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terrain.lua: add wea.calculate_slope()

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Starbeamrainbowlabs 2021-08-04 00:51:16 +01:00
parent a9b746986a
commit 1833e68ec5
Signed by: sbrl
GPG key ID: 1BE5172E637709C2
1 changed files with 32 additions and 7 deletions
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39
worldeditadditions/utils/terrain.lua
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@ -1,3 +1,4 @@
local wea = worldeditadditions
--- Given a manip object and associates, generates a 2D x/z heightmap.
-- Note that pos1 and pos2 should have already been pushed through
@ -20,7 +21,7 @@ function worldeditadditions.make_heightmap(pos1, pos2, manip, area, data)
-- Scan each column top to bottom
for y = pos2.y+1, pos1.y, -1 do
local i = area:index(x, y, z)
if not (worldeditadditions.is_airlike(data[i]) or worldeditadditions.is_liquidlike(data[i])) then
if not (wea.is_airlike(data[i]) or wea.is_liquidlike(data[i])) then
-- It's the first non-airlike node in this column
-- Start heightmap values from 1 (i.e. there's at least 1 node in the column)
heightmap[hi] = (y - pos1.y) + 1
@ -72,18 +73,42 @@ function worldeditadditions.calculate_normals(heightmap, heightmap_size)
-- print("[normals] LEFT | index", z*heightmap_size.x + (x-1), "x", x, "x-1", x - 1, "left", left, "limit", 0)
-- print("[normals] RIGHT | index", z*heightmap_size.x + (x+1), "x", x, "x+1", x + 1, "right", right, "limit", heightmap_size.x-1)
result[hi] = worldeditadditions.vector.normalize({
x = left - right,
y = 2, -- Z & Y are flipped
z = down - up
})
result[hi] = wea.vector3.new(
left - right, -- x
2, -- y - Z & Y are flipped
down - up -- z
):normalise()
-- print("[normals] at "..hi.." ("..x..", "..z..") normal "..worldeditadditions.vector.tostring(result[hi]))
-- print("[normals] at "..hi.." ("..x..", "..z..") normal "..result[hi])
end
end
return result
end
--- Converts a 2d heightmap into slope values in radians.
-- Convert a radians to degrees by doing (radians*math.pi) / 180 for display,
-- but it is STRONGLY recommended to keep all internal calculations in radians.
-- @param heightmap table A ZERO indexed flat heightmap. See worldeditadditions.make_heightmap().
-- @param heightmap_size int[] The size of the heightmap in the form [ z, x ]
-- @return Vector[] The calculated slope map, in the same form as the input heightmap. Each element of the array is a (floating-point) number representing the slope in that cell in radians.
function worldeditadditions.calculate_slope(heightmap, heightmap_size)
local normals = worldeditadditions.calculate_normals(heightmap, heightmap_size)
local slopes = { }
local up = wea.vector3(0, 1, 0) -- Z & Y are flipped
for z = heightmap_size.z-1, 0, -1 do
for x = heightmap_size.x-1, 0, -1 do
local hi = z*heightmap_size.x + x
-- Ref https://stackoverflow.com/a/16669463/1460422
slopes[hi] = wea.vector3.dot_product(normals[hi], up)
end
end
return slopes
end
--- Applies changes to a heightmap to a Voxel Manipulator data block.
-- @param pos1 vector Position 1 of the defined region
-- @param pos2 vector Position 2 of the defined region