dfhack/scripts/devel/test-perlin.lua

133 lines
3.5 KiB
Lua

-- Generates an image using multiple octaves of perlin noise.
local args = {...}
local rng = dfhack.random.new(3)
if #args < 3 then
qerror('Usage: devel/test-perlin <fname.pgm> <density> <coeff|expr...x[...y[...z]]>...')
end
local fname = table.remove(args,1)
local goal = tonumber(table.remove(args,1)) or qerror('Invalid density')
local zscale = 6
local coeffs = {}
local fns = {}
local env = copyall(math)
env.apow = function(x,y) return math.pow(math.abs(x),y) end
for i = 1,#args do
local fn = rng:perlin(3);
local fn2 = rng:perlin(3);
local fn3 = rng:perlin(3);
local fn4 = rng:perlin(3);
fns[i] = fn;
local val = string.match(args[i],'^([+-]?[%d.]+)$')
if val then
coeffs[i] = function(x) return x * val end
else
local argstr = 'x'
if string.match(args[i], '%f[%w]w%f[^%w]') then
argstr = 'x,y,z,w'
fns[i] = function(x,y,z)
return fn(x,y,z), fn2(x,y,z), fn3(x+0.5,y+0.5,z+0.5), fn4(x+0.5,y+0.5,z+0.5)
end
elseif string.match(args[i], '%f[%w]z%f[^%w]') then
argstr = 'x,y,z'
fns[i] = function(x,y,z)
return fn(x,y,z), fn2(x,y,z), fn3(x+0.5,y+0.5,z+0.5)
end
elseif string.match(args[i], '%f[%w]y%f[^%w]') then
argstr = 'x,y'
fns[i] = function(x,y,z)
return fn(x,y,z), fn2(x,y,z)
end
end
local f,err = load(
'return function('..argstr..') return ('..args[i]..') end',
'=(expr)', 't', env
)
if not f then
qerror(err)
end
coeffs[i] = f()
end
end
function render(thresh,file)
local area = 0
local line, arr = '', {}
for zy = 0,1 do
for y = 0,48*4-1 do
line = ''
for zx = 0,1 do
for x = 0,48*4-1 do
local tx = (0.5+x)/(48*2)
local ty = (0.5+y)/(48*2)
local tz = 0.5+(zx+zy*2)/(48*2/zscale)
local v1 = 0
for i = 1,#coeffs do
v1 = v1 + coeffs[i](fns[i](tx,ty,tz))
tx = tx*2
ty = ty*2
tz = tz*2
end
local v = -1
if v1 > thresh then
v = v1;
area = area + 1
end
if file then
local c = math.max(0, math.min(255, v * 127 + 128))
arr[2*x+1] = c
arr[2*x+2] = c
end
end
if file then
line = line..string.char(table.unpack(arr))
end
end
if file then
file:write(line,line)
end
end
end
return area/4/(48*4)/(48*4)
end
function search(fn,min,max,goal,eps)
while true do
local center = (max+min)/2
local cval = fn(center)
print('At '..center..': '..cval)
if math.abs(cval-goal) < eps then
return center
end
if cval > goal then
min = center
else
max = center
end
end
end
local thresh = search(render, -1, 1, goal, 0.001)
local file,err = io.open(fname, 'wb')
if not file then
print('error: ',err)
return
end
file:write('P5\n768 768\n255\n')
local area = render(thresh, file)
file:close()
print('Area fraction: '..area)