mirror of
https://github.com/sbrl/Minetest-WorldEditAdditions.git
synced 2024-06-30 17:04:56 +00:00
Starbeamrainbowlabs
fd5804dd9c
Specifically, I'm unsure about whether I'm happy with the effects of the algorithm. Also, we convolve with a 3x3 gaussian kernel after erosion is complete - and we have verified that the erosion is having an positive effect at "roughening up" a terrain surface. It seems like the initial blog post was correct: the algorithm does tend to make steep surfaces steeper. It also appears that it's more effective on larger areas, and 'gentler' curves. THis might be because the surface normals are more conducive to making the snowballs roll. Finally, 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.
60 lines
2.3 KiB
Lua
60 lines
2.3 KiB
Lua
|
|
--[[
|
|
Convolves over a given 2D heightmap with a given matrix.
|
|
Note that this *mutates* the given heightmap.
|
|
Note also that the dimensions of the matrix must *only* be odd.
|
|
@param {number[]} heightmap The 2D heightmap to convolve over.
|
|
@param {[number,number]} heightmap_size The size of the heightmap as [ height, width ]
|
|
@param {number[]} matrix The matrix to convolve with.
|
|
@param {[number, number]} matrix_size The size of the convolution matrix as [ height, width ]
|
|
]]--
|
|
function worldeditadditions.conv.convolve(heightmap, heightmap_size, matrix, matrix_size)
|
|
if matrix_size[0] % 2 ~= 1 or matrix_size[1] % 2 ~= 1 then
|
|
return false, "Error: The matrix size must contain only odd numbers (even number detected)"
|
|
end
|
|
|
|
local border_size = {}
|
|
border_size[0] = (matrix_size[0]-1) / 2 -- height
|
|
border_size[1] = (matrix_size[1]-1) / 2 -- width
|
|
-- print("[convolve] matrix_size", matrix_size[0], matrix_size[1])
|
|
-- print("[convolve] border_size", border_size[0], border_size[1])
|
|
-- print("[convolve] heightmap_size: ", heightmap_size[0], heightmap_size[1])
|
|
--
|
|
-- print("[convolve] z: from", (heightmap_size[0]-border_size[0]) - 1, "to", border_size[0], "step", -1)
|
|
-- print("[convolve] x: from", (heightmap_size[1]-border_size[1]) - 1, "to", border_size[1], "step", -1)
|
|
|
|
-- Convolve over only the bit that allows us to use the full convolution matrix
|
|
for z = (heightmap_size[0]-border_size[0]) - 1, border_size[0], -1 do
|
|
for x = (heightmap_size[1]-border_size[1]) - 1, border_size[1], -1 do
|
|
local total = 0
|
|
|
|
|
|
local hi = (z * heightmap_size[1]) + x
|
|
-- print("[convolve/internal] z", z, "x", x, "hi", hi)
|
|
|
|
-- No continue statement in Lua :-/
|
|
if heightmap[hi] ~= -1 then
|
|
for mz = matrix_size[0]-1, 0, -1 do
|
|
for mx = matrix_size[1]-1, 0, -1 do
|
|
local mi = (mz * matrix_size[1]) + mx
|
|
local cz = z + (mz - border_size[0])
|
|
local cx = x + (mx - border_size[1])
|
|
|
|
local i = (cz * heightmap_size[1]) + cx
|
|
|
|
-- A value of -1 = nothing in this column (so we should ignore it)
|
|
if heightmap[i] ~= -1 then
|
|
total = total + (matrix[mi] * heightmap[i])
|
|
end
|
|
end
|
|
end
|
|
-- Rounding hack - ref https://stackoverflow.com/a/18313481/1460422
|
|
-- heightmap[hi] = math.floor(total + 0.5)
|
|
heightmap[hi] = math.ceil(total)
|
|
end
|
|
end
|
|
end
|
|
|
|
return true, heightmap
|
|
end
|