2021-06-03 19:21:45 +02:00
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local modpath = mapgen_rivers.modpath
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2020-05-23 15:52:16 +02:00
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local transform_quadri = dofile(modpath .. 'geometry.lua')
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2021-06-06 13:25:43 +02:00
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local sea_level = mapgen_rivers.settings.sea_level
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local riverbed_slope = mapgen_rivers.settings.riverbed_slope * mapgen_rivers.settings.blocksize
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2020-05-23 15:52:16 +02:00
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2022-01-03 15:45:27 +01:00
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local out_elev = mapgen_rivers.settings.margin_elev
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2020-07-21 12:46:23 +02:00
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2022-01-03 11:56:16 +01:00
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-- Localize for performance
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local floor, min, max = math.floor, math.min, math.max
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local unpk = unpack
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2020-05-23 15:52:16 +02:00
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-- Linear interpolation
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local function interp(v00, v01, v11, v10, xf, zf)
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local v0 = v01*xf + v00*(1-xf)
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local v1 = v11*xf + v10*(1-xf)
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return v1*zf + v0*(1-zf)
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end
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2022-01-21 14:22:22 +01:00
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function mapgen_rivers.make_heightmaps(minp, maxp)
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2020-05-23 15:52:16 +02:00
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2022-01-21 14:22:22 +01:00
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local polygons = mapgen_rivers.make_polygons(minp, maxp)
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2020-07-21 12:46:23 +02:00
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local incr = maxp.z-minp.z+1
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2020-05-23 15:52:16 +02:00
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local terrain_height_map = {}
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local lake_height_map = {}
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local i = 1
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2020-07-21 12:46:23 +02:00
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for z=minp.z, maxp.z do
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for x=minp.x, maxp.x do
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2020-05-23 15:52:16 +02:00
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local poly = polygons[i]
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if poly then
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2020-12-22 16:38:30 +01:00
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local xf, zf = transform_quadri(poly.x, poly.z, x, z)
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2022-01-03 11:56:16 +01:00
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local i00, i01, i11, i10 = unpk(poly.i)
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2020-05-23 15:52:16 +02:00
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-- Load river width on 4 edges and corners
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2022-01-03 11:56:16 +01:00
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local r_west, r_north, r_east, r_south = unpk(poly.rivers)
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local c_NW, c_NE, c_SE, c_SW = unpk(poly.river_corners)
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2020-05-23 15:52:16 +02:00
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-- Calculate the depth factor for each edge and corner.
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-- Depth factor:
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-- < 0: outside river
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-- = 0: on riverbank
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-- > 0: inside river
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local depth_factors = {
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2022-01-19 17:58:46 +01:00
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r_west - xf , -- West edge (1)
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r_north - zf , -- North edge (2)
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r_east - (1-xf), -- East edge (3)
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r_south - (1-zf), -- South edge (4)
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c_NW - xf - zf , -- North-West corner (5)
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c_NE - (1-xf) - zf , -- North-East corner (6)
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c_SE - (1-xf) - (1-zf), -- South-East corner (7)
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c_SW - xf - (1-zf), -- South-West corner (8)
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2020-05-23 15:52:16 +02:00
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}
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2022-01-19 17:58:46 +01:00
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-- Find the maximal depth factor, which determines to which of the 8 river sections (4 edges + 4 corners) the current point belongs.
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-- If imax is still at 0, it means that we are not in a river.
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local dpmax = 0
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2020-05-23 15:52:16 +02:00
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local imax = 0
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for i=1, 8 do
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2022-01-19 17:58:46 +01:00
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if depth_factors[i] > dpmax then
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dpmax = depth_factors[i]
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2020-05-23 15:52:16 +02:00
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imax = i
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end
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end
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2022-01-19 17:58:46 +01:00
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-- Transform the coordinates to have xfc and zfc = 0 or 1 in rivers (to avoid rivers having lateral slope and to accomodate the riverbanks smoothly)
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local xfc, zfc
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-- xfc:
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if imax == 0 or imax == 2 or imax == 4 then -- river segment does not constrain X coordinate, so accomodate xf in function of other river sections
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local x0 = max(r_west-dpmax, c_NW-zf-dpmax, c_SW-(1-zf)-dpmax, 0) -- new xf will be bounded to 0 by western riverbank
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local x1 = 1-max(r_east-dpmax, c_NE-zf-dpmax, c_SE-(1-zf)-dpmax, 0) -- and bounded to 1 by eastern riverbank
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if x0 >= x1 then
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xfc = 0.5
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else
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xfc = (xf-x0) / (x1-x0)
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end
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elseif imax == 1 or imax == 5 or imax == 8 then -- river at the western side of the polygon
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xfc = 0
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else -- 3, 6, 7 : river at the eastern side of the polygon
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xfc = 1
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end
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-- Same for zfc:
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if imax == 0 or imax == 1 or imax == 3 then -- river segment does not constrain Z coordinate, so accomodate zf in function of other river sections
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local z0 = max(r_north-dpmax, c_NW-xf-dpmax, c_NE-(1-xf)-dpmax, 0) -- new zf will be bounded to 0 by northern riverbank
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local z1 = 1-max(r_south-dpmax, c_SW-xf-dpmax, c_SE-(1-xf)-dpmax, 0) -- and bounded to 1 by southern riverbank
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if z0 >= z1 then
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zfc = 0.5
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else
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zfc = (zf-z0) / (z1-z0)
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end
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elseif imax == 2 or imax == 5 or imax == 6 then -- river at the northern side of the polygon
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zfc = 0
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else -- 4, 7, 8 : river at the southern side of the polygon
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zfc = 1
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2020-05-23 15:52:16 +02:00
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end
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-- Determine elevation by interpolation
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local vdem = poly.dem
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2022-01-03 11:56:16 +01:00
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local terrain_height = floor(0.5+interp(
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2020-05-23 15:52:16 +02:00
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vdem[1],
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vdem[2],
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vdem[3],
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vdem[4],
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2022-01-19 17:58:46 +01:00
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xfc, zfc
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2020-05-23 15:52:16 +02:00
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))
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2020-12-22 18:34:30 +01:00
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-- Spatial gradient of the interpolation
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2022-01-19 17:58:46 +01:00
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local slope_x = zfc*(vdem[3]-vdem[4]) + (1-zfc)*(vdem[2]-vdem[1]) < 0
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local slope_z = xfc*(vdem[3]-vdem[2]) + (1-xfc)*(vdem[4]-vdem[1]) < 0
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2020-12-22 18:34:30 +01:00
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local lake_id = 0
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if slope_x then
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if slope_z then
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lake_id = 3
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else
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lake_id = 2
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end
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else
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if slope_z then
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lake_id = 4
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else
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lake_id = 1
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end
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end
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2022-01-03 11:56:16 +01:00
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local lake_height = max(floor(poly.lake[lake_id]), terrain_height)
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2020-12-22 18:34:30 +01:00
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2022-01-19 17:58:46 +01:00
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if imax > 0 and dpmax > 0 then
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terrain_height = min(max(lake_height, sea_level) - floor(1+dpmax*riverbed_slope), terrain_height)
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2020-05-23 15:52:16 +02:00
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end
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terrain_height_map[i] = terrain_height
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lake_height_map[i] = lake_height
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else
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2022-01-03 15:45:27 +01:00
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terrain_height_map[i] = out_elev
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lake_height_map[i] = out_elev
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2020-05-23 15:52:16 +02:00
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end
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i = i + 1
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end
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end
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return terrain_height_map, lake_height_map
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end
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