Return to Answer

\documentclass[tikz,border=5]{standalone} \usetikzlibrary{backgrounds,arrows.meta} \pgfdeclarelayer{foreground} \pgfdeclarelayer{before-background} \pgfsetlayers{background,before-background,main,foreground} \usepackage{luacode} \begin{luacode*} floor = math.floor ceil = math.ceil Maze = {} Maze.__index = Maze Maze.NORTH = 90 Maze.SOUTH = 270 Maze.EAST = 0 Maze.WEST = 180 Maze.new = function(r, c) local i, j, row, cell local obj = {} setmetatable(obj, Maze) obj.rows = r obj.cols = c obj:reset() return obj end Maze.reset = function(self) local i, j, row, cell self.cells = {} for i = 1,self.rows do row = {} for j = 1,self.cols do cell = {visited=false, visitable=true, north=true,south=true,east=true, west=true, meta=''} table.insert(row, cell) end table.insert(self.cells, row) end end Maze.visitable = function(self, i, j) return self.cells[i] and self.cells[i][j] and self.cells[i][j].visitable end Maze.isVisitable = function(self, i, j) return self.cells[i] and self.cells[i][j] and self.cells[i][j].visitable end Maze.setVisitable = function(self, i, j, visitable) self.cells[i][j].visitable = visitable self.cells[i][j].north = visitable self.cells[i][j].south = visitable self.cells[i][j].east = visitable self.cells[i][j].west = visitable end Maze.getMeta = function(self, i, j) return self.cells[i][j].meta end Maze.setMeta = function(self, i, j, meta) self.cells[i][j].meta = meta end Maze.create = function(self, start) local n, N, x, y, a, b, k, stack N = self.rows * self.cols for i = 1,self.rows do for j = 1,self.cols do if not self.cells[i][j].visitable then N = N - 1 end end end start = start or {x=1, y=1} x, y = start.x, start.y stack = {} table.insert(stack, {x=x, y=y}) self.cells[y][x].visited = true visited = 1 while visited < N do x = stack[#stack].x y = stack[#stack].y n = {} if self:isVisitable(y+1, x) and not self.cells[y+1][x].visited then table.insert(n, Maze.NORTH) end if self:isVisitable(y-1, x) and not self.cells[y-1][x].visited then table.insert(n, Maze.SOUTH) end if self:isVisitable(y, x+1) and not self.cells[y][x+1].visited then table.insert(n, Maze.EAST) end if self:isVisitable(y, x-1) and not self.cells[y][x-1].visited then table.insert(n, Maze.WEST) end if #n == 0 then table.remove(stack) else k = n[math.random(#n)] if k == Maze.NORTH then a, b = x, y+1 self.cells[y][x].north = false self.cells[b][a].south = false elseif k == Maze.SOUTH then a, b = x, y-1 self.cells[y][x].south = false self.cells[b][a].north = false elseif k == Maze.EAST then a, b = x+1, y self.cells[y][x].east = false self.cells[b][a].west = false elseif k == Maze.WEST then a, b = x-1, y self.cells[y][x].west = false self.cells[b][a].east = false end table.insert(stack, {x=a, y=b}) self.cells[b][a].visited = true visited = visited + 1 end end end m = Maze.new(70,55) for i = 1,m.rows do for j = 1,m.cols do m:setVisitable(i, j, false) end end -- tree tree_data = {1,1,1,3,3,3,5,5,7,7,9,11,11,13,15,17,19,23,27,21, 13,15,17,17,19,21,23,27,29,33,25, 19,21,21,23,25,27,29,33,35,39,31,25, 23,25,27,29,31,33,35,37,41,45,37,31,21} for i, x in ipairs(tree_data) do for j = 1, x do m:setVisitable(m.rows-i-5, floor((m.cols - x) / 2) + j, true) m:setMeta(m.rows-i-5, floor((m.cols - x) / 2) + j, 'green') end end -- decorations c = floor(m.cols/2) colors = {'red', 'orange', 'purple'} ncolors = 3 for q = 0,3 do for j = c-15, c+15 do if j < c then k = 3 else k = 1.625 end for r = -1,1 do m:setMeta(floor((j - c) / k) + 15 + q * 10 + r, j, colors[math.random(ncolors)]) end end end -- star star_data = {1,1,1,3,3,5,9,15,9,5,3,3,1,1,1} for i, x in ipairs(star_data) do for j = 1, x do m:setVisitable(m.rows-i+1, floor((m.cols - x) / 2) + j, true) m:setMeta(m.rows-i+1, floor((m.cols - x) / 2) + j, 'yellow') end end -- trunk trunk_data = {7,7,9,11} for i, x in ipairs(trunk_data) do for j = 1, x do m:setVisitable(m.rows-i-61, floor((m.cols - x) / 2) + j, true) m:setMeta(m.rows-i-61, floor((m.cols - x) / 2) + j, 'brown') end end -- snow for i = 1,5 do for j = 1, m.cols do m:setVisitable(i,j, true) m:setMeta(i,j, 'white') end end m:create({x=1, y=1}) m.cells[1][1].west = false m.cells[m.rows][ceil(m.cols/2)].north = false \end{luacode*} \tikzset{ crayon/.style={line width=0.1cm, line cap=round, draw=#1}, crayon/.default=none, sketch/.style={bend right, out=rand*10, in=180-rand*10} } \def\luaprint#1{\directlua{tex.print(#1)}} \def\ifluacondition#1#2#3{% \def\nexta{#2}\def\nextb{#3}% \csname if\directlua{tex.print(tostring(#1))}\endcsname% \let\next=\nexta% \else% \let\next=\nextb% \fi% \next% } \begin{document} \begin{tikzpicture}[show background rectangle, background rectangle/.style={fill=black!85}, >=stealth] \foreach \i in {1,...,\luaprint{m.rows}}{ \foreach \j in {1,...,\luaprint{m.cols}}{ % \tikzset{shift={(\j,\i)}} \edef\currentcolor{\luaprint{m:getMeta(\i,\j)}} \ifluacondition{m:isVisitable(\i,\j)}{ \begin{pgfonlayer}{before-background} \filldraw [\currentcolor!5!black] (0,0) rectangle (1,1); \end{pgfonlayer} }{ \pgfmathparse{int(random(1,10))} \ifnum\pgfmathresult=1 \shade [top color=white, bottom color=gray] (0.5+rand/4,0.5+rand/4) circle [radius=.125]; \fi } \ifluacondition{m.cells[\i][\j].north and not m:isVisitable(\i+1,\j)}{ \begin{pgfonlayer}{foreground} \shade [top color=white, bottom color=gray] (0,0.9) to [sketch] ++(1,0) arc (-90:90:.15) to [sketch] ++(-1,0) arc (90:270:.15); \end{pgfonlayer} }{} \ifluacondition{m.cells[\i][\j].south} {\draw [crayon=\currentcolor] (0,0) to [sketch] (1,0);}{} \ifluacondition{m.cells[\i][\j].west and not m:isVisitable(\i,\j-1)} {\draw [crayon=\currentcolor] (0,0) to [sketch] (0,1);}{} \ifluacondition{m.cells[\i][\j].east}% {\draw [crayon=\currentcolor] (1,0) to [sketch] (1,1);}{} }} \draw [crayon=red, line width=0.25cm, ->] (0,1.5) -- ++(1.5,0); \draw [crayon=red, line width=0.25cm, ->] (\luaprint{ceil(m.cols/2)}+.5,\luaprint{m.rows}+.5) -- ++(0,1.5); \end{tikzpicture} \end{document} 

\RequirePackage{luatex85} \documentclass[tikz,border=5]{standalone} \usetikzlibrary{backgrounds,arrows.meta} \pgfdeclarelayer{foreground} \pgfdeclarelayer{before-background} \pgfsetlayers{background,before-background,main,foreground} \usepackage{luacode} \begin{luacode*} floor = math.floor ceil = math.ceil Maze = {} Maze.__index = Maze Maze.NORTH = 90 Maze.SOUTH = 270 Maze.EAST = 0 Maze.WEST = 180 Maze.new = function(r, c) local i, j, row, cell local obj = {} setmetatable(obj, Maze) obj.rows = r obj.cols = c obj:reset() return obj end Maze.reset = function(self) local i, j, row, cell self.cells = {} for i = 1,self.rows do row = {} for j = 1,self.cols do cell = {visited=false, visitable=true, north=true,south=true,east=true, west=true, meta=''} table.insert(row, cell) end table.insert(self.cells, row) end end Maze.visitable = function(self, i, j) return self.cells[i] and self.cells[i][j] and self.cells[i][j].visitable end Maze.isVisitable = function(self, i, j) return self.cells[i] and self.cells[i][j] and self.cells[i][j].visitable end Maze.setVisitable = function(self, i, j, visitable) self.cells[i][j].visitable = visitable self.cells[i][j].north = visitable self.cells[i][j].south = visitable self.cells[i][j].east = visitable self.cells[i][j].west = visitable end Maze.getMeta = function(self, i, j) return self.cells[i][j].meta end Maze.setMeta = function(self, i, j, meta) self.cells[i][j].meta = meta end Maze.create = function(self, start) local n, N, x, y, a, b, k, stack N = self.rows * self.cols for i = 1,self.rows do for j = 1,self.cols do if not self.cells[i][j].visitable then N = N - 1 end end end start = start or {x=1, y=1} x, y = start.x, start.y stack = {} table.insert(stack, {x=x, y=y}) self.cells[y][x].visited = true visited = 1 while visited < N do x = stack[#stack].x y = stack[#stack].y n = {} if self:isVisitable(y+1, x) and not self.cells[y+1][x].visited then table.insert(n, Maze.NORTH) end if self:isVisitable(y-1, x) and not self.cells[y-1][x].visited then table.insert(n, Maze.SOUTH) end if self:isVisitable(y, x+1) and not self.cells[y][x+1].visited then table.insert(n, Maze.EAST) end if self:isVisitable(y, x-1) and not self.cells[y][x-1].visited then table.insert(n, Maze.WEST) end if #n == 0 then table.remove(stack) else k = n[math.random(#n)] if k == Maze.NORTH then a, b = x, y+1 self.cells[y][x].north = false self.cells[b][a].south = false elseif k == Maze.SOUTH then a, b = x, y-1 self.cells[y][x].south = false self.cells[b][a].north = false elseif k == Maze.EAST then a, b = x+1, y self.cells[y][x].east = false self.cells[b][a].west = false elseif k == Maze.WEST then a, b = x-1, y self.cells[y][x].west = false self.cells[b][a].east = false end table.insert(stack, {x=a, y=b}) self.cells[b][a].visited = true visited = visited + 1 end end end m = Maze.new(70,55) for i = 1,m.rows do for j = 1,m.cols do m:setVisitable(i, j, false) end end -- tree tree_data = {1,1,1,3,3,3,5,5,7,7,9,11,11,13,15,17,19,23,27,21, 13,15,17,17,19,21,23,27,29,33,25, 19,21,21,23,25,27,29,33,35,39,31,25, 23,25,27,29,31,33,35,37,41,45,37,31,21} for i, x in ipairs(tree_data) do for j = 1, x do m:setVisitable(m.rows-i-5, floor((m.cols - x) / 2) + j, true) m:setMeta(m.rows-i-5, floor((m.cols - x) / 2) + j, 'green') end end -- decorations c = floor(m.cols/2) colors = {'red', 'orange', 'purple'} ncolors = 3 for q = 0,3 do for j = c-15, c+15 do if j < c then k = 3 else k = 1.625 end for r = -1,1 do m:setMeta(floor((j - c) / k) + 15 + q * 10 + r, j, colors[math.random(ncolors)]) end end end -- star star_data = {1,1,1,3,3,5,9,15,9,5,3,3,1,1,1} for i, x in ipairs(star_data) do for j = 1, x do m:setVisitable(m.rows-i+1, floor((m.cols - x) / 2) + j, true) m:setMeta(m.rows-i+1, floor((m.cols - x) / 2) + j, 'yellow') end end -- trunk trunk_data = {7,7,9,11} for i, x in ipairs(trunk_data) do for j = 1, x do m:setVisitable(m.rows-i-61, floor((m.cols - x) / 2) + j, true) m:setMeta(m.rows-i-61, floor((m.cols - x) / 2) + j, 'brown') end end -- snow for i = 1,5 do for j = 1, m.cols do m:setVisitable(i,j, true) m:setMeta(i,j, 'white') end end m:create({x=1, y=1}) m.cells[1][1].west = false m.cells[m.rows][ceil(m.cols/2)].north = false \end{luacode*} \tikzset{ crayon/.style={line width=0.1cm, line cap=round, draw=#1}, crayon/.default=none, sketch/.style={bend right, out=rand*10, in=180-rand*10} } \def\luaprint#1{\directlua{tex.print(#1)}} \def\ifluacondition#1#2#3{% \def\nexta{#2}\def\nextb{#3}% \csname if\directlua{tex.print(tostring(#1))}\endcsname% \let\next=\nexta% \else% \let\next=\nextb% \fi% \next% } \begin{document} \begin{tikzpicture}[show background rectangle, background rectangle/.style={fill=black!85}, >=stealth] \foreach \i in {1,...,\luaprint{m.rows}}{ \foreach \j in {1,...,\luaprint{m.cols}}{ % \tikzset{shift={(\j,\i)}} \edef\currentcolor{\luaprint{m:getMeta(\i,\j)}} \ifluacondition{m:isVisitable(\i,\j)}{ \begin{pgfonlayer}{before-background} \filldraw [\currentcolor!5!black] (0,0) rectangle (1,1); \end{pgfonlayer} }{ \pgfmathparse{int(random(1,10))} \ifnum\pgfmathresult=1 \shade [top color=white, bottom color=gray] (0.5+rand/4,0.5+rand/4) circle [radius=.125]; \fi } \ifluacondition{m.cells[\i][\j].north and not m:isVisitable(\i+1,\j)}{ \begin{pgfonlayer}{foreground} \shade [top color=white, bottom color=gray] (0,0.9) to [sketch] ++(1,0) arc (-90:90:.15) to [sketch] ++(-1,0) arc (90:270:.15); \end{pgfonlayer} }{} \ifluacondition{m.cells[\i][\j].south} {\draw [crayon=\currentcolor] (0,0) to [sketch] (1,0);}{} \ifluacondition{m.cells[\i][\j].west and not m:isVisitable(\i,\j-1)} {\draw [crayon=\currentcolor] (0,0) to [sketch] (0,1);}{} \ifluacondition{m.cells[\i][\j].east}% {\draw [crayon=\currentcolor] (1,0) to [sketch] (1,1);}{} }} \draw [crayon=red, line width=0.25cm, ->] (0,1.5) -- ++(1.5,0); \draw [crayon=red, line width=0.25cm, ->] (\luaprint{ceil(m.cols/2)}+.5,\luaprint{m.rows}+.5) -- ++(0,1.5); \end{tikzpicture} \end{document} 

Here's a Christmas tree for 2015:

A bit late, but here's a simple Christmas tree for 2016:

\documentclass[border=5]{standalone} \usepackage{tikz} \newbox\stereogrambox \pgfmathdeclarerandomlist{colors}{{red}{green!50!black}{green}{white}{blue}} \begin{document} \setbox\stereogrambox=\hbox{% \begin{tikzpicture}[x=1/2pt,y=1/2pt] \foreach \x in {0,...,95} \foreach \y in {0,...,119}{ \pgfmathrandomitem\c{colors} \fill [fill=\c] (\x,\y) rectangle ++(1,1); } \end{tikzpicture}}% \begin{tikzpicture}[x=1pt,y=1pt, stereogram node/.style={inner sep=0, outer sep=0, anchor=south, fill=white, execute at begin node=\copy\stereogrambox }] \foreach \x in {0,...,1} \node [stereogram node] at (\x*52, 0) {}; \clip [shift={(0, 4)}] (0,0) -- (-4,0) -- (-4,4) -- (-18,4) -- (0,52) -- (18,4) -- (4,4) -- (4,0) -- cycle; \node [stereogram node] at (2, 0) {}; \end{tikzpicture} \end{document} 

And here's a Christmas tree for 2015:

Here's an invisible tree.

Here's a Christmas tree for 2015:

\documentclass[tikz,border=5]{standalone} \usetikzlibrary{backgrounds,arrows.meta} \pgfdeclarelayer{foreground} \pgfdeclarelayer{before-background} \pgfsetlayers{background,before-background,main,foreground} \usepackage{luacode} \begin{luacode*} floor = math.floor ceil = math.ceil Maze = {} Maze.__index = Maze Maze.NORTH = 90 Maze.SOUTH = 270 Maze.EAST = 0 Maze.WEST = 180 Maze.new = function(r, c) local i, j, row, cell local obj = {} setmetatable(obj, Maze) obj.rows = r obj.cols = c obj:reset() return obj end Maze.reset = function(self) local i, j, row, cell self.cells = {} for i = 1,self.rows do row = {} for j = 1,self.cols do cell = {visited=false, visitable=true, north=true,south=true,east=true, west=true, meta=''} table.insert(row, cell) end table.insert(self.cells, row) end end Maze.visitable = function(self, i, j) return self.cells[i] and self.cells[i][j] and self.cells[i][j].visitable end Maze.isVisitable = function(self, i, j) return self.cells[i] and self.cells[i][j] and self.cells[i][j].visitable end Maze.setVisitable = function(self, i, j, visitable) self.cells[i][j].visitable = visitable self.cells[i][j].north = visitable self.cells[i][j].south = visitable self.cells[i][j].east = visitable self.cells[i][j].west = visitable end Maze.getMeta = function(self, i, j) return self.cells[i][j].meta end Maze.setMeta = function(self, i, j, meta) self.cells[i][j].meta = meta end Maze.create = function(self, start) local n, N, x, y, a, b, k, stack N = self.rows * self.cols for i = 1,self.rows do for j = 1,self.cols do if not self.cells[i][j].visitable then N = N - 1 end end end start = start or {x=1, y=1} x, y = start.x, start.y stack = {} table.insert(stack, {x=x, y=y}) self.cells[y][x].visited = true visited = 1 while visited < N do x = stack[#stack].x y = stack[#stack].y n = {} if self:isVisitable(y+1, x) and not self.cells[y+1][x].visited then table.insert(n, Maze.NORTH) end if self:isVisitable(y-1, x) and not self.cells[y-1][x].visited then table.insert(n, Maze.SOUTH) end if self:isVisitable(y, x+1) and not self.cells[y][x+1].visited then table.insert(n, Maze.EAST) end if self:isVisitable(y, x-1) and not self.cells[y][x-1].visited then table.insert(n, Maze.WEST) end if #n == 0 then table.remove(stack) else k = n[math.random(#n)] if k == Maze.NORTH then a, b = x, y+1 self.cells[y][x].north = false self.cells[b][a].south = false elseif k == Maze.SOUTH then a, b = x, y-1 self.cells[y][x].south = false self.cells[b][a].north = false elseif k == Maze.EAST then a, b = x+1, y self.cells[y][x].east = false self.cells[b][a].west = false elseif k == Maze.WEST then a, b = x-1, y self.cells[y][x].west = false self.cells[b][a].east = false end table.insert(stack, {x=a, y=b}) self.cells[b][a].visited = true visited = visited + 1 end end end m = Maze.new(70,55) for i = 1,m.rows do for j = 1,m.cols do m:setVisitable(i, j, false) end end -- tree tree_data = {1,1,1,3,3,3,5,5,7,7,9,11,11,13,15,17,19,23,27,21, 13,15,17,17,19,21,23,27,29,33,25, 19,21,21,23,25,27,29,33,35,39,31,25, 23,25,27,29,31,33,35,37,41,45,37,31,21} for i, x in ipairs(tree_data) do for j = 1, x do m:setVisitable(m.rows-i-5, floor((m.cols - x) / 2) + j, true) m:setMeta(m.rows-i-5, floor((m.cols - x) / 2) + j, 'green') end end -- decorations c = floor(m.cols/2) colors = {'red', 'orange', 'purple'} ncolors = 3 for q = 0,3 do for j = c-15, c+15 do if j < c then k = 3 else k = 1.625 end for r = -1,1 do m:setMeta(floor((j - c) / k) + 15 + q * 10 + r, j, colors[math.random(ncolors)]) end end end -- star star_data = {1,1,1,3,3,5,9,15,9,5,3,3,1,1,1} for i, x in ipairs(star_data) do for j = 1, x do m:setVisitable(m.rows-i+1, floor((m.cols - x) / 2) + j, true) m:setMeta(m.rows-i+1, floor((m.cols - x) / 2) + j, 'yellow') end end -- trunk trunk_data = {7,7,9,11} for i, x in ipairs(trunk_data) do for j = 1, x do m:setVisitable(m.rows-i-61, floor((m.cols - x) / 2) + j, true) m:setMeta(m.rows-i-61, floor((m.cols - x) / 2) + j, 'brown') end end -- snow for i = 1,5 do for j = 1, m.cols do m:setVisitable(i,j, true) m:setMeta(i,j, 'white') end end m:create({x=1, y=1}) m.cells[1][1].west = false m.cells[m.rows][ceil(m.cols/2)].north = false \end{luacode*} \tikzset{ crayon/.style={line width=0.1cm, line cap=round, draw=#1}, crayon/.default=none, sketch/.style={bend right, out=rand*10, in=180-rand*10} } \def\luaprint#1{\directlua{tex.print(#1)}} \def\ifluacondition#1#2#3{% \def\nexta{#2}\def\nextb{#3}% \csname if\directlua{tex.print(tostring(#1))}\endcsname% \let\next=\nexta% \else% \let\next=\nextb% \fi% \next% } \begin{document} \begin{tikzpicture}[show background rectangle, background rectangle/.style={fill=black!85}, >=stealth] \foreach \i in {1,...,\luaprint{m.rows}}{ \foreach \j in {1,...,\luaprint{m.cols}}{ % \tikzset{shift={(\j,\i)}} \edef\currentcolor{\luaprint{m:getMeta(\i,\j)}} \ifluacondition{m:isVisitable(\i,\j)}{ \begin{pgfonlayer}{before-background} \filldraw [\currentcolor!5!black] (0,0) rectangle (1,1); \end{pgfonlayer} }{ \pgfmathparse{int(random(1,10))} \ifnum\pgfmathresult=1 \shade [top color=white, bottom color=gray] (0.5+rand/4,0.5+rand/4) circle [radius=.125]; \fi } \ifluacondition{m.cells[\i][\j].north and not m:isVisitable(\i+1,\j)}{ \begin{pgfonlayer}{foreground} \shade [top color=white, bottom color=gray] (0,0.9) to [sketch] ++(1,0) arc (-90:90:.15) to [sketch] ++(-1,0) arc (90:270:.15); \end{pgfonlayer} }{} \ifluacondition{m.cells[\i][\j].south} {\draw [crayon=\currentcolor] (0,0) to [sketch] (1,0);}{} \ifluacondition{m.cells[\i][\j].west and not m:isVisitable(\i,\j-1)} {\draw [crayon=\currentcolor] (0,0) to [sketch] (0,1);}{} \ifluacondition{m.cells[\i][\j].east}% {\draw [crayon=\currentcolor] (1,0) to [sketch] (1,1);}{} }} \draw [crayon=red, line width=0.25cm, ->] (0,1.5) -- ++(1.5,0); \draw [crayon=red, line width=0.25cm, ->] (\luaprint{ceil(m.cols/2)}+.5,\luaprint{m.rows}+.5) -- ++(0,1.5); \end{tikzpicture} \end{document} 

And here's an invisible tree from a couple of years ago.