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Save marceloCodget/3862929 to your computer and use it in GitHub Desktop.
-- passing a table like {255, 100, 20} | |
function application:rgbToHex(rgb) | |
local hexadecimal = '0X' | |
for key, value in pairs(rgb) do | |
local hex = '' | |
while(value > 0)do | |
local index = math.fmod(value, 16) + 1 | |
value = math.floor(value / 16) | |
hex = string.sub('0123456789ABCDEF', index, index) .. hex | |
end | |
if(string.len(hex) == 0)then | |
hex = '00' | |
elseif(string.len(hex) == 1)then | |
hex = '0' .. hex | |
end | |
hexadecimal = hexadecimal .. hex | |
end | |
return hexadecimal | |
end |
This is beautiful! Thanks :D
Thanks
If you want a string you can just string.format("%X", number)
. If you want specific formatting you can apply width flags (see man printf).
I.e. to make a HTML color code, string.format("#%02X%02X%02X", r, g, b)
.
An even better version without loops:
function rgbToHex(r,g,b)
-- EXPLANATION:
-- The integer form of RGB is 0xRRGGBB
-- Hex for red is 0xRR0000
-- Multiply red value by 0x10000(65536) to get 0xRR0000
-- Hex for green is 0x00GG00
-- Multiply green value by 0x100(256) to get 0x00GG00
-- Blue value does not need multiplication.
-- Final step is to add them together
-- (r * 0x10000) + (g * 0x100) + b =
-- 0xRR0000 +
-- 0x00GG00 +
-- 0x0000BB =
-- 0xRRGGBB
local rgb = (r * 0x10000) + (g * 0x100) + b
return string.format("%x", rgb)
end
This is horrible and unreliable. DO NOT USE THIS:
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pairs(rgb)
guarantees absolutely no order. If you pass the RGB values as a list{r, g, b}
, it will work though, becausepairs
traverses the list part in order. There's no guarantee this is the case though. Horrible bugs will happen as soon as you pass{r = r, g = g, b = b}
tables. For these, absolutely no order is guaranteed. You could be getting RGB if you're lucky, leading you not to discover this undefined behavior, you could also get BGR, GRB, ... though, scratching your head as to why it's not working. To "fix" this,ipairs
could be used. Additionally, this is basically a footgun. You can happily pass less than 3 or more than 4 numbers, leading to invalid hex color codes. It will also happily write numbers > 255, screwing up the hex color codes by displacing the following digits and creating a length > 6. -
Bad code quality, uneeded complexity.
application:
which is absolutely useless;self
isn't needed.key
is unused:_
should be used. Brackets instead of spaces around conditions. The inner while loop basically just doesstring.format("#%X", value)
, but a lot slower. The followingif
s do the padding, basicallystring.format("#%02X", value)
. -
Bad performance. This is unnecessarily slow.
Use string.format("#%02X%02X%02X", r, g, b)
instead.
Regarding the following:
An even better version without loops:
function rgbToHex(r,g,b) - ... local rgb = (r * 0x10000) + (g * 0x100) + b return string.format("%x", rgb) end
If you want padding, the last line needs to be return string.format("%06x", rgb)
.
If you want padding, the last line needs to be
return string.format("%06x", rgb)
.
Do you know where can I find a list of formattings and options for C-style string formatting?
If you want padding, the last line needs to be
return string.format("%06x", rgb)
.Do you know where can I find a list of formattings and options for C-style string formatting?
What about https://en.wikipedia.org/wiki/Printf_format_string?
What about https://en.wikipedia.org/wiki/Printf_format_string?
Thanks
would u let that one slide marcelo codget
im kinda noob at coding but here is my solution:
rgb = {235,123,175}
function convert_to_hex (rgb)
local hex = ""
for i = 1 , #rgb do
local hex_table = {"0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"}
local num = rgb[i]/16
local whole = math.floor( num )
local remainder = num - whole
hex = hex .. hex_table[whole+1] .. hex_table[remainder*16 + 1]
end
return hex
end
print(convert_to_hex(rgb))
That's a frightening piece of code you wrote up there
Really good. Thank you very much.