11 Commits

Author SHA1 Message Date
1adb4fbece Added an offset of 0.5 on terrain elevation
This prevents rounding errors and improves interpolation on nearly flat areas
2020-04-13 12:27:24 +02:00
13d3e70b66 Implemented variable river width.
Also changed the river data exported by terrain_rivers.py. They will not be compatible with what's generated by older versions.
2020-04-13 12:15:10 +02:00
4b63ed371e Add more information in the polygon table 2020-04-13 10:31:38 +02:00
eba90803fe Removed useless debug print 2020-04-13 10:01:23 +02:00
34de4269ee Add directly a reference to the polygon table in the polygon list, instead of adding an index 2020-04-13 09:54:04 +02:00
4e8288afbe Added screenshot in README 2020-04-13 09:27:41 +02:00
56cebecb13 More robust and faster code for grid twisting on the Lua side.
At chunkgen init, build a list of the polygons instead of calculating them for every node.
2020-04-13 09:27:41 +02:00
b7c6f71635 Implemented grid twisting. Still many possible bugs, potentially clumsy implementation, but it seems to work. 2020-04-13 09:27:41 +02:00
6314117642 Added bounds.py: twists the grid as if the rivers were elastic bounds. Unused for now. 2020-04-13 09:27:41 +02:00
ed34dec4fa Adjust number of octaves in function of map size 2020-04-12 17:26:37 +02:00
538bfb6d6d Added script to view map, using matplotlib 2020-04-12 16:44:29 +02:00
8 changed files with 309 additions and 56 deletions

6
.gitignore vendored
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@ -1,7 +1,9 @@
__pycache__/
dem
lakes
links
rivers
size
offset_x
offset_y
bounds_x
bounds_y
unused/

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@ -5,6 +5,8 @@ Procedural map generator for Minetest 5.x. Still experimental and basic.
Contains two distinct programs: Python scripts for pre-processing, and Lua scripts to generate the map on Minetest.
![Screenshot](https://user-images.githubusercontent.com/6905002/79073532-7a567f00-7ce7-11ea-9791-8fb453f5175d.png)
# Installation
This mod should be placed in the `/mods` directory like any other Minetest mod.

62
bounds.py Normal file
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@ -0,0 +1,62 @@
import numpy as np
import matplotlib.pyplot as plt
def make_bounds(dirs, rivers):
(Y, X) = dirs.shape
bounds_h = np.zeros((Y, X-1), dtype='i4')
bounds_v = np.zeros((Y-1, X), dtype='i4')
bounds_v += (rivers * (dirs==1))[:-1,:]
bounds_h += (rivers * (dirs==2))[:,:-1]
bounds_v -= (rivers * (dirs==3))[1:,:]
bounds_h -= (rivers * (dirs==4))[:,1:]
return bounds_h, bounds_v
def get_fixed(dirs):
borders = np.zeros(dirs.shape, dtype='?')
borders[-1,:] |= dirs[-1,:]==1
borders[:,-1] |= dirs[:,-1]==2
borders[0,:] |= dirs[0,:]==3
borders[:,0] |= dirs[:,0]==4
donors = np.zeros(dirs.shape, dtype='?')
donors[1:,:] |= dirs[:-1,:]==1
donors[:,1:] |= dirs[:,:-1]==2
donors[:-1,:] |= dirs[1:,:]==3
donors[:,:-1] |= dirs[:,1:]==4
return borders | ~donors
def twist(bounds_x, bounds_y, fixed, d=0.1, n=5):
moveable = ~fixed
(Y, X) = fixed.shape
offset_x = np.zeros((Y, X))
offset_y = np.zeros((Y, X))
for i in range(n):
force_long = np.abs(bounds_x) * (1+np.diff(offset_x, axis=1))
force_trans = np.abs(bounds_y) * np.diff(offset_x, axis=0)
force_x = np.zeros((Y, X))
force_x[:,:-1] = force_long
force_x[:,1:] -= force_long
force_x[:-1,:]+= force_trans
force_x[1:,:] -= force_trans
force_long = np.abs(bounds_y) * (1+np.diff(offset_y, axis=0))
force_trans = np.abs(bounds_x) * np.diff(offset_y, axis=1)
force_y = np.zeros((Y, X))
force_y[:-1,:] = force_long
force_y[1:,:] -= force_long
force_y[:,:-1]+= force_trans
force_y[:,1:] -= force_trans
length = np.hypot(force_x, force_y)
length[length==0] = 1
coeff = d / length * moveable
offset_x += force_x * coeff
offset_y += force_y * coeff
return offset_x, offset_y

45
geometry.lua Normal file
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@ -0,0 +1,45 @@
local function distance_to_segment(x1, y1, x2, y2, x, y)
-- get the distance between point (x,y) and segment (x1,y1)-(x2,y2)
local a = (x1-x2)^2 + (y1-y2)^2
local b = (x1-x)^2 + (y1-y)^2
local c = (x2-x)^2 + (y2-y)^2
if a + b < c then
return math.sqrt(b)
elseif a + c < b then
return math.sqrt(c)
else
return math.abs(x1 * (y2-y) + x2 * (y-y1) + x * (y1-y2)) / math.sqrt(a)
end
end
local function transform_quadri(X, Y, x, y)
-- X, Y 4-vectors giving the coordinates of the 4 nodes
-- x, y position to index.
local x1, x2, x3, x4 = unpack(X)
local y1, y2, y3, y4 = unpack(Y)
local d23 = distance_to_segment(x2,y2,x3,y3,x,y)
local d41 = distance_to_segment(x4,y4,x1,y1,x,y)
local xc = d41 / (d23+d41)
local d12 = distance_to_segment(x1,y1,x2,y2,x,y)
local d34 = distance_to_segment(x3,y3,x4,y4,x,y)
local yc = d12 / (d12+d34)
return xc, yc
end
local function area(X, Y) -- Signed area of polygon, in function of direction of rotation. Clockwise = positive.
local n = #X
local sum = X[1]*Y[n] - X[n]*Y[1]
for i=2, n do
sum = sum + X[i]*Y[i-1] - X[i-1]*Y[i]
end
return sum/2
end
return {
distance_to_segment = distance_to_segment,
transform_quadri = transform_quadri,
area = area,
}

203
init.lua
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@ -1,6 +1,7 @@
local modpath = minetest.get_modpath(minetest.get_current_modname()) .. '/'
local worldpath = minetest.get_worldpath() .. '/'
local load_map = dofile(modpath .. 'load.lua')
local geometry = dofile(modpath .. 'geometry.lua')
local function copy_if_needed(filename)
local wfilename = worldpath..filename
@ -26,26 +27,45 @@ copy_if_needed('dem')
local dem = load_map(worldpath..'dem', 2, true)
copy_if_needed('lakes')
local lakes = load_map(worldpath..'lakes', 2, true)
copy_if_needed('links')
local links = load_map(worldpath..'links', 1, false)
copy_if_needed('rivers')
local rivers = load_map(worldpath..'rivers', 4, false)
copy_if_needed('bounds_x')
local bounds_x = load_map(worldpath..'bounds_x', 4, false)
copy_if_needed('bounds_y')
local bounds_z = load_map(worldpath..'bounds_y', 4, false)
copy_if_needed('offset_x')
local offset_x = load_map(worldpath..'offset_x', 1, true)
for k, v in ipairs(offset_x) do
offset_x[k] = (v+0.5)/256
end
copy_if_needed('offset_y')
local offset_z = load_map(worldpath..'offset_y', 1, true)
for k, v in ipairs(offset_z) do
offset_z[k] = (v+0.5)/256
end
local function index(x, z)
return z*X+x+1
end
local function interp(v00, v01, v10, v11, xf, zf)
v0 = v01*xf + v00*(1-xf)
v1 = v11*xf + v10*(1-xf)
local function get_point_location(x, z)
local i = index(x, z)
return x+offset_x[i], z+offset_z[i]
end
local function interp(v00, v01, v11, v10, xf, zf)
local v0 = v01*xf + v00*(1-xf)
local v1 = v11*xf + v10*(1-xf)
return v1*zf + v0*(1-zf)
end
local data = {}
local blocksize = 6
local blocksize = 12
local sea_level = 1
local min_catchment = 25
local max_catchment = 40000
local storage = minetest.get_mod_storage()
if storage:contains("blocksize") then
@ -63,6 +83,25 @@ if storage:contains("min_catchment") then
else
storage:set_float("min_catchment", min_catchment)
end
if storage:contains("max_catchment") then
max_catchment = storage:get_float("max_catchment")
else
storage:set_float("max_catchment", max_catchment)
end
-- Width coefficients: coefficients solving
-- wfactor * min_catchment ^ wpower = 1/(2*blocksize)
-- wfactor * max_catchment ^ wpower = 1
local wpower = math.log(2*blocksize)/math.log(max_catchment/min_catchment)
local wfactor = 1 / max_catchment ^ wpower
local function river_width(flow)
flow = math.abs(flow)
if flow < min_catchment then
return 0
end
return math.min(wfactor * flow ^ wpower, 1)
end
local function generate(minp, maxp, seed)
local c_stone = minetest.get_content_id("default:stone")
@ -77,59 +116,122 @@ local function generate(minp, maxp, seed)
local a = VoxelArea:new({MinEdge = emin, MaxEdge = emax})
local ystride = a.ystride -- Tip : the ystride of a VoxelArea is the number to add to the array index to get the index of the position above. It's faster because it avoids to completely recalculate the index.
local chulens = maxp.z - minp.z + 1
local polygons = {}
local xpmin, xpmax = math.max(math.floor(minp.x/blocksize - 0.5), 0), math.min(math.ceil(maxp.x/blocksize), X-2)
local zpmin, zpmax = math.max(math.floor(minp.z/blocksize - 0.5), 0), math.min(math.ceil(maxp.z/blocksize), Z-2)
for xp = xpmin, xpmax do
for zp=zpmin, zpmax do
local iA = index(xp, zp)
local iB = index(xp+1, zp)
local iC = index(xp+1, zp+1)
local iD = index(xp, zp+1)
local poly_x = {offset_x[iA]+xp, offset_x[iB]+xp+1, offset_x[iC]+xp+1, offset_x[iD]+xp}
local poly_z = {offset_z[iA]+zp, offset_z[iB]+zp, offset_z[iC]+zp+1, offset_z[iD]+zp+1}
local polygon = {x=poly_x, z=poly_z, i={iA, iB, iC, iD}}
local bounds = {}
local xmin = math.max(math.floor(blocksize*math.min(unpack(poly_x)))+1, minp.x)
local xmax = math.min(math.floor(blocksize*math.max(unpack(poly_x))), maxp.x)
for x=xmin, xmax do
bounds[x] = {}
end
local i1 = 4
for i2=1, 4 do -- Loop on 4 edges
local x1, x2 = poly_x[i1], poly_x[i2]
local lxmin = math.floor(blocksize*math.min(x1, x2))+1
local lxmax = math.floor(blocksize*math.max(x1, x2))
if lxmin <= lxmax then
local z1, z2 = poly_z[i1], poly_z[i2]
local a = (z1-z2) / (x1-x2)
local b = blocksize*(z1 - a*x1)
for x=math.max(lxmin, minp.x), math.min(lxmax, maxp.x) do
table.insert(bounds[x], a*x+b)
end
end
i1 = i2
end
for x=xmin, xmax do
local xlist = bounds[x]
table.sort(xlist)
local c = math.floor(#xlist/2)
for l=1, c do
local zmin = math.max(math.floor(xlist[l*2-1])+1, minp.z)
local zmax = math.min(math.floor(xlist[l*2]), maxp.z)
local i = (x-minp.x) * chulens + (zmin-minp.z) + 1
for z=zmin, zmax do
polygons[i] = polygon
i = i + 1
end
end
end
polygon.dem = {dem[iA], dem[iB], dem[iC], dem[iD]}
polygon.lake = math.min(lakes[iA], lakes[iB], lakes[iC], lakes[iD])
local river_west = river_width(bounds_z[iA])
local river_north = river_width(bounds_x[iA-zp])
local river_east = 1-river_width(bounds_z[iB])
local river_south = 1-river_width(bounds_x[iD-zp-1])
if river_west > river_east then
local mean = (river_west + river_east) / 2
river_west = mean
river_east = mean
end
if river_north > river_south then
local mean = (river_north + river_south) / 2
river_north = mean
river_south = mean
end
polygon.rivers = {river_west, river_north, river_east, river_south}
end
end
local i = 1
for x = minp.x, maxp.x do
for z = minp.z, maxp.z do
local xb = x/blocksize
local zb = z/blocksize
local poly = polygons[i]
if poly then
local xf, zf = geometry.transform_quadri(poly.x, poly.z, x/blocksize, z/blocksize)
local i00, i01, i11, i10 = unpack(poly.i)
if xb >= 0 and xb < X-1 and zb >= 0 and zb < Z-1 then
local x0 = math.floor(xb)
local x1 = x0+1
local z0 = math.floor(zb)
local z1 = z0+1
local is_river = false
local r_west, r_north, r_east, r_south = unpack(poly.rivers)
if xf >= r_east then
is_river = true
xf = 1
elseif xf <= r_west then
is_river = true
xf = 0
end
if zf >= r_south then
is_river = true
zf = 1
elseif zf <= r_north then
is_river = true
zf = 0
end
local xf = xb - x0
local zf = zb - z0
if not is_river then
xf = (xf-r_west) / (r_east-r_west)
zf = (zf-r_north) / (r_south-r_north)
end
local i00 = index(x0,z0)
local i01 = index(x1,z0)
local i10 = index(x0,z1)
local i11 = index(x1,z1)
local terrain_height = math.floor(interp(
dem[i00],
dem[i01],
dem[i10],
dem[i11],
local vdem = poly.dem
local terrain_height = math.floor(0.5+interp(
vdem[1],
vdem[2],
vdem[3],
vdem[4],
xf, zf
))
local lake_height = math.floor(math.min(
lakes[i00],
lakes[i01],
lakes[i10],
lakes[i11]
))
local lake_height = math.floor(poly.lake)
local is_lake = lake_height > terrain_height
local is_river = false
if xf == 0 then
if links[i00] == 1 and rivers[i00] >= min_catchment then
is_river = true
elseif links[i10] == 3 and rivers[i10] >= min_catchment then
is_river = true
end
end
if zf == 0 then
if links[i00] == 2 and rivers[i00] >= min_catchment then
is_river = true
elseif links[i01] == 4 and rivers[i01] >= min_catchment then
is_river = true
end
end
local ivm = a:index(x, minp.y-1, z)
@ -164,6 +266,7 @@ local function generate(minp, maxp, seed)
end
end
end
i = i + 1
end
end

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@ -18,7 +18,7 @@ neighbours_dirs = np.array([
neighbours_pattern = neighbours_dirs > 0
def flow_dirs_lakes(dem, random=0.0625):
def flow_dirs_lakes(dem, random=0):
(Y, X) = dem.shape
dem_margin = np.zeros((Y+2, X+2))

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@ -4,6 +4,7 @@ import numpy as np
import noise
from save import save
from erosion import EvolutionModel
import bounds
import os
import sys
@ -22,7 +23,7 @@ n = np.zeros((mapsize, mapsize))
#micronoise_depth = 0.05
params = {
"octaves" : 8,
"octaves" : int(np.log2(mapsize)),
"persistence" : 0.5,
"lacunarity" : 2.,
}
@ -67,10 +68,18 @@ model.calculate_flow()
print('Done')
bx, by = bounds.make_bounds(model.dirs, model.rivers)
ox, oy = bounds.twist(bx, by, bounds.get_fixed(model.dirs))
offset_x = np.clip(np.floor(ox * 256), -128, 127)
offset_y = np.clip(np.floor(oy * 256), -128, 127)
save(model.dem, 'dem', dtype='>i2')
save(model.lakes, 'lakes', dtype='>i2')
save(model.dirs, 'links', dtype='u1')
save(model.rivers, 'rivers', dtype='>u4')
save(np.abs(bx), 'bounds_x', dtype='>i4')
save(np.abs(by), 'bounds_y', dtype='>i4')
save(offset_x, 'offset_x', dtype='i1')
save(offset_y, 'offset_y', dtype='i1')
with open('size', 'w') as sfile:
sfile.write('{:d}\n{:d}'.format(mapsize, mapsize))

30
view_map.py Executable file
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@ -0,0 +1,30 @@
#!/usr/bin/env python3
import numpy as np
import matplotlib.pyplot as plt
shape = np.loadtxt('size', dtype='u4')
n = shape[0] * shape[1]
dem = np.fromfile('dem', dtype='>i2').reshape(shape)
lakes = np.fromfile('lakes', dtype='>i2').reshape(shape)
rivers = np.fromfile('rivers', dtype='>u4').reshape(shape)
plt.subplot(1,3,1)
plt.pcolormesh(dem, cmap='viridis')
plt.gca().set_aspect('equal', 'box')
#plt.colorbar(orientation='horizontal')
plt.title('Raw elevation')
plt.subplot(1,3,2)
plt.pcolormesh(lakes, cmap='viridis')
plt.gca().set_aspect('equal', 'box')
#plt.colorbar(orientation='horizontal')
plt.title('Lake surface elevation')
plt.subplot(1,3,3)
plt.pcolormesh(np.log(rivers), vmin=0, vmax=np.log(n/25), cmap='Blues')
plt.gca().set_aspect('equal', 'box')
#plt.colorbar(orientation='horizontal')
plt.title('Rivers discharge')
plt.show()