From 15ad69b0fe1b1a7ef6e3d0627bd2d1754ef5f44d Mon Sep 17 00:00:00 2001
From: Lars Mueller <appgurulars@gmx.de>
Date: Sat, 10 Jun 2023 14:56:07 +0200
Subject: [PATCH] Add highly experimental texture generation

---
 init.lua                      |   3 +-
 minetest/texmod.lua           |   3 +-
 minetest/texmod/calc_dims.lua |   3 +-
 minetest/texmod/gen_tex.lua   | 190 +++++++++++++++++
 tex.lua                       | 386 ++++++++++++++++++++++++++++++++++
 5 files changed, 581 insertions(+), 4 deletions(-)
 create mode 100644 minetest/texmod/gen_tex.lua
 create mode 100644 tex.lua

diff --git a/init.lua b/init.lua
index 6141cc7..de53983 100644
--- a/init.lua
+++ b/init.lua
@@ -26,7 +26,8 @@ for _, file in pairs{
 	"base64",
 	"persistence",
 	"debug",
-	"web"
+	"web",
+	"tex"
 } do
 	modules[file] = file
 end
diff --git a/minetest/texmod.lua b/minetest/texmod.lua
index 5251b10..6553b6e 100644
--- a/minetest/texmod.lua
+++ b/minetest/texmod.lua
@@ -9,7 +9,8 @@ local texmod, metatable = component"dsl"
 local methods = metatable.__index
 methods.write = component"write"
 texmod.read = component("read", texmod)
-methods.calc_dims = component("calc_dims", texmod)
+methods.calc_dims = component"calc_dims"
+methods.gen_tex = component"gen_tex"
 
 function metatable:__tostring()
 	local rope = {}
diff --git a/minetest/texmod/calc_dims.lua b/minetest/texmod/calc_dims.lua
index 19e1764..292e937 100644
--- a/minetest/texmod/calc_dims.lua
+++ b/minetest/texmod/calc_dims.lua
@@ -46,7 +46,6 @@ do
 		return over_w, over_h
 	end
 	cd.blit = upscale_to_higher_res
-	cd.overlay = upscale_to_higher_res
 	cd.hardlight = upscale_to_higher_res
 end
 
@@ -95,4 +94,4 @@ function cd:png()
 	return png.width, png.height
 end
 
-return calc_dims
\ No newline at end of file
+return calc_dims
diff --git a/minetest/texmod/gen_tex.lua b/minetest/texmod/gen_tex.lua
new file mode 100644
index 0000000..acedd0b
--- /dev/null
+++ b/minetest/texmod/gen_tex.lua
@@ -0,0 +1,190 @@
+local tex = modlib.tex
+
+local paths = modlib.minetest.media.paths
+local function read_png(fname)
+	if fname == "blank.png" then return tex.new{w=1,h=1,0} end
+	return tex.read_png(assert(paths[fname]))
+end
+
+local gt = {}
+
+-- TODO colorizehsl, hsl, contrast
+-- TODO (...) inventorycube; this is nontrivial.
+
+function gt:file()
+	return read_png(self.filename)
+end
+
+function gt:opacity()
+	local t = self.base:gen_tex()
+	t:opacity(self.ratio / 255)
+	return t
+end
+
+function gt:invert()
+	local t = self.base:gen_tex()
+	t:invert(self.r, self.g, self.b, self.a)
+	return t
+end
+
+function gt:brighten()
+	local t = self.base:gen_tex()
+	t:brighten()
+	return t
+end
+
+function gt:noalpha()
+	local t = self.base:gen_tex()
+	t:noalpha()
+	return t
+end
+
+function gt:makealpha()
+	local t = self.base:gen_tex()
+	t:makealpha(self.r, self.g, self.b)
+	return t
+end
+
+function gt:multiply()
+	local c = self.color
+	local t = self.base:gen_tex()
+	t:multiply_rgb(c.r, c.g, c.b)
+	return t
+end
+
+function gt:screen()
+	local c = self.color
+	local t = self.base:gen_tex()
+	t:screen_blend_rgb(c.r, c.g, c.b)
+	return t
+end
+
+function gt:colorize()
+	local c = self.color
+	local t = self.base:gen_tex()
+	t:colorize(c.r, c.g, c.b, self.ratio)
+	return t
+end
+
+local function resized_to_larger(a, b)
+	if a.w * a.h > b.w * b.h then
+		b = b:resized(a.w, a.h)
+	else
+		a = a:resized(b.w, b.h)
+	end
+	return a, b
+end
+
+function gt:mask()
+	local a, b = resized_to_larger(self.base:gen_tex(), self._mask:gen_tex())
+	a:band(b)
+	return a
+end
+
+function gt:lowpart()
+	local t = self.base:gen_tex()
+	local over = self.over:gen_tex()
+	local lowpart_h = math.ceil(self.percent/100 * over.h) -- TODO (?) ceil or floor
+	if lowpart_h > 0 then
+		t, over = resized_to_larger(t, over)
+		local y = over.h - lowpart_h + 1
+		over:crop(1, y, over.w, over.h)
+		t:blit(1, y, over)
+	end
+	return t
+end
+
+function gt:resize()
+	return self.base:gen_tex():resized(self.w, self.h)
+end
+
+function gt:combine()
+	local t = tex.filled(self.w, self.h, 0)
+	for _, blt in ipairs(self.blits) do
+		t:blit(blt.x + 1, blt.y + 1, blt.texture:gen_tex())
+	end
+	return t
+end
+
+function gt:fill()
+	if self.base then
+		return self.base:gen_tex():fill(self.w, self.h, self.x, self.y, self.color:to_number())
+	end
+	return tex.filled(self.w, self.h, self.color:to_number())
+end
+
+function gt:blit()
+	local t, o = resized_to_larger(self.base:gen_tex(), self.over:gen_tex())
+	t:blit(1, 1, o)
+	return t
+end
+
+function gt:hardlight()
+	local t, o = resized_to_larger(self.base:gen_tex(), self.over:gen_tex())
+	t:hardlight_blend(o)
+	return t
+end
+
+-- TODO (...?) optimize this
+function gt:transform()
+	local t = self.base:gen_tex()
+	if self.flip_axis == "x" then
+		t:flip_x()
+	elseif self.flip_axis == "y" then
+		t:flip_y()
+	end
+	-- TODO implement counterclockwise rotations to get rid of this hack
+	for _ = 1, 360 - self.rotation_deg / 90 do
+		t = t:rotated_90()
+	end
+	return t
+end
+
+local frame = function(t, frame, framecount)
+	local fh = math.floor(t.h / framecount)
+	t:crop(1, frame * fh + 1, t.w, (frame + 1) * fh)
+end
+
+local crack = function(self, o)
+	local crack = read_png"crack_anylength.png"
+	frame(crack, self.frame, math.floor(crack.h / crack.w))
+	local t = self.base:gen_tex()
+	local tile_w, tile_h = math.floor(t.w / self.tilecount), math.floor(t.h / self.framecount)
+	crack = crack:resized(tile_w, tile_h)
+	for ty = 1, t.h, tile_h do
+		for tx = 1, t.w, tile_w do
+			t[o and "blito" or "blit"](t, tx, ty, crack)
+		end
+	end
+	return t
+end
+
+function gt:crack()
+	return crack(self, false)
+end
+
+function gt:cracko()
+	return crack(self, true)
+end
+
+function gt:verticalframe()
+	local t = self.base:gen_tex()
+	frame(t, self.frame, self.framecount)
+	return t
+end
+
+function gt:sheet()
+	local t = self.base:gen_tex()
+	local tw, th = math.floor(t.w / self.w), math.floor(t.h / self.h)
+	local x, y = self.x, self.y
+	t:crop(x * tw + 1, y * th + 1, (x + 1) * tw, (y + 1) * th)
+	return t
+end
+
+function gt:png()
+	return tex.read_png_string(self.data)
+end
+
+return function(self)
+	return assert(gt[self.type])(self)
+end
diff --git a/tex.lua b/tex.lua
new file mode 100644
index 0000000..006cded
--- /dev/null
+++ b/tex.lua
@@ -0,0 +1,386 @@
+--[[
+	This file does not follow the usual conventions;
+	it duplicates some code for performance reasons.
+
+	In particular, use of `modlib.minetest.colorspec` is avoided.
+
+	Most methods operate *in-place* (imperative method names)
+	rather than returning a modified copy (past participle method names).
+
+	Outside-facing methods consistently use 1-based indexing; indices are inclusive.
+]]
+
+local min, max, floor, ceil = math.min, math.max, math.floor, math.ceil
+local function round(x) return floor(x + 0.5) end
+local function clamp(x, mn, mx) return max(min(x, mx), mn) end
+
+-- ARGB handling utilities
+
+local function unpack_argb(argb)
+	return floor(argb / 0x1000000),
+			floor(argb / 0x10000) % 0x100,
+			floor(argb / 0x100) % 0x100,
+			argb % 0x100
+end
+
+local function pack_argb(a, r, g, b)
+	local argb = (((a * 0x100 + r) * 0x100) + g) * 0x100 + b
+	return argb
+end
+
+local function round_argb(a, r, g, b)
+	return round(a), round(r), round(g), round(b)
+end
+
+local function scale_0_1_argb(a, r, g, b)
+	return a / 255, r / 255, g / 255, b / 255
+end
+
+local function scale_0_255_argb(a, r, g, b)
+	return a * 255, r * 255, g * 255, b * 255
+end
+
+local tex = {}
+local metatable = {__index = tex}
+
+function metatable:__eq(other)
+	if self.w ~= other.w or self.h ~= other.h then return false end
+	for i = 1, #self do	if self[i] ~= other[i] then return false end end
+	return true
+end
+
+function tex:new()
+	return setmetatable(self, metatable)
+end
+
+function tex.filled(w, h, argb)
+	local self = {w = w, h = h}
+	for i = 1, w*h do
+		self[i] = argb
+	end
+	return tex.new(self)
+end
+
+function tex:copy()
+	local copy = {w = self.w, h = self.h}
+	for i = 1, #self do
+		copy[i] = self[i]
+	end
+	return tex.new(copy)
+end
+
+-- Reading & writing
+
+function tex.read_png_string(str)
+	local stream = modlib.text.inputstream(str)
+	local png = modlib.minetest.decode_png(stream)
+	assert(stream:read(1) == nil, "eof expected")
+	modlib.minetest.convert_png_to_argb8(png)
+	png.data.w, png.data.h = png.width, png.height
+	return tex.new(png.data)
+end
+
+function tex.read_png(path)
+	local png
+	modlib.file.with_open(path, "rb", function(f)
+		png = modlib.minetest.decode_png(f)
+		assert(f:read(1) == nil, "eof expected")
+	end)
+	modlib.minetest.convert_png_to_argb8(png)
+	png.data.w, png.data.h = png.width, png.height
+	return tex.new(png.data)
+end
+
+function tex:write_png_string()
+	return modlib.minetest.encode_png(self.w, self.h, self)
+end
+
+function tex:write_png(path)
+	modlib.file.write_binary(path, self:write_png_string())
+end
+
+function tex:fill(sx, sy, argb)
+	local w, h = self.w, self.h
+	for y = sy, h do
+		local i = (y - 1) * w + sx
+		for _ = sx, w do
+			self[i] = argb
+			i = i + 1
+		end
+	end
+end
+
+function tex:in_bounds(x, y)
+	return x >= 1 and y >= 1 and x <= self.w and y <= self.h
+end
+
+function tex:get_argb_packed(x, y)
+	return self[(y - 1) * self.w + x]
+end
+
+function tex:get_argb(x, y)
+	return unpack_argb(self[(y - 1) * self.w + x])
+end
+
+function tex:set_argb_packed(x, y, argb)
+	self[(y - 1) * self.w + x] = argb
+end
+
+function tex:set_argb(x, y, a, r, g, b)
+	self[(y - 1) * self.w + x] = pack_argb(a, r, g, b)
+end
+
+function tex:map_argb(func)
+	for i = 1, #self do
+		self[i] = pack_argb(func(unpack_argb(self[i])))
+	end
+end
+
+local function blit(s, x, y, t, o)
+	local sw, sh = s.w, s.h
+	local tw, th = t.w, t.h
+	-- Restrict to overlapping region
+	x, y = clamp(x, 1, sw), clamp(y, 1, sh)
+	local min_tx, min_ty = max(1, 2 - x), max(1, 2 - y)
+	local max_tx, max_ty = min(tw, sw - x + 1), min(th, sh - y + 1)
+	for ty = min_ty, max_ty do
+		local ti, si = (ty - 1) * tw, (y + ty - 2) * sw + x - 1
+		for _ = min_tx, max_tx do
+			ti, si = ti + 1, si + 1
+			local sa, sr, sg, sb = scale_0_1_argb(unpack_argb(s[si]))
+			if sa == 1 or not o then -- HACK because of dirty `[cracko`
+				local ta, tr, tg, tb = scale_0_1_argb(unpack_argb(t[ti]))
+				-- "`t` over `s`" (Porter-Duff-Algorithm)
+				local sata = sa * (1 - ta)
+				local ra = ta + sata
+				assert(ra > 0 or (sa == 0 and ta == 0))
+				if ra > 0 then
+					s[si] = pack_argb(round_argb(scale_0_255_argb(
+						ra,
+						(ta * tr + sata * sr) / ra,
+						(ta * tg + sata * sg) / ra,
+						(ta * tb + sata * sb) / ra
+					)))
+				end
+			end
+		end
+	end
+end
+
+-- Blitting with proper alpha blending.
+function tex.blit(s, x, y, t)
+	return blit(s, x, y, t, false)
+end
+
+-- Blit, but only on fully opaque base pixels. Only `[cracko` uses this.
+function tex.blito(s, x, y, t)
+	return blit(s, x, y, t, true)
+end
+
+function tex.combine_argb(s, t, cf)
+	assert(#s == #t)
+	for i = 1, #s do
+		s[i] = cf(s[i], t[i])
+	end
+end
+
+-- See https://github.com/TheAlgorithms/Lua/blob/162c4c59f5514c6115e0add8a2b4d56afd6d3204/src/bit/uint53/and.lua
+-- TODO (?) optimize fallback band using caching, move somewhere else
+local band = bit and bit.band or function(n, m)
+	local res = 0
+	local bit = 1
+	while n * m ~= 0 do -- while both are nonzero
+		local n_bit, m_bit = n % 2, m % 2 -- extract LSB
+		res = res + (n_bit * m_bit) * bit -- add AND of LSBs
+		n, m = (n - n_bit) / 2, (m - m_bit) / 2 -- remove LSB from n & m
+		bit = bit * 2 -- next bit
+	end
+	return res
+end
+
+function tex.band(s, t)
+	return s:combine_argb(t, band)
+end
+
+function tex.hardlight_blend(s, t)
+	return s:combine_argb(t, function(sargb, targb)
+		local sa, sr, sg, sb = scale_0_1_argb(unpack_argb(sargb))
+		local _, tr, tg, tb = scale_0_1_argb(unpack_argb(targb))
+		return pack_argb(round_argb(scale_0_255_argb(
+			sa,
+			sr < 0.5 and 2*sr*tr or 1 - 2*(1-sr)*(1-tr),
+			sr < 0.5 and 2*sg*tg or 1 - 2*(1-sg)*(1-tg),
+			sr < 0.5 and 2*sb*tb or 1 - 2*(1-sb)*(1-tb)
+		)))
+	end)
+end
+
+function tex:brighten()
+	return self:map_argb(function(a, r, g, b)
+		return round_argb((255 + a) / 2, (255 + r) / 2, (255 + g) / 2, (255 + b) / 2)
+	end)
+end
+
+function tex:noalpha()
+	for i = 1, #self do
+		self[i] = 0xFF000000 + self[i] % 0x1000000
+	end
+end
+
+function tex:makealpha(r, g, b)
+	local mrgb = r * 0x10000 + g * 0x100 + b
+	for i = 1, #self do
+		local rgb = self[i] % 0x1000000
+		if rgb == mrgb then
+			self[i] = rgb
+		end
+	end
+end
+
+function tex:opacity(factor)
+	for i = 1, #self do
+		self[i] = round(floor(self[i] / 0x1000000) * factor) * 0x1000000 + self[i] % 0x1000000
+	end
+end
+
+function tex:invert(ir, ig, ib, ia)
+	return self:map_argb(function(a, r, g, b)
+		if ia then a = 255 - a end
+		if ir then r = 255 - r end
+		if ig then g = 255 - g end
+		if ib then b = 255 - b end
+		return a, r, g, b
+	end)
+end
+
+function tex:multiply_rgb(r, g, b)
+	return self:map_argb(function(sa, sr, sg, sb)
+		return round_argb(sa, r * sr, g * sg, b * sb)
+	end)
+end
+
+function tex:screen_blend_rgb(r, g, b)
+	return self:map_argb(function(sa, sr, sg, sb)
+		return round_argb(sa,
+			255 - ((255 - sr) * (255 - r)) / 255,
+			255 - ((255 - sg) * (255 - g)) / 255,
+			255 - ((255 - sb) * (255 - b)) / 255)
+	end)
+end
+
+function tex:colorize(cr, cg, cb, ratio)
+	return self:map_argb(function(a, r, g, b)
+		local rat = ratio == "alpha" and a or ratio
+		return round_argb(
+			a,
+			rat * r + (1 - rat) * cr,
+			rat * g + (1 - rat) * cg,
+			rat * b + (1 - rat) * cb
+		)
+	end)
+end
+
+function tex:crop(from_x, from_y, to_x, to_y)
+	local w = self.w
+	local i = 1
+	for y = from_y, to_y do
+		local j = (y - 1) * w + from_x
+		for _ = from_x, to_x do
+			self[i] = self[j]
+			i, j = i + 1, j + 1
+		end
+	end
+	-- Remove remaining pixels
+	for j = i, #self do self[j] = nil end
+	self.w, self.h = to_x - from_x + 1, to_y - from_y + 1
+end
+
+function tex:flip_x()
+	for y = 1, self.h do
+		local i = (y - 1) * self.w
+		local j = i + self.w + 1
+		while i < j do
+			i, j = i + 1, j - 1
+			self[i], self[j] = self[j], self[i]
+		end
+	end
+end
+
+function tex:flip_y()
+	for x = 1, self.w do
+		local i, j = x, (self.h - 1) * self.w + x
+		while i < j do
+			i, j = i + self.w, j - self.w
+			self[i], self[j] = self[j], self[i]
+		end
+	end
+end
+
+--> copy of the texture, rotated 90 degrees clockwise
+function tex:rotated_90()
+	local w, h = self.w, self.h
+	local t = {w = h, h = w}
+	local i = 0
+	for y = 1, w do
+		for x = 1, h do
+			i = i + 1
+			t[i] = self[(h-x)*w + y]
+		end
+	end
+	t = tex.new(t)
+	return t
+end
+
+-- Uses box sampling. Hard to optimize.
+-- TODO (...) interpolate box samples; match what Minetest does
+--> copy of `self` resized to `w` x `h`
+function tex:resized(w, h)
+	--! This function works with 0-based indices.
+	local sw, sh = self.w, self.h
+	local fx, fy = sw / w, sh / h
+	local t = {w = w, h = h}
+	local i = 0
+	for y = 0, h - 1 do
+		for x = 0, w - 1 do
+			-- Sample the area
+			local vy_from = y * fy
+			local vy_to = vy_from + fy
+			local vx_from = x * fx
+			local vx_to = vx_from + fx
+
+			local a, r, g, b = 0, 0, 0, 0
+			local pf_sum = 0
+
+			local function blend(sx, sy, pf)
+				if pf <= 0 then return end
+				local sa, sr, sg, sb = unpack_argb(self[sy * sw + sx + 1])
+				pf_sum = pf_sum + pf -- TODO (?) eliminate `pf_sum`
+				sa = sa * pf
+				a = a + sa
+				r, g, b = r + sa * sr, g + sa * sg, b + sa * sb
+			end
+
+			local function srow(sy, pf)
+				if pf <= 0 then return end
+				local sx_from, sx_to = ceil(vx_from), floor(vx_to)
+				for sx = sx_from, sx_to - 1 do blend(sx, sy, pf) end -- whole pixels
+				-- Pixels at edges
+				blend(floor(vx_from), sy, pf * (sx_from - vx_from))
+				blend(floor(vx_to), sy, pf * (vx_to - sx_to))
+			end
+
+			local sy_from, sy_to = ceil(vy_from), floor(vy_to)
+			for sy = sy_from, sy_to - 1 do srow(sy, 1) end -- whole pixels
+			-- Pixels at edges
+			srow(floor(vy_from), sy_from - vy_from)
+			srow(floor(vy_to), vy_to - sy_to)
+			if a > 0 then r, g, b = r / a, g / a, b / a end
+			assert(pf_sum > 0)
+			i = i + 1
+			t[i] = pack_argb(round_argb(a / pf_sum, r, g, b))
+		end
+	end
+	return tex.new(t)
+end
+
+return tex