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Random Generation map error on Mobile

https://love2d.org./forums/viewtopic.php?t=93664

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Random Generation map error on Mobile

Posted: Tue Aug 16, 2022 4:47 pm
by owowow
I was making trees that generated in the tiled map randomly by using table.
My code works fine on my PC but when I run it on my Android it crashes when its checking tiles to place new tree.
I suspected the problem was because of difference of screen ratio or something and tried some size changes but didn't help any.

I attach my example code and error appears like this on mobile.
Please let me know if someone know what the problem is!


Code: Select all

function love.load()
    math.randomseed (os.clock ())
    screensizex=love.graphics.getWidth()
    screensizey=love.graphics.getHeight()
    tilesize=16
    map={}
    mapsizex = screensizex/tilesize     --30 tiles
    mapsizey = screensizey/tilesize     --20tiles
    TreeNums=50
    objects={}
    trees={}
    MakeNewMap()

    generateTrees()
end


function love.draw()

    if trees then
        for i,v in ipairs(trees) do
        love.graphics.rectangle("fill",v.x,v.y,v.w,v.h)
        end
    end

end



function generateTrees()
  
    for i=1,TreeNums do
        local tilex=math.random (1, mapsizex)
        local tiley=math.random (1, mapsizey)
        --x=clamp(0,x,screensizex)
        --y=clamp(0,y,screensizey)
        print("random x:"..tilex.." random y:"..tiley)
        if CheckTileByTilesize(tilex,tiley,0) then
            trees[i]={
                x=(tilex*tilesize)-tilesize,
                y=(tiley*tilesize)-tilesize,
                w=tilesize,
                h=tilesize
            }
            --tree[i]:SetCollision(true) --set circle collision
            table.insert(objects, #objects + 1, tree[i])
            map[tiley][tilex]=2
            
        end
    end
end




function MakeNewMap()
    for y = 1,mapsizey do
        map[y] = {}
        for x = 1,mapsizex do
            map[y][x]= 0
        end
        
    end
end



function CheckTileByTilesize(x,y,num)
    if map[y][x] == num then
        return true
    else
        return false
    end
end


function GetTilePos(x,y)

    local tilex=math.floor((x+tilesize)/tilesize)
    local tiley=math.floor((y+tilesize)/tilesize)
    tilex=clamp(1,tilex,mapsizex)
    tiley=clamp(1,tiley,mapsizey)
    local pos={x=tilex,y=tiley}
    return pos
end


function PrintMap()
    for i = 1, #map do
      
        local s = ""
        for j= 1, #map[i] do
            s = (s .. " " .. map[i][j])
        end
        print(s.." "..i)
    end
    for k= 1, #map do
        local m = ""
        for l= 1, #map[k] do
             m = (m.. " "..l)
        end
        if k==#map then print(m) end
    end
    
    print(" ")
end

function love.keypressed(key)
    if key=="space" then
        PrintMap()
    end
    if key=="g" then
        MakeNewMap()
        generateTrees()
        PrintMap()
    end

    if key=="n" then
        MakeNewMap()
    end
    
end

Code: Select all

Error

main.lua:69: attempt to index a nil value


Traceback

main.lua:69: in function 'CheckTileByTilesize'
main.lua:38: in function 'generateTrees'
main.lua:14: in function 'load'
[C]: in function 'xpcall'
[C]: in function 'xpcall'

Re: Random Generation map error on Mobile

Posted: Tue Aug 16, 2022 4:52 pm
by darkfrei
Please make the resolution independent code:

Code: Select all

screensizex=love.graphics.getWidth()
screensizey=love.graphics.getHeight()
mapsizex = 30
mapsizey = 20
tilesize = math.floor(math.min (screensizex/mapsizex, screensizey/mapsizey))
Also use table.insert (trees, tree) instead of trees[ i ] = tree: it finds the last i of the sequence and make +1 without errors.

Re: Random Generation map error on Mobile

Posted: Tue Aug 16, 2022 4:54 pm
by GVovkiv
Also, it's, probably, better to use love.math.random, and not lua's math.random

Re: Random Generation map error on Mobile

Posted: Tue Aug 16, 2022 4:58 pm
by 1414codeforge
Hi, in these lines:

Code: Select all

    mapsizex = screensizex/tilesize     --30 tiles
    mapsizey = screensizey/tilesize     --20tiles
You are not using integer division.
I wonder if you're experiencing some weird floating point rounding approximation error in your code that cascades all the way to those for loops, and, in turn, create a mess when you index the map table.
Have you tried using math.floor() on that?

Re: Random Generation map error on Mobile

Posted: Tue Aug 16, 2022 5:00 pm
by darkfrei
GVovkiv wrote: ↑Tue Aug 16, 2022 4:54 pm Also, it's, probably, better to use love.math.random, and not lua's math.random
No, math.random is better, but by the testing use the same seed, you don't need to get the error sometimes.

Re: Random Generation map error on Mobile

Posted: Tue Aug 16, 2022 6:30 pm
by milon
darkfrei wrote: ↑Tue Aug 16, 2022 5:00 pm No, math.random is better ...
How so? My impression is the exact opposite (although they're both generally fine depending on application).

Re: Random Generation map error on Mobile

Posted: Tue Aug 16, 2022 6:30 pm
by owowow
@darkfrei, Omg it was so quick and true!! It worked!! so it looks like the problem was the fixed tilesize! Thank you so much!

btw, i changed it like this. sorry that previously I forgot to change the part of trees and tree..

and i will change and try with math.random to love.math.random!

Code: Select all

function love.load()
    math.randomseed (os.clock ())
    screensizex=love.graphics.getWidth()
    screensizey=love.graphics.getHeight()
    mapsizex = math.floor(screensizex/16)
    mapsizey = math.floor(screensizey/16)
    tilesize = math.floor(math.min (screensizex/mapsizex, screensizey/mapsizey))
    map={}
    
    TreeNums=50
    --objects={} didnt need
    --trees={} moved in the generate function
    MakeNewMap()

    generateTrees()
end


function love.draw()

    if trees then
        for i,v in ipairs(trees) do
        love.graphics.rectangle("fill",v.x,v.y,v.w,v.h)
        end
    end

end



function generateTrees()
    tree={}
    trees={}
    for i=1,TreeNums do
        local tilex=math.random (1, mapsizex)
        local tiley=math.random (1, mapsizey)
        --x=clamp(0,x,screensizex)
        --y=clamp(0,y,screensizey)
        print("random x:"..tilex.." random y:"..tiley)
        if CheckTileByTilesize(tilex,tiley,0) then
            tree={
                x=(tilex*tilesize)-tilesize,
                y=(tiley*tilesize)-tilesize,
                w=tilesize,
                h=tilesize
            }

            table.insert(trees,tree)
            map[tiley][tilex]=2
            
        end
    end
end




function MakeNewMap()
    love.graphics.setColor(0,0,0,1)
        love.graphics.rectangle("fill",0,0,screensizex,screensizey)
        love.graphics.setColor(0,1,0,1)

    for y = 1,mapsizey do
        map[y] = {}
        for x = 1,mapsizex do
            map[y][x]= 0
        end
        
    end
end



function CheckTileByTilesize(x,y,num)
    if map[y][x] == num then
        return true
    else
        return false
    end
end


function GetTilePos(x,y)

    local tilex=math.floor((x+tilesize)/tilesize)
    local tiley=math.floor((y+tilesize)/tilesize)
    tilex=clamp(1,tilex,mapsizex)
    tiley=clamp(1,tiley,mapsizey)
    local pos={x=tilex,y=tiley}
    return pos
end


function PrintMap()
    for i = 1, #map do
      
        local s = ""
        for j= 1, #map[i] do
            s = (s .. " " .. map[i][j])
        end
        print(s.." "..i)
    end
    for k= 1, #map do
        local m = ""
        for l= 1, #map[k] do
             m = (m.. " "..l)
        end
        if k==#map then print(m) end
    end
    
    print(" ")
end

function love.keypressed(key)
    if key=="space" then
        PrintMap()
    end
    if key=="g" then
        
        MakeNewMap()
        generateTrees()
        PrintMap()
    end

    if key=="n" then
        MakeNewMap()
    end
    
end

Re: Random Generation map error on Mobile

Posted: Tue Aug 16, 2022 6:47 pm
by owowow
And anyone knows if thats better use love.window.getSafeArea( ) instead of love.graphics.getWidth()/Height()?

Code: Select all

	safex, safey, safew, safeh = love.window.getSafeArea( )
    screensizex=safew
    screensizey=safeh

Re: Random Generation map error on Mobile

Posted: Tue Aug 16, 2022 7:01 pm
by darkfrei
It must be as easy as

Code: Select all

-- License CC0 (Creative Commons license) (c) darkfrei, 2022

--love.window.setMode(1920, 1080, {resizable=true, borderless=false})
love.window.setMode(240, 320) -- QVGA, but vertical

function love.load()
	safeX, safeY, safeW, safeH = love.window.getSafeArea( )
end

function love.draw()
	love.graphics.translate(safeX, safeY)
	love.graphics.rectangle("line", 0, 0, safeW, safeH)
	love.graphics.line(0, 0, safeW, safeH)
	love.graphics.line(0, safeH, safeW, 0)
	love.graphics.circle ('line', safeW/2, safeH/2, safeW/2)
	love.graphics.circle ('line', safeW/2, safeH/2, safeH/2)
end


function love.mousepressed( x, y, button, istouch, presses )
	love.window.setMode(240, 320) -- QVGA, but vertical

	safeX, safeY, safeW, safeH = love.window.getSafeArea( )
end
safe-area-03.love
(482 Bytes) Downloaded 89 times
OR double the setMode

Code: Select all

function love.load()
	--love.window.setMode(1920, 1080, {resizable=true, borderless=false})
	love.window.setMode(240, 320) -- QVGA, but vertical
	love.window.setMode(240, 320) -- double it!
--	love.timer.sleep(1)
	safeX, safeY, safeW, safeH = love.window.getSafeArea( )
end

function love.draw()
	love.graphics.translate(safeX, safeY) -- or minus, not tested
	love.graphics.rectangle("line", 0, 0, safeW, safeH)
	love.graphics.line(0, 0, safeW, safeH)
	love.graphics.line(0, safeH, safeW, 0)
	love.graphics.circle ('line', safeW/2, safeH/2, safeW/2)
	love.graphics.circle ('line', safeW/2, safeH/2, safeH/2)
end
safe-area-06.love
(459 Bytes) Downloaded 88 times

Re: Random Generation map error on Mobile

Posted: Wed Aug 17, 2022 9:42 am
by Gunroar:Cannon()
darkfrei wrote: ↑Tue Aug 16, 2022 5:00 pm
GVovkiv wrote: ↑Tue Aug 16, 2022 4:54 pm Also, it's, probably, better to use love.math.random, and not lua's math.random
No, math.random is better, but by the testing use the same seed, you don't need to get the error sometimes.
Woah, why?
All times are UTC
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