I am making a custom Vector3 class for a 3D engine I am making. I am kinda new to lua and not at the stage I should be making a 3D engine, but who cares. My Vector3 script looks like this.
#Vector3.lua
function Vector3(x,y,z) end
Vector3 =
{
__add = function(a,b)
return Vector3(
a.x + b.x,
a.y + b.y,
a.z + b.z
)
end
}
Vector3.__index = Vector3
function Vector3.new(x,y,z)
local instance =
{
x = x or 0,
y = y or 0,
z = z or 0
}
setmetatable(instance, Vector3)
return instance
end
function Vector3:printX()
return self.x
end
and my main like this:
#main.lua
require "Vector3"
vec1 = Vector3.new(1,2,3)
vec2 = Vector3.new(5,1,0)
vec3 = vec1 + vec2
print(vec3.x)
But it gives an error when I run it:
attempt to index global 'Vector3' (a function value)
stack traceback
I did this trying to have the __add function able to add two Vector3 classes. I know I am doing it incorrectly and I can't find a solution. How would I add the __add function to my script? This is the original Vector3.lua:
#Vector3.lua
Vector3 = {}
Vector3.__index = Vector3
function Vector3.new(x,y,z)
local instance =
{
x = x or 0,
y = y or 0,
z = z or 0
}
setmetatable(instance, Vector3)
return instance
end
function Vector3:printX()
return self.x
end
The first definition of Vector3 that you have at the top of Vector3.lua is overwritten immediately:
function Vector3(x,y,z) end
Vector3 =
{
-- ...
}
Global Vector3 is now a table and not a function. Later on in __add you try to call constructor via simplified Vector3():
__add = function(a, b)
return Vector3(
-- ^^^^^^^^ here
a.x + b.x,
a.y + b.y,
a.z + b.z
)
end
Update that call to Vector3.new(...) or implement __call metamethod to construct the object (see 2.3 - Metatables and Metamethods). The error message suggests that there is another mix-up but if you clean up the code and implement one of the previous options it should be resolved.