VoxeLibre/mods/CORE/tga_encoder/init.lua

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tga_encoder = {}
local image = setmetatable({}, {
__call = function(self, ...)
local t = setmetatable({}, {__index = self})
t:constructor(...)
return t
end,
})
function image:constructor(pixels)
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self.pixels = pixels
self.width = #pixels[1]
self.height = #pixels
end
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local pixel_depth_by_color_format = {
["Y8"] = 8,
["A1R5G5B5"] = 16,
["B8G8R8"] = 24,
["B8G8R8A8"] = 32,
}
function image:encode_colormap_spec(properties)
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local colormap = properties.colormap
local colormap_pixel_depth = 0
if 0 ~= #colormap then
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colormap_pixel_depth = pixel_depth_by_color_format[
properties.color_format
]
-- ensure that each pixel references a legal colormap entry
for _, row in ipairs(self.pixels) do
for _, pixel in ipairs(row) do
local colormap_index = pixel[1]
if colormap_index >= #colormap then
error(
"colormap index " .. colormap_index ..
" not in colormap of size " .. #colormap
)
end
end
end
end
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local colormap_spec =
string.char(0, 0) .. -- first entry index
string.char(#colormap % 256, math.floor(#colormap / 256)) .. -- number of entries
string.char(colormap_pixel_depth) -- bits per pixel
self.data = self.data .. colormap_spec
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end
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function image:encode_image_spec(properties)
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local color_format = properties.color_format
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assert(
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"Y8" == color_format or -- (8 bit grayscale = 1 byte = 8 bits)
"A1R5G5B5" == color_format or -- (A1R5G5B5 = 2 bytes = 16 bits)
"B8G8R8" == color_format or -- (B8G8R8 = 3 bytes = 24 bits)
"B8G8R8A8" == color_format -- (B8G8R8A8 = 4 bytes = 32 bits)
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)
local scanline_order = properties.scanline_order
assert (
"bottom-top" == scanline_order or
"top-bottom" == scanline_order
)
local pixel_depth
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if 0 ~= #properties.colormap then
pixel_depth = self.pixel_depth
else
pixel_depth = pixel_depth_by_color_format[color_format]
end
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assert( nil ~= pixel_depth)
-- the origin is the bottom left corner of the image (always)
local x_origin_lo = 0
local x_origin_hi = 0
local y_origin_lo = 0
local y_origin_hi = 0
local image_descriptor = 0 -- equal to bottom-top scanline order
local width_lo = self.width % 256
local width_hi = math.floor(self.width / 256)
local height_lo = self.height % 256
local height_hi = math.floor(self.height / 256)
if "top-bottom" == scanline_order then
image_descriptor = 32
y_origin_lo = height_lo
y_origin_hi = height_hi
end
self.data = self.data .. string.char (
x_origin_lo, x_origin_hi,
y_origin_lo, y_origin_hi,
width_lo, width_hi,
height_lo, height_hi,
pixel_depth,
image_descriptor
)
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end
function image:encode_colormap(properties)
local colormap = properties.colormap
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if 0 == #colormap then
return
end
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local color_format = properties.color_format
assert (
"A1R5G5B5" == color_format or
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"B8G8R8" == color_format or
"B8G8R8A8" == color_format
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)
local colors = {}
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if "A1R5G5B5" == color_format then
-- 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
for i = 1,#colormap,1 do
local color = colormap[i]
local colorword = 32768 +
((math.floor((color[1] * max_sample_out / max_sample_in) + 0.5)) * 1024) +
((math.floor((color[2] * max_sample_out / max_sample_in) + 0.5)) * 32) +
((math.floor((color[3] * max_sample_out / max_sample_in) + 0.5)) * 1)
local color_bytes = string.char(
colorword % 256,
math.floor(colorword / 256)
)
colors[#colors + 1] = color_bytes
end
elseif "B8G8R8" == color_format then
for i = 1,#colormap,1 do
local color = colormap[i]
local color_bytes = string.char(
color[3], -- B
color[2], -- G
color[1] -- R
)
colors[#colors + 1] = color_bytes
end
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elseif "B8G8R8A8" == color_format then
for i = 1,#colormap,1 do
local color = colormap[i]
local color_bytes = string.char(
color[3], -- B
color[2], -- G
color[1], -- R
color[4] -- A
)
colors[#colors + 1] = color_bytes
end
end
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assert( 0 ~= #colors )
self.data = self.data .. table.concat(colors)
end
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function image:encode_header(properties)
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local color_format = properties.color_format
local colormap = properties.colormap
local compression = properties.compression
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local colormap_type
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local image_type
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if "Y8" == color_format and "RAW" == compression then
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colormap_type = 0
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image_type = 3 -- grayscale
elseif (
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"A1R5G5B5" == color_format or
"B8G8R8" == color_format or
"B8G8R8A8" == color_format
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) then
if "RAW" == compression then
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if 0 ~= #colormap then
colormap_type = 1
image_type = 1 -- colormapped RGB(A)
else
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colormap_type = 0
image_type = 2 -- RAW RGB(A)
end
elseif "RLE" == compression then
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colormap_type = 0
image_type = 10 -- RLE RGB
end
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end
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assert( nil ~= colormap_type )
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assert( nil ~= image_type )
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self.data = self.data
.. string.char(0) -- image id
.. string.char(colormap_type)
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.. string.char(image_type)
self:encode_colormap_spec(properties) -- color map specification
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self:encode_image_spec(properties) -- image specification
self:encode_colormap(properties)
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end
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function image:encode_data(properties)
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local color_format = properties.color_format
local colormap = properties.colormap
local compression = properties.compression
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local data_length_before = #self.data
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if "Y8" == color_format and "RAW" == compression then
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if 8 == self.pixel_depth then
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self:encode_data_Y8_as_Y8_raw()
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elseif 24 == self.pixel_depth then
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self:encode_data_R8G8B8_as_Y8_raw()
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end
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elseif "A1R5G5B5" == color_format then
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if 0 ~= #colormap then
if "RAW" == compression then
if 8 == self.pixel_depth then
self:encode_data_Y8_as_Y8_raw()
end
end
else
if "RAW" == compression then
self:encode_data_R8G8B8_as_A1R5G5B5_raw()
elseif "RLE" == compression then
self:encode_data_R8G8B8_as_A1R5G5B5_rle()
end
end
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elseif "B8G8R8" == color_format then
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if 0 ~= #colormap then
if "RAW" == compression then
if 8 == self.pixel_depth then
self:encode_data_Y8_as_Y8_raw()
end
end
else
if "RAW" == compression then
self:encode_data_R8G8B8_as_B8G8R8_raw()
elseif "RLE" == compression then
self:encode_data_R8G8B8_as_B8G8R8_rle()
end
end
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elseif "B8G8R8A8" == color_format then
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if 0 ~= #colormap then
if "RAW" == compression then
if 8 == self.pixel_depth then
self:encode_data_Y8_as_Y8_raw()
end
end
else
if "RAW" == compression then
self:encode_data_R8G8B8A8_as_B8G8R8A8_raw()
elseif "RLE" == compression then
self:encode_data_R8G8B8A8_as_B8G8R8A8_rle()
end
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end
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end
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local data_length_after = #self.data
assert(
data_length_after ~= data_length_before,
"No data encoded for color format: " .. color_format
)
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end
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function image:encode_data_Y8_as_Y8_raw()
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assert(8 == self.pixel_depth)
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local raw_pixels = {}
for _, row in ipairs(self.pixels) do
for _, pixel in ipairs(row) do
local raw_pixel = string.char(pixel[1])
raw_pixels[#raw_pixels + 1] = raw_pixel
end
end
self.data = self.data .. table.concat(raw_pixels)
end
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function image:encode_data_R8G8B8_as_Y8_raw()
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assert(24 == self.pixel_depth)
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local raw_pixels = {}
for _, row in ipairs(self.pixels) do
for _, pixel in ipairs(row) do
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-- the HSP RGB to brightness formula is
-- sqrt( 0.299 r² + .587 g² + .114 b² )
-- see <https://alienryderflex.com/hsp.html>
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local gray = math.floor(
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math.sqrt(
0.299 * pixel[1]^2 +
0.587 * pixel[2]^2 +
0.114 * pixel[3]^2
) + 0.5
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)
local raw_pixel = string.char(gray)
raw_pixels[#raw_pixels + 1] = raw_pixel
end
end
self.data = self.data .. table.concat(raw_pixels)
end
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function image:encode_data_R8G8B8_as_A1R5G5B5_raw()
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assert(24 == self.pixel_depth)
local raw_pixels = {}
-- 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
for _, row in ipairs(self.pixels) do
for _, pixel in ipairs(row) do
local colorword = 32768 +
((math.floor((pixel[1] * max_sample_out / max_sample_in) + 0.5)) * 1024) +
((math.floor((pixel[2] * max_sample_out / max_sample_in) + 0.5)) * 32) +
((math.floor((pixel[3] * max_sample_out / max_sample_in) + 0.5)) * 1)
local raw_pixel = string.char(colorword % 256, math.floor(colorword / 256))
raw_pixels[#raw_pixels + 1] = raw_pixel
end
end
self.data = self.data .. table.concat(raw_pixels)
end
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function image:encode_data_R8G8B8_as_A1R5G5B5_rle()
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assert(24 == self.pixel_depth)
local colorword = nil
local previous_r = nil
local previous_g = nil
local previous_b = nil
local raw_pixel = ''
local raw_pixels = {}
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local count = 1
local packets = {}
local raw_packet = ''
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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
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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
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count = 1
previous_r = pixel[1]
previous_g = pixel[2]
previous_b = pixel[3]
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else
count = count + 1
end
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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)
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end
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function image:encode_data_R8G8B8_as_B8G8R8_raw()
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assert(24 == self.pixel_depth)
local raw_pixels = {}
for _, row in ipairs(self.pixels) do
for _, pixel in ipairs(row) do
local raw_pixel = string.char(pixel[3], pixel[2], pixel[1])
raw_pixels[#raw_pixels + 1] = raw_pixel
end
end
self.data = self.data .. table.concat(raw_pixels)
end
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function image:encode_data_R8G8B8_as_B8G8R8_rle()
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assert(24 == self.pixel_depth)
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local previous_r = nil
local previous_g = nil
local previous_b = nil
local raw_pixel = ''
local raw_pixels = {}
local count = 1
local packets = {}
local raw_packet = ''
local rle_packet = ''
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
if 1 == count then
-- remember pixel verbatim for raw encoding
raw_pixel = string.char(previous_b, previous_g, previous_r)
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, previous_b, previous_g, previous_r)
packets[#packets +1] = rle_packet
end
end
count = 1
previous_r = pixel[1]
previous_g = pixel[2]
previous_b = pixel[3]
else
count = count + 1
end
end
end
if 1 == count then
raw_pixel = string.char(previous_b, previous_g, previous_r)
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, previous_b, previous_g, previous_r)
packets[#packets +1] = rle_packet
end
self.data = self.data .. table.concat(packets)
end
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function image:encode_data_R8G8B8A8_as_B8G8R8A8_raw()
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assert(32 == self.pixel_depth)
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local raw_pixels = {}
for _, row in ipairs(self.pixels) do
for _, pixel in ipairs(row) do
local raw_pixel = string.char(pixel[3], pixel[2], pixel[1], pixel[4])
raw_pixels[#raw_pixels + 1] = raw_pixel
end
end
self.data = self.data .. table.concat(raw_pixels)
end
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function image:encode_data_R8G8B8A8_as_B8G8R8A8_rle()
assert(32 == self.pixel_depth)
local previous_r = nil
local previous_g = nil
local previous_b = nil
local previous_a = nil
local raw_pixel = ''
local raw_pixels = {}
local count = 1
local packets = {}
local raw_packet = ''
local rle_packet = ''
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 pixel[4] ~= previous_a or count == 128 then
if nil ~= previous_r then
if 1 == count then
-- remember pixel verbatim for raw encoding
raw_pixel = string.char(previous_b, previous_g, previous_r, previous_a)
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, previous_b, previous_g, previous_r, previous_a)
packets[#packets +1] = rle_packet
end
end
count = 1
previous_r = pixel[1]
previous_g = pixel[2]
previous_b = pixel[3]
previous_a = pixel[4]
else
count = count + 1
end
end
end
if 1 == count then
raw_pixel = string.char(previous_b, previous_g, previous_r, previous_a)
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, previous_b, previous_g, previous_r, previous_a)
packets[#packets +1] = rle_packet
end
self.data = self.data .. table.concat(packets)
end
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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)
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end
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function image:encode(properties)
local properties = properties or {}
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properties.colormap = properties.colormap or {}
properties.compression = properties.compression or "RAW"
properties.scanline_order = properties.scanline_order or "bottom-top"
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self.pixel_depth = #self.pixels[1][1] * 8
local color_format_defaults_by_pixel_depth = {
[8] = "Y8",
[24] = "B8G8R8",
[32] = "B8G8R8A8",
}
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if nil == properties.color_format then
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if 0 ~= #properties.colormap then
properties.color_format =
color_format_defaults_by_pixel_depth[
#properties.colormap[1] * 8
]
else
properties.color_format =
color_format_defaults_by_pixel_depth[
self.pixel_depth
]
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end
end
assert( nil ~= properties.color_format )
self.data = ""
self:encode_header(properties) -- header
-- no color map and image id data
self:encode_data(properties) -- encode data
-- no extension or developer area
self:encode_footer() -- footer
end
function image:save(filename, properties)
self:encode(properties)
local f = assert(io.open(filename, "wb"))
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f:write(self.data)
f:close()
end
tga_encoder.image = image