MineClone2/init.lua

159 lines
4.6 KiB
Lua
Raw Normal View History

2021-05-01 16:52:16 +02:00
tga_encoder = {}
local image = setmetatable({}, {
__call = function(self, ...)
local t = setmetatable({}, {__index = self})
t:constructor(...)
return t
end,
})
function image:constructor(pixels)
2021-05-02 17:47:46 +02:00
self.data = ""
2021-05-01 16:52:16 +02:00
self.pixels = pixels
self.width = #pixels[1]
self.height = #pixels
self:encode()
end
function image:encode_colormap_spec()
2021-05-02 17:47:46 +02:00
self.data = self.data
.. string.char(0, 0) -- first entry index
.. string.char(0, 0) -- number of entries
.. string.char(0) -- bits per pixel
2021-05-01 16:52:16 +02:00
end
function image:encode_image_spec()
2021-05-02 17:47:46 +02:00
self.data = self.data
.. string.char(0, 0) -- X-origin
.. string.char(0, 0) -- Y-origin
.. string.char(self.width % 256, math.floor(self.width / 256)) -- width
.. string.char(self.height % 256, math.floor(self.height / 256)) -- height
.. string.char(16) -- pixel depth (ARRRRRGGGGGBBBBB = 2 bytes = 16 bits)
2021-05-02 17:47:46 +02:00
.. string.char(0) -- image descriptor
2021-05-01 16:52:16 +02:00
end
function image:encode_header()
2021-05-02 17:47:46 +02:00
self.data = self.data
.. string.char(0) -- image id
.. string.char(0) -- color map type
2021-11-04 01:53:58 +01:00
.. string.char(10) -- image type (RLE RGB = 10)
2021-05-02 17:47:46 +02:00
self:encode_colormap_spec() -- color map specification
self:encode_image_spec() -- image specification
2021-05-01 16:52:16 +02:00
end
function image:encode_data()
local colorword = nil
local previous_r = nil
local previous_g = nil
local previous_b = nil
local raw_pixel = ''
local raw_pixels = {}
2021-11-04 01:53:58 +01:00
local count = 1
local packets = {}
local raw_packet = ''
2021-11-04 01:53:58 +01:00
local rle_packet = ''
-- Sample depth rescaling is done according to the algorithm presented in:
-- <https://www.w3.org/TR/2003/REC-PNG-20031110/#13Sample-depth-rescaling>
local max_sample_in = math.pow(2, 8) - 1
local max_sample_out = math.pow(2, 5) - 1
2021-05-01 16:52:16 +02:00
for _, row in ipairs(self.pixels) do
for _, pixel in ipairs(row) do
if pixel[1] ~= previous_r or pixel[2] ~= previous_g or pixel[3] ~= previous_b or count == 128 then
if nil ~= previous_r then
colorword = 32768 +
((math.floor((previous_r * max_sample_out / max_sample_in) + 0.5)) * 1024) +
((math.floor((previous_g * max_sample_out / max_sample_in) + 0.5)) * 32) +
((math.floor((previous_b * max_sample_out / max_sample_in) + 0.5)) * 1)
if 1 == count then
-- remember pixel verbatim for raw encoding
raw_pixel = string.char(colorword % 256, math.floor(colorword / 256))
raw_pixels[#raw_pixels + 1] = raw_pixel
if 128 == #raw_pixels then
raw_packet = string.char(#raw_pixels - 1)
packets[#packets + 1] = raw_packet
for i=1, #raw_pixels do
packets[#packets +1] = raw_pixels[i]
end
raw_pixels = {}
end
else
-- encode raw pixels, if any
if #raw_pixels > 0 then
raw_packet = string.char(#raw_pixels - 1)
packets[#packets + 1] = raw_packet
for i=1, #raw_pixels do
packets[#packets +1] = raw_pixels[i]
end
raw_pixels = {}
end
-- RLE encoding
rle_packet = string.char(128 + count - 1, colorword % 256, math.floor(colorword / 256))
packets[#packets +1] = rle_packet
end
end
2021-11-04 01:53:58 +01:00
count = 1
previous_r = pixel[1]
previous_g = pixel[2]
previous_b = pixel[3]
2021-11-04 01:53:58 +01:00
else
count = count + 1
end
2021-05-01 16:52:16 +02:00
end
end
colorword = 32768 +
((math.floor((previous_r * max_sample_out / max_sample_in) + 0.5)) * 1024) +
((math.floor((previous_g * max_sample_out / max_sample_in) + 0.5)) * 32) +
((math.floor((previous_b * max_sample_out / max_sample_in) + 0.5)) * 1)
if 1 == count then
raw_pixel = string.char(colorword % 256, math.floor(colorword / 256))
raw_pixels[#raw_pixels + 1] = raw_pixel
raw_packet = string.char(#raw_pixels - 1)
packets[#packets + 1] = raw_packet
for i=1, #raw_pixels do
packets[#packets +1] = raw_pixels[i]
end
raw_pixels = {}
else
-- encode raw pixels, if any
if #raw_pixels > 0 then
raw_packet = string.char(#raw_pixels - 1)
packets[#packets + 1] = raw_packet
for i=1, #raw_pixels do
packets[#packets +1] = raw_pixels[i]
end
raw_pixels = {}
end
-- RLE encoding
rle_packet = string.char(128 + count - 1, colorword % 256, math.floor(colorword / 256))
packets[#packets +1] = rle_packet
end
self.data = self.data .. table.concat(packets)
2021-05-01 16:52:16 +02:00
end
2021-05-02 17:47:46 +02:00
function image:encode_footer()
self.data = self.data
.. string.char(0, 0, 0, 0) -- extension area offset
.. string.char(0, 0, 0, 0) -- developer area offset
.. "TRUEVISION-XFILE"
.. "."
.. string.char(0)
2021-05-01 16:52:16 +02:00
end
2021-05-02 17:47:46 +02:00
function image:encode()
self:encode_header() -- header
-- no color map and image id data
self:encode_data() -- encode data
-- no extension or developer area
self:encode_footer() -- footer
2021-05-01 16:52:16 +02:00
end
function image:save(filename)
local f = assert(io.open(filename, "wb"))
2021-05-01 16:52:16 +02:00
f:write(self.data)
f:close()
end
tga_encoder.image = image