Lua Programming Help Thread

[pspaquaforce]

I don't like animlib i have a differnt code thats easier in my opion but i need the animation to stay in one place is there differnt side sroller that can have an object stay in one place?

[Merick]

try something like this:

-- this creates a table with 3 images for the animation
-- if you want to use more than three, just continue with 4 =, 5 =, etc...
animation = { 1 = Image.load(frame1.png), 2 = Image.load(frame2.png), 3 = Image.load(frame3.png)}

-- this function draws the current frame
function animate(animx, animy, frame)
     screen:blit(animx, animy, animation[frame])
end

animx and animy are the coordinates where you want the animation to appear at.if you want your animation to always appear at the same place on the screen then you could call it like this:

frame = frame + 1
if frame > 3 then frame = 1
animate(50, 50, frame)

replace the 50, 50 with whatever coordinates it is where you want the animation to appear at, and the animation will always be at that location. Just remember that for it to be visible you'll have to place the function call after the background images.

[pspaquaforce]

thanks but i already have something like that. It's my side scroller that's causeing the problem i need something a little better because this one kind of sucks

[Merick]

hmm...

Oh wait, I think I understand. Are you saying you want the animation to move with the background as it scrolls? Like say if you have a flag by a house in the bg and you want the flag to be waving in the wind

for x use (backx + animx)
for y use (backy + animy)

this will make the animation move with the bg as it scrolls

[Anti-QuickJay]

I don't like animlib i have a differnt code thats easier in my opion but i need the animation to stay in one place is there differnt side sroller that can have an object stay in one place?

Use animlib, You say that you have an easier way yet your having so many problems, Just download animlib and learn how to use it.

[pspaquaforce]

i keep getting an error :Cry:

[Merick]

what error?

[pspaquaforce]

i can't really read it. It flashes to fast. here's the demo you can take a look because i'm really tired http://www.sendspace.com/file/dvgxx3

[eyece]

I got no error while playing.

[pspaquaforce]

Thats because i didn't post the one with the error

[Merick]

here change your animation calls to look like this:

if currentFrame == 1 then --draw first frame
      screen:blit(Back3.x - 370,50,frame1)
   elseif currentFrame == 2 then --draw second frame
      screen:blit(Back3.x - 370,50,frame2)
   elseif currentFrame == 3 then --draw third frame
      screen:blit(Back3.x - 370,50,frame3)
   end

As you can see, the rain doesn't quite match up with the clouds, but to fix that all you have to do is tinker around with how much you subtract from Back3.x.
-= Double Post =-
heh, I went ahead and figured it out for you, even added a few lines to double the size of the animation:

if currentFrame == 1 then --draw first frame
      screen:blit(Back3.x - 480,50,frame1)
      screen:blit(Back3.x - 397,50,frame2)
   elseif currentFrame == 2 then --draw second frame
      screen:blit(Back3.x - 480,50,frame2)
      screen:blit(Back3.x - 397,50,frame3)
   elseif currentFrame == 3 then --draw third frame
      screen:blit(Back3.x - 480,50,frame3)
      screen:blit(Back3.x - 397,50,frame1)
   end

[pspaquaforce]

thank you so much :ROFL: :Punk: :Jump:

[Merick]

hehe, no problem, I haven't had this much fun with a programming language in years

and here's another way to do it:

for i = 536,314, -83 do
   if currentFrame == 1 then --draw first frame
         screen:blit(Back3.x - i,50,frame1)
      elseif currentFrame == 2 then --draw second frame
         screen:blit(Back3.x - i,50,frame2)
      elseif currentFrame == 3 then --draw third frame
         screen:blit(Back3.x - i,50,frame3)
        end
end

-= Double Post =-
ok, I really need some help with this. First, I have my tile loader function. When my program runs through this, it appears to be loading the images like I want it to:

tiles = {}     -- store tile images
tfiles = {}    -- store tile filenames

-- load all images from tiles folder
function loadtiles()
	screen:clear()
	screen:fontPrint(hyperion, 100, 100, "loading tiles", red)
	screen:flip()
   screen:clear()
	local files = System.listDirectory("./tiles")
   tiles[(table.getn(files))] = {}
	for i = 3, table.getn(files) do
		tiles[i-2] = Image.load("./tiles/"..files[i].name)
		tfiles[i-2] = (files[i].name)
		end
	screen:fontPrint(hyperion, 100, 150, "done", blue)
	screen:flip()
   for i = 1, 100000 do end
	return
end

However, when I try to display one of the tiles like this:

   screen:blit(xpos, ypos, tiles[currenttile])
   screen:flip()

nothing shows up on the screen

*edit*

nvm,LOL

the problem was with my algorithm to determine the xpos and ypos

[pspaquaforce]

merick what kind of game are you making?

[Merick]

Well, right now I'm not actually making a game. What I'm working on is a program to draw game maps using graphics tiles.

[emericaska8r]

hey guys, when i use math.floor, i want to round off to the nearest whole number, but it is rounding me off to the first decimal place. any solutions?

[Merick]

can we see how you're using it? I just did a small test, and using math.floor(199.99) gave me the result of 199, so it's probably something to do with the way you're coding it

[eyece]

function math.round(a)
	if a-math.floor(a) >= 0.5 then
		return math.ceil(a)
	else
		return math.floor(a)
	end
end

[emericaska8r]

can we see how you're using it? I just did a small test, and using math.floor(199.99) gave me the result of 199, so it's probably something to do with the way you're coding it

well i have a timer, but i don't want it to show it in milliseconds, so i used:

gametime = math.floor((10000 - timer1:time())/10) -- it shows 10000 - time because it is supposed to be counting down

-= Double Post =-
actually, now that i think about it i think i put the "/ 10" after the math.floor, which would, in any case that the number was not divisible by ten, make the number a decimal again.

and eyece, thanks for teaching me that there was a such thing as math.ceil. I understand why ceiling and floor were named what they are now lol.

[dracule]

what does floor in math.floor stand for?

[eyece]

what does floor in math.floor stand for?

it drops a decimal number to the last (next lowest) whole number.
http://lua-users.org/wiki/MathLibraryTutorial

[Merick]

arrg, I'm really not getting tables. I'm trying to create a table for a map grid, where I can set point x,y in the grid as number like so:

map point x,y = number of the tile to be displayed

no matter how I try to set it up, I keep getting errors like "attempt to index field '?' (a nil value)" or "table index is nil"

[eyece]

i assume you loop through the table when processing tiles? if so, make sure your loop starts at 1.

otherwise show me some code.

[Merick]

a = {}

for i= 1, 10 do
   for j = 1, 10 do
      count = count +1
     a[i,j] = count -- right here i get this: ']' expected near ','
   end
end

--

a = {}

for i= 1, 10 do
   for j = 1, 10 do
      count = count +1
     a[i],[j] = count  -- unexpected symbol near '['
   end
end

--

a = {}

for i= 1, 10 do
   for j = 1, 10 do
      count = count +1
     a[i][j] = count --attempt to index field '?' (a nil value)
   end
end

--
b = {}
a[b] = {} --attempt to index field '?' (a nil value)

for i= 1, 10 do
   for j = 1, 10 do
      count = count +1
     a[i].j  = count
   end
end

-= Double Post =-
It's been a long time and my memory is kinda fuzzy, but i remember it being much easier do to this kind of thins in quickbasic
-= Double Post =-
I just want something that will let me declare a table as a matrix array with xsize number of columns and ysize number of rows, then will let me say that point x,y is equal to some number
-= Double Post =-
.

why does this always happen to me? I struggle for hours to figure something out, but I come up with an answer only after I post a question about it:

a = {}

for i= 1, 10 do
   a[i] = {}
   for j = 1, 10 do
      count = count +1
     a[i][j]  = count
   end
end

[emericaska8r]

i'm not sure how to make a table into an array as you are talking about, but you could always use seperate tables like:

row1 = {}
row2 = {}
row3 = {}
row4 = {}
row5 = {}
for i = 1, 5 do
row1[i] = i
row2[i] = i
row3[i] = i
row4[i] = i
row5[i] = i
end

[Merick]

lol, look in my last double post merge post above, I have found the answer I was looking for

a = {}

for i= 1, x do
   a[i] = {}
   for j = 1, y do
      a[i][j] ={}
   end
end

this bit of code creates a matrix array of x columns by y rows. Since I'm not assigning any values here, all points are = nil, but once this bit of code has run, you can access any point in the matrix with: a[xpos][ypos]

[Aphonia]

Could someone give me examples/tell me how to use these functions?

Gu.light, Gu.lightAtt, Gu.lightColor, Gu.lightMode, Gu.lightSpot

I don't even know where to begin. I just started 3D, and I can at least tinker (poorly) with all the other functions, but the best I get from these is an error.

[eyece]

aphonia, i just took a crack at Gu.light, i got nothing also, so i had a look at the function to see how many arguments it did need, 6 apparently. 1st one looks to be an id i don't know what the next 2 do, but then the other 3 should be the xyz of the light:

static int lua_sceGuLight(lua_State *L) {
	int argc = lua_gettop(L); 
	if (argc != 6) return luaL_error(L, "wrong number of arguments");
	ScePspFVector3 v;
	v.x = luaL_checknumber(L, 4);
	v.y = luaL_checknumber(L, 5);
	v.z = luaL_checknumber(L, 6);
	sceGuLight(luaL_checkint(L, 1), luaL_checkint(L, 2), luaL_checkint(L, 3), &v);
	return 0;
}

but, i have tried and failed maybe my source is different for some reason, could someone enlighten me please :P

EDIT:
lol, my bad the num of arguments error was coming from line 136, not the line 146 with Gu.light, so i just spent 15 minutes trying to fix something that wasn't broken, it'll try again. - ignore the last part of my post :P

[emericaska8r]

lol, look in my last double post merge post above, I have found the answer I was looking for

lol, i didn't see it

[Merick]

can anyone point me to some code that can rotate an image?