
player.x = player.x - 5
end
end

function AI()
follow = math.random(3)
if follow == 1 then
if player.x > enemy.x then
enemy.x = enemy.x + 10
end
if player.x < enemy.x then
enemy.x = enemy.x - 10
end
if player.y > enemy.y then
enemy.y = enemy.y + 10
end
if player.y < enemy.y then
enemy.y = enemy.y - 10
end
end
end

function collision()
if enemy.y > player.y + player:height() and enemy.y + enemy:height() < player.y and enemy.x < player.x + player:width() and enemy.x + enemy:width() > player.x then
enemy.x = oldenemyx
enemy.y = oldenemyy
player.x = oldplayerx
player.y = oldplayery
player.image:width() = player.image:width() - 1
player.image:height() = player.image:height() - 1
end
end

function endofgame()
if player:width() = 0 and player:height() = 0 then
screen:clear()
screen:print(194, 136, "Game Over", red)
end
end

while true do
oldenemyy = enemy.y
oldenemyx = enemy.x
playery = player.y
playerx = player.x
screen:clear()
pad = Controls.read()
screen:blit(player.x, player.y, player.image)
screen:blit(enemy.x, enemy.y, enemy.image)

movement()

AI()

collision()

endofgame()

screen.flip()
screen.waitVblankStart()
end

That is my script and I get error. Index.lua 50:unexpected symbol near "=".
Can someone help me I am just trying out to get my AI down and collision and a bunch of stuff working together. I don't even see an error at all.

[EminentJonFrost]

System.usbDiskModeActivate()
blue = Color.new(0,0,255)
green = Color.new(0,255,0)
red = Color.new(255, 0, 0)

player = {x = 1, y = 1, image = Image.createEmpty(32,32)}
enemy = {x = 448, y = 240, image = Image.createEmpty(5,5)}
player.image:clear(blue)
enemyimg = enemy.image:clear(green)

function movement()
if pad:up() then
player.y = player.y - 5
end
if pad:down() then
player.y = player.y + 5
end
if pad:right() then
player.x = player.x + 5
end
if pad:left() then
player.x = player.x - 5
end
end

function AI()
follow = math.random(3)
if follow == 1 then
if player.x > enemy.x then
enemy.x = enemy.x + 10
end
if player.x < enemy.x then
enemy.x = enemy.x - 10
end
if player.y > enemy.y then
enemy.y = enemy.y + 10
end
if player.y < enemy.y then
enemy.y = enemy.y - 10
end
end
end

function collision()
if enemy.y > player.y + player:height() and enemy.y + enemy:height() < player.y and enemy.x < player.x + player:width() and enemy.x + enemy:width() > player.x then
enemy.x = oldenemyx
enemy.y = oldenemyy
player.x = oldplayerx
player.y = oldplayery
player.image:width() = player.image:width() - 1
player.image:height() = player.image:height() - 1
end
end

function endofgame()
if player:width() = 0 and player:height() = 0 then
screen:clear()
screen:print(194, 136, "Game Over", red)
end
end

while true do
oldenemyy = enemy.y
oldenemyx = enemy.x
playery = player.y
playerx = player.x
screen:clear()
pad = Controls.read()
screen:blit(player.x, player.y, player.image)
screen:blit(enemy.x, enemy.y, enemy.image)

movement()

AI()

collision()

endofgame()

screen.flip()
screen.waitVblankStart()
end

That is my script and I get error. Index.lua 50:unexpected symbol near "=".
Can someone help me I am just trying out to get my AI down and collision and a bunch of stuff working together. I don't even see an error at all.

try changing height and width to number values.

[TacticalPenguin]

No.

if player:width() = 0 and player:height() = 0 then

needs to be

if player:width() == 0 and player:height() == 0 then

[psp11]

No.

if player:width() = 0 and player:height() = 0 then

needs to be

if player:width() == 0 and player:height() == 0 then

Yah, I did screw up there but I still get the same error. I think it is before that.

[TacticalPenguin]

To use the analog stick, refer to the lua snippets thread which tells you how.

[psp11]

I think I know the problem. This is just a guess. The width and height can not be change in my example. I think that they just return numbers and that they can't be changed. I am going to try it out right now.

[emericaska8r]

who here knows how to use the analog stick?

if you don't look at the snippet, the analog stick's values can be stored into two variables, which show the x and y of the analog stick.

for example,
dx = pad:analogX()
dy = pad:analogY()

if you move it left, the value of dx will equal -127.
if you move right, the value of dx will equal 128
up, and dy equals -127
down, and dy equals 128

[HeaD_ShOt]

-- EVILMANA.COM PSP LUA CODEBASE
-- www.evilmana.com/tutorials/codebase
-- Menu
-- SUBMITTED BY: nathan42100
-- changed for my purposes(changed by Cheese the Psp(

System.usbDiskModeActivat e()

----------index.lua----------
currstate="startup"
function printCentered(y, text, color)
local tl=string.len(text)
local xmod = 240-((tl*10)/2)
screenrint(xmod, y, text, color)
end
-----------------
white = Color.new(255,255,255)
red = Color.new(255,0,0)
-----------------
screen:clear()
printCentered(131,"Starti ng up...",white)
screen.waitVblankStart(3)
screen.flip()
-----------------
menu={}
menu[1] = "Play Game"
menu[2] = "Controls"
menu[3] = "Credits"
menu[4] = "Exit"
menu[currselect] =1
menu[entries]=table.getn(menu) - 2
-----------------
menuBackground=Image.load ("background.png")
-----------------
screen:clear()
printCentered(131,"Loaded !",white)
screen.waitVblankStart(3)
screen.flip()
currstate="menu"
-----------------
while not Controls.read():start()
do pad=Controls.read()
screen:clear()
if currstate=="menu" then
screen:blit(0,0,menuBackg round)
for i=1,menu[entries] do
if i==menu[currselect] then
printCentered((20+((i-1)*10)), menu[i], red)
else
printCentered((20+((i-1)*10)), menu[i], white)
end
end
end

if pad:cross() then
if i==1 then --SP
dofile("game.lua")
elseif i==2 then --MP
dofile("help.lua")
elseif i==3 then --Options
dofile("credits.lua")
elseif i==4 then --Quit
break
end
elseif pad:down() then
if menu[currselect]==4 then
menu[currselect]=1
else
menu[currselect]=menu[currselect]+1
end
elseif pad:up() then
if menu[currselect]==1 then
menu[currselect]=4
else
menu[currselect]=menu[currselect]-1
end
end

screen.flip()
screen.waitVblankStart()
end

im trying out htis menu style from evilmana
adn i keep getting an error saying
table index is nil

[Anti-QuickJay]

Why not use an easier menu code? If you want, Their is easier ones to learn on evilmana.

[yaustar]

menu[currselect] =1
menu[entries]=table.getn(menu) - 2

Neither currselect or entries have been given a value by this point in the code so what actually happens is:

menu[nil] =1
menu[nil]=table.getn(menu) - 2

Causing the error.

[ramoneur]

how do i disable the home button? i dont want that "do you want to quit the game?" screen to come up. i want nothing to happen when you push home. is it possible to do this in lua?

[TacticalPenguin]

Nope, the main system overrides anything lua tells it to do. You can use the home button but the home screen will still come up.

[ramoneur]

ah damn

[TacticalPenguin]

Just do if pad:home() then os.exit() end

[ramoneur]

Just do if pad:home() then os.exit() end

thanks, but ive already tried that, it makes the psp freeze in some weird way at the "do you want to quit this game?" screen

[TacticalPenguin]

ok then get the luaplayer mod and use System.quit()

[Anti-QuickJay]

I really dont like the way it exits, Cause if os.exit does not work, The you have to use systemquit but not everyone has the LUA Mod by cools, So i just put a break

[TacticalPenguin]

But that doesnt work with home.

[Anti-QuickJay]

Well, Then everyone should just get the LUA Player mod and then we can use systemquit!

[gameo]

Allright, ball moves at the start now, but when it hits the bat's, it just moves through them, and when it hits the end of the room, (which is, when its about to move out of the PSP screen) THEN it bounces away.

There must be something wrong with the collosion, here is the edited script:

white = Color.new(255, 255, 255)

screenrint(136, 136, "Loading LUA Pong...", white)
screen.flip()

background = Image.load("Background.pn g")

bat1 = { x = 20, y = 100, }--Put the images in tables
bat2 = { x = 460, y = 100, }

ball = { x = 240, y = 146, mx = 1, my = 0 }--Put ball's image in it's table
--MX and MY are movemenyx and movementy. Start off mx at 1
screen.waitVblankStart(60 )

ball2 = Image.load("Ball.png")

bat11 = Image.load("bat1.png")

bat21 = Image.load("bat2.png")

while true do

screen:clear()

pad = Controls.read()

screen:blit(bat1.x, bat1.y, bat11, true)
screen:blit(bat2.x, bat2.y, bat21, true)
screen:blit(ball.x, ball.y, ball2, true)

--theres collision for bat1 now for bat 2
if ball.x == bat1.x and ball.y >= bat1.y and ball.x < (16*64) then
ball.mx = -ball.mx
end

--theres paddle 2's collision
if ball.x == bat2.x and ball.y >= bat2.y and ball.x < (16*64) then
ball.mx = -ball.mx --That should make it opposite of ball.mx, making it change directions.
end

--with ballmoving you had the idea but you need more

ball.x = ball.x + ball.mx --This makes the ball move to the right when ball.mx is positive, to the left when its negative.

--Then you can add some stuff dealing with my later. For making it move up//down, do something like
--ball.y = ball.y-ball.my

if pad:down() then
bat1.y = bat1.y +2
end

if pad:up() then
bat1.y = bat1.y -2
end

if pad:cross() then
bat2.y = bat2.y +2
end

if pad:triangle() then
bat2.y = bat2.y -2
end

if pad:start() then
break
end

screenrint(136, 136, "Welcome to the world of PPP.", white)
screen.waitVblankStart()
screen.flip()
end

[yaustar]

ball.x == bat2.x

Bad check. If the ball is moving 3 pxs per frame in the X direction, how can you guarantee that the ball's X and bat's X will be in the exact same postion?

[Highsight]

Is it possible to drop the decimal in a number? Cause I can't seem to find any distinction between an integer and a double in LUA.

[yaustar]

Use the math library's floor or ceil function. It basically rounds down or up respectively.

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

You won't be able to tell the difference between an image, sound, integer, double, float, string, characters etc in Lua. It is just the way all scripting languages are for them to work as scripting languages.

[Highsight]

Ok, I got it now, thanks! :)

[GuitarGod1134]

Does anyone know how to view an entire text file in lua. I know its possible because fosk and them have done it but i dont want to take any of thier code so does anyone know a tutorial that explains how to open text files and view them in lua?

[Anti-QuickJay]

y = 10

file = io.open("testRead.txt","r")

for line in file:lines() do
y = y + 10
screen:print(100,y,line,white)
end

file:close()

This is how you will view the entire txt file.
You must declare the color "white"(You can use other colors too.)

[TacticalPenguin]

Good job copying a snippet from evilmana
BTW that one has no scrolling.

[gameo]

... I guess im bothering you Tactical, maybe ill just wait for EminentJonFrost or eldiablov...

I'm just so sad... this is the first game i've ever made, (Exept if you count my windows clone on PC) so its not that i cant wait, its just that i h8 my self because i dont know a 0.000000001 part of lua. (Allright, maybe more) but still...

Whitehawk's tut didn't help a lot, only a little, and after the tut, it says:

"Congratulations, you are now a developer!"
|
|
Yeah right, i leaned how to blit an image, to write text on screen, and to play a sound. Thats great.

[TacticalPenguin]

Actually you just arent quite being clear. What do you need help in right now? Also I recommend the tuts over at evilmana to learn more if youd like.

[eldiablov]

Evilmana is noob friendly but it is so tempting to copy from