Lua Programming Help Thread

[myschoo]

glad to help u mate ;)

[slicer4ever]

or use cmd and it won't do that

[the undead]

ok im working on this game(cant discus it at the moment) but ive been trying hard and cant find a solution for my problem. I have a pic right, im tyring to get that pic go accross the screen(left to right, and right to left) at different y points(think like a grid...up and down)...but i need them to have collison(i have the function down, i just need to fill in some parts, when i get this part finished) If any one helps me they will be given the credit they diserve.

Any one?

[slicer4ever]

i did i was like right below it

[the undead]

i did i was like right below it

oh, ok thanks ill look at it
-= Double Post =-
wait...i dont understand it.....can u explain it to me please?

[slicer4ever]

you were asking how to move it across the screen so thus when you blit the image it would be something like:

screen:blit(playerx,playe ry,player)

so to move it left you decrease the playerx and vice versa for right

now then to make it move to the left when the playery reaches a certain point you place an if statement to check when the playery hit's a certain area like:

if playery == 20 then
playerx = playerx - 1
end

i hope i explained it enough

[the undead]

oh ok.....i understand it now, but what i wanted was it to blit an enimey at random and move it across the screen(left to right, right to left)

[slicer4ever]

o well we will work with one enemy than

enemy = Image.load("image")
--if i remeber correctly the random call starts at 0 to number that you define
direction = 0
-- 0 = left 1 = right
enemyx = 0
enemyy = 0
enemy_move = 0
-- 0 = yes 1 = no
while true do
if enemy_move == 0 then 
enemyx = random(480)
enemyy = random(272)
enemy_move = 1
direction = random(1)
end
if enemy_move == 1 then
if direction == 0 then
enemyx = enemyx - 1
end
if direction == 1 then
enemyx = enemyx + 1
end
end
if enemyx < 0 or enemyx > 480 then
enemy_move = 0
end
screen:blit(enemyx,enemyy,enemy)
end

[the undead]

k ill try that
-= Double Post =-
i did it but i get an error "attempt to call global 'random'<a nil value>

[GuitarGod1134]

how do i make it so that an image dissapears when another one touches it for example a bullet hitting a creature.
you would do collsion detection like

if bullet[1].x == creature[1].x and bullet[1].y == creature[1].y then
what would i put right here????
end

[slicer4ever]

o i think it's math.random(number) sorry it's been a little bit since i coded in lua
@ gurtar god you just reset it off the screen so it can be used again later if you want code i need to see some of your code so i can help you more also you don't want to use == as that's to precise

but if i can make any sense try:

if bullet[1].x == creature[1].x and bullet[1].y == creature[1].y then
bullet[1].x = -50
bullet[1].y = -50

--other bullet variables are reset to
end

also i just thought of this try:

if bullet[1].x ~= creature[1].x and bullet[1].y ~= creature[1].y then
screen:blit(bullet[1].x,bullet[1].y,bullet)
end

but that would only be used if the creature isn't moving

[the undead]

ok now it works....but when it moves it just paste one image after the next like here is a pic

[Ninjax1]

How do I create a background color?

[slicer4ever]

did you use a screen:clear() right after you call while true do?

[the undead]

did you use a screen:clear() right after you call while true do?

me?...ill try it

[slicer4ever]

@ninj 3 ways:

1:
color = Color.new(0,0,0)
while true do
screen:clear()
screen:fillRect(0,0,480,2 72,color)
code
screen.flip()
screen.waitVblankStart()
end

2:
--sorry if i incorrectly call the following command
color = Color.new(0,0,0)
bg = Image.new(272,480)
bg:clear(color)
while true do
screen:clear()
screen:blit(0,0,bg)
code
screen:flip()
screen:waitVblankStrart()
end

or 3:
color = Color.new(0,0,0)
while true do
screen:clear(color)
code
screen.flip()
screen.waitVblankStart()
end

the 3rd way works the best but they all would work

edit: and yes you dead

[the undead]

ok, cool now it works....now i think i can do the rest myself(ima add other enemys...oh and thx, ill give u credit)

[slicer4ever]

np just here 2 help

[the undead]

if i have any more problems ill come back =)

[slicer4ever]

you can just pm me with any probs i'm ganna be on a lot more unless i'm codeing even then i'm usually on

[Grimfate126]

how do i make it so that an image dissapears when another one touches it for example a bullet hitting a creature.
you would do collsion detection like

if bullet[1].x == creature[1].x and bullet[1].y == creature[1].y then
what would i put right here????
end

ok. that will screw it up. there is a basic formula for 2d collisions:

if ((object.x + object.width) >= enemy.x) and (object.x <= (enemy.x + enemy.width)) and ((object.y + object.height) >= enemy.y) and (object.y <= (enemy.y + enemy.height)) then
--collision is true --
end

just fill in the blanks.
-= Double Post =-

o i think it's math.random(number) sorry it's been a little bit since i coded in lua
@ gurtar god you just reset it off the screen so it can be used again later if you want code i need to see some of your code so i can help you more also you don't want to use == as that's to precise

but if i can make any sense try:

if bullet[1].x == creature[1].x and bullet[1].y == creature[1].y then
bullet[1].x = -50
bullet[1].y = -50

--other bullet variables are reset to
end

also i just thought of this try:

if bullet[1].x ~= creature[1].x and bullet[1].y ~= creature[1].y then
screen:blit(bullet[1].x,bullet[1].y,bullet)
end

but that would only be used if the creature isn't moving

what???? do you know what the ~= operator means?

it means "NOT equal". i think you thought that it meant "approximately equal"

[MSeven]

here is my code so far for my new game, problem is, when i press x to shoot, the bullet just appears and disappears in the bottom left corner with out moving in any direction any reason why?

green=Color.new(0,255,0)
white = Color.new(255,255,255)

red = Color.new(255,0,0)

dofile("animLib.lua")


System.usbDiskModeActivate()


runR = ANIM.new(7, "RunR-", "png", "Player/Run/")
runL = ANIM.new(7, "RunL-", "png", "Player/Run/")

standR = ANIM.new(3, "StandR-", "png", "Player/Stand/")
standL = ANIM.new(3, "StandL-", "png", "Player/Stand/")

shootR = ANIM.new(2, "ShootR-", "png", "Player/Shooting/")
shootL = ANIM.new(2, "ShootL-", "png", "Player/Shooting/")

playerState = "standingR"
shootDirection = "right"

playerX = 10
playerY = 200

--Create a blank image and fill it with green. This will be our bullet.
bullet = Image.load("Player/Shooting/bullet.png")

while true do

oldpad = Controls.read()
pad = Controls.read()
	screen:clear()

if pad:right() then
		playerState = "runningR"
		playerX = playerX + 3
		shootDirection = "right"
	end

	if pad:left() then
		playerState = "runningL"
		playerX = playerX - 3
		shootDirection = "left"
	end
	
	if pad:select() then
		break
	end
	

	if shootDirection == "right" and not pad:right() and not pad:left() then
		playerState = "standingR"
	elseif shootDirection == "left" and not pad:right() and not pad:left() then
		playerState = "standingL"
	end
	
		if playerState == "standingR" and pad:cross() then
		playerState = "shootingR"
		playerX = playerX
		shootDirection = "right"
	end
	
	if playerState == "standingL" and pad:cross() then
		playerState = "shootingL"
		playerX = playerX
		shootDirection = "left"
	end
	
			if playerState == "runningR" and pad:cross() then
		playerState = "shootingR"
		playerX = playerX
		shootDirection = "right"
	end
	
	if playerState == "runningL" and pad:cross() then
		playerState = "shootingL"
		playerX = playerX
		shootDirection = "left"
	end


	if playerState == "standingR" then
		standR:blit(playerX, playerY, 100)
	elseif playerState == "standingL" then
		standL:blit(playerX, playerY, 100)
	elseif playerState == "runningR" then
		runR:blit(playerX, playerY, 50)
	elseif playerState == "runningL" then
		runL:blit(playerX, playerY, 50)
	elseif playerState == "shootingR" then
		shootR:blit(playerX, playerY, 50)
	elseif playerState == "shootingL" then
		shootL:blit(playerX, playerY, 50)
	end
	
currentBullet = 0
direction = "right"


Player = {}
Player[1] = { x = 10, y = 200 }


BulletInfo = {}
for a = 1,5 do
BulletInfo[a] = { pic = bullet , firing = false, direction = "right", x = Player[1].x + 32,
y = Player[1].y + 16 }
end



function bulletSetup()
if currentBullet < 5 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 = 1,5 do
if BulletInfo[i].firing == true then
if BulletInfo[i].direction == "right" then BulletInfo[i].x = BulletInfo[i].x + 10 end
if BulletInfo[i].direction == "left" then BulletInfo[i].x = BulletInfo[i].x - 10 end
if BulletInfo[i].direction == "up" then BulletInfo[i].y = BulletInfo[i].y - 10 end
if BulletInfo[i].direction == "down" then BulletInfo[i].y = BulletInfo[i].y + 10 end
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

function movePlayer()
pad = Controls.read()
if pad:left() then
Player[1].x = Player[1].x - 1
direction = "left"
end
if pad:right() then
Player[1].x = Player[1].x + 1
direction = "right"
end
if pad:up() then
Player[1].y = Player[1].y - 1
direction = "up"
end
if pad:down() then
Player[1].y = Player[1].y + 1
direction = "down"
end
end


if pad:cross() and oldpad:cross() ~= pad:cross() then
bulletSetup()
end

movePlayer()

bulletFire()

screen.waitVblankStart()
screen.flip()
oldpad = pad
end

[Grimfate126]

here is my code so far for my new game, problem is, when i press x to shoot, the bullet just appears and disappears in the bottom left corner with out moving in any direction any reason why?

green=Color.new(0,255,0)
white = Color.new(255,255,255)

red = Color.new(255,0,0)

dofile("animLib.lua")


System.usbDiskModeActivate()


runR = ANIM.new(7, "RunR-", "png", "Player/Run/")
runL = ANIM.new(7, "RunL-", "png", "Player/Run/")

standR = ANIM.new(3, "StandR-", "png", "Player/Stand/")
standL = ANIM.new(3, "StandL-", "png", "Player/Stand/")

shootR = ANIM.new(2, "ShootR-", "png", "Player/Shooting/")
shootL = ANIM.new(2, "ShootL-", "png", "Player/Shooting/")

playerState = "standingR"
shootDirection = "right"

playerX = 10
playerY = 200

--Create a blank image and fill it with green. This will be our bullet.
bullet = Image.load("Player/Shooting/bullet.png")

while true do

oldpad = Controls.read()
pad = Controls.read()
	screen:clear()

if pad:right() then
		playerState = "runningR"
		playerX = playerX + 3
		shootDirection = "right"
	end

	if pad:left() then
		playerState = "runningL"
		playerX = playerX - 3
		shootDirection = "left"
	end
	
	if pad:select() then
		break
	end
	

	if shootDirection == "right" and not pad:right() and not pad:left() then
		playerState = "standingR"
	elseif shootDirection == "left" and not pad:right() and not pad:left() then
		playerState = "standingL"
	end
	
		if playerState == "standingR" and pad:cross() then
		playerState = "shootingR"
		playerX = playerX
		shootDirection = "right"
	end
	
	if playerState == "standingL" and pad:cross() then
		playerState = "shootingL"
		playerX = playerX
		shootDirection = "left"
	end
	
			if playerState == "runningR" and pad:cross() then
		playerState = "shootingR"
		playerX = playerX
		shootDirection = "right"
	end
	
	if playerState == "runningL" and pad:cross() then
		playerState = "shootingL"
		playerX = playerX
		shootDirection = "left"
	end


	if playerState == "standingR" then
		standR:blit(playerX, playerY, 100)
	elseif playerState == "standingL" then
		standL:blit(playerX, playerY, 100)
	elseif playerState == "runningR" then
		runR:blit(playerX, playerY, 50)
	elseif playerState == "runningL" then
		runL:blit(playerX, playerY, 50)
	elseif playerState == "shootingR" then
		shootR:blit(playerX, playerY, 50)
	elseif playerState == "shootingL" then
		shootL:blit(playerX, playerY, 50)
	end
	
currentBullet = 0
direction = "right"


Player = {}
Player[1] = { x = 10, y = 200 }


BulletInfo = {}
for a = 1,5 do
BulletInfo[a] = { pic = bullet , firing = false, direction = "right", x = Player[1].x + 32,
y = Player[1].y + 16 }
end



function bulletSetup()
if currentBullet < 5 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 = 1,5 do
if BulletInfo[i].firing == true then
if BulletInfo[i].direction == "right" then BulletInfo[i].x = BulletInfo[i].x + 10 end
if BulletInfo[i].direction == "left" then BulletInfo[i].x = BulletInfo[i].x - 10 end
if BulletInfo[i].direction == "up" then BulletInfo[i].y = BulletInfo[i].y - 10 end
if BulletInfo[i].direction == "down" then BulletInfo[i].y = BulletInfo[i].y + 10 end
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

function movePlayer()
pad = Controls.read()
if pad:left() then
Player[1].x = Player[1].x - 1
direction = "left"
end
if pad:right() then
Player[1].x = Player[1].x + 1
direction = "right"
end
if pad:up() then
Player[1].y = Player[1].y - 1
direction = "up"
end
if pad:down() then
Player[1].y = Player[1].y + 1
direction = "down"
end
end


if pad:cross() and oldpad:cross() ~= pad:cross() then
bulletSetup()
end

movePlayer()

bulletFire()

screen.waitVblankStart()
screen.flip()
oldpad = pad
end

i dont have time to look over the entire thing, but you are just copying and pasting. you have multiple "players" and no organization. write the code yourself. copying wont make you learn.

[MSeven]

i have 2 players on purpose, one is the one that shoots the bullet, and over it would be the player with animation, since i dontk now how to fuse them, i did that, not copied and pasted ignorantly...

[Anti-QuickJay]

It has 2 white pixels on the left side of the screen, But they arent moving, They just stay still, I tried to run this in both the PSP and the PC and still, Theirs 2 white pixels on the left side, Anyone know why?

starfield = {}
math.randomseed(os.time())

function createStar(i)
  starfield[i] = {}
  starfield[i].x = math.random(2*width) - width
  starfield[i].y = math.random(2*height) - height
  starfield[i].z = zMax
end

for i = 1, size do
  createStar(i)
  starfield[i].z = math.random(zMax)
end

white = Color.new(255, 255, 255)
black = Color.new(0, 0, 0)

while true do
  screen:clear(black)
  screen:blit(0, 0, background)
  for i = 1, size do
    starfield[i].z = starfield[i].z - speed
    if starfield[i].z < speed then createStar(i) end
    x = width / 2 + starfield[i].x / starfield[i].z
    y = height / 2 + starfield[i].y / starfield[i].z
    if x < 0 or y < 0 or x >= width or y >= height then
      createStar(i)
    else
      screen:pixel(x, y, white)
    end
  end
  screen.waitVblankStart()
  screen.flip()
  if Controls.read():start() then 
break 
end
end

[slicer4ever]

@ grimfate yes i do know what that means it means not now then if you read what he was asking you would know why i did that instead of going off at me about it he was asking how to make the bullet disappear when it hit so i said the following:

if bullet[1].x ~= creature[1].x and bullet[1].y ~= creature[1].y then
screen:blit(bullet[1].x,bullet[1].y,bullet)
end

which if you had read it like said is saying if the bullet isn't hitting the target x/y then show the bullet and as i look at it i should have put or instead of and

[MSeven]

omg, can someone please tell me why my bullet is not moving?

[slicer4ever]

@pspgamer because you have to say screenixel(x,y,white) inside the for loop and at the starfield x and y otherwise it's only returning the last starfield x/y of the loop
-= Double Post =-
@yoyo i surgest you re-write it as it is extreamly messy which i am trying to look though it and it is most likly you have a conflicting variable somewhere which is reseting the bullet
-= Double Post =-
also because you appear to be calling functions inside the while true do it is very messy although

[Anti-QuickJay]

Thanks for your help!

[slicer4ever]

np anytime=-)
-= Double Post =-
@ yoyo i see why it's because your constantly setting the currentbullet to 0 look after your first few elseif's and it well say currentBullet = 0 delete that
-= Double Post =-
which means i was right and it was a conflicting variable