Minetest-WorldEditAdditions/worldeditadditions/torus.lua

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--- Overlap command. Places a specified node on top of
-- @module worldeditadditions.overlay
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function worldeditadditions.torus(position, major_radius, minor_radius, target_node, hollow)
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-- position = { x, y, z }
local total_radius = major_radius + minor_radius
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local inner_minor_radius = minor_radius - 2
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local major_radius_sq = major_radius*major_radius
local minor_radius_sq = minor_radius*minor_radius
local inner_minor_radius_sq = inner_minor_radius*inner_minor_radius
-- Fetch the nodes in the specified area
-- OPTIMIZE: We should be able to calculate a more efficient box-area here
local manip, area = worldedit.manip_helpers.init_radius(position, total_radius)
local data = manip:get_data()
local node_id = minetest.get_content_id(target_node)
local node_id_air = minetest.get_content_id("air")
local stride_z, stride_y = area.zstride, area.ystride
local count = 0 -- The number of nodes replaced
local idx_z_base = area:index(position.x - total_radius, position.y - total_radius, position.z - total_radius) -- initial z offset
for z = -total_radius, total_radius do
local z_sq = z*z
local idx_y_base = idx_z_base
for y = -total_radius, total_radius do
local y_sq = y*y
local i = idx_y_base
for x = -total_radius, total_radius do
local x_sq = x*x
-- (x^2+y^2+z^2-(a^2+b^2))^2-4 a b (b^2-z^2)
-- Where:
-- (x, y, z) is the point
-- a is the major radius (centre to centre of circle)
-- b is the minor radius (radius of circle
local comp_a = (x_sq+y_sq+z_sq - (major_radius_sq+minor_radius_sq))
local test_value = comp_a*comp_a - 4*major_radius*minor_radius*(minor_radius_sq-z_sq)
-- If we're inside the torus, then fill it in
if test_value <= 1 then
local place_ok = not hollow;
if not place_ok then
-- It must be hollow! Do some additional calculations.
local inner_comp_a = (x_sq+y_sq+z_sq - (major_radius_sq+inner_minor_radius_sq))
local inner_test_value = inner_comp_a*inner_comp_a - 4*major_radius*inner_minor_radius*(inner_minor_radius_sq-z_sq)
-- It's only ok to place it if it's outside our inner torus
place_ok = inner_test_value >= 0
end
if place_ok then
data[i] = node_id
count = count + 1
end
end
i = i + 1
end
idx_y_base = idx_y_base + stride_y
end
idx_z_base = idx_z_base + stride_z
end
-- Save the modified nodes back to disk & return
worldedit.manip_helpers.finish(manip, data)
return count
end