modlib/vector.lua

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local mt_vector = vector
local vector = getfenv(1)
function new(v)
return setmetatable(v, vector)
end
function from_xyzw(v)
return new{v.x, v.y, v.z, v.w}
end
function to_xyzw(v)
return {x = v[1], y = v[2], z = v[3], w = v[4]}
end
function to_minetest(v)
return mt_vector.new(unpack(v))
end
function combine(v1, v2, f)
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local new_vector = {}
for key, value in pairs(v1) do
new_vector[key] = f(value, v2[key])
end
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return new(new_vector)
end
function apply(v, s, f)
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local new_vector = {}
for key, value in pairs(v) do
new_vector[key] = f(value, s)
end
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return new(new_vector)
end
function combinator(f)
return function(v1, v2)
return combine(v1, v2, f)
end, function(v, s)
return apply(v, s, f)
end
end
add, add_scalar = combinator(function(a, b) return a + b end)
subtract, subtract_scalar = combinator(function(a, b) return a - b end)
multiply, multiply_scalar = combinator(function(a, b) return a * b end)
divide, divide_scalar = combinator(function(a, b) return a / b end)
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function norm(v)
local sum = 0
for _, c in pairs(v) do
sum = sum + c*c
end
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return sum
end
function length(v)
return math.sqrt(norm(v))
end
function normalize(v)
return divide_scalar(v, length(v))
end