Fix river shape in confluences (less sharp riverbeds when a small rivers joins a big one)
Also cleaned and commented the code
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Gael-de-Sailly
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fce6a33818
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02f9805507
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@ -46,50 +46,57 @@ local function heightmaps(minp, maxp)
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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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r_west - xf,
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r_north - zf,
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xf - r_east,
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zf - r_south,
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c_NW-xf-zf,
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xf-zf-c_NE,
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xf+zf-c_SE,
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zf-xf-c_SW,
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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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}
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-- Find the maximal depth factor and determine to which river it belongs
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local depth_factor_max = 0
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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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local imax = 0
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for i=1, 8 do
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if depth_factors[i] > depth_factor_max then
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depth_factor_max = depth_factors[i]
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if depth_factors[i] > dpmax then
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dpmax = depth_factors[i]
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imax = i
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end
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end
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-- Transform the coordinates to have xf and zf = 0 or 1 in rivers (to avoid rivers having lateral slope and to accomodate the surrounding smoothly)
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if imax == 0 then
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local x0 = max(r_west, c_NW-zf, zf-c_SW)
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local x1 = min(r_east, c_NE+zf, c_SE-zf)
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local z0 = max(r_north, c_NW-xf, xf-c_NE)
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local z1 = min(r_south, c_SW+xf, c_SE-xf)
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xf = (xf-x0) / (x1-x0)
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zf = (zf-z0) / (z1-z0)
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elseif imax == 1 then
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xf = 0
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elseif imax == 2 then
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zf = 0
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elseif imax == 3 then
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xf = 1
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elseif imax == 4 then
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zf = 1
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elseif imax == 5 then
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xf, zf = 0, 0
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elseif imax == 6 then
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xf, zf = 1, 0
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elseif imax == 7 then
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xf, zf = 1, 1
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elseif imax == 8 then
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xf, zf = 0, 1
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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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end
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-- Determine elevation by interpolation
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@ -99,12 +106,12 @@ local function heightmaps(minp, maxp)
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vdem[2],
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vdem[3],
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vdem[4],
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xf, zf
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xfc, zfc
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))
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-- Spatial gradient of the interpolation
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local slope_x = zf*(vdem[3]-vdem[4]) + (1-zf)*(vdem[2]-vdem[1]) < 0
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local slope_z = xf*(vdem[3]-vdem[2]) + (1-xf)*(vdem[4]-vdem[1]) < 0
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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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local lake_id = 0
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if slope_x then
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if slope_z then
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@ -121,8 +128,8 @@ local function heightmaps(minp, maxp)
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end
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local lake_height = max(floor(poly.lake[lake_id]), terrain_height)
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if imax > 0 and depth_factor_max > 0 then
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terrain_height = min(max(lake_height, sea_level) - floor(1+depth_factor_max*riverbed_slope), terrain_height)
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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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end
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terrain_height_map[i] = terrain_height
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@ -236,15 +236,15 @@ local function make_polygons(minp, maxp)
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end
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end
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polygon.river_corners = {riverA, 1-riverB, 2-riverC, 1-riverD}
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polygon.river_corners = {riverA, riverB, riverC, riverD}
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-- Flow directions
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local dirA, dirB, dirC, dirD = dirs[iA], dirs[iB], dirs[iC], dirs[iD]
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-- Determine the river flux on the edges, by testing dirs values
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local river_west = (dirA==1 and riverA or 0) + (dirD==3 and riverD or 0)
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local river_north = (dirA==2 and riverA or 0) + (dirB==4 and riverB or 0)
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local river_east = 1 - (dirB==1 and riverB or 0) - (dirC==3 and riverC or 0)
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local river_south = 1 - (dirD==2 and riverD or 0) - (dirC==4 and riverC or 0)
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local river_east = (dirB==1 and riverB or 0) + (dirC==3 and riverC or 0)
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local river_south = (dirD==2 and riverD or 0) + (dirC==4 and riverC or 0)
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polygon.rivers = {river_west, river_north, river_east, river_south}
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end
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