abi>>forums - Common Code Fragments

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abi>>forums (http://www.anythingbutipod.com/forum/index.php)

- Zen X-Fi2 Applications & Development (http://www.anythingbutipod.com/forum/forumdisplay.php?f=221)

- - Common Code Fragments (http://www.anythingbutipod.com/forum/showthread.php?t=52312)

bzdbbb

02-07-2010 08:29 AM

Common Code Fragments

Now that the SKD has been released and more people are getting into writing apps I thought it would be a good idea to have a thread devoted to useful reusable code functions that are not included in the standard Libraries.

I'll kick things off; :P

Returns true if the point x,y is within the region at rx,ry with the width w and height h, else returns false:

Code:

function withinRegion(x, y, rx, ry, w, h)



        if x >= rx and x <= (rx + w) and y >= ry and y <= (ry + h) then

                return true;

        else

                return false;

        end;



end;

Returns the distance in pixels between x,y and x1,y1

Code:

function pointDistance(x,y,x1,y1)

        local xdist;

        local ydist;

        local dist;

        xdist = math.abs(x-x1);

        ydist = math.abs(y-y1);

        dist = math.sqrt((xdist*xdist)+(ydist*ydist));

        return dist;

end;

If you've written any other useful functions or have a improvement to one already listed, please post :)

badazzmofo

02-08-2010 01:35 PM

does zenlua support class structure?

can i say

Quote:

class one
public function one( arg ) echo arg . 1; end;
private function two() return 2; end;
public function three( arg ) return two() + 1; end;
end;

so if you went

var test= new one("test");
you'd get test1

if you went
echo test.three()

you get a result of 3

but if you went
echo test.two()

you'd get nothing or an error

bzdbbb

02-08-2010 02:03 PM

Nope - Lua doesn't support classes. You can try and emulate them but its still just functions :P (I'm doing this in the scrolling shooter to allow instances)

badazzmofo

02-08-2010 02:11 PM

you mean like
function one()
public function one( arg ) echo arg . 1; end;
private function two() return 2; end;
public function three( arg ) return two() + 1; end;
end;

ive done that in javascript

how about private/public? does that work?

bzdbbb

02-08-2010 02:24 PM

You can't nest functions and there's no need for public/private stuff. There is just functions, that's it :P What you can do to emulate classes is to create a table which holds functions e.g. math.sqrt() is a function called sqrt in a table called math. This makes "math" like a class in other languages, but in Lua its just a table :P

ThievingSix

02-09-2010 08:20 PM

Classes can be emulated as Modules. Private/Public is done via the local command. Check out Apeopex for an example of that.

delirius

02-19-2010 10:38 AM

TILED map viewer

1 Attachment(s)

I have implemented simple viewer of tile maps. I just wanted to test if it can be done on X-fi 2, and how much of memory i will waste by map.

Currently there is not culling of not visible tiles, but it is still pretty fluent with map slightly bigger than screen.

Tiles are from TILED editor (free editor)

If someone finds it usefull, go ahead and use/change code.

xConStruct

02-26-2010 11:52 AM

Classes can best be simulated by metatables, e.g. something like this:

Code:

-- The class structure

local MyClass = {}

local MyClass_mt = {__index = MyClass}



function MyClass:New(a, b)

    local instance = {aValue = a, bValue = b}

    return setmetatable(instance, MyClass_mt)

end



function MyClass:GetSum()

    return self.aValue + self.bValue

end



-- The instances

local object1 = MyClass:New(1, 3)

print( object1.aValue ) -- prints '1'

print( object1:GetSum() ) -- prints '4'



local object2 = MyClass:New(4, 5)

print (object2:GetSum() ) -- prints '9'

Note the difference between using dot . and colon : when doing function calls, because the colon also passes the current table as 'self'. There are more details about this technique here.

cilmaviel

02-26-2010 07:03 PM

these may not be common, but they are probably helpful if you need them...

the distance between coordinates function can be shortened to

Code:

function dist(x1,y1,x2,y2)

    return math.sqrt((math.abs(x1-x2)*math.abs(x1-x2))+(math.abs(y1-y2)*math.abs(y1-y2)))

end

this function takes 3 coordinates and returns the area of any triangle, it uses the function above.

Code:

function triarea(x1,y1,x2,y2,x3,y3)

    local as = dist(x1,y1,x2,y2)

    local bs = dist(x2,y2,x3,y3)

    local cs = dist(x3,y3,x1,y1)

    local s = (as+bs+cs)/2

    return math.sqrt(s*(s-as)*(s-bs)*(s-cs))

end

this one is also dependent on the function above, it will return 1 if a point (x,y) is the the triangle, 0 if not.

Code:

function pointintriangle(ax,ay,bx,by,cx,cy)

    local defined_tri = (triarea(ax,ay,bx,by,cx,cy))

    local tri1 = (triarea(x,y,ax,ay,bx,by))

    local tri2 = (triarea(x,y,bx,by,cx,cy))

    local tri3 = (triarea(x,y,cx,cy,ax,ay))

    if math.floor(tri1+tri2+tri3) == math.floor(defined_tri) then

        return 1

    else

        return 0

    end

end

here is a simple collision system using point and box, i use it in monkey ball. ballsize is the diameter of the ball, bx and by are the coordinates of the center of the ball. bufferxavg and bufferyavg is the data from the accelerometer about the direction of tilt. if xmove or ymore are 0 (there is a check done elsewhere in the program before the ball is allowed to move). note, there may be a problem if a collision happens at a perfect 45 degree angle but i have not found any issues with it.

Code:

function obsticalarea(xmin,xmax,ymin,ymax)

    local ballright = ((bx ) + (ballsize / 2))

    local ballleft = ((bx ) - (ballsize / 2))

    local balltop = ((by ) - (ballsize / 2))

    local ballbottom = ((by ) + (ballsize / 2))

    local cright = xmax

    local cleft = xmin

    local ctop = ymin

    local cbottom = ymax

    cx = ((xmax-xmin)/2)+xmin

    cy = ((ymax-ymin)/2)+ymin

    xoffset = math.abs(bx-cx)

    yoffset = math.abs(by-cy)

    if bx < cx and xoffset > yoffset and ballright > cleft then

        if bufferxavg < 0 then

            xmove = 0

        else

            xmove = 1

        end

        ymove = 1

    elseif bx > cx and xoffset > yoffset and ballleft < cright then

        if bufferxavg > 0 then

            xmove = 0

        else

            xmove = 1

        end

        ymove = 1

    elseif by < cy and yoffset > xoffset and ballbottom > ctop then

        if bufferyavg > 0 then

            ymove = 0

        else

            ymove = 1

        end

        xmove = 1

    elseif by > cy and yoffset > xoffset and balltop < cbottom then

        if bufferyavg < 0 then

            ymove = 0

        else

            ymove = 1

        end

        xmove = 1

    else

        xmove = 1

        ymove = 1

    end

end

and here is a link to a psp lua development board. being psp most of the code is different but it may have some useful ideas.
http://forums.qj.net/psp-development...-snippets.html

Habhome

02-27-2010 02:01 AM

Quote:

Originally Posted by cilmaviel (Post 446258)

these may not be common, but they are probably helpful if you need them...

the distance between coordinates function can be shortened to

Code:

function dist(x1,y1,x2,y2)

    return math.sqrt((math.abs(x1-x2)*math.abs(x1-x2))+(math.abs(y1-y2)*math.abs(y1-y2)))

end

this function takes 3 coordinates and returns the area of any triangle, it uses the function above.

Code:

function triarea(x1,y1,x2,y2,x3,y3)

    local as = dist(x1,y1,x2,y2)

    local bs = dist(x2,y2,x3,y3)

    local cs = dist(x3,y3,x1,y1)

    local s = (as+bs+cs)/2

    return math.sqrt(s*(s-as)*(s-bs)*(s-cs))

end

this one is also dependent on the function above, it will return 1 if a point (x,y) is the the triangle, 0 if not.

Code:

function pointintriangle(ax,ay,bx,by,cx,cy)

    local defined_tri = (triarea(ax,ay,bx,by,cx,cy))

    local tri1 = (triarea(x,y,ax,ay,bx,by))

    local tri2 = (triarea(x,y,bx,by,cx,cy))

    local tri3 = (triarea(x,y,cx,cy,ax,ay))

    if math.floor(tri1+tri2+tri3) == math.floor(defined_tri) then

        return 1

    else

        return 0

    end

end

Nice! I have been starting to ponder over functions like these, now I don't have to come u with them myself anymore =P Thanks

xConStruct

03-09-2010 09:44 AM

A function to find out, whether the application is running on the Zen or the simulator, maybe good for debugging functions:

Code:

local function isZen()

    return debug.traceback():match("a:/") and true

end

Function to check whether two rectangles / regions are intersecting each other:
- region a with coords (aX, aY) and size (aW, aH)
- region b with coords (bX, bY) and size (bW, bH)

Code:

function intersects(aX, aY, aW, aH,    bX, bY, bW, bH)

    return (aX < bX + bW) and (bX < aX + aW) and (aY < bY + bH) and (bY < aY + aH)

end

Diddykong13

03-09-2010 10:35 AM

Animation

A function for realtime animation:

Code:

--LeftAnim

function moveleft()



Timer = Timer + 1;



    if Timer>= 9 or Timer<=0  then



    Timer = 0;



      end







        if Timer==2 then



        CurrentPlayerImg = manLeft1;



        end







        if Timer==4 then



        CurrentPlayerImg = manLeft2;



        end





                 

    if Timer==6 then

 

        CurrentPlayerImg = manLeft3;



        end





        if Timer==8 then

 

        CurrentPlayerImg = manLeft2;



        end



end

-Place this function in a while loop for it to animate
-Put a CurrentPlayerImg:draw(playerx,playery); in the draw screen function to make it update

ThievingSix

03-13-2010 07:03 PM

Want to compile your code like Creatives Sudoku game? If so read on:

Quote:

Originally Posted by ThievingSix (Post 450860)

Haha, Ok I'll explain it.

First this is a script you run in the simulator or your player.

Code:

CodeOutput = io.open("CompiledCode.lua","wb");

Open the file you want your compiled application to output too.

Code:

CodeOutput:write(string.dump(assert(loadfile("MyCode.lua"))));

Lets break it down:
-loadfile("MyCode.lua")
>Basically this loads MyCode.lua from plaintext(the kind we type) and compiles it.
-assert(...)
>This makes sure that the file compiled error free.
-string.dump(...)
>This dumps the compiled code from our file into byte form so we can output it to file.
-CodeOutput:write(...)
>This writes the dumped data to the file.

Code:

io.close(CodeOutput);

Saves the compiled code we just wrote.

Now you have a file that contains compiled code("CompiledCode.lua") from a file that we just wrote and was not compiled("MyCode.lua"). You can now rename "CompildCode.lua" to "Main.lua" and it will run like normal, only no one can edit it. It can be mostly decompiled but its better than not.

cilmaviel

03-24-2010 06:50 PM

with the new firmware and everything, here is a script that creates a file "functions.lua" and lists all of the functions available.

Code:

local seen={}

file = io.open("functions.lua","w")

function dump(t,i)

    seen[t]=true

    local s={}

    local n=0

    for k in pairs(t) do

        n=n+1 s[n]=k

    end

    table.sort(s)

    for k,v in ipairs(s) do

        print(i,v)

        file:write(i, v, "\n")

        v=t[v]

        if type(v)=="table" and not seen[v] then

            dump(v,i.."\t")

        end

    end

end

dump(_G,"")

ThievingSix

03-24-2010 06:52 PM

My internet is too slow to update right now, any new functions found with that dump function?

cilmaviel

03-24-2010 07:13 PM

the accelerometer functions are the same as in the api. the only ones i have noticed are os.execute() and os.tmpname() i have not tested them yet though.

Tetrajak

03-24-2010 07:14 PM

New functions as listed by cilmaviel;

Quote:

os.tmpname ()
Returns a string with a file name that can be used for a temporary file. The file must be explicitly opened before its use and explicitly removed when no longer needed.
On some systems (POSIX), this function also creates a file with that name, to avoid security risks. (Someone else might create the file with wrong permissions in the time between getting the name and creating the file.) You still have to open the file to use it and to remove it (even if you do not use it).
When possible, you may prefer to use io.tmpfile, which automatically removes the file when the program ends.

In the POSIX shell of the X-Fi2, the os.tmpfile function can be used to create new files on the device.

Quote:

os.execute ([command])
This function is equivalent to the C function system. It passes command to be executed by an operating system shell. It returns a status code, which is system-dependent. If command is absent, then it returns nonzero if a shell is available and zero otherwise.

os.execute can be used to run POSIX commandline functions, although what the returned codes mean, I am unsure.

Dump of output of cilmaviel's function, assess at your will;

Code:

_G

_VERSION

accelerometer

 close

 get_datatype

 get_samplerate

 getdata

 open

 set_datatype

 set_samplerate

assert

audio

 beep

 channel

 mute

 volume

button

 click

 event

 hold

 home

 power

 up

collectgarbage

color

 a

 b

 g

 new

 r

control

 isButton

 isSensor

 isTouch

 read

coroutine

 create

 resume

 running

 status

 wrap

 yield

debug

 debug

 getfenv

 gethook

 getinfo

 getlocal

 getmetatable

 getregistry

 getupvalue

 setfenv

 sethook

 setlocal

 setmetatable

 setupvalue

 traceback

dofile

dump

error

file

gcinfo

getfenv

getmetatable

image

 close

 create

 draw

 fill

 height

 load

 setbg

 setresource

 width

io

 close

 flush

 input

 lines

 open

 output

 popen

 read

 stderr

 stdin

 stdout

 tmpfile

 type

 write

ipairs

load

loadfile

loadstring

math

 abs

 acos

 asin

 atan

 atan2

 ceil

 cos

 cosh

 deg

 div

 exp

 floor

 fmod

 frexp

 huge

 ldexp

 log

 log10

 max

 min

 mod

 modf

 pi

 pow

 rad

 random

 randomseed

 sin

 sinh

 sqrt

 tan

 tanh

module

newproxy

next

os

 clock

 date

 difftime

 exit

 getenv

 ostime

 remove

 rename

 setlocale

 sleep

 time

 wait

package

 config

 cpath

 loaded

  _G

  accelerometer

  audio

  button

  color

  control

  coroutine

  debug

  image

  io

  math

  os

  package

  screen

   backlight

   clear

   drawline

   drawpixel

   drawrect

   fillrect

   height

   orientation

   update

   width

  string

   byte

   char

   dump

   find

   format

   gfind

   gmatch

   gsub

   len

   lower

   match

   rep

   reverse

   sub

   upper

  table

   concat

   foreach

   foreachi

   getn

   insert

   maxn

   remove

   setn

   sort

  text

   color

   draw

   size

  touch

   click

   down

   event

   hold

   move

   pos

   up

  wav

   close

   load

   play

   time

 loaders

  1

  2

  3

  4

 loadlib

 path

 preload

 seeall

pairs

pcall

print

rawequal

rawget

rawset

require

screen

select

setfenv

setmetatable

string

table

text

toint

tonumber

tostring

touch

type

unpack

wav

xpcall

ThievingSix

03-24-2010 07:18 PM

So accelerometer.set_senddatatype is now accelerometer.set_datatype. Same with the respective get().

I didn't notice os.execute() in the list?

Tetrajak

03-24-2010 07:23 PM

Quote:

Originally Posted by ThievingSix (Post 454919)

So accelerometer.set_senddatatype is now accelerometer.set_datatype. Same with the respective get().

I didn't notice os.execute() in the list?

Indeed, os.execute is not in the list. You'll have to ask cilmaviel about that one.

cilmaviel

03-24-2010 07:32 PM

Quote:

Originally Posted by ThievingSix (Post 454919)

So accelerometer.set_senddatatype is now accelerometer.set_datatype. Same with the respective get().

I didn't notice os.execute() in the list?

it's weird those 2 functions were in the list, but i ran it again and they were gone. when i turned the player off and back on after i installed the firmware it reset like others said, i may have ran this before it reset. execute may be limited to a small window of use.

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