Lua Programming Help Thread

[TacticalPenguin]

gman -
string.gsub(stringname,wh attoreplace,whattoreplace itwith)

[myschoo]

tactical: how does string.sub() works? same like gsub?

[LMelior]

tactical: how does string.sub() works? same like gsub?

No:

Doesnt anyone go to lua.org anymore?

http://www.lua.org/manual/5.1/manual.html#5.4

Not the people who need to the most.

[myschoo]

oh yeah... ill test it thx

[Bob Hoil]

nvm SG57 i figured it out.

[TacticalPenguin]

myschoo - sub returns a portion of the string specified by one or two nuber arguments, gsub returns the string with the certain parts replaced.

[youresam]

http://lua-users.org/wiki/TutorialDirectory

Not that anyone cares that every lua function and method is documented there.

[TacticalPenguin]

Yea I spent like a day reading crap there if you guys care. So seriously read it nao.

[Merick]

Maybe one of the mods or admins should put a large banner message at the top of the forum with a link to the lua tuts in it.

Well, maybe not. The people who are really dumb probably wouldn't notice it, and the people who are really lazy would probably just ignore it and ask the stupid questions anyway

[yumCOOKIEZZ]

How do I make the image flip around. I want the character to face right when right it pushed...

[PSPJunkie_]

How do I make the image flip around. I want the character to face right when right it pushed...

Sprites. Look around, sprite examples are everywhere.

[yumCOOKIEZZ]

hmm...so theirs no way I can just flip this single image around the other way?

[Grimfate126]

hmm...so theirs no way I can just flip this single image around the other way?

no. (not in lua atleast)just make another image, and use a image edting program to mirror your character.

[yumCOOKIEZZ]

I guess. I was hoping I wouldn't have to do this because in total there are 199 different parts to my character >.< Different positions when using a different weapon etc. Thanks for the help anyway -.-

[youresam]

no. (not in lua atleast)just make another image, and use a image edting program to mirror your character.

...theres this magical thing called the GU.
If your player is less than 64x64 use Gu.SPRITE mode, if not, youll have to draw every vertex with Gu.TRIANGLE_STRIP.
If worse comes to worse and you have to use TRIANGLE_STRIP, remember to use the following vertex pattern: (X2,Y2) (X1,Y2) (X2,Y1) (Y1,X1)

[yumCOOKIEZZ]

Thanks. I'll try that tomorrow after I get home from school. I had already re done 10 pictures in their opposite but if this works it will save me the time of changing 100's of pictures..

[Grimfate126]

...theres this magical thing called the GU.
If your player is less than 64x64 use Gu.SPRITE mode, if not, youll have to draw every vertex with Gu.TRIANGLE_STRIP.
If worse comes to worse and you have to use TRIANGLE_STRIP, remember to use the following vertex pattern: (X2,Y2) (X1,Y2) (X2,Y1) (Y1,X1)

i REALLY dont think he's upto that yet, but he may be. i dunno.

[youresam]

Thanks. I'll try that tomorrow after I get home from school. I had already re done 10 pictures in their opposite but if this works it will save me the time of changing 100's of pictures..

Yeah, saves load time and memory. I'll show you how to use it tomorrow.

[Merick]

Actually, Gu.SPRITE mode will work with images over 64x64. Thanks to some help I got from Cools, I was able to put together this function for flipping images with the Gu.

function Gu.blit(x, y, image, scale, flip)

	if not scale or type(scale) == "string" then 
		flip = scale
		scale = 1
	end
	
	if flip then
		if flip == "H" then
			x_start = image:width()
			y_start = 0
			x_end  = 0
			y_end = image:height()
		elseif  flip == "V" then
			x_start = 0
			y_start = image:height()
			x_end  = image:width()
			y_end = 0
		elseif flip == "HV" then
			x_start = image:width()
			y_start = image:height()
			x_end = 0
			y_end = 0
		end
	else
		x_start = 0
		y_start = 0
		x_end = image:width()
		y_end = image:height()
	end
	
	width = (image:width()*scale)+x
	height = (image:height()*scale)+y

	temp = {
	{x_start, y_start, x, y, 0},
	{x_end, y_end, width, height, 0}
	}

	Gu.enable(Gu.TEXTURE_2D)
	Gu.texImage(image)
	Gum.drawArray(Gu.SPRITES, Gu.TEXTURE_32BITF+Gu.VERTEX_32BITF+Gu.TRANSFORM_2D, temp)
end

Use it like this:

Gu.start3d() 
Gu.blit( 20,   20, image, 0.5, "H")  -- this will blit the image at half normal size and flipped horizontally
Gu.blit(100,  20, image, 1.5, "V")  -- this will blit it at 1.5 times normal size, flipped vertically
Gu.blit(300,  20, image, "HV")  -- this will blit it at normal size, flipped both horizontally and vertically
Gu.end3d()

Although the function takes four arguments, because the last one is a string I've been able to set it up so that you can skip the 3rd argument "scale" and still have it work properly (see the third example). Put any images you want to blit as resized or flipped between the Gu.start and Gu.end, however don't try to use the regular blit while the Gu is running or the game will crash. I've used this without problems with images over 100 pixels in both the official Lua PLayer v0.20 and in Cools mod 3, but I haven't tried it with any of the earlier versions.

The reason I've set it up without the Gu.start3d and Gu.end3d inside the function itself is because if you're going to be using this for a lot of images, starting and stopping the gu from inside the function would slow down your program quite a bit.

[youresam]

Actually, Gu.SPRITE mode will work with images over 64x64.

Em, it *does* but is oh-my-god slow. Not worth it, it'll cut your FPS in half.

[emericaska8r]

ok, will the flipping function using the gu work fine if the rest of your code is non-gu? Because i heard that using the gu with other regualr 2-d things won't work right or something?

or maybe i have no idea what i am talking about, because i don't really even know what the gu is. just 3-d enabled stuff?

[KleptoOne]

This is a function posted on Evilmana and modded slightly by merick
It'll take care of the flipping for you.

function Gu.blit(x, y, image, scale, flip) 
    
   if scale then 
      if type(scale) == "string" then 
         flip = scale 
         scale = 1 
      else 
         scale = (scale/100) 
      end 
   end 
    
   if flip then 
      if flip == "H" then 
         x_start = image:width() 
         y_start = 0 
         x_end  = 0 
         y_end = image:height() 
      elseif  flip == "V" then 
         x_start = 0 
         y_start = image:height() 
         x_end  = image:width() 
         y_end = 0 
      elseif flip == "HV" then 
         x_start = image:width() 
         y_start = image:height() 
         x_end = 0 
         y_end = 0 
      end 
   else 
      x_start = 0 
      y_start = 0 
      x_end = image:width() 
      y_end = image:height() 
   end 
    
   temp = { 
   {x_start, y_start, 0+x, 0+y, 0}, 
   {x_end, y_end, (image:width()*scale)+x, (image:height()*scale)+y, 0} 
   } 
   Gu.enable(Gu.TEXTURE_2D) 
   Gu.texImage(image) 
   Gum.drawArray(Gu.SPRITES, Gu.TEXTURE_32BITF+Gu.VERTEX_32BITF+Gu.TRANSFORM_2D, temp) 
end

Merick:
use it like this:

Gu.start3d()
Gu.blit(x, y, image, scale in %, flip mode)
Gu.end3d()

for flip mode, you have to put in a string - "H" for horizontal, "V" for vertical, and "HV" for both

Also, I put in a type checker so if you want to just flip the image and not resize it you can just leave out the scale parameter and it'll automatically swap the the flip code string to the flip parameter:

Gu.blit(x, y, image, flip mode)

Klepto:
I've tested this and it works great. Also, you can blit as many thing as you like in between the start and end 3d calls.

[yumCOOKIEZZ]

Thanks =D


I already converted 36 images but this will definitely save me the time... in total the different characters add up to like 700 sprites..but I may not include them all.


The Largest sprite is like 35x 24 or around there, so would I use that function and then use like
gu.blit(x, y, body, h)

And it will be facing opposite?


Also, will this affect the collision codes (when I add them). It would really suck if the character cant be hit when facing right -.-
-= Double Post =-

if char then
screen:clear()
screen:blit(0,0, background, true)
screen:blit(x,y, Stand1, true)
screen:blit(x-3,y-34, Head, true)
screen:blit(x+17,y+2, Arm, true)
screen:blit(x, y-18, FaceSmile, true)
screen:blit(x-10,y-38, Hair, true)
else
screen:clear()
screen:blit(0,0, background, true)
Gu.start3d()
Gu.blit(x, y, Stand1,100, h)
gu.blit(x-3,y-34, Head, h)
gu.blit(x+17,y+2, Arm, h)
gu.blit(x, y-18, FaceSmile, h)
gu.blit(x-10,y-38, Hair, h)
Gu.end3d()
end

I get errors on the bolded area. I have the function on a different LUA file that is accessed through DoFile.

[KleptoOne]

The H has to be a string, so you have to pass, "H" <- quotes included

Also, this shouldn't hinder collision in the least, as your coordinate system is identical using the Gu in this manner.

[Grimfate126]

ok, will the flipping function using the gu work fine if the rest of your code is non-gu? Because i heard that using the gu with other regualr 2-d things won't work right or something?

or maybe i have no idea what i am talking about, because i don't really even know what the gu is. just 3-d enabled stuff?

the GU is the PSP's graphics utility. you use it without knowing, if youre using lua, or graphics.c. all 2d and 3d functions are done with the GU.

about your question: what do you mean by non-gu? you may have to mod the code a bit, but it shouldnt be too much of a hassle in lua. (i think ) for the record, i havent used the gu in lua at all, so meh.

[yumCOOKIEZZ]

I fixed it, but now, when I do it, no person. He disappears.

Heres my code o.O

if char then
screen:clear()
screen:blit(0,0, background, true)
screen:blit(x,y, Stand1, true)
screen:blit(x-3,y-34, Head, true)
screen:blit(x+17,y+2, Arm, true)
screen:blit(x, y-18, FaceSmile, true)
screen:blit(x-10,y-38, Hair, true)
else
screen:clear()
screen:blit(0,0, background, true)
Gu.start3d()
Gu.blit(x, y, Stand1,100, "H")
Gu.blit(x-3,y-34, Head, "H")
Gu.blit(x+17,y+2, Arm, "H")
Gu.blit(x, y-18, FaceSmile, "H")
Gu.blit(x-10,y-38, Hair, "H")
Gu.end3d()
end

[Merick]

Lol Klepto, I already posted that on the previous page, also the version I posted has some small changes to it. The original version (which you just posted) was written so that the scale argument would be divided by 100, I.E. putting 100 for scale would equal 100%, or normal size. However, I realized that having the function divide a number every time it was called would probably slow down the program, so I edited it to take out the divide by 100 part.

yumCOOKIEZZ, in that code, is it only the Stand1 image which doesn't get displayed? if you're using the version of the function that I posted, then in this line:

Gu.blit(x, y, Stand1,100, "H")

you should remove the 100, because with that version using 100 for scale would mean 100 times the normal size, and at that size the of the image would be larger than the screen size.

emericaska8r:
As for your question about the Gu, the problems your talking about only happen if you try to use the regular blit function while the Gu is running. Basically, when you use the regular blit it starts the Gu, draws the image, then stops the Gu. So, if the Gu is already running and you try to use screen:blit it tries to start it again, and thats what causes lua player to crash. As long at you don't use the regular blit function inside the Gu.start3d() and Gu.end3d() statements, you shouldn't have any problems

[emericaska8r]

ok thanks everyone for the clarification. helped a lot!!!

[yumCOOKIEZZ]

They all disappear. I'll make some experiments and see if I can fix it.

[yumCOOKIEZZ]

Hrm...Still nothing. Whenever I turn right, the entire character disappears...