Lua Programming Help Thread

[Bob Hoil]

Yes the character moves. If you were to run the fiel the character would move but then you are supposed to be able to hit triangle to shoot up square to shooot left and so on but when i hit one of those buttons i encounter that error i posted on the last page.

[Urameshi]

try this:

if pad:triangle() and BulletInfo[i].direction == "up" then
		BulletInfo[i].y = BulletInfo[i].y - 10 
		end
	end

wait a sec i got another question about your code

BulletInfo[a] = { pic = bullet , firing = false, direction = "right", x = Player[1].x + 32, 
	y = Player[1].y + 16 }
end

you have BulletInfo[a] but every where else you put BulletInfo[i], maybe taht has something to do with your error

[Bob Hoil]

Ok here is a code that acccesdenied helped me with that runs put does not shoot. Maybe we should start here then add to it and try to get it to shoot.

green=Color.new(0,255,0)
grass=Image.load("grass.png")
player=Image.load("player.png")
tree=Image.load("tree.png")
bullet = Image.createEmpty(4,4)
bullet:clear(green)

screenwidth=480-player:width()
screenheight=272-player:width()

Player={}
Player[1]={x=200, y=50}

oldpad = Controls.read()
currentBullet = 0

BulletInfo = {}
for a = 1,800 do
	BulletInfo[a] = { pic = bullet , firing = false, direction = "right", x = Player[1].x + 32, 
	y = Player[1].y + 16 }
end

function bulletSetup()
	if currentBullet < 800 then
		currentBullet = currentBullet + 1
	else
		currentBullet = 1
	end
end
function bulletFire()
	for i = 1,800 do
		if BulletInfo[i].firing == true then
			screen:blit(BulletInfo[i].x,BulletInfo[i].y,BulletInfo[i].pic)
		end
		if BulletInfo[i].x < 0 or BulletInfo[i].x > 480 or BulletInfo[i].y < 0 or BulletInfo[i].y > 272 then 
			BulletInfo[i].firing = false 
		end
	end
end

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

	bulletSetup()

	for a=0, 14 do
		for b=0, 8 do
			screen:blit(32 * a, 32 * b, grass)
		end
	end

	screen:blit(100,100,tree)
	screen:blit(300,220,tree)
	screen:blit(87,46,tree)
	screen:blit(400,150,tree)
	screen:blit(Player[1].x,Player[1].y,player)

	if pad:left() and Player[1].x>0 then
		Player[1].x=Player[1].x-3
	end

	if pad:right() and Player[1].x<screenwidth then
		Player[1].x=Player[1].x+3
	end

	if pad:up() and Player[1].y>0 then
		Player[1].y=Player[1].y-3
	end

	if pad:down() and Player[1].y<screenheight then 
		Player[1].y=Player[1].y+3
	end

	if pad:triangle() then
		if BulletInfo[i].direction == "up" then 
			BulletInfo[i].y = BulletInfo[i].y - 10 
		end
	end
	if pad:circle() then
		if BulletInfo[i].direction == "right" then 
			BulletInfo[i].x = BulletInfo[i].x + 10 
		end
	end
	if pad:cross() then
		if BulletInfo[i].direction == "down" then 
			BulletInfo[i].y = BulletInfo[i].y + 10 
		end
	end
	if pad:square() then
		if BulletInfo[i].direction == "left" then 
			BulletInfo[i].x = BulletInfo[i].x - 10 
		end
	end

	bulletFire()

	screen.waitVblankStart()
	screen.flip()
end

[Urameshi]

? could you plz break that sentence up for me, there's no commas, and that threw me off

[Bob Hoil]

NVM hold on that code is not running right anymore.

Well that one gets the same error as the last one. To restat that sentence, that code is a code that AccessDenied helped me with. It did run but it does not seem to anymore. I hope i typed this one better.


And thanks for all the help by the way
-= Double Post =-

green=Color.new(0,255,0)
grass=Image.load("grass.png")
player=Image.load("player.png")
tree=Image.load("tree.png")
bullet = Image.createEmpty(4,4)
bullet:clear(green)

screenwidth=480-player:width()
screenheight=272-player:width()

Player={}
Player[1]={x=200, y=50}

oldpad = Controls.read()
currentBullet = 0

BulletInfo = {}
for a = 1,800 do
	BulletInfo[a] = { pic = bullet , firing = false, direction = "right", x = Player[1].x + 32, 
	y = Player[1].y + 16 }
end

function bulletSetup()
	if currentBullet < 800 then
		currentBullet = currentBullet + 1
	else
		currentBullet = 1
	end
end
function bulletFire()
	for i = 1,800 do
		if BulletInfo[i].firing == true then
			screen:blit(BulletInfo[i].x,BulletInfo[i].y,BulletInfo[i].pic)
		end
		if BulletInfo[i].x < 0 or BulletInfo[i].x > 480 or BulletInfo[i].y < 0 or BulletInfo[i].y > 272 then 
			BulletInfo[i].firing = false 
		end
	end
end

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

	bulletSetup()

	for a=0, 14 do
		for b=0, 8 do
			screen:blit(32 * a, 32 * b, grass)
		end
	end

	screen:blit(100,100,tree)
	screen:blit(300,220,tree)
	screen:blit(87,46,tree)
	screen:blit(400,150,tree)
	screen:blit(Player[1].x,Player[1].y,player)

	if pad:left() and Player[1].x>0 then
		Player[1].x=Player[1].x-3
	end

	if pad:right() and Player[1].x<screenwidth then
		Player[1].x=Player[1].x+3
	end

	if pad:up() and Player[1].y>0 then
		Player[1].y=Player[1].y-3
	end

	if pad:down() and Player[1].y<screenheight then 
		Player[1].y=Player[1].y+3
	end

	if pad:triangle() then
		if BulletInfo[i].direction == "up" then 
			BulletInfo[i].y = BulletInfo[i].y - 10 
		end
	end
	if pad:circle() then
		if BulletInfo[i].direction == "right" then 
			BulletInfo[i].x = BulletInfo[i].x + 10 
		end
	end
	if pad:cross() then
		if BulletInfo[i].direction == "down" then 
			BulletInfo[i].y = BulletInfo[i].y + 10 
		end
	end
	if pad:square() then
		if BulletInfo[i].direction == "left" then 
			BulletInfo[i].x = BulletInfo[i].x - 10 
		end
	end

	bulletFire()

	screen.waitVblankStart()
	screen.flip()
end

There i just tryed that code and it worked. But when i hit the button to shoot i get the error.

[Urameshi]

well you still have that BulletInfo[a] did it work when you changed the [a] to [i]?

[Bob Hoil]

i got a table error
-= Double Post =-
When i put a instead of i

[youresam]

well you still have that BulletInfo[a] did it work when you changed the [a] to [i]?

i got a table error
When i put a instead of i

...

[nUke_moose]

hi,

i just started with lua, so im a complete noob. i did some of the tutorials and they were quite helpfull, and now im just making small, pointless games to get better at it. my question is, if my sprite would only be black on a white background, do i get any advanteges, eg the game running smoother, if i "wrote" the sprite in lua, so its not a picture/image?
2nd question: i got the free sprites on evilmana.com, but they still have white around them and if i would use it , it would still be in a white square, so u wont see the background or the floor, can that white be made invisible or just "deleted" ?

[myschoo]

1st question:

i think if you just create Image.createEmpty(32,32) it will be faster then making 32x32 picture in paint

2nd q:

those are gifs, so they should have invisible bg...

[nUke_moose]

if i had no images in a game at all, how much better would it run? and is it worth the effort?

[pspfreak9]

I have a couple lua questions:

1) Can you rotate images in lua. If so how?

2) Can you zoom into images? If so how?

3) Can you blit images from a sprite sheet? if so how?

Ex:
aaabbbccc
aaabbbccc
dddeeeffff
dddeeeffff
dddeeeffff
gggggggg
So how would I only blit the 'e' section of the image.

Thx in advance

[Bob Hoil]

Hey guys i need some help with my code. I am combining tutorials to make a small game to help me learn lua. This is my code but when i try to shoot i get a nil value error. Can anyone help me out here. I changed it a little from the last code i posted a while back but still get the same error.

green=Color.new(0,255,0)
grass=Image.load("grass.png")
player=Image.load("player.png")
tree=Image.load("tree.png")
bullet = Image.createEmpty(4,4)
bullet:clear(green)

screenwidth=480-player:width()
screenheight=272-player:width()

Player={}
Player[1]={x=200, y=50}

oldpad = Controls.read()
currentBullet = 0

BulletInfo = {}
for a = 1,800 do
	BulletInfo[a] = { pic = bullet , firing = false, direction = "right", x = Player[1].x + 32, 
	y = Player[1].y + 16 }
end

function bulletSetup()
	if currentBullet < 800 then
		currentBullet = currentBullet + 1
	else
		currentBullet = 1
	end
if direction == "left" then 
BulletInfo[currentBullet].x = Player[1].x 
BulletInfo[currentBullet].y = Player[1].y + 16
end
if direction == "right" then 
BulletInfo[currentBullet].x = Player[1].x + 32 
BulletInfo[currentBullet].y = Player[1].y + 16 
end
if direction == "up" then 
BulletInfo[currentBullet].x = Player[1].x + 16 
BulletInfo[currentBullet].y = Player[1].y 
end
if direction == "down" then 
BulletInfo[currentBullet].x = Player[1].x + 16
BulletInfo[currentBullet].y = Player[1].y + 32 
end

BulletInfo[currentBullet].direction = direction
BulletInfo[currentBullet].firing = true
end

function bulletFire()
	for i = 1,800 do
		if BulletInfo[i].firing == true then
			screen:blit(BulletInfo[i].x,BulletInfo[i].y,BulletInfo[i].pic)
		end
		if BulletInfo[i].x < 0 or BulletInfo[i].x > 480 or BulletInfo[i].y < 0 or BulletInfo[i].y > 272 then 
			BulletInfo[i].firing = false 
		end
	end
end

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

	bulletSetup()

	for a=0, 14 do
		for b=0, 8 do
			screen:blit(32 * a, 32 * b, grass)
		end
	end

	screen:blit(100,100,tree)
	screen:blit(300,220,tree)
	screen:blit(87,46,tree)
	screen:blit(400,150,tree)
	screen:blit(Player[1].x,Player[1].y,player)

	if pad:left() and Player[1].x>0 then
		Player[1].x=Player[1].x-3
	end

	if pad:right() and Player[1].x<screenwidth then
		Player[1].x=Player[1].x+3
	end

	if pad:up() and Player[1].y>0 then
		Player[1].y=Player[1].y-3
	end

	if pad:down() and Player[1].y<screenheight then 
		Player[1].y=Player[1].y+3
	end

	if pad:triangle() and BulletInfo[i].direction == "up" then
			bulletFire()
			BulletInfo[i].y = BulletInfo[i].y - 10 
		end
	if pad:circle() and BulletInfo[i].direction == "right" then 
			bulletFire()
			BulletInfo[i].x = BulletInfo[i].x + 10 
		end
	if pad:cross() and BulletInfo[i].direction == "down" then 
			bulletFire()
			BulletInfo[i].y = BulletInfo[i].y + 10 
		end
	if pad:square() and BulletInfo[i].direction == "left" then 
			bulletFire()
			BulletInfo[i].x = BulletInfo[i].x - 10 
		end
	screen.waitVblankStart()
	screen.flip()
end

[Urameshi]

@pspfreak

ex:

Sasuke=Image.load(where ever the file is)

r1=Image.createEmpty(66,45)

r1:blit(0,0,Sasuke,0,3,66,45)

1st line: Sasuke is the spritesheet

2nd line: r1 is the name and Image.createEmpty is making a blank image the size of 66,45

3rd line: r1 is the name and you blit it from 0,0 which is the size of the whole sprite sheet
and Sasuke is the sprite sheet
the 0,3 is where it is on the sprite sheet and 66,45 is the size

now all you have to do is basically put it like that but sub in your own info

[Merick]

while that does work, creating new images like that uses up memory. A better way to do it is to skip over the image create and just blit directly to the screen:

screen:blit(0,0,Sasuke,0, 3,66,45)

[pspfreak9]

cool thanks
EDIT:
what about rotating images?

[Merick]

there are a few different ways to do that (check the evilmana codebase for one of them)

however, doing it that way is slow, so in order to keep your program running smoothly you'd have to pre-render the rotated images, which again will eat up your free memory. The only other way to do it that I've found uses the 3d gu, and while using the 3d functions is fast, but that it doesn't work well when you try to combine it with regular 2d blits

[Yongobongo]

Damn why won't this work!

for i = 1,100 do
coinx = i*x
screen:blit(olx + coinx, oly, coinage[i])
coinage[i]:blit(0,0,coin)

if collision(mariox, marioy, 47, 55, coinx, oly, 25, 25) then
coinage[i]:clear()
coins = coins + 1
end
end

It's not detecting collision (no im not dumb i have the function) for some reason to do with the loop, and out of the loop it wont detect anyway Please help!

[Merick]

maybe you need to use olx+coinx when you call the collision function?

[ahrimanes]

heyyy hay there this is my fiorst post in this forum, well i was learning somthing about lua stuff here is a code for make a simple starfield by the way does any body know how to, a = a + 1 like a++ or a:+1 or a+=1
this is a common addition in some languages.. but i cant find how to do on lua

heres is my starfield code:

System.usbDiskModeActivate()
blanco = Color.new(255,255,255)
width = 480
height = 272
offscreen = Image.createEmpty(width,height)
maxstars = 200
maxzlevel = 5
time1 = 0
starfield = {}
math.randomseed(os.time())
function createStar(i)
	starfield[i] = {}
	starfield[i].x = math.random(width-1)
	starfield[i].y = math.random(height-1)
	starfield[i].z = math.random(maxzlevel)
	grey = (255/maxzlevel)*starfield[i].z
	starfield[i].color = Color.new(grey,grey,grey)
	starfield[i].colorb = Color.new(grey*2,grey*2,grey*2)
	starfield[i].speed = starfield[i].z*0.5
end
for i = 1, maxstars do
	createStar(i)
end
function drawstars()
	for i = 1, maxstars do
		if starfield[i].speed < 1 then zise = 1 else zise = starfield[i].speed end
		if math.mod(time1,math.random(100)) == 0  then
			offscreen:fillRect(starfield[i].x-starfield[i].speed/2,starfield[i].y-starfield[i].speed/2,zise,zise,starfield[i].colorb)
		else
			offscreen:fillRect(starfield[i].x-starfield[i].speed/2,starfield[i].y-starfield[i].speed/2,zise,zise,starfield[i].color)
		end
		--offscreen:print(starfield[i].x+5,starfield[i].y,starfield[i].z,starfield[i].color)
		starfield[i].y = starfield[i].y + starfield[i].speed
		if starfield[i].y > height-1 then
			starfield[i].y = 0
			starfield[i].x = math.random(width-1)
		end
	end
end
while true do
	time1 = time1 + 1
	screen:clear()
	offscreen:clear()
	drawstars()
	screen:blit(0,0,offscreen,false)
	screen.flip()
	screen:waitVblankStart()
	pad = Controls.read()
	if pad:start() then
		break
	end
end

[Anti-QuickJay]

offscreen = Image.createEmpty(width,h eight)

Dont you have to fill in the width and height part first?
-= Double Post =-
Also, a = a + 1
You can do that in Lua, Just do that

a = 0

)blah blah)

a = a + 1

[Grimfate126]

just a reminder people, PLEASE USE TAB. you're code is so messy i dont even want to look at it. (talking to everybody here)

[SuperBatXS]

just a reminder people, PLEASE USE TAB. you're code is so messy i dont even want to look at it. (talking to everybody here)

Lol, you are right. Agreed.

[youresam]

offscreen = Image.createEmpty(width,h eight)

Dont you have to fill in the width and height part first?

...he did. Shine put the values on the line right before it. Look next time.

Also, a = a + 1
You can do that in Lua, Just do that

a = 0

)blah blah)

a = a + 1

wtf? He was asking how to do it differently! He already typed a = a + 1, but he was asking how to do a shortcut. Read next time. The answer is there is no other way.

I am begining to think that you are here simply to (A) Raise your post count and (B) confuse n00bs even more. Please stop.

[Anti-QuickJay]

...he did. Shine put the values on the line right before it. Look next time.


wtf? He was asking how to do it differently! He already typed a = a + 1, but he was asking how to do a shortcut. Read next time. The answer is there is no other way.

I am begining to think that you are here simply to (A) Raise your post count and (B) confuse n00bs even more. Please stop.

(C) I misread. Bingo!
-= Double Post =-
Wouldn't you just put,

offscreen = Image.createEmpty(480, 272)

[youresam]

(C) I misread. Bingo!
-= Double Post =-
Wouldn't you just put,

offscreen = Image.createEmpty(480, 272)

No, actually learn lua before you come here and try to help. Image.createEmpty takes 2 number arguements, and he passed them through the variables width and height.

[youresam]

Your still mad about yesterday, Arent you?

As said by abe froeman: "Keep everything that happens away from the forums, away from the forums"

kthx.

[ahrimanes]

wwwtfff... i copyed my code fron my text editor, sooo why my "tabs" is not working here,, i tried to edit the post and see it have "tabs".... wyyyyyyyyyyy.......
by the way... im just using height, width, i feell bether whit them example scrcenter = {x = height/2, y = width/2}.
here is another interesting code.

while true do
screen:clear()
for x = 0, 255 do
   for y = 0 , 255 do
        screen:pixel(x,y,Color.new(x,y,128))
   end
end
screen:flip()
screen:waitVblankStart()
pad = Controls.read()
if pad:start() then
     break
end
end

hope this help to understand the rgb. of color,,, seyaaaa
haa b the way does any body knows how to read the item count of an array ? i mean somthing like......
a = {}
a[1].x = 10
a[2].x = 20
then i want to know how many itemss a got.. like count = a.itemcount() or count = a.listcount() then count should be 2 in this case.
???

[youresam]

wrap it in the [code] tag...

[Merick]

b the way does any body knows how to read the item count of an array ? i mean somthing like......
a = {}
a[1].x = 10
a[2].x = 20
then i want to know how many itemss a got.. like count = a.itemcount() or count = a.listcount() then count should be 2 in this case.
???

count = table.getn(a) will give you the number of entries in the table