mirror of
https://github.com/sbrl/Minetest-WorldEditAdditions.git
synced 2024-11-05 07:43:02 +00:00
144 lines
5.5 KiB
Lua
144 lines
5.5 KiB
Lua
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-- Test command: //multi //fp set1 1313 6 5540 //fp set2 1338 17 5521 //erode snowballs
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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 = {
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x = (math.random() * 2 - 1) * params.init_velocity,
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z = (math.random() * 2 - 1) * params.init_velocity
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}
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local heightmap_length = #heightmap
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-- print("[snowball] startpos ("..pos.x..", "..pos.z.."), velocity: ("..velocity.x..", "..velocity.z..")")
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local hist_velocity = {}
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for i = 1, params.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.x + 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_size.x-1 or z >= heightmap_size.z-1 then
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-- print("[snowball] hit edge; stopping at ("..x..", "..z.."), (bounds @ "..(heightmap_size.x-1)..", "..(heightmap_size.z-1)..")", "x", x, "/", heightmap_size.x-1, "z", z, "/", heightmap_size.z-1)
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return true, i
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end
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if #hist_velocity > 0 and i > 5
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and worldeditadditions.average(hist_velocity) < 0.03 then
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-- print("[snowball] It looks like we've stopped")
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return true, i
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end
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if normalmap[hi].y == 1 then return true, i end
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if hi > heightmap_length then return false, "Out-of-bounds on the array, hi: "..hi..", heightmap_length: "..heightmap_length end
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-- NOTE: We need to decide whether we want to keep the precomputed normals as we have now, or whether we want to dynamically compute them at the some of request.
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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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-- 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_deposit - step_erode)
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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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-- print("[snowball] now at ("..x..", "..z..") velocity "..worldeditadditions.vector.lengthsquared(velocity)..", sediment "..sediment)
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local new_vel_sq = worldeditadditions.vector.lengthsquared(velocity)
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if new_vel_sq > 1 then
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-- print("[snowball] velocity squared over 1, normalising")
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velocity = worldeditadditions.vector.normalize(velocity)
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end
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table.insert(hist_velocity, new_vel_sq)
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if #hist_velocity > params.velocity_hist_count then table.remove(hist_velocity, 1) end
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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_erode - step_deposit) -- Needs to be erosion - deposit, which is the opposite to the above
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end
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return true, params.max_steps
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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_initial, heightmap, heightmap_size, region_height, params_custom)
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local params = {
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rate_deposit = 0.03, -- 0.03
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rate_erosion = 0.04, -- 0.04
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friction = 0.07,
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speed = 1,
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max_steps = 80,
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velocity_hist_count = 3,
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init_velocity = 0.25,
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scale_iterations = 0.04,
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maxdiff = 0.4,
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count = 25000
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}
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-- Apply the default settings
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worldeditadditions.table_apply(params_custom, params)
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-- print("[erode/snowballs] params: ")
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-- print(worldeditadditions.format.map(params))
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local normals = worldeditadditions.calculate_normals(heightmap, heightmap_size)
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local stats_steps = {}
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for i = 1, params.count do
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-- print("[snowballs] starting snowball ", i)
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local success, steps = snowball(
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heightmap, normals, heightmap_size,
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{
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x = math.random() * (heightmap_size.x - 1),
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z = math.random() * (heightmap_size.z - 1)
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},
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params
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)
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table.insert(stats_steps, steps)
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if not success then return false, "Error: Failed at snowball "..i..":"..steps end
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end
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-- print("[snowballs] "..#stats_steps.." snowballs simulated, max "..params.max_steps.." steps, averaged ~"..worldeditadditions.average(stats_steps).."")
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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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local clamp_limit = math.floor(region_height * params.maxdiff + 0.5)
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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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if heightmap[i] < 0 then heightmap[i] = 0 end
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-- Limit the distance to params.maxdiff% of the region height
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if math.abs(heightmap_initial[i] - heightmap[i]) > region_height * params.maxdiff then
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if heightmap_initial[i] - heightmap[i] > 0 then
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heightmap[i] = heightmap_initial[i] - clamp_limit
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else
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heightmap[i] = heightmap_initial[i] + clamp_limit
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end
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end
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end
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if not params.noconv then
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local success, matrix = worldeditadditions.get_conv_kernel("gaussian", 3, 3)
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if not success then return success, matrix end
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matrix_size = {} matrix_size[0] = 3 matrix_size[1] = 3
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worldeditadditions.conv.convolve(
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heightmap, heightmap_size,
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matrix,
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matrix_size
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)
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end
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return true, ""..#stats_steps.." snowballs simulated, max "..params.max_steps.." steps (averaged ~"..worldeditadditions.average(stats_steps).." steps)"
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end
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