Implemented grid twisting. Still many possible bugs, potentially clumsy implementation, but it seems to work.

This commit is contained in:
Gael-de-Sailly 2020-04-12 09:40:10 +02:00
parent 6314117642
commit b7c6f71635
5 changed files with 134 additions and 12 deletions

2
.gitignore vendored
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@ -4,4 +4,6 @@ lakes
links
rivers
size
offset_x
offset_y
unused/

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 d12 = distance_to_segment(x1,y1,x2,y2,x,y)
local d34 = distance_to_segment(x3,y3,x4,y4,x,y)
local xc = d12 / (d12+d34)
local d23 = distance_to_segment(x2,y2,x3,y3,x,y)
local d41 = distance_to_segment(x4,y4,x1,y1,x,y)
local yc = d41 / (d23+d41)
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,
}

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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
@ -31,19 +32,37 @@ local links = load_map(worldpath..'links', 1, false)
copy_if_needed('rivers')
local rivers = load_map(worldpath..'rivers', 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 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, v10, v11, xf, zf)
v0 = v01*xf + v00*(1-xf)
v1 = v11*xf + v10*(1-xf)
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 = 20
local sea_level = 1
local min_catchment = 25
@ -82,15 +101,62 @@ local function generate(minp, maxp, seed)
for z = minp.z, maxp.z do
local xb = x/blocksize
local zb = z/blocksize
local xc = math.floor(xb+0.5)
local zc = math.floor(zb+0.5)
if xb >= 0 and xb < X-1 and zb >= 0 and zb < Z-1 then
local x0 = math.floor(xb)
local x0, z0
if xc >= 0 and zc >= 0 and xc < X and zc < Z then
local xoff, zoff = get_point_location(xc, zc)
local north, east, south, west
if xc > 0 then
local x1off, z1off = get_point_location(xc-1, zc)
west = geometry.area({xoff, x1off, xb}, {zoff, z1off, zb}) <= 0
else
west = zb > zoff
end
if zc > 0 then
local x2off, z2off = get_point_location(xc, zc-1)
north = geometry.area({xoff, x2off, xb}, {zoff, z2off, zb}) <= 0
else
north = xb > xoff
end
if xc < X-1 then
local x3off, z3off = get_point_location(xc+1, zc)
east = geometry.area({xoff, x3off, xb}, {zoff, z3off, zb}) <= 0
else
east = zb < zoff
end
if zc < Z-1 then
local x4off, z4off = get_point_location(xc, zc+1)
south = geometry.area({xoff, x4off, xb}, {zoff, z4off, zb}) <= 0
else
south = xb < xoff
end
if west and not north then
x0, z0 = xc-1, zc-1
elseif north and not east then
x0, z0 = xc, zc-1
elseif east and not south then
x0, z0 = xc, zc
elseif south and not west then
x0, z0 = xc-1, zc
else
x0, z0 = xc, zc
end
end
if x0 and z0 and x0 >= 0 and x0 < X-1 and z0 >= 0 and z0 < Z-1 then
local x1 = x0+1
local z0 = math.floor(zb)
local z1 = z0+1
local xf = xb - x0
local zf = zb - z0
local xf, zf
do
local xA, zA = get_point_location(x0, z0)
local xB, zB = get_point_location(x0, z1)
local xC, zC = get_point_location(x1, z1)
local xD, zD = get_point_location(x1, z0)
xf, zf = geometry.transform_quadri({xA, xB, xC, xD}, {zA, zB, zC, zD}, xb, zb)
end
local i00 = index(x0,z0)
local i01 = index(x1,z0)
@ -115,7 +181,7 @@ local function generate(minp, maxp, seed)
local is_lake = lake_height > terrain_height
local is_river = false
if xf == 0 then
if xf < 1/6 then
if links[i00] == 1 and rivers[i00] >= min_catchment then
is_river = true
elseif links[i10] == 3 and rivers[i10] >= min_catchment then
@ -123,7 +189,7 @@ local function generate(minp, maxp, seed)
end
end
if zf == 0 then
if zf < 1/6 then
if links[i00] == 2 and rivers[i00] >= min_catchment then
is_river = true
elseif links[i01] == 4 and rivers[i01] >= min_catchment then

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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
@ -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(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))