mirror of
https://github.com/sbrl/Minetest-WorldEditAdditions.git
synced 2024-11-09 00:43:48 +01:00
69 lines
2.6 KiB
Lua
69 lines
2.6 KiB
Lua
local wea_c = worldeditadditions_core
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local Vector3 = wea_c.Vector3
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--[[
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Convolves over a given 2D heightmap with a given matrix.
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Note that this *mutates* the given heightmap.
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Note also that the dimensions of the matrix must *only* be odd.
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@param {number[]} heightmap The 2D heightmap to convolve over.
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@param Vector3 heightmap_size The size of the heightmap as an X/Z Vector3 instance.
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@param {number[]} matrix The matrix to convolve with.
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@param Vector3 matrix_size The size of the convolution matrix as an X/Z Vector3 instance.
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]]--
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function worldeditadditions.conv.convolve(heightmap, heightmap_size, matrix, matrix_size)
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if matrix_size.x % 2 ~= 1 or matrix_size.z % 2 ~= 1 then
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return false, "Error: The matrix size must contain only odd numbers (even number detected)"
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end
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-- We need to reference a *copy* of the heightmap when convolving
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-- This is because we need the original values when we perform a
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-- convolution on a given pixel
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local heightmap_copy = wea_c.table.shallowcopy(heightmap)
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local border_size = Vector3.new(
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(matrix_size.x-1) / 2, -- x = height
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0,
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(matrix_size.z-1) / 2 -- z = width
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)
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-- print("[convolve] matrix_size", matrix_size.x, matrix_size.z)
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-- print("[convolve] border_size", border_size.x, border_size.z)
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-- print("[convolve] heightmap_size: ", heightmap_size.z, heightmap_size.x)
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--
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-- print("[convolve] z: from", (heightmap_size.z-border_size.x) - 1, "to", border_size.x, "step", -1)
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-- print("[convolve] x: from", (heightmap_size.x-border_size.z) - 1, "to", border_size.z, "step", -1)
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-- Convolve over only the bit that allows us to use the full convolution matrix
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for z = (heightmap_size.z-border_size.x) - 1, border_size.x, -1 do
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for x = (heightmap_size.x-border_size.z) - 1, border_size.z, -1 do
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local total = 0
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local hi = (z * heightmap_size.x) + x
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-- print("[convolve/internal] z", z, "x", x, "hi", hi)
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-- No continue statement in Lua :-/
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if heightmap_copy[hi] ~= -1 then
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for mz = matrix_size.x-1, 0, -1 do
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for mx = matrix_size.z-1, 0, -1 do
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local mi = (mz * matrix_size.z) + mx
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local cz = z + (mz - border_size.x)
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local cx = x + (mx - border_size.z)
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local i = (cz * heightmap_size.x) + cx
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-- A value of -1 = nothing in this column (so we should ignore it)
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if heightmap_copy[i] ~= -1 then
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total = total + (matrix[mi] * heightmap_copy[i])
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end
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end
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end
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-- Rounding hack - ref https://stackoverflow.com/a/18313481/1460422
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-- heightmap[hi] = math.floor(total + 0.5)
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heightmap[hi] = math.ceil(total)
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end
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end
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end
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return true, heightmap
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end
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