Lua Programming Help Thread

[hakk3r]

Awesome thanks!

[FaT3oYCG]

Have a look at the 3D cube example that comes with Lua. It's pretty much direct PSPgl commands.

I also remember a tut from a while back, I'll see if I can find it.

EDIT: Found it (From the GDI)

thanks i will do it in 3d then, i hope your all looking forward to it i am lol

wow i didn't realize that 3d was so easy i thought it would be much harder i spent some time messing around with the different functions e.g. views rotation zoom and things like that and it is pretty simple i think that i should have a poc out for ut lua very soon

thanks

[andyauff]

locations = {}
function addLocation(x,y)
table.insert(locations,{x=x,y=y})
end

while true do
pad = Controls.read()
screen:clear()
if pad:cross() then addLocation(cursorx,cursory) end
for i = 1, table.getn(locations) do
screen:blit(locations[i].x,locations[i].y,img)
end
screen.waitVblankStart()
screen.flip()
end

Ah, I see. Thanks a lot. I figured it would have to do with using tables- that's definitely one thing I need to learn more about.

[FaT3oYCG]

Ah, I see. Thanks a lot. I figured it would have to do with using tables- that's definitely one thing I need to learn more about.

hey andy use this link for some good tuts on tables and how they work it also shows the two different methods of using tables http://www.evilmana.com/tutorials/lua_tutorial_05.php

[hakk3r]

thanks i will do it in 3d then, i hope your all looking forward to it i am lol

wow i didn't realize that 3d was so easy i thought it would be much harder i spent some time messing around with the different functions e.g. views rotation zoom and things like that and it is pretty simple i think that i should have a poc out for ut lua very soon

thanks

Funny I couldn't get the script I put together to work it kept giving me a Wrong number of vertexes or something like that error.

[FaT3oYCG]

hmm first off i modified the 3d cube example to understand what each function did

here is my modified code

red = Color.new(255, 0, 0)
green = Color.new(0, 255, 0)
blue = Color.new(0, 0, 255)
black = Color.new(0, 0, 0)
white = Color.new(255, 255, 255)
gray = Color.new(128, 128, 128)
cyan = Color.new(100, 255, 255)

sqre = 0
trng = 0
lr = 0


logo = Image.createEmpty(64, 64)
logo:clear(gray)
logo:print(20, 20, "Lua", black)
logo:print(10, 40, "Player", black)

cube = {
    {0, 0, red, -1, -1,  1},  -- 0
    {2, 0, red, -1,  1,  1},  -- 4
    {2, 2, red,  1,  1,  1},  -- 5

    {0, 0, red, -1, -1,  1},  -- 0
    {2, 2, red,  1,  1,  1},  -- 5
    {0, 2, red,  1, -1,  1},  -- 1

    {0, 0, red, -1, -1, -1},  -- 3
    {2, 0, red,  1, -1, -1},  -- 2
    {2, 2, red,  1,  1, -1},  -- 6

    {0, 0, red, -1, -1, -1},  -- 3
    {2, 2, red,  1,  1, -1},  -- 6
    {0, 2, red, -1,  1, -1},  -- 7

    {0, 0, green,  1, -1, -1},  -- 0
    {2, 0, green,  1, -1,  1},  -- 3
    {2, 2, green,  1,  1,  1},  -- 7

    {0, 0, green,  1, -1, -1},  -- 0
    {2, 2, green,  1,  1,  1},  -- 7
    {0, 2, green,  1,  1, -1},  -- 4

    {0, 0, green, -1, -1, -1},  -- 0
    {2, 0, green, -1,  1, -1},  -- 3
    {2, 2, green, -1,  1,  1},  -- 7

    {0, 0, green, -1, -1, -1},  -- 0
    {2, 2, green, -1,  1,  1},  -- 7
    {0, 2, green, -1, -1,  1},  -- 4

    {0, 0, blue, -1,  1, -1},  -- 0
    {2, 0, blue,  1,  1, -1},  -- 1
    {2, 2, blue,  1,  1,  1},  -- 2

    {0, 0, blue, -1,  1, -1},  -- 0
    {2, 2, blue,  1,  1,  1},  -- 2
    {0, 2, blue, -1,  1,  1},  -- 3

    {0, 0, blue, -1, -1, -1},  -- 4
    {2, 0, blue, -1, -1,  1},  -- 7
    {2, 2, blue,  1, -1,  1},  -- 6

    {0, 0, blue, -1, -1, -1},  -- 4
    {2, 2, blue,  1, -1,  1},  -- 6
    {0, 2, blue,  1, -1, -1},  -- 5
}

plane = {
    {blue, -8, -3,  0},
    {cyan, 8,  3,  0},
    {blue,  8,  -3,  0},
    {cyan, 8, 3,  0},
    {blue, -8,  -3,  0},
    {cyan,  -8,  3,  0},
}

while true do
    Gu.start3d()

    -- clear screen
    Gu.clearDepth(0);
    Gu.clear(Gu.COLOR_BUFFER_BIT+Gu.DEPTH_BUFFER_BIT)

    -- setup projection and view matrices

    Gum.matrixMode(Gu.PROJECTION)
    Gum.loadIdentity()
    Gum.perspective(75, 16/9, 0.1, 4000)

    Gum.matrixMode(Gu.VIEW)
    Gum.loadIdentity()

    -- setup matrix for triangle
    Gum.matrixMode(Gu.MODEL)
    Gum.loadIdentity()
    Gum.translate(0, 0, -5);

    -- draw triangle without texture

    Gu.disable(Gu.TEXTURE_2D)
    Gum.drawArray(Gu.TRIANGLES, Gu.COLOR_8888+Gu.VERTEX_32BITF+Gu.TRANSFORM_3D, plane)

    -- setup texture

    Gu.enable(Gu.BLEND)
    Gu.blendFunc(Gu.ADD, Gu.SRC_ALPHA, Gu.ONE_MINUS_SRC_ALPHA, 0, 0)
    Gu.enable(Gu.TEXTURE_2D);
    Gu.texImage(logo)
    Gu.texFunc(Gu.TFX_MODULATE, Gu.TCC_RGBA)
    Gu.texEnvColor(white)
    Gu.texFilter(Gu.LINEAR, Gu.LINEAR)
    Gu.texScale(1, 1)
    Gu.texOffset(0, 0)
    Gu.ambientColor(white)

    -- setup matrix for cube

    Gum.matrixMode(Gu.MODEL)
    Gum.loadIdentity()
    Gum.translate(0, 0, -3);
    Gum.rotateXYZ(sqre, trng, lr)

    -- draw cube

    Gum.drawArray(Gu.TRIANGLES, Gu.TEXTURE_32BITF+Gu.COLOR_8888+Gu.VERTEX_32BITF+Gu.TRANSFORM_3D, cube)

degr = (Gu.PI/180)

if Controls.read():square() then
sqre = sqre + (10 * degr)
end

if Controls.read():circle() then
sqre = sqre - (10 * degr)
end

if Controls.read():triangle() then
trng = trng + (10 * degr)
end

if Controls.read():cross() then
trng = trng - (10 * degr)
end

if Controls.read():l() then
lr = lr + (10 * degr)
end

if Controls.read():r() then
lr = lr - (10 * degr)
end

    Gu.end3d()

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

    screen.waitVblankStart()
    screen.flip()
end

now for my question i am reading a file and i have the string how would i say read from a certain point in that string until another point say 5 letters in a 20 letter sentence thanks EDIT: nvm i found out how to do it i used string.sub(string, start, finish) thanks ne way

[andyauff]

hey andy use this link for some good tuts on tables and how they work it also shows the two different methods of using tables http://www.evilmana.com/tutorials/lua_tutorial_05.php

Yeah, those (the evilmana ones) are basically the only tutorials I have used (besides one tut for 3D). I need more in-depth explanations of the table functions such as table.getn and the use if "i". I'll be checking out lua.org and other good resources when I get a chance. Thanks for the consideration though, even if I have already gone through that tutorial! :)

[FaT3oYCG]

oh ok well the table.getn() command and such are easy to use you almost never need to use them unless you are creating a file browser which i can post an example of if you want and ill add in some comments explaining what each function does

[andyauff]

That's okay, I think I understand, I just need to practice using them. Thanks.

[FaT3oYCG]

ok no probs if you need help or get stuck you know where to come

[FreePlay]

Yea but you could still make a 3D tutorial.
All I want it to be able to do is walk around.

Seriously? You think this is simple stuff?

You're making it pretty obvious that you've done little to no coding yourself...

[TuxThePenguin]

You use table.getn in MANY more situations than a filebrowser. Wanna run through every entry of a table? Wanna find out how many of something you have? etc

table.getn returns the number of items in the given table.

table1 = {3,2,4,5,6,3,5}
print(table.getn(table1)) --will print 7
table2 = {{1,2,3},{4,5,6},{7,8,9}}
print(table.getn(table2)) --will print 3

For the whole i thing, look at the lua-users.org for loop tutorial.

Tables: http://lua-users.org/wiki/TablesTutorial
For loops: http://lua-users.org/wiki/ForTutorial

[FaT3oYCG]

i didn't say that there weren't more uses i said you hardly ever need to do something like that except for in file browsers

[TuxThePenguin]

By hardly ever, you were implying that filebrowsers were one of the very select few applications of table.getn when in fact filebrowsers are just one of several implementations of it. I use it in almost every program I make.

[Nielkie]

By hardly ever, you were implying that filebrowsers were one of the very select few applications of table.getn when in fact filebrowsers are just one of several implementations of it. I use it in almost every program I make.

Same here.

In a game, for example, it's easy to just chuck all objects in a table and loop through them to render them. That also makes it easy to construct levels and make a level editor.

[hakk3r]

Seriously? You think this is simple stuff?

You're making it pretty obvious that you've done little to no coding yourself...

I never said it would be simple. All I said was I want a tutorial. Also why aren't you flaming the guy who said:

thanks i will do it in 3d then, i hope your all looking forward to it i am lol

wow i didn't realize that 3d was so easy i thought it would be much harder i spent some time messing around with the different functions e.g. views rotation zoom and things like that and it is pretty simple i think that i should have a poc out for ut lua very soon

thanks

Durr

[eldiablov]

FreePlay is ten times smarter than you'll ever be. Lua isn't the language (for PSP) to learn how to make a model with a high number of polygons walk around. Sure the cube sample is easy but that involves barely any physics.

[FaT3oYCG]

Seriously? You think this is simple stuff?

You're making it pretty obvious that you've done little to no coding yourself...

I never said it would be simple. All I said was I want a tutorial. Also why aren't you flaming the guy who said:

thanks i will do it in 3d then, i hope your all looking forward to it i am lol

wow i didn't realize that 3d was so easy i thought it would be much harder i spent some time messing around with the different functions e.g. views rotation zoom and things like that and it is pretty simple i think that i should have a poc out for ut lua very soon

thanks

Durr

hmm let me think i understand lua i havent just started learning it - i ask for places to learn, and try to fix my own mistakes if i dont have time or i cant fix it myself then i will post here before asking someone like freeplay for an example 3d world where i can walk arround - as that in its self would take a while to make

and as i do have previous experience i will find it easier to use the basic 3d commands and learn how to use the advanced ones so unless you are going to make a 3d game or something

shut up !!!!!

[hakk3r]

I was just saying that freeplay doesn't need to be such a jerk just because he knows more than us.

[andyauff]

Okay, so I have used TuxThePenguin's advice for blitting multiple images using a cursor, and it works great. But now I need to be able to erase whichever one is underneath the cursor when another button is pressed. I have tried using the table.remove function, which works, but it needs a number for which entry to delete. I don't know which entries are which... I simply need to erase whichever one is underneath the cursor. Would there be a way to do something like that without too much stress?

[Anti-QuickJay]

hmm let me think i understand lua i havent just started learning it - i ask for places to learn, and try to fix my own mistakes if i dont have time or i cant fix it myself then i will post here before asking someone like freeplay for an example 3d world where i can walk arround - as that in its self would take a while to make

and as i do have previous experience i will find it easier to use the basic 3d commands and learn how to use the advanced ones so unless you are going to make a 3d game or something

shut up !!!!!

You miss need to shut up.
Your saying how 3d is soooo easy yet I bet you cant do any more than a cube example if that without looking at the already made one. Also, no you do not understand Lua.

[hakk3r]

Have you learned 3D? If not then how do you know its soo easy. If so then I'm sorry I asked.

[TuxThePenguin]

I dont have much time right now to scribble up some code but here's what I can tell you you should be aiming at

-When button is pressed, start a for loop (for i = 1, table.getn(placedimgs) do)
-In that for loop, check if the mouse is over that image by comparing placedimgs[i].x and y and the cursor x and y and the width/height of placed image
if the cursor IS over that image then
table.remove(placedimngs, i)
break
end

[andyauff]

I see. I will try that for sure. Thanks a lot.

[Judas]

logo:print(20, 20, "Lua", black)
logo:print(10, 40, "Player", black)

Are you coding Lua or HTML?

[FaT3oYCG]

Are you coding Lua or HTML?

lua obv soz about that it is the way the forum put it,

its supposed to be

logo:print(20, 20, "Lua", black)
logo:print(10, 40, "Player", black)

[andyauff]

Is there a function to completely empty a table?

EDIT: Nevermind, I figured it out.

[TuxThePenguin]

tablename = {}

lol

[andyauff]

huh. :Argh:

[TuxThePenguin]

lemme guess, you were doing something like

for i = 1, table.getn(table) do
table.remove(table,i)
end