2013-10-02 10:00:03 -06:00
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-- Generates an image using multiple octaves of perlin noise.
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2015-11-04 05:14:10 -07:00
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--[[=begin
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devel/test-perlin
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=================
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Generates an image using multiple octaves of perlin noise.
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Used by `3dveins`?
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=end]]
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2013-10-02 10:00:03 -06:00
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local args = {...}
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local rng = dfhack.random.new(3)
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if #args < 3 then
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2013-10-09 10:56:46 -06:00
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qerror('Usage: devel/test-perlin <fname.pgm> <density> <expr> [-xy <xyscale>] [-z <zscale>]')
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2013-10-02 10:00:03 -06:00
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end
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local fname = table.remove(args,1)
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local goal = tonumber(table.remove(args,1)) or qerror('Invalid density')
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2013-10-09 10:56:46 -06:00
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local expr = table.remove(args,1) or qerror('No expression')
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local zscale = 2
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local xyscale = 1
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2013-10-02 10:00:03 -06:00
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2013-10-09 10:56:46 -06:00
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for i = 1,#args,2 do
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if args[i] == '-xy' then
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xyscale = tonumber(args[i+1]) or qerror('Invalid xyscale')
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end
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if args[i] == '-z' then
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zscale = tonumber(args[i+1]) or qerror('Invalid zscale')
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end
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end
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2013-10-02 10:00:03 -06:00
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2013-10-09 10:56:46 -06:00
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local fn_env = copyall(math)
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fn_env.rng = rng
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fn_env.apow = function(x,y) return math.pow(math.abs(x),y) end
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fn_env.spow = function(x,y) return x*math.pow(math.abs(x),y-1) end
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-- Noise functions are referenced from expressions
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-- as variables of form like "x3a", where:
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-- 1) x is one of x/y/z/w independent functions in each octave
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-- 2) 3 is the octave number; 0 corresponds to the whole range
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-- 3) a is the subtype
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-- Independent noise functions: support 4
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local ids = { 'x', 'y', 'z', 'w' }
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-- Subtype: provides an offset to the coordinates
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local subs = {
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[''] = { 0, 0, 0 },
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a = { 0.5, 0, 0 },
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b = { 0, 0.5, 0 },
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c = { 0.5, 0.5, 0 },
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d = { 0, 0, 0.5 },
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e = { 0.5, 0, 0.5 },
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f = { 0, 0.5, 0.5 },
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g = { 0.5, 0.5, 0.5 },
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}
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function mkdelta(v)
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if v == 0 then
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return ''
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else
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return '+'..v
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end
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end
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2013-10-02 10:00:03 -06:00
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2013-10-09 10:56:46 -06:00
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function mkexpr(expr)
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-- Collect referenced variables
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local max_octave = -1
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local vars = {}
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2013-10-02 10:00:03 -06:00
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2013-10-09 10:56:46 -06:00
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for var,id,octave,subtype in string.gmatch(expr,'%f[%w](([xyzw])(%d+)(%a*))%f[^%w]') do
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if not vars[var] then
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octave = tonumber(octave)
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2013-10-02 10:00:03 -06:00
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2013-10-09 10:56:46 -06:00
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if octave > max_octave then
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max_octave = octave
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2013-10-02 10:00:03 -06:00
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end
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2013-10-09 10:56:46 -06:00
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local sub = subs[subtype] or qerror('Invalid subtype: '..subtype)
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vars[var] = { id = id, octave = octave, subtype = subtype, sub = sub }
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2013-10-02 10:00:03 -06:00
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end
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2013-10-09 10:56:46 -06:00
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end
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if max_octave < 0 then
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qerror('No noise function references in expression.')
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end
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2013-10-02 10:00:03 -06:00
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2013-10-09 10:56:46 -06:00
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-- Allocate the noise functions
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local code = ''
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for i = 0,max_octave do
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for j,id in ipairs(ids) do
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code = code .. 'local _fn_'..i..'_'..id..' = rng:perlin(3)\n';
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2013-10-02 10:00:03 -06:00
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end
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end
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2013-10-09 10:56:46 -06:00
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-- Evaluate variables
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code = code .. 'return function(x,y,z)\n'
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for var,info in pairs(vars) do
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local fn = '_fn_'..info.octave..'_'..info.id
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local mul = math.pow(2,info.octave)
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mul = math.min(48*4, mul)
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code = code .. ' local '..var
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.. ' = _fn_'..info.octave..'_'..info.id
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.. '(x*'..mul..mkdelta(info.sub[1])
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.. ',y*'..mul..mkdelta(info.sub[2])
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.. ',z*'..mul..mkdelta(info.sub[3])
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.. ')\n'
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end
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-- Complete and compile the function
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code = code .. ' return ('..expr..')\nend\n'
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local f,err = load(code, '=(expr)', 't', fn_env)
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if not f then
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qerror(err)
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end
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return f()
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2013-10-02 10:00:03 -06:00
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end
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2013-10-09 10:56:46 -06:00
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local field_fn = mkexpr(expr)
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2013-10-02 10:00:03 -06:00
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function render(thresh,file)
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local area = 0
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local line, arr = '', {}
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for zy = 0,1 do
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for y = 0,48*4-1 do
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line = ''
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for zx = 0,1 do
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for x = 0,48*4-1 do
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2013-10-09 10:56:46 -06:00
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local tx = (0.5+x)/(48*4/xyscale)
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local ty = (0.5+y)/(48*4/xyscale)
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local tz = 0.3+(zx+zy*2)/(48*4/zscale)
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local v1 = field_fn(tx, ty, tz)
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2013-10-02 10:00:03 -06:00
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local v = -1
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if v1 > thresh then
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v = v1;
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area = area + 1
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end
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if file then
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local c = math.max(0, math.min(255, v * 127 + 128))
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arr[2*x+1] = c
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arr[2*x+2] = c
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end
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end
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if file then
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line = line..string.char(table.unpack(arr))
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end
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end
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if file then
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file:write(line,line)
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end
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end
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end
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return area/4/(48*4)/(48*4)
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end
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function search(fn,min,max,goal,eps)
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2013-10-09 10:56:46 -06:00
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local center
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for i = 1,32 do
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center = (max+min)/2
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2013-10-02 10:00:03 -06:00
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local cval = fn(center)
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print('At '..center..': '..cval)
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if math.abs(cval-goal) < eps then
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2013-10-09 10:56:46 -06:00
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break
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2013-10-02 10:00:03 -06:00
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end
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if cval > goal then
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min = center
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else
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max = center
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end
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end
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2013-10-09 10:56:46 -06:00
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return center
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2013-10-02 10:00:03 -06:00
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end
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2013-10-09 10:56:46 -06:00
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local thresh = search(render, -2, 2, goal, math.min(0.001,goal/20))
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2013-10-02 10:00:03 -06:00
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local file,err = io.open(fname, 'wb')
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if not file then
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print('error: ',err)
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return
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end
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2013-10-09 10:56:46 -06:00
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file:write('P5\n')
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file:write('# '..goal..' '..expr..' '..xyscale..' '..zscale..'\n')
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file:write('768 768\n255\n')
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2013-10-02 10:00:03 -06:00
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local area = render(thresh, file)
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file:close()
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print('Area fraction: '..area)
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