Lua Programming Help Thread

@hallo007

Zitat:

---

Zitat von hallo007

is it possible to clear some part of the screen and not everything

---

I'm not sure what you mean...just stop blitting whatever it is to screen? But you could always cheat and make a rectangle to cover up part of the screen.

Code:

---

coverup=Image.createEmpty(240,272)
screen:blit(0,0,coverup)

---

To cover up the left half. Many coders use a separate image variable that they "build up" and then they only have to blit that to screen. I call mine "prescreen" but you may have seen "offscreen" in some codes:

Code:

---

prescreen=Image.createEmpty(480,272)
-- (blit everything to prescreen)
coverup=Image.createEmpty(240,272)
prescreen:blit(0,0,coverup)
screen:blit(0,0,prescreen)

---

I've been told this is faster than blitting everything directly to the screen buffer, though I've never actually tested this. It just seems cleaner so I always do it.



@ Gonrai

Zitat:

---

Zitat von Gonrai

2. There is no end under the counter variable.

---

Direct from your post above (with indentations left in):

Code:

---

                displayTime = math.random(500,2000)
                counter = 0
        end

---

Sure looks like it to me, and besides SG57 even told you that it wouldn't work (he teases Lua coders for kicks :p).

index.lua:2: error loading sound? help?!
edit. heres the code
iyk = Sound.load("iyk.wav")
iyk:play()
Music.volume(128)

actually, that presreen thing will use more RAM and be slower, because it has to create the image

Zitat:

---

Zitat von xsorifc28

index.lua:2: error loading sound? help?!
edit. heres the code
iyk = Sound.load("iyk.wav")
iyk:play()
Music.volume(128)

---

i dont get it. why am i getting an error?

My code:

Code:

---

-- Alien Crosshair Game Screen
-- Completally Coded by Mailas Gonrai
-- Most errors fixed by pjspeedy and yaustar
-- Colors
black = Color.new(0,0,0)
blue = Color.new(191, 255, 195)
yellow = Color.new(255, 255, 0, 200)
green=Color.new(0,255,0, 195)
white = Color.new(255,255,255)
red = Color.new(255,69,0, 195)

-- ETC Variables
displayTime = math.random(2,5)
counter = 0
speed = 1
offscreen = false
pad = Controls.read()
-- Functions
function RandomPoint()
end
math.randomseed(os.time())

-- Images
back = Image.load("./Images/back_game.png")
crosshair = Image.load("./Images/crosshair.png")
border = Image.load("./Images/game_border.png")
alienimage = Image.load("./Images/alien.png")

-- Music
Music.playFile("./Music/grmus.it")

-- Objects
Player = {}
Player.x = 208
Player.y = 112

alien = {}
alien.x = math.random(1,3)
alien.y = math.random (1,3)
alien = {x = 0, y = 200}
x_point = 23
y_point = 83

-- Health Equivelent Options
Player.health = 100
healthbar = {}
healthbar.y = 10


function movePlayer()
        if pad:left() then
                Player.x = Player.x - 4
        end

        if pad:right() then
                Player.x = Player.x + 4
        end
       
        if pad:down() then
                Player.y = Player.y + 4
        end

        if pad:up() then
                Player.y = Player.y - 4
        end
end

function perimeterSize()
        if Player.x > 480 - 64 then
                Player.x = 480 - 64
        end
       
        if Player.x < 0 then
                Player.x = 0
        end

        if Player.y > 272 - 64 then
                Player.y = 272 - 64
        end
       
        if Player.y < 0 then
                Player.y = 0
        end
end



-- THE LOOP!----------------------------------------------------------

while true do

        screen:clear()
        x_point = math.random(1,480)
y_point = math.random(1,272)
AlienMove()

        if alien.x < x_point then
alien.x = alien.x + 2
end
if alien.x > x_point then
alien.x = alien.x - 2
end
if alien.y < y_point then
alien.y = alien.y + 2
end
if alien.y < y_point then
alien.y = alien.y - 2
end
if alien.x == x_point and alien.y == y_point then
RandomPoint()
end
                                       
               
                counter = counter + 1
       
                if counter >= displayTime then
                        alien.x = math.random(1,3)
                        alien.y = math.random (1,3)
                                end
       
                if alien.x == 1 then
                        alien.x = 224
                        alien.y = 182
                end
       
                if alien.x == 2 then
                        alien.x = 60
                        alien.y = 132
                end
       
                if alien.x == 3 then
                        alien.x = 404
                        alien.y = 154
                end
       
                       
               
        screen:blit(0,0,back)
                    screen:blit(alien.x,alien.y,alienimage)       
                    screen:blit(Player.x,Player.y,crosshair)
        screen:blit(0,0,border)
       
        screen:fillRect(320,240,Player.health,healthbar.y,green)
        screen:print(320,230,Player.health,blue)
       
        movePlayer()
        perimeterSize()
        alienscreenSize()
       
        if pad:l() then
                dofile("menu.lua")
        end

        screen.waitVblankStart()
        screen.flip()
end

---

It now gives me this error:

Code:

---

error: ./game.lua:95: attempt to call a global /ALienMove/ ( a nil value)
Error: No script file found.
Press start to Restart.

---

Alienmove isnt classed as a function
-= Double Post =-
You never did function Alienmove()
You just did Alienmove()
-= Double Post =-

Zitat:

---

Zitat von xsorifc28

i dont get it. why am i getting an error?

---

Have you checked that the sound file is not too big or too long for Lua Player

ok heres the deal..

i need some code to make my character shoot a bullet at wherever my crosshair image is. ive tried ALOT and cant get anything working

my character scrolls left to right at the bottom of my screen. The crosshair can go anywhere by using the directional buttons.

so could someone tell me how to do this?

jamz:
http://www.evilmana.com/tutorials/lu...et_bullets.php

trust me ive studied that, it just shoots them left right up or down


i need mine to shhot to wherever the crosshair is (that could be any x,y position)

make the cross hairs position x and y.

Then just have the bullets final location as X and Y