Lua Programming Help Thread

[slicer4ever]

yes you could do sometin like this:

me = 5
you = 6
them = 7
nine = 9
screen:drawline(me,you,th em,nine,red)

they just use x0,y0,x1,y1 as examples you could call variables whatever you want it don't matter

[PSPduh]

Thanks everybody!

[EminentJonFrost]

drawing a curved line?
how about those old "y = x^2" (i think its like that...) formulas?

anyone whos used a graphing calculator should know what i mean. you can make the "y" be the position of the pixels, right?

and then make a "for" loop so that the pixels make a (curved) line.

[PSPduh]

I'll try that. But I'm having trouble with this code:

black = Color.new(0, 0, 0)
white = Color.new(255, 255, 255)
grey = Color.new(127,127,127)
red = Color.new(255, 0, 0) 
green = Color.new(0, 255, 0)
blue = Color.new(0, 0, 255)
yellow = Color.new(255,255,0)
purple = Color.new(120,0,120)
pink = Color.new(255,0,255)
orange = Color.new(255,110,0)

width = 50
height = 100
x = 10
y = 136
x1 = 470
y1 = 136

screencolor = white
paddlecolor = black

while true do
screen:clear(white)
pad = Controls.read()

if pad:up() then
y = y + 2
screen.waitVblankStart(4)
end

if pad:down() then
y = y - 2
screen.waitVblankStart(4)
end

if pad:cross() then
y1 = y1 - 2
screen.waitVblankStart(4)
end

if pad:triangle() then
y1 = y1 + 2
screen.waitVblankStart(4)
end

if y1 <= -1 then
y1 = 0
end

if y <= -1 then
y = 0
end

if y <= 273 then
y = 272
end

if y1 <= 273 then
y1 = 272
end

screen:fillRect(x,y,width,height,black)
screen:fillRect(x1,y1,width,height,black)

screen.waitVblankStart()
screen.flip()
end

Yes I'm trying to make a pong game, but the rectangles wont show up.

[EminentJonFrost]

try switching back the colors. (blocks are white, background is black.)
and leave the "screen:clear()" alone, so it doesnt mention a color.

[PSPduh]

try switching back the colors. (blocks are white, background is black.)
and leave the "screen:clear()" alone, so it doesnt mention a color.

Meh, I took white out of screen:clear(), and changed the color of the paddles to white, and it didn't show up still. I guess I'll use pre-set images, or Image.createEmpty.

[EminentJonFrost]

wait, isnt it supposed to be "drawRect" instead of "fillRect"?

[PSPduh]

wait, isnt it supposed to be "drawRect" instead of "fillRect"?

Whne I tried that it gave me that drawRect was a nil value.

[Grimfate126]

I'll try that. But I'm having trouble with this code:

black = Color.new(0, 0, 0)
white = Color.new(255, 255, 255)
grey = Color.new(127,127,127)
red = Color.new(255, 0, 0) 
green = Color.new(0, 255, 0)
blue = Color.new(0, 0, 255)
yellow = Color.new(255,255,0)
purple = Color.new(120,0,120)
pink = Color.new(255,0,255)
orange = Color.new(255,110,0)

width = 50
height = 100
x = 10
y = 136
x1 = 470
y1 = 136

screencolor = white
paddlecolor = black

while true do
screen:clear(white)
pad = Controls.read()

if pad:up() then
y = y + 2
screen.waitVblankStart(4)
end

if pad:down() then
y = y - 2
screen.waitVblankStart(4)
end

if pad:cross() then
y1 = y1 - 2
screen.waitVblankStart(4)
end

if pad:triangle() then
y1 = y1 + 2
screen.waitVblankStart(4)
end

if y1 <= -1 then
y1 = 0
end

if y <= -1 then
y = 0
end

if y <= 273 then
y = 272
end

if y1 <= 273 then
y1 = 272
end

screen:fillRect(x,y,width,height,black)
screen:fillRect(x1,y1,width,height,black)

screen.waitVblankStart()
screen.flip()
end

Yes I'm trying to make a pong game, but the rectangles wont show up.

three things:

1. why do you have screen.waitVblankStart(4) after everytime you move??

2. the screen:fillRect is muuch too complicated for what you need. a simple Image.createEmpty command will work just as fine.

3. thats one big list of colors you got. ;)

[EminentJonFrost]

three things:

1. why do you have screen.waitVblankStart(4) after everytime you move??

2. the screen:fillRect is muuch too complicated for what you need. a simple Image.createEmpty command will work just as fine.

3. thats one big list of colors you got. ;)

the screen.waitVblankStarts are so the effects of pressing a button dont accidently repeat more than what you want.

i agree with the amount of colors. thats alot. why do you have so many? if its so you dont have to remember them, then put this in your Favorites.

http://www.pitt.edu/~nisg/cis/web/cgi/rgb.html

[PSPduh]

I dont know why I have so many colors. I just like to have a lot to choose from.

[ShockD]

I have a question. I'm using a sprite sheet for a game I'm making. I wanted to ask if anybody can tell me how you set a certain point on the sprite sheet into a variable? For example, as seen on EvilMana:

screen:blit(x, y, Image source, [sourcex, sourcey, width, height], [alpha = true])

Well, I wanted to know if you can put the sourcex, sourcey, width, and height into a variable when you load an image instead of using the blit command. I think it will be much easier that way to do animation and such without loading a lot of image files.

Any help will be appreciated. Thanks.

ShockD

[emericaska8r]

Shock D, if i understand you correctly, then this might answer your question.

You could put:
image = Image.load("image.png")
height = image:height()
width = image:width()

as for sourcex and sourcey, i'm not really even sure what they are/do.

[Bronx]

wats wrong with this code?

while true do
screen:clear()
screen:blit(0, 0, menu)
screen.flip()
screen.waitVblankStart(120)
end

pad = Controls.read()
if pad:CROSS() then
screen:clear()
end
i=1
while i<=17 do
    screen:clear()
    counter:start()
    screen:blit(0, 0, background)
    screen:print(5, 100, questions[i], black)
    screen:print(5, 200, answerOne[i], white)
    screen:print(5, 215, answerTwo[i], white)
    screen:print(5, 230, answerThree[i], white)
    screen:print(5, 245, answerFour[i], white)
    inputreceived=0
     screen.flip()
    screen.waitVblankStart()
    while inputreceived==0 do
        pad = Controls.read()

        if pad:up() then
           screen.flip()
           if correctanswer[i]==1 then
               screen:print(5, 110, "You're Correct!", green)
           else
               screen:print(5, 110, "Sorry, incorrect.", red)
               i=0
           end
           inputreceived=1
        end

        if pad:right() then
           screen.flip()
           if correctanswer[i]==2 then
               screen:print(5, 110, "You're Correct!", green)
           else
               screen:print(5, 110, "Sorry, incorrect.", red)
               i=0
           end
           inputreceived=1
        end
        
        if pad:left() then
           screen.flip()
           if correctanswer[i]==3 then
               screen:print(5, 110, "You're Correct!", green)
           else
               screen:print(5, 110, "Sorry, incorrect.", red)
               i=0
           end
           inputreceived=1
        end
        
        if pad:down() then
           screen.flip()
           if correctanswer[i]==4 then
               screen:print(5, 110, "You're Correct!", green)
           else
               screen:print(5, 110, "Sorry, incorrect.", red)
               i=0
           end
           inputreceived=1
        end
    end
    i = i+1
    screen.flip()
screen.waitVblankStart(120)
end
while true do
screen:clear()
 counter:stop()
    currentTime = counter:time()
    screen:print(10,10,"Your time is " .. currentTime,red)
    screen.flip()
screen.waitVblankStart(240)
end

[agashka]

im working right now on a load/save feature for my game, loading is easy but when it come to saving:

file = io.open("loadsave/posx.txt","w")
file:write("posx = ".. posx )
file:write()
file:close()

this will save "posx = 0" (example) on a file, yeah, but how could i save more then 1 value, mutli-lines.

[emericaska8r]

bronxbomber92, i believe your code should read :
if pad:cross() the cross shouldn't be in caps.

[TheMarioKarters]

bronx, the cross shouldn't be caps!

EDIT: I was beat..

[emericaska8r]

Yes, i actually beat someone :)

[ShockD]

Shock D, if i understand you correctly, then this might answer your question.

You could put:
image = Image.load("image.png")
height = image:height()
width = image:width()

as for sourcex and sourcey, i'm not really even sure what they are/do.

Thanks for the reply emericaska8r.

The sourcex and sourcey tells the program where to get the width and height from the image. For example, if you have 4 sprites on the sheet, for sourcex you would have to specify how many pixels to the right the 4th sprite is and same with sourcey. Eh... I hope you understood that. If not then oh well.

Well anyway, that is a good idea. I'm going to play with that for awhile.

Much thanks,
ShockD

Edit: Damn... this stuff is frustrating. When I load my game into the PSP, the background image becomes all distorted (the image is a jpg). It works fine with the windows LUA player. When I convert it into a .png it says error loading image. I set the correct path and extention all right.

Also, it's a bit laggy but I think I know why. If anyone has some pointers on getting rid of lag, that would be great.

Thanks again,
ShockD

[Bronx]

bronxbomber92, i believe your code should read :
if pad:cross() the cross shouldn't be in caps.

i tried that in windows lua player both ways, but the main menu screen would appear but when i press "c" (which is cross on windows) nothing happens, so it doesnt go on to the rest of the code. any help with that? thanks

[ShockD]

@bronxbomber92

In your screen.waitVblankStart, why is there a 12, two spaces, then a zero? I'm just curious as to what that zero does. And also, shouldn't all of that code (the one outside the main loop with the Controls.read()) be in a function?

ShockD

[Altair]

the spaces are because of the formatting of the text of this forum. It should read screen.waitVblankStart(12 0). The 120 means it waits 120 cycles of the screen refreshing. So that means it waits 2 seconds, since the refreshing rate is 60 Hz.

[Bronx]

@bronxbomber92

In your screen.waitVblankStart, why is there a 12, two spaces, then a zero? I'm just curious as to what that zero does. And also, shouldn't all of that code (the one outside the main loop with the Controls.read()) be in a function?

ShockD

theere isnt really two spaces, the forum did that...and i dont think the Controls.read() should be in a function. if u look lower in the code i have a controls.read() and that works their. so no, i don't think so

[EminentJonFrost]

like this, agashka:

file = io.open("loadsave/posx.txt","w")
file:write("posx = ".. posx\n"posx2 = " ..posx2)
file:close()

[ShockD]

the spaces are because of the formatting of the text of this forum. It should read screen.waitVblankStart(12 0). The 120 means it waits 120 cycles of the screen refreshing. So that means it waits 2 seconds, since the refreshing rate is 60 Hz.

Yeah that's what I was thinking too. Oh yeah, Altair, I saw your post in the ps2dev site and I was wondering if you could tell me how you used a 1000x1000 image without any distortion or anything?

Thanks.

[Grimfate126]

Yeah that's what I was thinking too. Oh yeah, Altair, I saw your post in the ps2dev site and I was wondering if you could tell me how you used a 1000x1000 image without any distortion or anything?

Thanks.

its not possible to load images greater than 480x272 in luaplayer unless there is a version i dont know about. youll just have to make seperate images i guess.

[Grimfate126]

hi, i have an analog problem. here is my code:

function movePlayer()

pad = Controls.read()

dx = pad:analogX()

if math.abs(dx) < -100 then
Player[1].x = Player[1].x - 5 
playerpic = 1
goingf = true

elseif math.abs(dx) > 120 then
Player[1].x=Player[1].x + 5
playerpic = 2
goingb = true
end

end

when i move the analog nub right then player goes right, BUT when i move it left, the player STILL goes right. help.

[ShockD]

its not possible to load images greater than 480x272 in luaplayer unless there is a version i dont know about. youll just have to make seperate images i guess.

It's not possible to load an image greater than 512x512. Yeah that's exactly what I did so thanks anyway.

ShockD

[EminentJonFrost]

function movePlayer()

pad = Controls.read()

dx = pad:analogX()

if math.abs(dx) < -100 then
Player[1].x = Player[1].x - 5 
playerpic = 1
goingf = true

elseif math.abs(dx) > 120 then
Player[1].x=Player[1].x + 5
playerpic = 2
goingb = true
end

end

the absolute value of "dx" should not be able to be less than negative100.

[Grimfate126]

function movePlayer()

pad = Controls.read()

dx = pad:analogX()

if math.abs(dx) < -100 then
Player[1].x = Player[1].x - 5 
playerpic = 1
goingf = true

elseif math.abs(dx) > 120 then
Player[1].x=Player[1].x + 5
playerpic = 2
goingb = true
end

end

the absolute value of "dx" should not be able to be less than negative100.

so how would i fix it. sry, im a total n00b at analog controls. it would have been much easier if it was like:

if analog:right() then
... blah

but life aint fair. thx for the help!