Lua Programming Help Thread

[yumCOOKIEZZ]

O gawd more questions.

I have the analog working fine, but all the person does it move to the right and down. How do I make left and up.

Heres my code.
while true do
pad = Controls.read()
ax = pad:analogX()
if math.abs(ax) > 32 then
x = x + 3
end
if math.abs(ax) <-32 then
x = x - 3
end
ay = pad:analogY()
if math.abs(ay) > 32 then
y = y + 3
end
if math.abs(ay) <-32 then
y = y - 3
end

I added the negative codes to see if they would work. It didn't.

[Urameshi]

there should be a pad:analogY() also

[yumCOOKIEZZ]

while true do
pad = Controls.read()
ax = pad:analogX()
if math.abs(ax) > 32 then
x = x + 3
end
if math.abs(ax) <-32 then
x = x - 3
end
while true do
pad = Controls.read()
ax = pad:analogX()
if math.abs(ax) > 32 then
x = x + 3
end
if math.abs(ax) <-32 then
x = x - 3
end
ay = pad:analogY()
if math.abs(ay) > 32 then
y = y + 3
end
if math.abs(ay) <-32 then
y = y - 3
end

I do have one.

I just want to be able to move up and left.

[KleptoOne]

ther is no way math.abs(ax) <-32 is going to be true

math.abs() returns the absolute value of the number meaning if it is -50 it will return 50.
-= Double Post =-

collectgarbage() doesnt work for me, and i still dont know what it does

Collectgarbage forces lua to free memory that is flagged as unused. Lua does this periodically, but sometimes when you are unloading a bunch of graphics, you want to have lua do it immediately. ie

function unloadimages()
   image1 = null
   image2 = null
   image3 = null
   collectgarbage()
end

[Urameshi]

blargh im so stuck

like when something collides in my game then i want one of them to like become inactive and disappear, so that the game doesnt restart

[yumCOOKIEZZ]

ther is no way math.abs(ax) <-32 is going to be true

math.abs() returns the absolute value of the number meaning if it is -50 it will return 50.
-= Double Post =-


Collectgarbage forces lua to free memory that is flagged as unused. Lua does this periodically, but sometimes when you are unloading a bunch of graphics, you want to have lua do it immediately. ie

function unloadimages()
   image1 = null
   image2 = null
   image3 = null
   collectgarbage()
end

ahh I understand.

The thing I was following didn't explain what these things meant. It just told me to do them -.-

I got it working now. I have an arrow pointer thingy from the computer onto my little program thing.

[myschoo]

blargh im so stuck

like when something collides in my game then i want one of them to like become inactive and disappear, so that the game doesnt restart

so create universal function for that ;) with collectgarbage() ;)

[KleptoOne]

so create universal function for that ;) with collectgarbage() ;)

you shouldn't have to use collect garbage for that purpose, say it was an enemy, why unload it when you kill it, what if you wanted to use another one of those enemies later on? I guess it depends on your game.

Easiest way to handle your situation is to hold all your enemies in a table, and when a collision occurs, remove that table element. To add more enemies, add it to the end of the table.

It should be a very simple process.

[xmex]

function MedCol()
for y=1,en_2 do
for u=1,no_bull do
if asteroidmed[y].x+24>bullet[u].x and asteroidmed[y].x<bullet[u].x+6 and asteroidmed[y].y+24>bullet[u].y and asteroidmed[y].y<bullet[u].y+6 then
score=score+20
asteroidsm[en_3+1]={x=asteroidmed[y].x, y=asteroidmed[y].y, width=32, height=32, vspeed=(math.random(0,1))-(math.random(0,2)), hspeed=(math.random(0,1))-(math.random(0,2))}
en_3=en_3+1
asteroidmed[y].x=489346983
bullet[u].x=-99999999999
end
end
end
end

I get an error that in the collision if "attempt to index field "?" null value". There is a asteroidmed array, en_2 is equal to 1, there are several bullets, no_bull is the amount of bullets, there is an asteroidmed[1] and it has x and y coordinates, same as the bullet. However i see no difference with this code and my other one:

function Collision()
for f=1,en_1 do
for g=1, no_bull do
if asteroid[f].x+32>bullet[g].x and asteroid[f].x<bullet[g].x+6 and asteroid[f].y+32>bullet[g].y and asteroid[f].y<bullet[g].y+6 then
score=score+20
asteroid[en_2+1]={x=asteroid[f].x, y=asteroid[f].y, width=32, height=32, vspeed=(math.random(0,1))-(math.random(0,2)), hspeed=(math.random(0,1))-(math.random(0,2))}
en_2=en_2+1
asteroid[f].x=489346983
bullet[g].x=-99999999999
end
end
end
end

Apart from the names. any help?!

[yumCOOKIEZZ]

New problemm. I want to make it so whenever I click X within a certain perimeter it will do the USB thing. That works. Next I would like to make it so clicking there again it will disable. Theres my problem.

Heres what I have so far:

sl = pad:cross()
if x>20 and x<70 and y > 20 and y < 70 and sl then
System.usbDiskModeActivate()

end

That works fine. When I click there USB starts up. I don't know how to make a deactivate though. Heres what I tried.

sl = pad:cross()
if x>20 and x<70 and y > 20 and y < 70 and sl and v = 1 then
System.usbDiskModeActivate()
v = v + 1
end
if x>20 and x<70 and y > 20 and y < 70 and sl and v = 1 then
System.usbDiskModeActivate()
v = v - 1
end

pad and v are already set earlier. Nothing I'm trying is working. Help please?

[emericaska8r]

do:

v = 0
sl = pad:cross()
if x>20 and x<70 and y > 20 and y < 70 and sl and v = 0 then
System.usbDiskModeActivate()
v = 1
end
if x>20 and x<70 and y > 20 and y < 70 and sl and v = 1 then
System.usbDiskModeDeactivate() -- not sure what it is for deactivate though. this may be right i dunno
v = 0
end

[yumCOOKIEZZ]

Still doesn't work. I tried that once but copied it wrong. I just added a different activation point for it.

[youresam]

Thats right..

[yumCOOKIEZZ]

o.o Are you sure? I tried multiple times. D=

[KleptoOne]

Still doesn't work. I tried that once but copied it wrong. I just added a different activation point for it.

Look at the rest of his code, the conditions of your if's are flawed.

[yumCOOKIEZZ]

Copied right from my code

if x>20 and x<70 and y > 20 and y < 70 and sl and v=0 then
System.usbDiskModeActivat e()
v=1
screen:blit(380, yy, usb, true)
screen.flip()
end

if x>90 and x<140 and y>20 and y<70 and sl and v=1 then
System.usbDiskModeDeactiv ate()
screen:blit(380, yy, offusb, true)
screen.flip()
v=0
end

Error: Program.LUA:47: 'then' expected near '='

Line 47 is the first line I posted. Removing the v=0 part makes it work.
-= Double Post =-
Another question...(sorry for so many questions)

Can I write a file in a separate LUA file, and tell the main one to open this one.
This would help me keep organized between my codes. I basically want a second frame typed thing.

[KleptoOne]

Copied right from my code

if x>20 and x<70 and y > 20 and y < 70 and sl and v=0 then
System.usbDiskModeActivat e()
v=1
screen:blit(380, yy, usb, true)
screen.flip()
end

if x>90 and x<140 and y>20 and y<70 and sl and v=1 then
System.usbDiskModeDeactiv ate()
screen:blit(380, yy, offusb, true)
screen.flip()
v=0
end

Error: Program.LUA:47: 'then' expected near '='

Line 47 is the first line I posted. Removing the v=0 part makes it work.
-= Double Post =-
Another question...(sorry for so many questions)

Can I write a file in a separate LUA file, and tell the main one to open this one.
This would help me keep organized between my codes. I basically want a second frame typed thing.

v==0 is required

in an if statement your are checking if two values are equal, this is done by ==
to set one value equal to another, you use =

as for the other item, research the dofile() command.

[youresam]

as for the other item, research the dofile() command.

But make sure you dont call it much. Having an external file is great, but it shouldnt be called much. What I do is use external files to define functions, so each file only gets ran once at startup (a lot of people make files that do stuff like display "GAME OVER", someone even had a file ran every loop that checked for collision...very bad)

[Bob Hoil]

Hey guys i am trying to get the battery percent to print to the screen so i am creating a function for it. her is what i have so far:
function power()
power = System.powerGetBatteryLif ePercent()

Now when i try to print it to the screen i get an error so i am obviousley missing something. I tryed a few things but they did not work either.

Thanks Bob Hoil

[youresam]

Hey guys i am trying to get the battery percent to print to the screen so i am creating a function for it. her is what i have so far:
function power()
power = System.powerGetBatteryLif ePercent()

Now when i try to print it to the screen i get an error so i am obviousley missing something. I tryed a few things but they did not work either.

Thanks Bob Hoil

...why...

do this...

screen:print(x,y, System.powerGetBatteryLif ePercent())

[yumCOOKIEZZ]

But make sure you dont call it much. Having an external file is great, but it shouldnt be called much. What I do is use external files to define functions, so each file only gets ran once at startup (a lot of people make files that do stuff like display "GAME OVER", someone even had a file ran every loop that checked for collision...very bad)

I only plan on using it to open seperate windows for my program. N0t every window but the bigger ones with more coding that will get confusing.

Thanks for the help once again =D

[Urameshi]

you shouldn't have to use collect garbage for that purpose, say it was an enemy, why unload it when you kill it, what if you wanted to use another one of those enemies later on? I guess it depends on your game.

Easiest way to handle your situation is to hold all your enemies in a table, and when a collision occurs, remove that table element. To add more enemies, add it to the end of the table.

It should be a very simple process.

how do you remove the table element?

[yaustar]

how do you remove the table element?

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

[Urameshi]

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

:Jump: thanks thanks thanks:Jump: , that was a good read and very informative

[youresam]

:Jump: thanks thanks thanks:Jump: , that was a good read and very informative

Yeah... http://lua-users.org/wiki/TutorialDirectory I keep giving out this link everywhere, yet no one seems to want to read it, instead they just ask everyone else.

[yumCOOKIEZZ]

Is there a list of codes and stuff for LUA that would help me with my PSP. I looked but couldn't find anything and after a while you people will probably get annoyed with my constant errors.
-= Double Post =-
if x>20 and x<70 and y > 20 and y < 70 and sl and v == 0 then
System.usbDiskModeActivat e()
v = 1
end
if x>20 and x<70 and y > 20 and y < 70 and sl and v == 1 then
System.usbDiskModeDeactiv ate()
v = 0
end

Arh. Heres exactly what I have. When I go into my program and click within those boundaries, nothing happens.

[Urameshi]

Yeah... http://lua-users.org/wiki/TutorialDirectory I keep giving out this link everywhere, yet no one seems to want to read it, instead they just ask everyone else.

I never seen you give that out

[youresam]

Is there a list of codes and stuff for LUA that would help me with my PSP. I looked but couldn't find anything and after a while you people will probably get annoyed with my constant errors.

Yeah... http://lua-users.org/wiki/TutorialDirectory I keep giving out this link everywhere, yet no one seems to want to read it, instead they just ask everyone else.

Even when the preceding reply was the answer.
I rest my case.

[Bob Hoil]

Thanks Yonathan for the help i got it to work.

[yumCOOKIEZZ]

Oh sorry. I didn't refresh the page >.<