Quick questions about Gideros&Lua

Apollo14 · February 2018

That is awesome! I will use constants wherever I can!

I'm looking at Lua's table manipulation functions.
table.pack doesn't work in Gideros?

myTab = {1,2,3,"four"}
print(table.pack(myTab)) --spawns error message

Apollo14 · February 2018

Guys! I don't get how does "setVolume" work.
Let's say we want to play sound louder and louder with every click.
I expected something like this, but of course it doesn't work:

currVolumeVar = 0
newSound = Sound.new("audio/piano_a.wav")
newSound:setVolume(currVolumeVar)
 
co = coroutine.create(function()
	for i=1, 10 do
	print("current volume:",currVolumeVar)
	newSound:play()
	currVolumeVar += 0.1
	newSound:setVolume(currVolumeVar)
	coroutine.yield()
	end
end)
 
function onMouseDownFunc()
	coroutine.resume(co)
end
 
stage:addEventListener(Event.MOUSE_DOWN, onMouseDownFunc)

(I didn't find examples how to work with SoundChannel)

hgy29 · February 2018

Try this:

currVolumeVar = 0
newSound = Sound.new("audio/piano_a.wav")
 
co = coroutine.create(function()
	for i=1, 10 do
        currVolumeVar += 0.1
	print("current volume:",currVolumeVar)
	local channel= newSound:play()
	channel:setVolume(currVolumeVar)
	coroutine.yield()
	end
end)
 
function onMouseDownFunc()
	coroutine.resume(co)
end
 
stage:addEventListener(Event.MOUSE_DOWN, onMouseDownFunc)

Apollo14 · February 2018

Guys, how do we usually stop a fake thread like this? Is it even stoppable?

function pulse()
  local i=0
 
  while (true) do
    pulsingSprite:setAlpha((math.sin(i))^2)
    i=i+0.1
    Core.yield(true)
  end
end
 
Core.asyncCall(pulse)
 
function onMouseDownFunc()
	--some command to stop pulsing
end
 
stage:addEventListener(Event.MOUSE_DOWN, onMouseDownFunc)

hgy29 · February 2018

use a global or upvalue as a condition to exit your while loop:

local pulseRunning=true
function pulse()
  local i=0
 
  while (pulseRunning) do
    pulsingSprite:setAlpha((math.sin(i))^2)
    i=i+0.1
    Core.yield(true)
  end
end
 
Core.asyncCall(pulse)
 
function onMouseDownFunc()
	-- pulse thread will exit at next iteration
        pulseRunning=false
end
 
stage:addEventListener(Event.MOUSE_DOWN, onMouseDownFunc)

Apollo14 · February 2018

How to get current frame while MovieClip is playing? Something like:

myAnim = MovieClip.new{
{1, 10, myTable[1]},
{10, 20, myTable[2]},
{20, 30, myTable[3]},
}
--let's say animation started and we wanna get number of current frame:
currentFrameVar = myAnim:getCurrentFrame()

(I didn't find in documentation)

oleg · February 2018

alternative

myAnim = MovieClip.new{
{1, 10, myTable[1]},
{10, 20, myTable[2]},
{20, 30, myTable[3]},
}
--let's say animation started and we wanna get number of current frame:
currentFrameVar = 30
myAnim:gotoAndStop(currentFrameVar )

totebo · February 2018

MovieClip:getFrame() was added a while back, but not yet added to docs.

oleg · February 2018

@totebo GiderosApi.pdf is automatically generated - why not there ??

totebo · February 2018

I don't think it's added to the actual docs. I've made a start of adding it, but not quite sure how to do it.

oleg · February 2018

you misunderstood me
I'm talking about it
http://giderosmobile.com/forum/discussion/7215/generated-gideros-api-reference-manual#latest

antix · February 2018

@totebo, the docs are the xml files in the docsrc folder which are edited manually by @hgy29. He then syncs these to the MySQL database.. and then there is a script that converts them into the actual documents. That is my understanding anyway.

I have created a Gideros program that converts all of the XML files into Lua Tables, and then encodes them into JSON strings.

I have been trying to create an editor for these JSON strings but it appears there is no way to accomplish this in a web browser, no way to accomplish this in Gideros (because like no access to ENTER or DELETE keys etc in KeyCode) and currently trying to deserialize the JSON strings in VB.NET has sucked days from my life

I am getting near the point where I think I should throw JSON out the window (and VB.NET) and store everything in a simple text format that is easy to edit.

Apollo14 · February 2018

MovieClip:getFrame() really works, thx!

Guys, what undocumented options are available for Texture.new, besides "wrap = Texture.REPEAT"? What do "format" and "extend" options do?
Texture.new(filename, filtering [, options])
http://docs.giderosmobile.com/reference/gideros/Texture/new

hgy29 · February 2018

extend: Boolean indicating if texture should be extended in memory to the next power of two size, default to true
format: actual texture format in memory, like RGB, RGBA, Y (greyscale) and so on. Useful when creating textures from byte arrays

Apollo14 · February 2018

Author of this article writes this drag&drop function:

function moveBall(event)
 
    if ball:hitTestPoint(event.x, event.y) then
        local dx = event.x - ball:getX()
        local dy = event.y - ball:getY()
 
        ball:setX(ball:getX() + dx)
        ball:setY(ball:getY() + dy)
        ball.x0 = event.x
        ball.y0 = event.y
 
        event:stopPropagation()
    end
end

I don't get why not just set ball's X&Y directly?

function moveBall(event)
 
    if ball:hitTestPoint(event.x, event.y) then
    ballSprite:setPosition(event.x, event.y)
    event:stopPropagation()
    end
end

dragging visually looks same

How to regulate dragging speed? As it is, ball moves instantly, what if we need it slower.

oleg · February 2018

filter =0.9

 --  ball:setX(ball:getX() + dx)
     --   ball:setY(ball:getY() + dy)
 ball:setX(ball:getX()*filter  + dx*(1-filter ))
        ball:setY(ball:getY()*filter  + dy*(1-filter ))

Apollo14 · February 2018

oleg said:

filter =0.9

 --  ball:setX(ball:getX() + dx)
     --   ball:setY(ball:getY() + dy)
 ball:setX(ball:getX()*filter  + dx*(1-filter ))
        ball:setY(ball:getY()*filter  + dy*(1-filter ))

For some reason it doesn't work for me, do you know why? (no errors shown, but the ball's drag&drop is broken.

function moveBall(event)
filter=.9
    if ballSprite:hitTestPoint(event.x, event.y) then
		--ballSprite:setPosition(event.x, event.y)
        local dx = event.x - ballSprite:getX()
        local dy = event.y - ballSprite:getY()
 
        ballSprite:setX(ballSprite:getX()*filter + dx*(1-filter ))
        ballSprite:setY(ballSprite:getY()*filter + dy*(1-filter ))
        ballSprite.x0 = event.x
        ballSprite.y0 = event.y
 
        event:stopPropagation()
    end
end
-- when we move the mouse then ball also moves
ballSprite:addEventListener(Event.MOUSE_MOVE, moveBall)

oleg · February 2018

set filter = 0.3

filter=0.3
local function onMouseDown(self, event)
	if self:hitTestPoint(event.x, event.y) then
		self.isFocus = true
 
		self.x0 = event.x
		self.y0 = event.y
 
		event:stopPropagation()
	end
end
 
local function onMouseMove(self, event)
	if self.isFocus then
		local dx = event.x - self.x0
		local dy = event.y - self.y0
		print(self:getX()*filter + dx*(1-filter ),"new")
		print(self:getX() + dx )
		self:setX(self:getX() + dx*(1-filter ))
		self:setY(self:getY() + dy*(1-filter ))
 
		self.x0 = event.x
		self.y0 = event.y
 
		event:stopPropagation()
	end
end

Apollo14 · February 2018

oleg said:
set filter = 0.3

it doesn't work

oleg · February 2018

--[[ 
 
Drag the shapes around with your mouse or fingers
 
This code is MIT licensed, see <a href="http://www.opensource.org/licenses/mit-license.php" rel="nofollow">http://www.opensource.org/licenses/mit-license.php</a>
(C) 2010 - 2011 Gideros Mobile 
 
]]
filter=0.3
local function onMouseDown(self, event)
	if self:hitTestPoint(event.x, event.y) then
		self.isFocus = true
 
		self.x0 = event.x
		self.y0 = event.y
 
		event:stopPropagation()
	end
end
 
local function onMouseMove(self, event)
	if self.isFocus then
		local dx = event.x - self.x0
		local dy = event.y - self.y0
		print(self:getX()*filter + dx*(1-filter ),"new")
		print(self:getX() + dx )
		self:setX(self:getX() + dx*(1-filter ))
		self:setY(self:getY() + dy*(1-filter ))
 
		self.x0 = event.x
		self.y0 = event.y
 
		event:stopPropagation()
	end
end
 
local function onMouseUp(self, event)
	if self.isFocus then
		self.isFocus = false
		event:stopPropagation()
	end
end
 
for i=1,5 do
	local shape = Shape.new()
 
	shape:setLineStyle(3, 0x000000)
	shape:setFillStyle(Shape.SOLID, 0xff0000, 0.5)
	shape:beginPath()
	shape:moveTo(0, 0)
	shape:lineTo(100, 0)
	shape:lineTo(100, 50)
	shape:lineTo(0, 50)
	shape:closePath()
	shape:endPath()
 
	shape:setX(math.random(0, 320 - 100))
	shape:setY(math.random(0, 480 - 50))
 
	shape.isFocus = false
 
	shape:addEventListener(Event.MOUSE_DOWN, onMouseDown, shape)
	shape:addEventListener(Event.MOUSE_MOVE, onMouseMove, shape)
	shape:addEventListener(Event.MOUSE_UP, onMouseUp, shape)
 
	stage:addChild(shape)
end
 
 
local info = TextField.new(nil, "drag the shapes around with your mouse or fingers")
info:setPosition(23, 50)
stage:addChild(info)

oleg · February 2018

I gave a bad example
effect" dragging speed" should be done through the ENTER_FRAME or through Movieclip

antix · February 2018

Just to muddy the waters here a little but when you have a game object it is a good practice to use a 2D vector to describe it's position in the game world...

-- generally a lot of people use this...
local object.x0, object.y0 = 320, 160
 
-- this is better
object.position = (x = 320, y = 160}
 
-- and to access it...
local p = object.position
local x0, y0 = p.x, p.y
 
x0 -= 4
y0 += 7
 
p.x, p.y = x0, y0

The main reason I bring this up is that when you start to create more complex applications and you need help from the internet.. 99% of places you go will be using 2D vectors. Mashing code from online into your own projects becomes much easier

Apollo14 · February 2018

Guys, I'm confused about different font methods:
Perfomance-wise, what is a better practice - to always use TTFont.new or Font.new?

newFont1= TTFont.new("stylus.ttf", 50, true)
newFont2= Font.new("stylus.txt", "stylus.png", true)
newFont3= BMFont.new("stylus.txt", "stylus.png")

BTW how do we adopt bitmap fonts like this for Gideros?

There are plenty of them on the web, but their metadata is different from what we need. How to set up their metadata?

oleg · February 2018

I cache only the required characters

local font = TTFont.new("font/ELEPHNT.TTF", 20, "SCORE")

totebo · February 2018

If you cache the TTFont, I don't think there is much in it in terms of performance.

I think you can adopt a bitmap font with some manual work, not quite sure what's involved though.

antix · February 2018

The bitmap font will require manually editing (or generating) a .fnt file that accompanies the png image of the font.

You can generate a bitmap font using Gideros Font Maker and check out the fnt file to see how it is formatted.

Apollo14 · February 2018

When we call

print(_VERSION)

it displays "Lua 5.1", while last official Lua version is 5.3.4

Is implementing Lua 5.3.4 too complicated so maintainers decided to skip it?
(actually I don't think we're gonna miss anything from 5.3.4, because 5.1 is more than enough for all and everything

Apollo14 · February 2018

Guys, did I get it right? "Macro Functions" serve the purpose of perfomance only?
Or they are also convenient for some other purposes?

oleg · February 2018

macro functions are constants, they are more economical than variables

Apollo14 · February 2018

Guys, few more questions appeared!

#1 How does Screen:setPosition() work?

I've tested this line:

Screen:setPosition(50,50)

Application just spawns error:

main.lua:467: index '__userdata' cannot be found
stack traceback:
main.lua:467: in main chunk

#2 And how does application:setKeyboardVisibility work?
This added line doesn't show anything on my Android device:

application:setKeyboardVisibility(visible)

#3 I've seen in 2017.9 release notes:

Consistent random number generator (Core.random()/Core.randomSeed())

I've tested it, so what is the difference between this generator and Lua's original math.random?

This method always assigns the same value to 'randNum':

math.randomseed(10)
randNum = math.random(1,10)
print(randNum)

While new method assigns different values everytime:

Core.randomSeed(10)
randNum = Core.random(1,10)
print(randNum)

In what cases new method is more convenient?

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