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100 lines
3.5 KiB
Lua
100 lines
3.5 KiB
Lua
--- Generates torus shapes.
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-- @module worldeditadditions.torus
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--- Generates a torus shape at the given position with the given parameters.
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-- @param position Vector The position at which to generate the torus.
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-- @param major_radius number The major radius of the torus - i.e. the distance from the middle to the ring.
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-- @param minor_radius number The minor radius of the torus - i.e. the radius fo the ring itself.
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-- @param target_node string The name of the target node to generate the torus with.
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-- @param axes=xz string|nil The axes upon which the torus should lay flat.
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-- @param hollow=false boolean Whether the generated torus should be hollow or not.
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function worldeditadditions.torus(position, major_radius, minor_radius, target_node, axes, hollow)
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local matrix = {x='yz', y='xz', z='xy'}
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if type(axes) ~= "string" then axes = "xz" end
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if #axes == 1 and axes:match('[xyz]') then axes = matrix[axes] end
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-- position = { x, y, z }
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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
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local minor_radius_sq = minor_radius*minor_radius
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local inner_minor_radius_sq = inner_minor_radius*inner_minor_radius
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-- Fetch the nodes in the specified area
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-- OPTIMIZE: We should be able to calculate a more efficient box-area here
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-- This is complicated by the multiple possible axes though
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local manip, area = worldedit.manip_helpers.init_radius(position, total_radius)
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local data = manip:get_data()
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local node_id = minetest.get_content_id(target_node)
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local node_id_air = minetest.get_content_id("air")
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local stride_z, stride_y = area.zstride, area.ystride
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local count = 0 -- The number of nodes replaced
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local idx_z_base = area:index(position.x - total_radius, position.y - total_radius, position.z - total_radius) -- initial z offset
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for z = -total_radius, total_radius do
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local z_sq = z*z
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local idx_y_base = idx_z_base
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for y = -total_radius, total_radius do
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local y_sq = y*y
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local i = idx_y_base
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for x = -total_radius, total_radius do
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local x_sq = x*x
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local sq = vector.new(x_sq, y_sq, z_sq)
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-- Default: xy
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if axes == "xz" then
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sq.x, sq.y, sq.z = sq.x, sq.z, sq.y
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elseif axes == "yz" then
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sq.x, sq.y, sq.z = sq.y, sq.z, sq.x
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end
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-- (x^2+y^2+z^2-(a^2+b^2))^2-4 a b (b^2-z^2)
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-- Where:
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-- (x, y, z) is the point
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-- a is the major radius (centre of the ring to the centre of the torus)
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-- b is the minor radius (radius of the ring)
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local comp_a = (sq.x+sq.y+sq.z - (major_radius_sq+minor_radius_sq))
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local test_value = comp_a*comp_a - 4*major_radius*minor_radius*(minor_radius_sq-sq.z)
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-- If we're inside the torus, then fill it in
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if test_value <= 1 then
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local place_ok = not hollow;
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if not place_ok then
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-- It must be hollow! Do some additional calculations.
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local inner_comp_a = (sq.x+sq.y+sq.z - (major_radius_sq+inner_minor_radius_sq))
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local inner_test_value = inner_comp_a*inner_comp_a - 4*major_radius*inner_minor_radius*(inner_minor_radius_sq-sq.z)
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-- It's only ok to place it if it's outside our inner torus
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place_ok = inner_test_value >= 0
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end
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if place_ok then
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data[i] = node_id
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count = count + 1
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end
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end
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i = i + 1
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end
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idx_y_base = idx_y_base + stride_y
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end
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idx_z_base = idx_z_base + stride_z
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end
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-- Save the modified nodes back to disk & return
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worldedit.manip_helpers.finish(manip, data)
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return count
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end
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