Optionally disable distorsion

by setting 'mapgen_rivers_distort = false' in minetest.conf

init.lua

@@ -8,6 +8,7 @@ local blocksize = mapgen_rivers.blocksize
 local sea_level = mapgen_rivers.sea_level
 local riverbed_slope = mapgen_rivers.riverbed_slope
 local elevation_chill = mapgen_rivers.elevation_chill
+local use_distort = mapgen_rivers.distort
 
 dofile(modpath .. 'noises.lua')
 
@@ -48,21 +49,28 @@ local function generate(minp, maxp, seed)
 			y = chulens.y+1,
 			z = chulens.z,
 		}
+		if use_distort then
 			noise_x_obj = minetest.get_perlin_map(mapgen_rivers.noise_params.distort_x, mapsize)
 			noise_z_obj = minetest.get_perlin_map(mapgen_rivers.noise_params.distort_z, mapsize)
+			noise_distort_obj = minetest.get_perlin_map(mapgen_rivers.noise_params.distort_amplitude, chulens)
+		end
 		noise_heat_obj = minetest.get_perlin_map(mapgen_rivers.noise_params.heat, chulens)
 		noise_heat_blend_obj = minetest.get_perlin_map(mapgen_rivers.noise_params.heat_blend, chulens)
-		noise_distort_obj = minetest.get_perlin_map(mapgen_rivers.noise_params.distort_amplitude, chulens)
 		init = true
 	end
 
 	local minp2d = {x=minp.x, y=minp.z}
+	if use_distort then
 		noise_x_obj:get_3d_map_flat(minp, noise_x_map)
 		noise_z_obj:get_3d_map_flat(minp, noise_z_map)
 		noise_distort_obj:get_2d_map_flat(minp2d, noise_distort_map)
+	end
 	noise_heat_obj:get_2d_map_flat(minp2d, noise_heat_map)
 	noise_heat_blend_obj:get_2d_map_flat(minp2d, noise_heat_blend_map)
 
+	local terrain_map, lake_map, incr, i_origin
+
+	if use_distort then
 		local xmin, xmax, zmin, zmax = minp.x, maxp.x, minp.z, maxp.z
 		local i = 0
 		local i2d = 0
@@ -87,9 +95,12 @@ local function generate(minp, maxp, seed)
 
 		local pminp = {x=math.floor(xmin), z=math.floor(zmin)}
 		local pmaxp = {x=math.floor(xmax)+1, z=math.floor(zmax)+1}
-	local incr = pmaxp.x-pminp.x+1
+		incr = pmaxp.x-pminp.x+1
-	local i_origin = 1 - pminp.z*incr - pminp.x
+		i_origin = 1 - pminp.z*incr - pminp.x
-	local terrain_map, lake_map = heightmaps(pminp, pmaxp)
+		terrain_map, lake_map = heightmaps(pminp, pmaxp)
+	else
+		terrain_map, lake_map = heightmaps(minp, maxp)
+	end
 
 	local c_stone = minetest.get_content_id("default:stone")
 	local c_dirt = minetest.get_content_id("default:dirt")
@@ -119,7 +130,14 @@ local function generate(minp, maxp, seed)
 			local ivm = a:index(x, minp.y, z)
 			local ground_above = false
 			local temperature = noise_heat_map[i2d]+noise_heat_blend_map[i2d]
+			local terrain, lake
+			if not use_distort then
+				terrain = terrain_map[i2d]
+				lake = lake_map[i2d]
+			end
+
 			for y = maxp.y+1, minp.y, -1 do
+				if use_distort then
 					local xn = noise_x_map[nid]
 					local zn = noise_z_map[nid]
 					local x0 = math.floor(xn)
@@ -130,9 +148,11 @@ local function generate(minp, maxp, seed)
 					local i2 = i1+incr
 					local i3 = i2-1
 
-				local terrain = interp(terrain_map[i0], terrain_map[i1], terrain_map[i2], terrain_map[i3], xn-x0, zn-z0)
+					terrain = interp(terrain_map[i0], terrain_map[i1], terrain_map[i2], terrain_map[i3], xn-x0, zn-z0)
+					lake = math.min(lake_map[i0], lake_map[i1], lake_map[i2], lake_map[i3])
+				end
+
 				if y <= maxp.y then
-					local lake = math.min(lake_map[i0], lake_map[i1], lake_map[i2], lake_map[i3])
 
 					local is_lake = lake > terrain
 					local ivm = a:index(x, y, z)
@@ -166,13 +186,21 @@ local function generate(minp, maxp, seed)
 				ground_above = y <= terrain
 
 				ivm = ivm + ystride
+				if use_distort then
 					nid = nid + incrY
 				end
+			end
+
+			if use_distort then
 				nid = nid + incrX
+			end
 			i2d = i2d + 1
 		end
+
+		if use_distort then
 			nid = nid + incrZ
 		end
+	end
 
 	vm:set_data(data)
 	minetest.generate_ores(vm, minp, maxp)

settings.lua

@@ -47,7 +47,7 @@ mapgen_rivers.sea_level = get_settings('sea_level', 'int', 1)
 mapgen_rivers.min_catchment = get_settings('min_catchment', 'float', 25)
 mapgen_rivers.max_catchment = get_settings('max_catchment', 'float', 40000)
 mapgen_rivers.riverbed_slope = get_settings('riverbed_slope', 'float', 0.4) * mapgen_rivers.blocksize
---mapgen_rivers.distort = get_settings('distort', 'bool', true) To be implemented: should be possible to disable distorsion
+mapgen_rivers.distort = get_settings('distort', 'bool', true)
 mapgen_rivers.glaciers = get_settings('glaciers', 'bool', true)
 mapgen_rivers.glacier_factor = get_settings('glacier_factor', 'float', 8)
 mapgen_rivers.elevation_chill = get_settings('elevation_chill', 'float', 0.25)