mirror of
https://github.com/sbrl/Minetest-WorldEditAdditions.git
synced 2024-11-05 06:53:52 +01:00
93 lines
3.1 KiB
Lua
93 lines
3.1 KiB
Lua
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-- Test command: //multi //fp set1 1312 5 5543 //fp set2 1336 18 5521 //erode//multi //fp set1 1312 5 5543 //fp set2 1336 18 5521 //erode
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local function snowball(heightmap, normalmap, heightmap_size, startpos, params)
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local sediment = 0
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local pos = { x = startpos.x, z = startpos.z }
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local pos_prev = { x = pos.x, z = pos.z }
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local velocity = { x = 0, z = 0 }
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local heightmap_length = #heightmap
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-- print("[snowball] startpos ("..pos.x..", "..pos.z..")")
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for i = 1, params.snowball_max_steps do
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local x = pos.x
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local z = pos.z
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local hi = math.floor(z+0.5)*heightmap_size[1] + math.floor(x+0.5)
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-- Stop if we go out of bounds
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if x < 0 or z < 0
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or x >= heightmap[1]-1 or z >= heightmap[0]-1 then
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-- print("[snowball] hit edge; stopping at ("..x..", "..z.."), (bounds @ "..heightmap_size[1]..", "..heightmap_size[0]..")")
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return
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end
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-- print("[snowball] now at ("..x..", "..z..") (bounds @ "..heightmap_size[1]..", "..heightmap_size[0]..")")
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if hi > heightmap_length then print("[snowball] out-of-bounds on the array, hi: "..hi..", heightmap_length: "..heightmap_length) return end
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-- print("[snowball] sediment", sediment, "rate_deposit", params.rate_deposit, "normalmap[hi].z", normalmap[hi].z)
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local step_deposit = sediment * params.rate_deposit * normalmap[hi].z
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local step_erode = params.rate_erosion * (1 - normalmap[hi].z) * math.min(1, i*params.scale_iterations)
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local step_diff = step_deposit - step_erode
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-- Erode / Deposit, but only if we are on a different node than we were in the last step
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if math.floor(pos_prev.x) ~= math.floor(x)
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and math.floor(pos_prev.z) ~= math.floor(z) then
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heightmap[hi] = heightmap[hi] + step_diff
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end
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velocity.x = params.friction * velocity.x + normalmap[hi].x * params.speed
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velocity.z = params.friction * velocity.z + normalmap[hi].y * params.speed
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pos_prev.x = x
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pos_prev.z = z
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pos.x = pos.x + velocity.x
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pos.z = pos.z + velocity.z
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sediment = sediment + step_diff
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end
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end
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--[[
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2D erosion algorithm based on snowballs
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Note that this *mutates* the given heightmap.
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@source https://jobtalle.com/simulating_hydraulic_erosion.html
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]]--
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function worldeditadditions.erode.snowballs(heightmap, heightmap_size, params)
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-- Apply the default settings
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worldeditadditions.table_apply({
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rate_deposit = 0.03,
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rate_erosion = 0.04,
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friction = 0.07,
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speed = 0.15,
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radius = 0.8,
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snowball_max_steps = 80,
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scale_iterations = 0.04,
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drops_per_cell = 0.4,
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snowball_count = 50000
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}, params)
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print("[erode/snowballs] params: "..worldeditadditions.map_stringify(params))
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local normals = worldeditadditions.calculate_normals(heightmap, heightmap_size)
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for i = 1, params.snowball_count do
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snowball(
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heightmap, normals, heightmap_size,
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{
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x = math.random() * (heightmap_size[1] - 1),
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z = math.random() * (heightmap_size[0] - 1)
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},
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params
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)
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end
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-- Round everything to the nearest int, since you can't really have
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-- something like .141592671 of a node
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-- Note that we do this after *all* the erosion is complete
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for i,v in ipairs(heightmap) do
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heightmap[i] = math.floor(heightmap[i] + 0.5)
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end
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return true, params.snowball_count.." snowballs simulated"
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end
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