Lua Programming Help Thread

[Baresark]

Hi cool thread helped me alot

[slicer4ever]

hello and well i guess welcome to the forums it looks like=-)

[Altair]

]edit: the not symbol(~) is just what i needed to cut down my code just enough to get it working=-)

Good to hear. Atleast I helped you with one thing

[Grimfate126]

Can Someone Pleassssssssssssss Help Me Wit My Question On The Last Page??

[slicer4ever]

can you upload your code or pm a link to where i can see it?

[Grimfate126]

can you upload your code or pm a link to where i can see it?

me?? i was just asking if there was a way to not use oldpad statements. my question is on the last page. and my code is the bullets snippet from pspmillionaire.

[Altair]

@ Grimfate126:
I never used his snippets, but I can't imagine why the oldpad way wouldn't work. Or he/you made a mistake with it. Otherwise it should know weither or not you press the button again.

[JoeDaStudd]

Grimfate126 if you show us the code that doesnt work then we can see if theres a mistake (evilmana.com doesnt work anymore for some reason so we cant see it from there)

[slicer4ever]

just do a couple of replaces:

for example:

1. find and replace:

and oldpadbutton used)() ~= padbutton used)()

with

(nothing)

next search for oldpad and replace that with nothing

this well make it so now when you hold down the button to fire it well keep firing

but wait you are limited by 5 bullets(if i remeber correctly) so go find the array that says bullets and you should see a loop above it change the 5 to say 20 that should be enough to clear them off the screen in time o and go to your bulletsetup array and you well see sometin like:

if currentbullet > 5 then
currentbullet = 1
else
currentbullet = currentbullet + 1
end

change the 5 to the samething you changed the the loop with

[Access_Denied]

Does anyone know if there is a save state function in lua?

[PSPduh]

Does anyone know if there is a save state function in lua?

You would have to make it up yourself.

file = io.open("highscore.txt", "w") --Open the file in write mode
file:write("Highscore = " .. highscore) --Write the highscore to the file
file:close() --Close the file.

My lua is a bit rusty, but I think that is how it is.
Yep, it is. I tested it and it works perfectly.

[Grimfate126]

just do a couple of replaces:

for example:

1. find and replace:

and oldpadbutton used)() ~= padbutton used)()

with

(nothing)

next search for oldpad and replace that with nothing

this well make it so now when you hold down the button to fire it well keep firing

but wait you are limited by 5 bullets(if i remeber correctly) so go find the array that says bullets and you should see a loop above it change the 5 to say 20 that should be enough to clear them off the screen in time o and go to your bulletsetup array and you well see sometin like:

if currentbullet > 5 then
currentbullet = 1
else
currentbullet = currentbullet + 1
end

change the 5 to the samething you changed the the loop with

the problem with that is when you TAP x, 3-4 bullets come out at once, and if you HOLD it, the bullets just line up in front of you and release once you let go of x. thats bad cause then you have 20 bullets going all at once , which is really cheap.

[Altair]

So without the oldpad it does work?

[slicer4ever]

yes it well the thing is it seems like it lags there are multiple ways of doing this like creating a timer and if you press x then the timer resets etc etc but i advise using oldpad just try diffrent things...

[Zion]

Does anyone have a guide on making a simple pong game? I just havn't a clue on where to start making one

[daurnimator]

.. just think...

i would start with paddle movement, then add a ball with reflections off walls, then add in an angle thing to the paddle, so when it hits a paddle, it goes off at an angle depending how far up it the ball hits....

you really need to think on your own if you want to program

[Cheater]

I recently decided to try making some homebrew games for the PSP. I'm trying to make a game similar to breakout. I'm having a problem with figuring out how to get the ball to move realistically (bouncing off walls and the paddle at the right angle). Could someone explain to me what math formula I would need to use to accomplish this? I've tried searching, but I haven't come accross a source code for another breakout (I know they exist, I just can't find them). So, feel free to post a link to another source code, and I will see how they did it.

[Electro]

id like to know how to get the bounce off wall thing too,,

[Altair]

just reverse the direction of the ball.

Say you have a vertical wall
then if the x component of the ball's speed is say 1 (m/s or whatever) and its y component is 2. Then if it hits the wall th x component will reverse. So it will become -1 and the y will remain the same. Very easy.

If you want it to change the direction you will have to calculate the correct angle. You can use PSPGolf as an example for that.

[cwirsing]

Can someone take a look at my code.
The problem is at line 275 and the animation loops at the end.

Here is my LUA Script
http://www.sendspace.com/file/sw0ghd

[Cheater]

just reverse the direction of the ball.

Say you have a vertical wall
then if the x component of the ball's speed is say 1 (m/s or whatever) and its y component is 2. Then if it hits the wall th x component will reverse. So it will become -1 and the y will remain the same. Very easy.

If you want it to change the direction you will have to calculate the correct angle. You can use PSPGolf as an example for that.

Wouldn't that get the ball into an infinite loop between 2 points?

[Altair]

nope.

say the wall starts at xwall
and the ball goes with 1 pixel per loop to the right, where vx is the speed of the ball (vx=1 at the start)

if xball==xwall then
vx=-vx
end

x=x+vx

[Cheater]

Have a look at the image I attached. It might clear up why I believe that the ball will be in an infinite loop.

[Altair]

I think i get why you think it'll loop. I was talking about a verticle wall starting at xwall and a ball moving from the left side of it to the right.
In case of a horizontal wall you do the same but then with the y component of the speed.

Also the ball doesn't just move one pixel to the left, but its speed is one pixel to the left/loop. I hop it makes it clear. If not you'll have to try and see for yourself.

[Electro]

do any of you know how to change the colour of an image
like something like this
default image :)
then some code to change the yellow to purple like this :o

ive seen it done in psp air hockey, but i cant locate where it does it
any help?

[slicer4ever]

by loading multiple images of the same thing but with diffrent colors for example:

purple_ball = image.load(purpleball)
orange_ball = image.load(orangeball)
green_ball = image.load(greenball)

currentball = purple_ball
oldpad = nil

function change_ball_color()
if pad:cross() and oldpad:cross() ~= pad:cross() then
if currentball == purple_ball then
currentball = orange_ball
elseif currentball == orange_ball then
currentball = green_ball
elseif currentball == green_ball then
currentball = purple_ball
end
end
end

while true do

pad = Controls.read()

change_ball_color()

screen:blit(240,136,currentball)
screen.flip()
screen.waitVblankStart()
oldpad = pad
end

that is all you have to do (note elseif is important because if you just use if then it well run threw each one and you well end up back at the purple ball

[Altair]

that, which is faster, or you make a function that checks for yellow pixels and if it finds one, it changes it to purple.

[Gutya]

I just dug out LUA again to work on a projet. But havent worked in it for a while so i'm just making little test scripts, for some reason my function won't work, i get

Error: functions.lua:6: '=' expected near 'function'

Line 6 days 'function cursor()'

[slicer4ever]

hmmm..unsure also altair how would you do sometin like that?

[fchaos]

that, which is faster, or you make a function that checks for yellow pixels and if it finds one, it changes it to purple.

That would be pretty sloooow. Unless your working with small images. As for how you can change the color of an image, maybe take a solid color image (red, blue, etc) and place it on top of the other image with a alpha transparency?