51 lines
1.3 KiB
Lua
51 lines
1.3 KiB
Lua
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-- https://github.com/minetest/minetest/pull/11932 / https://github.com/aerkiaga
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-- Map each facedir to the result of applying
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-- right-hand rotation around y+ or z+ vector
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local rotated_facedir_map = {
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["y+"] = {
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[0] = 3, 0, 1, 2,
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19, 16, 17, 18,
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15, 12, 13, 14,
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7, 4, 5, 6,
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11, 8, 9, 10,
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21, 22, 23, 20
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},
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["z+"] = {
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[0] = 12, 13, 14, 15,
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7, 4, 5, 6,
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9, 10, 11, 8,
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20, 21, 22, 23,
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0, 1, 2, 3,
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16, 17, 18, 19,
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},
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}
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-- Map rotations on all 6 orthogonal vectors to
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-- rotations around just y+ and z+
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local vector_lambda_map = {
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["x+"] = function (f, r, x)
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return f(3, "y+", f(r, "z+", f(1, "y+", x))) end,
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["x-"] = function (f, r, x)
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return f(1, "y+", f(r, "z+", f(3, "y+", x))) end,
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["y+"] = function (f, r, x)
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return f(r, "y+", x) end,
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["y-"] = function (f, r, x)
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return f(4 - r, "y+", x) end,
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["z+"] = function (f, r, x)
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return f(r, "z+", x) end,
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["z-"] = function (f, r, x)
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return f(4 - r, "z+", x) end,
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}
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function mtscad.rotate_facedir(rotation, vector_name, facedir)
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facedir = facedir or 0
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local function lookup_function(r, n, x)
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if r == 0 then return x end
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return lookup_function(r - 1, n, rotated_facedir_map[n][x])
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end
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local translation_function = vector_lambda_map[vector_name]
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or function () return nil end
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return translation_function(lookup_function, rotation % 4, facedir)
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end
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