Lua Programming Help Thread

[yaustar]

LuaPlayer print text function doesn't support linebreaks. No other reason really.

[sony psp player]

I have a image with a player on it and I was able to get it on the screen and move it. My problem is that I don't know how to remove the background from the player image (blue).

[romulator]

LuaPlayer print text function doesn't support linebreaks. No other reason really.

Well if this is true, then how will you print half of a string on one line and half on the next? Man this is starting to frustrate me. And if Lua does not support this, why is it included in the lua dev kit snippets?

[eldiablov]

remove the line that says clear:image blue or something like that. I havent done lua in a while.

romulator move onto C OR C++ if you are getting frustrated.

[Fuzzie360]

I have a image with a player on it and I was able to get it on the screen and move it. My problem is that I don't know how to remove the background from the player image (blue).

Make a .png with a alpha channel. The easiest way i can think of is making the image in photoshop with no color/transparent as background and saving as a .png. If you are using paint though you have no way of adding transparency. .png transparency is very useful too, you can get not only full transparency but also anything between 1~99% too.

My only gripe about the lua transparency support is that when you blit a image with transparency onto another image you will lose all transparency. What made it worse is that you can't create an image with transparency by script (easily and resource freindly).

[sony psp player]

Can I add transperency with the gimp?

[yaustar]

Well if this is true, then how will you print half of a string on one line and half on the next? Man this is starting to frustrate me. And if Lua does not support this, why is it included in the lua dev kit snippets?

Lua's default print function that prints to the console supports line breaks. LuaPlayer print to screen function that prints to the screen doesn't.

[romulator]

How can I use the default functions that print to the console or am I stuck to figure out a way on my own? (It's 12:33 am so I'm very tired). Thanks for your help anyway yaustar if you can't figure this out.

[eldiablov]

I only knew about the screen:Print function when i used lua. Never knew of another way ...

Yaustar would it be easier for me to go to C if i plan on using the gu because i have something lined up now.

[myschoo]

How can I use the default functions that print to the console or am I stuck to figure out a way on my own? (It's 12:33 am so I'm very tired). Thanks for your help anyway yaustar if you can't figure this out.

print("text")

[romulator]

Ummm I tried that and that didn't help. Unless you could explain further, I won't be able to do it.

[LMelior]

Can I add transperency with the gimp?

Assuming you've got the image saved as a png:

Go to Select>By Color
Click on your background (make sure your background is a color not used anywhere else on your sprite)
Go to Layer>Transparency>Color to Alpha
Choose your background color by clicking on the color box
Click OK.

If that transparency option is greyed out, there should be one that isn't, which is Add Alpha Channel. Guess what that does.

How can I use the default functions that print to the console or am I stuck to figure out a way on my own? (It's 12:33 am so I'm very tired). Thanks for your help anyway yaustar if you can't figure this out.

This is sort of what the Lua Code Challenge 3 was on Evilmana.com:
http://forums.evilmana.com/index.php?topic=601.15

Have a look at the last post (#20), you can use whatever you need from it, if you like. I believe I commented it pretty well.

[moncristo_da_dev]

ok, i have this really simple jump theory, here is the code with the animation and the problem is that it doesn't come back down when prompted to

standright = Image.load("images/jack/jackstandright.png")
jump = Image.load("images/jack/jackjumpright1.png")
jump2 = Image.load("images/jack/jackjumpright2.png")
jump3 = Image.load("images/jack/jackjumpright3.png")
player = {}
player.x = 20
player.y = 200
player.img = standright
Timer1 = 0

function jumpright()

Timer1 = Timer1 + 1


        if Timer1==5 then

        player.img = jump

        end



        if Timer1==10 then

        player.img = jump2

        end


                 if Timer1==15 then
 
                 player.img = jump3

                 end

while true do  ----MAIN LOOP----

oldx = player.x
oldy = player.y


screen:clear()


pad = Controls.read()

if pad:up() then
jumpright()
player.y = player.y + 10   --player y is 20 so if you add it it will go 30
end

if pad:up() and player.y == 30 then  
--since player y is 30 because of the last loop, i want it to come back down to 20

player.y = player.y + 10
end

screen:blit(player.x, player.y, player.img)

screen.flip()
oldpad = pad
screen.waitVblankStart()
end

also, when the animatin stops, it won't clear the scrren and replaye it with player.img, even with the running animation

[KleptoOne]

the function is only being called one time, specifically when the button is pressed. No button, no function. Try using a flag like player.jumping = true and have a function run while that flag is true and not run when it is false.

[Grimfate126]

ok, i have this really simple jump theory, here is the code with the animation and the problem is that it doesn't come back down when prompted to

standright = Image.load("images/jack/jackstandright.png")
jump = Image.load("images/jack/jackjumpright1.png")
jump2 = Image.load("images/jack/jackjumpright2.png")
jump3 = Image.load("images/jack/jackjumpright3.png")
player = {}
player.x = 20
player.y = 200
player.img = standright
Timer1 = 0

function jumpright()

Timer1 = Timer1 + 1


        if Timer1==5 then

        player.img = jump

        end



        if Timer1==10 then

        player.img = jump2

        end


                 if Timer1==15 then
 
                 player.img = jump3

                 end

while true do  ----MAIN LOOP----

oldx = player.x
oldy = player.y


screen:clear()


pad = Controls.read()

if pad:up() then
jumpright()
player.y = player.y + 10   --player y is 20 so if you add it it will go 30
end

if pad:up() and player.y == 30 then  
--since player y is 30 because of the last loop, i want it to come back down to 20

player.y = player.y + 10
end

screen:blit(player.x, player.y, player.img)

screen.flip()
oldpad = pad
screen.waitVblankStart()
end

also, when the animatin stops, it won't clear the scrren and replaye it with player.img, even with the running animation

you should give animlib a try. (unless you already have).

[sony psp player]

Now I have a image with an alpha channel. How do I use it in lua?

This is my code, but it doesn't work:
screen:blit(movey, movex, player, alpha = true)

[yaustar]

How can I use the default functions that print to the console or am I stuck to figure out a way on my own? (It's 12:33 am so I'm very tired). Thanks for your help anyway yaustar if you can't figure this out.

The short answer is that you write your function that parses the string for line breaks and prints the text in the right positions.
-= Double Post =-

I only knew about the screen:Print function when i used lua. Never knew of another way ...

Yaustar would it be easier for me to go to C if i plan on using the gu because i have something lined up now.

It be easier in some ways and harder in others. In short, I honestly don't know. You still have to face the same challenges but the difference is that it be in a different language.

If it was me, I would just use an existing engine (eg LTE) rather then re-inventing the wheel.

[HaxxBlaster]

Now I have a image with an alpha channel. How do I use it in lua?

This is my code, but it doesn't work:
screen:blit(movey, movex, player, alpha = true)

The alpha is true as default in the image:blit() function, you don't need to type true or false.

screen:blit(movey, movex, player, alpha = true)

The red area is the error, why you saw 'alpha = true' in the LUA function page is because they were stating to the user that it represents the boolean of the alpha to the blitting.

screen:blit(movey, movex, player, true)

But as i said it's default, so you don't need it.

[sony psp player]

Thanks!

[moncristo_da_dev]

you should give animlib a try. (unless you already have).

i don't want to put that big code in the beginning, i just want to blit and play a sprite animation, so can you give me the code simplified for that?

[eldiablov]

big code ???!!!

dofile("animlib.lua")

If that's big to you then you must be an extremely tiny person.
or just have a really tiny computer

[xpack]

Is it possible to run an EBOOT using lua

[youresam]

Is it possible to run an EBOOT using lua

....NO

[TacticalPenguin]

^^ what he said

[Merick]

can someone give me an explanation of Gum.perspective?

Gum.perspective(50, 16/9, 0.5, 1000)


I know that the 16/9 is for the aspect ratio of the psp's screen, but what are the other 3 numbers for?

[yaustar]

In order:
Field of View (FoV)
Aspect ratio
Near clipping plane
Far clipping plane

http://fly.cc.fer.hr/~unreal/theredbook/chapter03.html
About halfway down the page.

[Urameshi]

the 50 is i think like the field
and .5 is like how close the cam can be, and the 1000 is how far it could be

[TacticalPenguin]

50 is field of view aka how much canm be seen 0.5 is how close something can get before being clipped and 1000 is how far it can get before being clipped.

[Merick]

field of view - how does that work exactly?

[yaustar]

FOV is how many degree you want the field of vision to be. It is usually in degrees.

http://fly.cc.fer.hr/~unreal/theredb...es/Fig3-12.gif