"Questions that don't deserve their own thread" thread

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s-ol
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Re: "Questions that don't deserve their own thread" thread

Post by s-ol » Wed Jan 28, 2015 7:35 pm

Bindie wrote:Awesome. Lol, *Bow wow*

Let's say I have:

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function love.keypressed(key)
    if key == " " then
    return true
    end
end
Inside of love.load()

And inside love.update() I want to

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if key == " " and CheckCollision(Players coordinates, Machines coordinates) then
Machine.on = not Machine.on
     if Machine.on == true then
     play(On-Sound)
     else
     play(Off-Sound)
     end

end
How do I?
wait what?

For one, why put love.keypressed into love.load? Actually that might work, but it also might not (I never tried). It serves no purpose though and only leaves room for error. And why does it return anything? love.keypressed isn't supposed to return something, so anything you do return just gets thrown away. So basically your keypressed function doesn't do anything at all.

Second: where is key in love.update coming from?

And lastly: what exactly are you asking? You seem to have a general outline of what you want to do, but what you just wrote doesn't really make much sense.

s-ol.nu /blog  -  p.s-ol.be /st8.lua  -  g.s-ol.be /gtglg /curcur

Code: Select all

print( type(love) )
if false then
  baby:hurt(me)
end

Muris
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Re: "Questions that don't deserve their own thread" thread

Post by Muris » Wed Jan 28, 2015 7:41 pm

Bindie wrote:How do I?
If I understand correctly what you want to do, you could do something like this:

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local movSpeed = 100 -- move 100 pixels per second
local angle = 0

local player = {
	x = 20,
	y = 40,
	width = 20,
	height = 20,
}

local machine = {
	on = true,
	x = 200,
	y = 200,
	width = 50,
	height = 60
}

local keys = {}


local function checkCollision( obj1, obj2 )
	if obj1.x + obj1.width < obj2.x or
	   obj2.x + obj2.width < obj1.x or 
	   obj1.y + obj1.height < obj2.y or
	   obj2.y + obj2.height < obj1.y then

			return false
	end	
	return true
end


function love.load()
end

function love.draw()
	love.graphics.setColor(255, 255, 0 ) 
	love.graphics.rectangle("fill", machine.x, machine.y, machine.width, machine.height )
	love.graphics.setColor(255, 0, 0 ) 
	love.graphics.rectangle("fill", player.x, player.y, player.width, player.height )
	if machine.on then 
		love.graphics.setColor( 255,255,255,128 )
		love.graphics.arc("fill", machine.x + machine.width / 2, machine.y + machine.height / 2, 100, angle, angle + 0.5)
	end


end





function love.update(dt)
	angle = angle + dt * 5
	if keys.w then
		player.y = player.y - dt * movSpeed
	elseif keys.s then
		player.y = player.y + dt * movSpeed
	end
	if keys.a then
		player.x = player.x - dt * movSpeed
	elseif keys.d then
		player.x = player.x + dt * movSpeed
	end
end

function love.keypressed( key )
	if key == "q" or key == "escape" then
		love.event.quit()

	elseif key == " " and checkCollision( player, machine ) then
		machine.on = not machine.on
		if machine.on then
			print( "play sound on")
		else
			print( "play sound off ")
		end
	end
	keys[ key ] = true
end

function love.keyreleased( key )
	keys[ key ] = false
end

Bindie
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Re: "Questions that don't deserve their own thread" thread

Post by Bindie » Wed Jan 28, 2015 7:57 pm

Thanks ok. So anytime I want code executed from pressing a key a single time, I have to write it inside the love.keypressed function. That works.

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Zilarrezko
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Re: "Questions that don't deserve their own thread" thread

Post by Zilarrezko » Wed Jan 28, 2015 8:39 pm

Bindie wrote:Thanks ok. So anytime I want code executed from pressing a key a single time, I have to write it inside the love.keypressed function. That works.
assuming you don't have love.keyboard.setKeyRepeat set to true, than yes.

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Re: "Questions that don't deserve their own thread" thread

Post by Bindie » Thu Jan 29, 2015 7:53 pm

Does that mean I could call the function from anywhere? Instead of having to write all inside keypressed

Muris
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Re: "Questions that don't deserve their own thread" thread

Post by Muris » Fri Jan 30, 2015 1:50 am

You do not need to call the function by yourself, every time you press a key love.keypress is being called automatically. When you release the key love.keyreleased will be called.

If you define a function, without word local, it will always be globally visible, meaning if you define a function on any of the lua-files you make, and then require it, it will be globally available from any other files.

If you define a local function, it will be only visible inside that file and only after you have declared it. For example if you need to use function that calls other function that calls back to yours, you need to define them before using them. Basically this means that you're splitting something like recursive function into several functions.

Not very good example, but example regardless:

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--f1() -- cannot be called here because f1 isn't declared yet, will give an error
local f2 -- defining f2, so that the variable is visible into function f1
local function f1(a)
	print("f1 called with:", a)
	if a then return end
	f2(1)
end

f2 = function(a)
	print("f2 called with:", a)
	f1(a)
end
f1()
On the other hand if you create global functions, they can have cross calls without any problem, and they can be called from any other file, which you might want to prevent for most cases.

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function f3(a)
	print("f3 called with:", a)
	if a then return end
	f4(1)
end
f4 = function(a)
	print("f4 called with:", a)
	f3(a)
end
f3()
Basically this is kind of the reason why up to my understanding C and C++ use separate header files. Also how I understand Lua, which probably isn't the case, lua only executes the code in file only once when first time required. This is something I bumped into couple of days ago, when I had kind of like data in lua files, then I changed the data, and wanted to reset the data by new require. This didn't really work, so I had to do copy of the table from the require and use the copy, then copy the table again when resetting.

For example if otherfile.lua looks like this:

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print("required file otherfile")

function f5()
	print("f5 called")
end

return {}
And main file:

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--f5() -- cannot call f5 from here, because the lua doesn't know its existence
local r1 = require 'otherfile'
local r2 = require 'otherfile'
f5() -- can be called from here, because it was declared in otherfile.lua
r1.x = 3
print( r2.x )
You can notice that r1 and r2 are actually same tables. So chanigng r1 also changes r2. Also you can notice that you can call functions defined in other file, as long as you have first required the file, as long as the functions are globally defined, not local functions.

Hopefully this answer was even slightly helpful.

Bindie
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Re: "Questions that don't deserve their own thread" thread

Post by Bindie » Fri Jan 30, 2015 4:15 pm

I think I am very unclear, basically I was just wondering why there isn't a love.keypressed(key) that can return true and then you could use it like love.keyboard.isDown(key).

For example:

Code: Select all

if love.keyboard.isDown("1") then 
laser = not laser
end

-- And I wonder why there is no:

if love.keypressed("1") then
laser = not laser
end
In requiring libraries and files I now know that if for example functions are declared local in libariries and files they can't be reached, thanks.

pajh
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Re: "Questions that don't deserve their own thread" thread

Post by pajh » Fri Jan 30, 2015 4:57 pm

I'm having problems seeing console output using Love & and the latest version Zerobrane.

I have a print statement in love.conf which I can see in ZB's output window, however no print statement from main.lua (for example in love.load) show up at all. This isn't a matter of delayed output, they don't show up when the program stops either. Running from ZB either using a plain run or a debug seems to make no difference.

any ideas?

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Doctory
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Re: "Questions that don't deserve their own thread" thread

Post by Doctory » Fri Jan 30, 2015 5:21 pm

love.keypressed is supposed to be used independet of love.update
it is also supposed to be used for buttons that shouldnt repeat

Bindie
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Re: "Questions that don't deserve their own thread" thread

Post by Bindie » Fri Jan 30, 2015 6:05 pm

I see.

Thanks.

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