temperature affected by latitude, non-linearly

this is like from 2 days ago but i forgot to commit it

ReadMe.md

@@ -0,0 +1,29 @@
+# OrangeDream
+Eventually, it's supposed to be a survival/crafting game with space travel. Hence why it's world-shaped.
+
+Using the heightmap generator from here: https://github.com/TangentFoxy/heightmap
+
+## Tasks
+- [ ] Make a GitHub mirror for this repo.
+- [ ] Remove heightmap library
+  - [ ] Update ReadMe
+  - [ ] ReadMe should also point out where the simplex implementation comes from
+- [x] Update the `simplex` library to the latest version with FBM
+- [x] Round the new map generator to a planet shape
+- [ ] Move `tile_size` out of the map generator (this is a render feature, not a map feature)
+- [x] Turn the new map gen into a wrapper kind of like my heightmap wrapper? (This is sorta already done in a sloppy way.)
+- [ ] Rebuild the multi-noise map system.
+  - [ ] Renormalize to Earth extremes. :D (This will probably give bad initial results and need extensive changes.)
+  - [x] Use a spreadsheet to map -0.9 to 0.9 to find a mapping function to modify initial values to realistic height ranges!
+    (This was done with -1 to 1)
+  - [x] Rename `humidity` to `rainfall`.
+- [ ] make documentation of how this is all working so I can remember when I forget to work on it for a while
+
+### Long-Term
+- [ ] Do all terrain generation within a radius check so unnecessary work isn't done and discarded.
+  - [ ] Terrain generation steps should happen within a single loop wherever possible?
+
+## Reference
+- Out of 52 seeds randomly tested, the current code creates a temperature range between -80.64 and 33.78 C.
+
+(Tasks/Issues are stored in the ReadMe instead of using a webUI issue tracker due to how using such a tracker negatively influences portability of the project.)

disorganized biome notes.txt

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+DDG summary:
+aquatic -> freshwater / marine,
+grassland (2nd largest?),
+forest -> tropical / temperate,
+desert,
+tundra,
+
+---
+
+Wikipedia:
+ice sheet / polar desert,
+tundra (tree growth hindered by cold and short growing seasons; arctic, alpine, antarctic; shrubs, grasses, mosses, lichen; soil high N & P, biomass, methane, CO2, permafrost),
+taiga (boreal forest, snow forest, coniferous forest; pines, spruces, larches; largest land biome),
+temperate broadleaf forest,
+temperate steppe and savanna,
+subtropical evergreen forest,
+Mediterranean vegetation,
+monsoon forests and mosaic,
+arid desert,
+xeric shrubland,
+dry steppe and thorn forest,
+semiarid desert,
+grass savanna,
+tree savanna,
+dry forest and woodland savanna,
+tropical rainforest (evergreen?),
+alpine tundra,
+montane forests and grasslands,
+- what variables control whether it develops a forest or grassland?
+
+alts:
+deciduous forest (not evergreen - can be cold or dry to cause leaves to fall; trees, shrubs, perennials),
+high plateaus (flat raised plains),
+
+---
+
+savanna seems to just mean grassland with some shrubs and trees? (dry)
+steppe is grasslands with NO trees (dry, often cold)
+meadow is wet grasslands
+hypoxic / anoxic waters FORM dead zones (nutrient concentration -> bloom, low water movement, high temperature; deepest waters?), gyre centers (ocean currents)
+- use of absolute deepest water as a shortcut should be fine,
+- use of highest temperature in water would also be a decent shortcut
+
+("continentalness" may be useful)
+
+tropical just means low latitude - these are small
+montane just means mountain
+
+(one mm of rainfall == 1 L/m^3)
+
+---
+
+coastal forest? (tropical moist broadleaf)
+montanes are often forested?
+what's the difference between a swamp and marsh? and bog?
+I should sprinkle volcanoes in (but that would work better with some kind of fault sim)
+- these form jungle/forest easier? more nutrients in soil
+what's a moorland?
+jungle vs rainforest?
+
+rifts and rivers?
+temperature should decrease by 0.0065 per meter (but this only holds above water?)

src/lib/running_average.lua

@@ -0,0 +1,27 @@
+local running_average = {
+  trackers = {}
+}
+
+local trackers = running_average.trackers
+
+running_average.track = function(name, value)
+  if not trackers[name] then
+    trackers[name] = { running_total = 0, count = 0, }
+  end
+  local track = trackers[name]
+
+  track.running_total = track.running_total + value
+  track.count = track.count + 1
+
+  return track.running_total / track.count
+end
+
+running_average.average = function(name)
+  return trackers[name] and trackers[name].running_total / trackers[name].count
+end
+
+running_average.count = function(name)
+  return trackers[name] and trackers[name].count
+end
+
+return running_average

src/lib/simplex.lua

@@ -0,0 +1,576 @@
+-----------------------------------------------
+---Simplex Noise
+-- Original Java Source: http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
+-- (most) Original comments included
+-----------------------------------------------
+
+local math = math
+local table = table
+local tonumber = tonumber
+local ipairs = ipairs
+local error = error
+
+local simplex = {}
+
+simplex.DIR_X = 0
+simplex.DIR_Y = 1
+simplex.DIR_Z = 2
+simplex.DIR_W = 3
+simplex.internalCache = false
+
+
+local Gradients3D = {{1,1,0},{-1,1,0},{1,-1,0},{-1,-1,0},
+{1,0,1},{-1,0,1},{1,0,-1},{-1,0,-1},
+{0,1,1},{0,-1,1},{0,1,-1},{0,-1,-1}};
+local Gradients4D = {{0,1,1,1}, {0,1,1,-1}, {0,1,-1,1}, {0,1,-1,-1},
+{0,-1,1,1}, {0,-1,1,-1}, {0,-1,-1,1}, {0,-1,-1,-1},
+{1,0,1,1}, {1,0,1,-1}, {1,0,-1,1}, {1,0,-1,-1},
+{-1,0,1,1}, {-1,0,1,-1}, {-1,0,-1,1}, {-1,0,-1,-1},
+{1,1,0,1}, {1,1,0,-1}, {1,-1,0,1}, {1,-1,0,-1},
+{-1,1,0,1}, {-1,1,0,-1}, {-1,-1,0,1}, {-1,-1,0,-1},
+{1,1,1,0}, {1,1,-1,0}, {1,-1,1,0}, {1,-1,-1,0},
+{-1,1,1,0}, {-1,1,-1,0}, {-1,-1,1,0}, {-1,-1,-1,0}};
+local p = {151,160,137,91,90,15,
+131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
+190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
+88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
+77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
+102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
+135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
+5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
+223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
+129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
+251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
+49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
+138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180};
+
+-- To remove the need for index wrapping, double the permutation table length
+
+for i=1,#p do
+	p[i-1] = p[i]
+	p[i] = nil
+end
+
+for i=1,#Gradients3D do
+	Gradients3D[i-1] = Gradients3D[i]
+	Gradients3D[i] = nil
+end
+
+for i=1,#Gradients4D do
+	Gradients4D[i-1] = Gradients4D[i]
+	Gradients4D[i] = nil
+end
+
+local perm = {}
+
+for i=0,255 do
+	perm[i] = p[i]
+	perm[i+256] = p[i]
+end
+
+-- A lookup table to traverse the sim around a given point in 4D.
+-- Details can be found where this table is used, in the 4D noise method.
+
+local sim = {
+{0,1,2,3},{0,1,3,2},{0,0,0,0},{0,2,3,1},{0,0,0,0},{0,0,0,0},{0,0,0,0},{1,2,3,0},
+{0,2,1,3},{0,0,0,0},{0,3,1,2},{0,3,2,1},{0,0,0,0},{0,0,0,0},{0,0,0,0},{1,3,2,0},
+{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},
+{1,2,0,3},{0,0,0,0},{1,3,0,2},{0,0,0,0},{0,0,0,0},{0,0,0,0},{2,3,0,1},{2,3,1,0},
+{1,0,2,3},{1,0,3,2},{0,0,0,0},{0,0,0,0},{0,0,0,0},{2,0,3,1},{0,0,0,0},{2,1,3,0},
+{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},{0,0,0,0},
+{2,0,1,3},{0,0,0,0},{0,0,0,0},{0,0,0,0},{3,0,1,2},{3,0,2,1},{0,0,0,0},{3,1,2,0},
+{2,1,0,3},{0,0,0,0},{0,0,0,0},{0,0,0,0},{3,1,0,2},{0,0,0,0},{3,2,0,1},{3,2,1,0}};
+
+local function Dot2D(tbl, x, y)
+	return tbl[1]*x + tbl[2]*y;
+end
+
+local function Dot3D(tbl, x, y, z)
+	return tbl[1]*x + tbl[2]*y + tbl[3]*z
+end
+
+local function Dot4D( tbl, x,y,z,w)
+	return tbl[1]*x + tbl[2]*y + tbl[3]*z + tbl[3]*w;
+end
+
+local Prev2D = {}
+
+
+-- 2D simplex noise
+
+function simplex.Noise2D(xin, yin)
+	if simplex.internalCache and Prev2D[xin] and Prev2D[xin][yin] then return Prev2D[xin][yin] end
+
+	local n0, n1, n2; -- Noise contributions from the three corners
+	-- Skew the input space to determine which simplex cell we're in
+	local F2 = 0.5*(math.sqrt(3.0)-1.0);
+	local s = (xin+yin)*F2; -- Hairy factor for 2D
+	local i = math.floor(xin+s);
+	local j = math.floor(yin+s);
+	local G2 = (3.0-math.sqrt(3.0))/6.0;
+
+	local t = (i+j)*G2;
+	local X0 = i-t; -- Unskew the cell origin back to (x,y) space
+	local Y0 = j-t;
+	local x0 = xin-X0; -- The x,y distances from the cell origin
+	local y0 = yin-Y0;
+
+	-- For the 2D case, the simplex shape is an equilateral triangle.
+	-- Determine which simplex we are in.
+	local i1, j1; -- Offsets for second (middle) corner of simplex in (i,j) coords
+	if(x0>y0) then
+		i1=1
+		j1=0  -- lower triangle, XY order: (0,0)->(1,0)->(1,1)
+	else
+		i1=0
+		j1=1 -- upper triangle, YX order: (0,0)->(0,1)->(1,1)
+	end
+
+	-- A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
+	-- a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
+	-- c = (3-sqrt(3))/6
+
+	local x1 = x0 - i1 + G2; -- Offsets for middle corner in (x,y) unskewed coords
+	local y1 = y0 - j1 + G2;
+	local x2 = x0 - 1.0 + 2.0 * G2; -- Offsets for last corner in (x,y) unskewed coords
+	local y2 = y0 - 1.0 + 2.0 * G2;
+
+	-- Work out the hashed gradient indices of the three simplex corners
+	local ii = math.floor(i % 255)
+	local jj = math.floor(j % 255)
+	local gi0 = perm[ii+perm[jj]] % 12;
+	local gi1 = perm[ii+i1+perm[jj+j1]] % 12;
+	local gi2 = perm[ii+1+perm[jj+1]] % 12;
+
+	-- Calculate the contribution from the three corners
+	local t0 = 0.5 - x0*x0-y0*y0;
+	if t0<0 then
+		n0 = 0.0;
+	else
+		t0 = t0 * t0
+		n0 = t0 * t0 * Dot2D(Gradients3D[gi0], x0, y0); -- (x,y) of Gradients3D used for 2D gradient
+	end
+
+	local t1 = 0.5 - x1*x1-y1*y1;
+	if (t1<0) then
+		n1 = 0.0;
+	else
+		t1 = t1*t1
+		n1 = t1 * t1 * Dot2D(Gradients3D[gi1], x1, y1);
+	end
+
+	local t2 = 0.5 - x2*x2-y2*y2;
+	if (t2<0) then
+		n2 = 0.0;
+	else
+		t2 = t2*t2
+		n2 = t2 * t2 * Dot2D(Gradients3D[gi2], x2, y2);
+	end
+
+
+	-- Add contributions from each corner to get the final noise value.
+	-- The result is scaled to return values in the localerval [-1,1].
+
+	local retval = 70.0 * (n0 + n1 + n2)
+
+	if simplex.internalCache then
+		if not Prev2D[xin] then Prev2D[xin] = {} end
+		Prev2D[xin][yin] = retval
+	end
+
+	return retval;
+end
+
+local Prev3D = {}
+
+-- 3D simplex noise
+function simplex.Noise3D(xin, yin, zin)
+
+	if simplex.internalCache and Prev3D[xin] and Prev3D[xin][yin] and Prev3D[xin][yin][zin] then return Prev3D[xin][yin][zin] end
+
+	local n0, n1, n2, n3; -- Noise contributions from the four corners
+
+	-- Skew the input space to determine which simplex cell we're in
+	local F3 = 1.0/3.0;
+	local s = (xin+yin+zin)*F3; -- Very nice and simple skew factor for 3D
+	local i = math.floor(xin+s);
+	local j = math.floor(yin+s);
+	local k = math.floor(zin+s);
+
+	local G3 = 1.0/6.0; -- Very nice and simple unskew factor, too
+	local t = (i+j+k)*G3;
+
+	local X0 = i-t; -- Unskew the cell origin back to (x,y,z) space
+	local Y0 = j-t;
+	local Z0 = k-t;
+
+	local x0 = xin-X0; -- The x,y,z distances from the cell origin
+	local y0 = yin-Y0;
+	local z0 = zin-Z0;
+
+	-- For the 3D case, the simplex shape is a slightly irregular tetrahedron.
+	-- Determine which simplex we are in.
+	local i1, j1, k1; -- Offsets for second corner of simplex in (i,j,k) coords
+	local i2, j2, k2; -- Offsets for third corner of simplex in (i,j,k) coords
+
+	if (x0>=y0) then
+		if (y0>=z0) then
+			i1=1; j1=0; k1=0; i2=1; j2=1; k2=0; -- X Y Z order
+		elseif (x0>=z0) then
+			i1=1; j1=0; k1=0; i2=1; j2=0; k2=1; -- X Z Y order
+		else
+			i1=0; j1=0; k1=1; i2=1; j2=0; k2=1;  -- Z X Y order
+		end
+	else -- x0<y0
+		if (y0<z0) then
+			i1=0; j1=0; k1=1; i2=0; j2=1; k2=1; -- Z Y X order
+		elseif (x0<z0) then
+			i1=0; j1=1; k1=0; i2=0; j2=1; k2=1; -- Y Z X order
+		else
+			i1=0; j1=1; k1=0; i2=1; j2=1; k2=0; -- Y X Z order
+		end
+	end
+
+	-- A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
+	-- a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
+	-- a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
+	-- c = 1/6.
+
+	local x1 = x0 - i1 + G3; -- Offsets for second corner in (x,y,z) coords
+	local y1 = y0 - j1 + G3;
+	local z1 = z0 - k1 + G3;
+
+	local x2 = x0 - i2 + 2.0*G3; -- Offsets for third corner in (x,y,z) coords
+	local y2 = y0 - j2 + 2.0*G3;
+	local z2 = z0 - k2 + 2.0*G3;
+
+	local x3 = x0 - 1.0 + 3.0*G3; -- Offsets for last corner in (x,y,z) coords
+	local y3 = y0 - 1.0 + 3.0*G3;
+	local z3 = z0 - 1.0 + 3.0*G3;
+
+	-- Work out the hashed gradient indices of the four simplex corners
+	local ii = math.floor(i % 255)
+	local jj = math.floor(j % 255)
+	local kk = math.floor(k % 255)
+
+	local gi0 = perm[ii+perm[jj+perm[kk]]] % 12;
+	local gi1 = perm[ii+i1+perm[jj+j1+perm[kk+k1]]] % 12;
+	local gi2 = perm[ii+i2+perm[jj+j2+perm[kk+k2]]] % 12;
+	local gi3 = perm[ii+1+perm[jj+1+perm[kk+1]]] % 12;
+
+	-- Calculate the contribution from the four corners
+	local t0 = 0.5 - x0*x0 - y0*y0 - z0*z0;
+
+	if (t0<0) then
+		n0 = 0.0;
+	else
+		t0 = t0*t0;
+		n0 = t0 * t0 * Dot3D(Gradients3D[gi0], x0, y0, z0);
+	end
+
+	local t1 = 0.5 - x1*x1 - y1*y1 - z1*z1;
+
+	if (t1<0) then
+		n1 = 0.0;
+	else
+		t1 = t1*t1;
+		n1 = t1 * t1 * Dot3D(Gradients3D[gi1], x1, y1, z1);
+	end
+
+	local t2 = 0.5 - x2*x2 - y2*y2 - z2*z2;
+
+	if (t2<0) then
+		n2 = 0.0;
+	else
+		t2 = t2*t2;
+		n2 = t2 * t2 * Dot3D(Gradients3D[gi2], x2, y2, z2);
+	end
+
+	local t3 = 0.5 - x3*x3 - y3*y3 - z3*z3;
+
+	if (t3<0) then
+		n3 = 0.0;
+	else
+		t3 = t3*t3;
+		n3 = t3 * t3 * Dot3D(Gradients3D[gi3], x3, y3, z3);
+	end
+
+
+	-- Add contributions from each corner to get the final noise value.
+	-- The result is scaled to stay just inside [-1,1]
+	local retval = 32.0*(n0 + n1 + n2 + n3)
+
+	if simplex.internalCache then
+		if not Prev3D[xin] then Prev3D[xin] = {} end
+		if not Prev3D[xin][yin] then Prev3D[xin][yin] = {} end
+		Prev3D[xin][yin][zin] = retval
+	end
+
+	return retval;
+end
+
+local Prev4D = {}
+
+-- 4D simplex noise
+function simplex.Noise4D(x,y,z,w)
+
+	if simplex.internalCache and Prev4D[x] and Prev4D[x][y] and Prev4D[x][y][z] and Prev4D[x][y][z][w] then return Prev4D[x][y][z][w] end
+
+	-- The skewing and unskewing factors are hairy again for the 4D case
+	local F4 = (math.sqrt(5.0)-1.0)/4.0;
+	local G4 = (5.0-math.sqrt(5.0))/20.0;
+	local n0, n1, n2, n3, n4; -- Noise contributions from the five corners
+	-- Skew the (x,y,z,w) space to determine which cell of 24 simplices we're in
+	local s = (x + y + z + w) * F4; -- Factor for 4D skewing
+	local i = math.floor(x + s);
+	local j = math.floor(y + s);
+	local k = math.floor(z + s);
+	local l = math.floor(w + s);
+	local t = (i + j + k + l) * G4; -- Factor for 4D unskewing
+	local X0 = i - t; -- Unskew the cell origin back to (x,y,z,w) space
+	local Y0 = j - t;
+	local Z0 = k - t;
+	local W0 = l - t;
+	local x0 = x - X0; -- The x,y,z,w distances from the cell origin
+	local y0 = y - Y0;
+	local z0 = z - Z0;
+	local w0 = w - W0;
+	-- For the 4D case, the simplex is a 4D shape I won't even try to describe.
+	-- To find out which of the 24 possible simplices we're in, we need to
+	-- determine the magnitude ordering of x0, y0, z0 and w0.
+	-- The method below is a good way of finding the ordering of x,y,z,w and
+    -- then find the correct traversal order for the simplex we're in.
+	-- First, six pair-wise comparisons are performed between each possible pair
+	-- of the four coordinates, and the results are used to add up binary bits
+	-- for an localeger index.
+	local c1 = (x0 > y0) and 32 or 1;
+	local c2 = (x0 > z0) and 16 or 1;
+	local c3 = (y0 > z0) and 8 or 1;
+	local c4 = (x0 > w0) and 4 or 1;
+	local c5 = (y0 > w0) and 2 or 1;
+	local c6 = (z0 > w0) and 1 or 1;
+	local c = c1 + c2 + c3 + c4 + c5 + c6;
+	local i1, j1, k1, l1; -- The localeger offsets for the second simplex corner
+	local i2, j2, k2, l2; -- The localeger offsets for the third simplex corner
+	local i3, j3, k3, l3; -- The localeger offsets for the fourth simplex corner
+
+	-- sim[c] is a 4-vector with the numbers 0, 1, 2 and 3 in some order.
+	-- Many values of c will never occur, since e.g. x>y>z>w makes x<z, y<w and x<w
+	-- impossible. Only the 24 indices which have non-zero entries make any sense.
+	-- We use a thresholding to set the coordinates in turn from the largest magnitude.
+	-- The number 3 in the "sim" array is at the position of the largest coordinate.
+
+	i1 = sim[c][1]>=3 and 1 or 0;
+	j1 = sim[c][2]>=3 and 1 or 0;
+	k1 = sim[c][3]>=3 and 1 or 0;
+	l1 = sim[c][4]>=3 and 1 or 0;
+	-- The number 2 in the "sim" array is at the second largest coordinate.
+	i2 = sim[c][1]>=2 and 1 or 0;
+	j2 = sim[c][2]>=2 and 1 or 0;
+	k2 = sim[c][3]>=2 and 1 or 0;
+	l2 = sim[c][4]>=2 and 1 or 0;
+	-- The number 1 in the "sim" array is at the second smallest coordinate.
+	i3 = sim[c][1]>=1 and 1 or 0;
+	j3 = sim[c][2]>=1 and 1 or 0;
+	k3 = sim[c][3]>=1 and 1 or 0;
+	l3 = sim[c][4]>=1 and 1 or 0;
+	-- The fifth corner has all coordinate offsets = 1, so no need to look that up.
+	local x1 = x0 - i1 + G4; -- Offsets for second corner in (x,y,z,w) coords
+	local y1 = y0 - j1 + G4;
+	local z1 = z0 - k1 + G4;
+	local w1 = w0 - l1 + G4;
+	local x2 = x0 - i2 + 2.0*G4; -- Offsets for third corner in (x,y,z,w) coords
+	local y2 = y0 - j2 + 2.0*G4;
+	local z2 = z0 - k2 + 2.0*G4;
+	local w2 = w0 - l2 + 2.0*G4;
+	local x3 = x0 - i3 + 3.0*G4; -- Offsets for fourth corner in (x,y,z,w) coords
+	local y3 = y0 - j3 + 3.0*G4;
+	local z3 = z0 - k3 + 3.0*G4;
+	local w3 = w0 - l3 + 3.0*G4;
+	local x4 = x0 - 1.0 + 4.0*G4; -- Offsets for last corner in (x,y,z,w) coords
+	local y4 = y0 - 1.0 + 4.0*G4;
+	local z4 = z0 - 1.0 + 4.0*G4;
+	local w4 = w0 - 1.0 + 4.0*G4;
+
+	-- Work out the hashed gradient indices of the five simplex corners
+	local ii = math.floor(i % 255)
+	local jj = math.floor(j % 255)
+	local kk = math.floor(k % 255)
+	local ll = math.floor(l % 255)
+	local gi0 = perm[ii+perm[jj+perm[kk+perm[ll]]]] % 32;
+	local gi1 = perm[ii+i1+perm[jj+j1+perm[kk+k1+perm[ll+l1]]]] % 32;
+	local gi2 = perm[ii+i2+perm[jj+j2+perm[kk+k2+perm[ll+l2]]]] % 32;
+	local gi3 = perm[ii+i3+perm[jj+j3+perm[kk+k3+perm[ll+l3]]]] % 32;
+	local gi4 = perm[ii+1+perm[jj+1+perm[kk+1+perm[ll+1]]]] % 32;
+
+
+	-- Calculate the contribution from the five corners
+	local t0 = 0.5 - x0*x0 - y0*y0 - z0*z0 - w0*w0;
+	if (t0<0) then
+		n0 = 0.0;
+	else
+		t0 = t0*t0;
+		n0 = t0 * t0 * Dot4D(Gradients4D[gi0], x0, y0, z0, w0);
+	end
+
+	local t1 = 0.5 - x1*x1 - y1*y1 - z1*z1 - w1*w1;
+	if (t1<0) then
+		n1 = 0.0;
+	else
+		t1 = t1*t1;
+		n1 = t1 * t1 * Dot4D(Gradients4D[gi1], x1, y1, z1, w1);
+	end
+
+	local t2 = 0.5 - x2*x2 - y2*y2 - z2*z2 - w2*w2;
+	if (t2<0) then
+		n2 = 0.0;
+	else
+		t2 = t2*t2;
+		n2 = t2 * t2 * Dot4D(Gradients4D[gi2], x2, y2, z2, w2);
+	end
+
+	local t3 = 0.5 - x3*x3 - y3*y3 - z3*z3 - w3*w3;
+	if (t3<0) then
+		n3 = 0.0;
+	else
+		t3 = t3*t3;
+		n3 = t3 * t3 * Dot4D(Gradients4D[gi3], x3, y3, z3, w3);
+	end
+
+	local t4 = 0.5 - x4*x4 - y4*y4 - z4*z4 - w4*w4;
+	if (t4<0) then
+		n4 = 0.0;
+	else
+		t4 = t4*t4;
+		n4 = t4 * t4 * Dot4D(Gradients4D[gi4], x4, y4, z4, w4);
+	end
+
+	-- Sum up and scale the result to cover the range [-1,1]
+
+	local retval = 27.0 * (n0 + n1 + n2 + n3 + n4)
+
+	if simplex.internalCache then
+		if not Prev4D[x] then Prev4D[x] = {} end
+		if not Prev4D[x][y] then Prev4D[x][y] = {} end
+		if not Prev4D[x][y][z] then Prev4D[x][y][z] = {} end
+		Prev4D[x][y][z][w] = retval
+	end
+
+	return retval;
+
+
+end
+
+local e = 2.71828182845904523536
+
+local PrevBlur2D = {}
+
+function simplex.GBlur2D(x,y,stdDev)
+	if simplex.internalCache and PrevBlur2D[x] and PrevBlur2D[x][y] and PrevBlur2D[x][y][stdDev] then return PrevBlur2D[x][y][stdDev] end
+	local pwr = ((x^2+y^2)/(2*(stdDev^2)))*-1
+	local ret = (1/(2*math.pi*(stdDev^2)))*(e^pwr)
+
+	if simplex.internalCache then
+		if not PrevBlur2D[x] then PrevBlur2D[x] = {} end
+		if not PrevBlur2D[x][y] then PrevBlur2D[x][y] = {} end
+		PrevBlur2D[x][y][stdDev] = ret
+	end
+	return ret
+end
+
+local PrevBlur1D = {}
+
+function simplex.GBlur1D(x,stdDev)
+	if simplex.internalCache and PrevBlur1D[x] and PrevBlur1D[x][stdDev] then return PrevBlur1D[x][stdDev] end
+	local pwr = (x^2/(2*stdDev^2))*-1
+	local ret = (1/(math.sqrt(2*math.pi)*stdDev))*(e^pwr)
+
+	if simplex.internalCache then
+		if not PrevBlur1D[x] then PrevBlur1D[x] = {} end
+		PrevBlur1D[x][stdDev] = ret
+	end
+	return ret
+end
+
+function simplex.FractalSum(func, iter, ...)
+    local ret = func(...)
+    for i=1,iter do
+        local power = 2^iter
+        local s = power/i
+
+        local scaled = {}
+        for elem in ipairs({...}) do
+            table.insert(scaled, elem*s)
+        end
+        ret = ret + (i/power)*(func(unpack(scaled)))
+    end
+    return ret
+end
+
+function simplex.FractalSumAbs(func, iter, ...)
+    local ret = math.abs(func(...))
+    for i=1,iter do
+        local power = 2^iter
+        local s = power/i
+
+        local scaled = {}
+        for elem in ipairs({...}) do
+            table.insert(scaled, elem*s)
+        end
+        ret = ret + (i/power)*(math.abs(func(unpack(scaled))))
+    end
+    return ret
+end
+
+function simplex.Turbulence(func, direction, iter, ...)
+    local ret = math.abs(func(...))
+    for i=1,iter do
+        local power = 2^iter
+        local s = power/i
+
+        local scaled = {}
+        for elem in ipairs({...}) do
+            table.insert(scaled, elem*s)
+        end
+        ret = ret + (i/power)*(math.abs(func(unpack(scaled))))
+    end
+    local args = {...}
+    local dir_component = args[direction+1]
+    return math.sin(dir_component+ret)
+end
+
+function simplex.Seed(seed)
+    math.randomseed(seed)
+    local integers = {}
+    perm = {}
+    for i = 1, 256 do
+        integers[i] = i
+    end
+    while next(integers) do
+        perm[#perm + 1] = table.remove(integers, math.random(1, #integers))
+    end
+    perm[0] = perm[#perm]
+    perm[#perm] = nil
+    for i=0,255 do
+        perm[i+256] = perm[i]
+    end
+end
+
+-- TODO test functionality
+function simplex.FractalBrownianMotion2D(x, y, octaves, lacunarity, gain)
+    octaves = octaves or 4
+    lacunarity = lacunarity or 2
+    gain = gain or 0.5
+
+    local total, amplitude, frequency, peak_amplitude = 0, 1, 1, 0
+    for i = 1, octaves do
+        total = total + amplitude * simplex.Noise2D(x * frequency, y * frequency)
+        peak_amplitude = peak_amplitude + amplitude
+        amplitude = amplitude * gain
+        frequency = frequency * lacunarity
+    end
+
+    return total / peak_amplitude   -- normalize to [-1, 1]
+end
+
+return simplex

src/lib/simplex_map.lua

@@ -0,0 +1,77 @@
+local simplex = require "lib.simplex"
+
+local simplex_map = {}
+
+simplex_map.min = function(map)
+  local r = math.huge
+  for i=1,#map do
+    if map[i] then
+      for j=1,#map[1] do
+        local v = map[i][j]
+        if v and r > v then r = v end
+      end
+    end
+  end
+  return r
+end
+simplex_map.max = function(map)
+  local r = -math.huge
+  for i=1,#map do
+    if map[i] then
+      for j=1,#map[1] do
+        local v = map[i][j]
+        if v and r < v then r = v end
+      end
+    end
+  end
+  return r
+end
+
+simplex_map.normalize = function(map, new_min, new_max)
+  local minimum = simplex_map.min(map)
+  local initialRange = simplex_map.max(map) - minimum
+  local finalRange = new_max - new_min
+  for i = 1, #map do
+    for j = 1, #map[1] do
+      map[i][j] = (map[i][j] - minimum) / initialRange * finalRange + new_min
+    end
+  end
+  map.min = simplex_map.min(map)
+  map.max = simplex_map.max(map)
+  return map -- superfluous
+end
+
+simplex_map.generate = function(size, scale, min, max, octaves, lacunarity, gain)
+  if type(size) == "table" then
+    scale = size.scale
+    min = size.min
+    max = size.max
+    octaves = size.octaves
+    lacunarity = size.lacunarity
+    gain = size.gain
+
+    size = size.size
+  end
+
+  simplex.Seed(math.random())
+  local map = {}
+  map.size = size
+
+  scale = scale or 0.005
+  for x = 1, map.size do
+    map[x] = {}
+    for y = 1, map.size do
+      map[x][y] = simplex.FractalBrownianMotion2D(x * scale, y * scale, octaves, lacunarity, gain)
+    end
+  end
+
+  if min or max then
+    min = min or 0
+    max = max or 1
+    simplex_map.normalize(map, min, max)
+  end
+
+  return map
+end
+
+return simplex_map

src/main.lua

@@ -1,129 +1,85 @@
-local heightmap = require "lib.heightmap"
+math.randomseed(os.time())
+
+local map_generator = require "map_nextgen"
 local lovebird = require "lib.lovebird"
 local lume = require "lib.lume"
+local running_average = require "lib.running_average"
+local simplex_map = require "lib.simplex_map"
 
-local map = {}
+local map
 
 love.load = function()
-  map.size = 150
-  map.height = heightmap.create(map.size, map.size, 0, 1)
-  map.temperature = heightmap.create(map.size, map.size, 0, 1)
-  map.humidity = heightmap.create(map.size, map.size, 0, 1)
-
-  -- weird mixing idea test
-  -- why does this average things out?
-  -- trying to renormalize it now..
-  local temporary_maps = {}
-  for i = 1, 3 do
-    temporary_maps[i] = heightmap.create(map.size, map.size, 0, 1)
-  end
-  for x = 0, map.height.w do
-    for y = 0, map.height.h do
-      map.height[x][y] = (map.height[x][y] + temporary_maps[1][x][y] + temporary_maps[2][x][y] + temporary_maps[3][x][y] ) / 4
-    end
-  end
-  heightmap.normalize(map.height, 0, 1)
+  map = map_generator.generate()
+  map.temperature.min = simplex_map.min(map.temperature)
+  map.temperature.max = simplex_map.max(map.temperature)
+  print("Min Temperature", map.temperature.min, "Average", running_average.track("minT", map.temperature.min))
+  print("Max Temperature", map.temperature.max, "Average", running_average.track("maxT", map.temperature.max))
 
   -- if true then return end
 
   -- lower temperature by half height
   -- NOTE ruins "normalization" but that's fine once we have "real" numbers to work with
-  for x = 0, map.temperature.w do
-    for y = 0, map.temperature.h do
-      map.temperature[x][y] = math.max(0, map.temperature[x][y] - map.height[x][y] / 2)
-    end
-  end
+  -- for x = 0, map.temperature.w do
+  --   for y = 0, map.temperature.h do
+  --     map.temperature[x][y] = math.max(0, map.temperature[x][y] - map.altitude[x][y] / 2)
+  --   end
+  -- end
+  -- heightmap.normalize(map.temperature, -89.2, 56.7)
 
   -- modify temperature by latitude
   -- TODO would be more efficient to calculate Y in outer loop, since X does not change the distance
   -- NOTE only subtracts temperature, which further "ruins normalization" and makes everything too cold:
-  local center_y = map.size / 2
-  for x = 0, map.temperature.w do
-    for y = 0, map.temperature.h do
-      local distance = math.abs(y - center_y)
-      map.temperature[x][y] = lume.clamp(map.temperature[x][y] - distance / map.size / 2, 0, 1)
-    end
-  end
+  -- local center_y = map.size / 2
+  -- for x = 0, map.temperature.w do
+  --   for y = 0, map.temperature.h do
+  --     local distance = math.abs(y - center_y)
+  --     map.temperature[x][y] = lume.clamp(map.temperature[x][y] - distance / map.size, 0, 1)
+  --   end
+  -- end
+  -- heightmap.normalize(map.temperature, -89.2, 56.7)
 
   -- increase humidity by half temperature
-  for x = 0, map.humidity.w do
-    for y = 0, map.humidity.h do
-      map.humidity[x][y] = math.min(1, map.humidity[x][y] + map.temperature[x][y] / 2)
-    end
-  end
-
-  -- planetizer!
-  local radius = (map.size / 2)^2
-  for x = 0, map.height.w do
-    for y = 0, map.height.h do
-      if lume.distance(x, y, map.size / 2, map.size / 2, true) > radius then
-        map.height[x][y] = nil
-      end
-    end
-  end
+  -- for x = 0, map.humidity.w do
+  --   for y = 0, map.humidity.h do
+  --     map.humidity[x][y] = math.min(1, map.humidity[x][y] + map.temperature[x][y] / 2)
+  --   end
+  -- end
+  -- heightmap.normalize(map.humidity, 18, 3240)
 end
 
+local camera = {
+  x = 0, y = 0,
+  speed = 500,
+}
 love.update = function(dt)
   lovebird.update()
+
+  if love.keyboard.isDown("w") then
+    camera.y = camera.y - camera.speed * dt
+  end
+  if love.keyboard.isDown("s") then
+    camera.y = camera.y + camera.speed * dt
+  end
+  if love.keyboard.isDown("a") then
+    camera.x = camera.x - camera.speed * dt
+  end
+  if love.keyboard.isDown("d") then
+    camera.x = camera.x + camera.speed * dt
+  end
 end
 
+local window_width, window_height = love.graphics.getDimensions()
 love.draw = function()
-  local tile_size = 2
+  love.graphics.translate(window_width / 2 - (map.size * map.tile_size) / 2 - camera.x, window_height / 2 - (map.size * map.tile_size) / 2 - camera.y)
 
-  for x = 0, map.height.w do
-    for y = 0, map.height.h do
-      -- raw heightmap
-      -- NOTE will break with planetizer enabled!
-      -- local value = map.height[x][y]
-      -- love.graphics.setColor(value, value, value, 1)
-      -- love.graphics.rectangle("fill", x * tile_size, y * tile_size, tile_size, tile_size)
-
-      -- even weighting between height and temperature
-      -- local value = map.height[x][y] / 2 + map.temperature[x][y] / 2
-      -- if value < 0.2 then
-      --   love.graphics.setColor(0, 0, 1, 1)
-      -- elseif value < 0.215 then
-      --   love.graphics.setColor(1, 1, 0, 1)
-      -- elseif value < 0.34 then
-      --   love.graphics.setColor(0, 1, 0, 1)
-      -- elseif value < 0.72 then
-      --   love.graphics.setColor(0, 0.67, 0, 1)
-      -- elseif value < 0.9 then
-      --   love.graphics.setColor(0.67, 0.67, 0.67, 1)
-      -- else
-      --   -- love.graphics.setColor(0, 0, 0, 1) -- temporary nothing
-      --   love.graphics.setColor(1, 1, 1, 1)
-      -- end
-      -- love.graphics.rectangle("fill", x * tile_size, y * tile_size, tile_size, tile_size)
-
-      -- temperature map
+  for x = 1, map.size do
+    for y = 1, map.size do
+      -- local value = map.biome[x][y]
       local value = map.temperature[x][y]
-      love.graphics.setColor(value, 0, 0, 1)
-      love.graphics.rectangle("fill", map.size * tile_size + x * tile_size, y * tile_size, tile_size, tile_size)
-
-      -- humidity map
-      local value = map.humidity[x][y]
-      love.graphics.setColor(0, 0, value, 1)
-      love.graphics.rectangle("fill", x * tile_size, map.size * tile_size + y * tile_size, tile_size, tile_size)
-
-      -- "naive" biomed map
-      local value = map.height[x][y]
       if value then
-        if value < 0.2 then
-          love.graphics.setColor(0, 0, 1, 1)
-        elseif value < 0.215 then
-          love.graphics.setColor(1, 1, 0, 1)
-        elseif value < 0.34 then
-          love.graphics.setColor(0, 1, 0, 1)
-        elseif value < 0.72 then
-          love.graphics.setColor(0, 0.67, 0, 1)
-        elseif value < 0.9 then
-          love.graphics.setColor(0.67, 0.67, 0.67, 1)
-        else
-          -- love.graphics.setColor(0, 0, 0, 1) -- temporary nothing
-          love.graphics.setColor(1, 1, 1, 1)
-        end
-        love.graphics.rectangle("fill", map.size * tile_size + x * tile_size, map.size * tile_size + y * tile_size, tile_size, tile_size)
+        -- love.graphics.setColor(value)
+        love.graphics.setColor( (value + map.temperature.max) / (map.temperature.max + math.abs(map.temperature.min)) , 0, 0, 1)
+        love.graphics.rectangle("fill", x * map.tile_size, y * map.tile_size, map.tile_size, map.tile_size)
       end
     end
   end
@@ -134,5 +90,9 @@ love.keypressed = function(key)
     love.event.quit()
   elseif key == "r" then
     love.load()
+  elseif key == "=" then
+    map.tile_size = map.tile_size * 2
+  elseif key == "-" then
+    map.tile_size = map.tile_size / 2
   end
 end

src/map_generator.lua

@@ -0,0 +1,181 @@
+local heightmap = require "lib.heightmap"
+local lume = require "lib.lume"
+
+local biomes = {
+  -- [5] = {
+  --   name = "ocean",
+  --   altitude = {min = 0, max = 0.2}, -- bottom of world is the only part that matters
+  --   temperature = {min = 0, max = 1},
+  --   humidity = {min = 0, max = 1},
+  --   color = {0, 0, 0.67, 1},
+  -- },
+  -- [6] = {
+  --   name = "beach",
+  --   altitude = {min = 0.2, max = 0.205}, -- just above ocean
+  --   temperature = {min = 0, max = 1},
+  --   humidity = {min = 0, max = 0.8}, -- excluding upper humidity for swamp
+  --   color = {1, 1, 0.33, 1}, -- brighter yellow to distinguish from sand
+  -- },
+  -- [8] = {
+  --   name = "swamp", -- fun idea, but generates between ocean and water too often?
+  --   altitude = {min = 0, max = 1},
+  --   temperature = {min = 0.5, max = 1},
+  --   humidity = {min = 0.95, max = 1},
+  --   color = {0, 0.5, 0.33, 1},
+  -- },
+  -- [10] = {
+  --   name = "water",
+  --   altitude = {min = 0, max = 0.9}, -- top excluded because it should've gone downhill
+  --   temperature = {min = 0.1, max = 0.9}, -- bottom should be ice, top should evaporate
+  --   humidity = {min = 0.8, max = 1}, -- only the wettest places
+  --   color = {0, 0, 1, 1},
+  -- },
+  -- [20] = {
+  --   name = "sand",
+  --   altitude = {min = 0.2, max = 0.9}, -- top falls down, bottom is underwater
+  --   temperature = {min = 0, max = 1},
+  --   humidity = {min = 0, max = 0.2}, -- only where dry makes more sense for a desert
+  --   color = {1, 1, 0, 1},
+  -- },
+  -- [30] = {
+  --   name = "grass",
+  --   altitude = {min = 0.3, max = 0.9}, -- top of the world not enough air, bottom too wet / leaving space for others
+  --   temperature = {min = 0.2, max = 0.8}, -- not very sensitive to temperature
+  --   humidity = {min = 0.2, max = 0.6}, -- not very sensitive to humidity; but excluded from the worst
+  --   color = {0, 1, 0, 1},
+  -- },
+  -- [40] = {
+  --   name = "trees",
+  --   altitude = {min = 0.4, max = 0.7}, -- more sensitive than grass
+  --   temperature = {min = 0, max = 0.7},
+  --   humidity = {min = 0.3, max = 0.8}, -- these are not desert trees, they need more water
+  --   color = {0, 0.67, 0, 1},
+  -- },
+  -- [60] = {
+  --   name = "stone",
+  --   altitude = {min = 0, max = 1},
+  --   temperature = {min = 0, max = 1},
+  --   humidity = {min = 0, max = 1},
+  --   color = {0.67, 0.67, 0.67, 1},
+  -- },
+  -- [50] = {
+  --   name = "ice",
+  --   altitude = {min = 0, max = 1},
+  --   temperature = {min = 0, max = 0.01},
+  --   humidity = {min = 0.2, max = 1},
+  --   color = {1, 1, 1, 1},
+  -- },
+  [900] = {
+    name = "deep ocean",
+    altitude = {min = -math.huge, max = -5000},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {0, 0, 0.25, 1},
+  },
+  [1000] = {
+    name = "ocean (definition, 0 meters)",
+    altitude = {min = -math.huge, max = 0},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {0, 0, 0.5, 1},
+  },
+  [2000] = {
+    name = "snowline (middle estimate)",
+    altitude = {min = 4000, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {1, 1, 1, 1},
+  },
+  [2100] = {
+    name = "alpine zone",
+    altitude = {min = 3500, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {0.8, 0.8, 0.8, 1},
+  },
+  [2200] = {
+    name = "subalpine zone",
+    altitude = {min = 3000, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {0.67, 0.67, 0.67, 1},
+  },
+  [2300] = {
+    name = "montane zone",
+    altitude = {min = 2500, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    humidity = {min = -math.huge, max = math.huge},
+    color = {0.67, 0.67, 0.5, 1},
+  },
+}
+
+local function generate()
+  local map = {}
+
+  map.size = 500
+  map.tile_size = 1
+  map.altitude = heightmap.create(map.size, map.size, 0, 1) -- meters
+  map.temperature = heightmap.create(map.size, map.size, -89.2, 56.7) -- celsius
+  map.humidity = heightmap.create(map.size, map.size, 18, 3240) -- millimeters rainfall
+
+  -- local function earthlike_altitude_adjustment(altitude)
+  --   -- max too low, min too high, too much ocean
+  --   return 6099 - 114909 * altitude + 830891 * altitude^2 - 2.72e6 * altitude^3 + 4.19e6 * altitude^4 - 3.02e6 * altitude^5 + 815866 * altitude^6
+  -- end
+  local function earthlike_altitude_adjustment(altitude)
+    -- good oceans, too much high altitude
+    return -10948 + 101018 * altitude - 643382 * altitude^2 + 2.17e6 * altitude^3 - 3.62e6 * altitude^4 + 2.87e6 * altitude^5 -852042 * altitude^6
+  end
+  -- local function earthlike_altitude_adjustment(altitude)
+  --   -- only creates ocean (wtf)
+  --   return -10851 + 151279 * altitude - 1.14e6 * altitude^2 +3.84e6 * altitude^3 -6.11e6 * altitude^4 +4.48e6 * altitude^5 - 1.21e6 * altitude^6
+  -- end
+  local min, max = math.huge, -math.huge
+  for x = 0, map.size do
+    for y = 0, map.size do
+      local value = earthlike_altitude_adjustment(map.altitude[x][y])
+      if value > max then max = value end
+      if value < min then min = value end
+      map.altitude[x][y] = value
+    end
+  end
+  print("Altitude", "Min: ", min, "Max:", max)
+
+  -- planetizer!
+  local biome_order = {}
+  for order in pairs(biomes) do
+    biome_order[#biome_order + 1] = order
+  end
+  table.sort(biome_order)
+
+  map.terrain = {w = map.size, h = map.size}
+  local radius = (map.size / 2)^2
+  for x = 0, map.size do
+    map.terrain[x] = {}
+    for y = 0, map.size do
+      if lume.distance(x, y, map.size / 2, map.size / 2, true) < radius then
+        -- for _, biome in ipairs(biomes) do
+        for _, order in ipairs(biome_order) do
+          local biome = biomes[order]
+          local altitude = map.altitude[x][y]
+          if altitude >= biome.altitude.min and altitude <= biome.altitude.max then
+            local temperature = map.temperature[x][y]
+            if temperature >= biome.temperature.min and temperature <= biome.temperature.max then
+              local humidity = map.humidity[x][y]
+              if humidity >= biome.humidity.min and humidity <= biome.humidity.max then
+                map.terrain[x][y] = biome.color
+                break
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+
+  return map
+end
+
+return {
+  generate = generate,
+}

src/map_nextgen.lua

@@ -0,0 +1,138 @@
+-- NOTE the API of this file should probably change?
+
+local lume = require "lib.lume"
+local simplex_map = require "lib.simplex_map"
+
+local biomes = {
+  -- biomes are checked in order, with the first candidate always being selected
+  [900] = {
+    name = "deep ocean",
+    altitude = {min = -math.huge, max = -5000},
+    temperature = {min = -math.huge, max = math.huge},
+    rainfall = {min = -math.huge, max = math.huge},
+    color = {0, 0, 0.25, 1},
+  },
+  [1000] = {
+    name = "ocean (definition, 0 meters)",
+    altitude = {min = -math.huge, max = 0},
+    temperature = {min = -math.huge, max = math.huge},
+    rainfall = {min = -math.huge, max = math.huge},
+    color = {0, 0, 0.5, 1},
+  },
+  [2000] = {
+    name = "snowline (middle estimate)",
+    altitude = {min = 4000, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    rainfall = {min = -math.huge, max = math.huge},
+    color = {1, 1, 1, 1},
+  },
+  [2100] = {
+    name = "alpine zone",
+    altitude = {min = 3500, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    rainfall = {min = -math.huge, max = math.huge},
+    color = {0.8, 0.8, 0.8, 1},
+  },
+  [2200] = {
+    name = "subalpine zone",
+    altitude = {min = 3000, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    rainfall = {min = -math.huge, max = math.huge},
+    color = {0.67, 0.67, 0.67, 1},
+  },
+  [2300] = {
+    name = "montane zone",
+    altitude = {min = 2500, max = math.huge},
+    temperature = {min = -math.huge, max = math.huge},
+    rainfall = {min = -math.huge, max = math.huge},
+    color = {0.67, 0.67, 0.5, 1},
+  },
+}
+
+local generate = function()
+  local map = {}
+  map.size = 500
+  map.tile_size = 1 -- TODO tile_size really shouldn't be the responsibility of the map generator - it's a rendering detail, not a map feature
+  map.altitude = simplex_map.generate{   -- will be converted to meters
+    size = map.size, scale = 0.001, min = 0, max = 1,
+    octaves = 7, lacunarity = 2, gain = 0.5,
+  }
+  map.temperature = simplex_map.generate{   -- in celsius
+    -- -20 to 45 chosen by looking at the temperature range shown on https://openclimatemap.org/
+    size = map.size, scale = 0.005, min = -20, max = 45, -- approximate target extremes of -89.2 to 56.7
+    octaves = 1, lacunarity = 2, gain = 0.5,
+  }
+  map.rainfall = simplex_map.generate{   -- in millimeters of rainfall
+    size = map.size, scale = 0.005, -- min = 18, max = 3240,
+    octaves = 1, lacunarity = 2, gain = 0.5,
+  }
+
+  local function earthlike_altitude_adjustment(altitude)
+    -- TODO replace with a simpler function?
+    return 6099 - 114909 * altitude + 830891 * altitude^2 - 2.72e6 * altitude^3 + 4.19e6 * altitude^4 - 3.02e6 * altitude^5 + 815866 * altitude^6
+  end
+
+  for x = 1, map.size do
+    for y = 1, map.size do
+      map.altitude[x][y] = earthlike_altitude_adjustment(map.altitude[x][y])
+    end
+  end
+  map.altitude.min = simplex_map.min(map.altitude)
+  map.altitude.max = simplex_map.max(map.altitude)
+
+  local biome_order = {}
+  for order in pairs(biomes) do
+    biome_order[#biome_order + 1] = order
+  end
+  table.sort(biome_order)
+
+  local radius_squared = (map.size / 2)^2
+  map.biome = {}
+  for x = 1, map.size do
+    map.biome[x] = {}
+    for y = 1, map.size do
+      if lume.distance(x, y, map.size / 2, map.size / 2, true) < radius_squared then
+        local altitude = map.altitude[x][y]
+        local temperature = map.temperature[x][y]
+        local rainfall = map.rainfall[x][y]
+
+        -- modify temperature based on altitude
+        if altitude > 0 then
+          temperature = temperature - 0.0065 * altitude  -- -6.5 C / km
+        else
+          temperature = temperature + altitude / 1000 -- -1 C / km (deep water adjustment)
+        end
+        -- modify temperature by latitude
+        local polar_distance = math.abs(y - (map.size / 2))^1.1 -- experimenting with slight non-linearity
+        local max_temperature_delta = 40
+        temperature = temperature - (polar_distance / map.size * 2 * max_temperature_delta)
+        -- 'save' temperature changes
+        map.temperature[x][y] = temperature
+
+        -- choose biome
+        for _, order in ipairs(biome_order) do
+          local biome = biomes[order]
+          if altitude >= biome.altitude.min and altitude <= biome.altitude.max then
+            if temperature >= biome.temperature.min and temperature <= biome.temperature.max then
+              if rainfall >= biome.rainfall.min and rainfall <= biome.rainfall.max then
+                map.biome[x][y] = biome.color
+                break
+              end
+            end
+          end
+        end
+      else
+        -- clear non-planet zones
+        map.altitude[x][y] = nil
+        map.temperature[x][y] = nil
+        map.rainfall[x][y] = nil
+      end
+    end
+  end
+
+  return map
+end
+
+return {
+  generate = generate,
+}