Rangefinder

This script uses raycasting to measure distances:

-- This is a comment. Any text after -- is ignored by Lua.
--
-- It is considered good practice to document your code. Try to explain why
-- things happen. The code should describe how. We will deviate from this
-- recommendation here in order to provide a more thorough explanation.
--
-- Create a new behaviour called Rangefinder. Use behaviour() instead of
-- class() to enable hot-reloading.
behaviour("Rangefinder")

-- This function is called once every frame.
function Rangefinder:Update()
        -- Create a ray originating from the object's origin position, pointing
        -- in the object's forwards direction. Forwards is along the Z-axis
        -- (the blue axis in the Unity Editor.) The "object" refereed to here
        -- is the Unity GameObject who's ScriptedBehaviour component is
        -- executing this Ravenscript.
        local ray = Ray(self.transform.position, self.transform.forward)

        -- Detect intersections with objects on the ProjectileHit layer such as
        -- enemies, vehicles, walls, and the ground. The Ray will pass through
        -- all other objects.
        local target = RaycastTarget.ProjectileHit

        -- Limit the ray's travel distance. We don't need to look further than
        -- 500 meters.
        local distance = 500

        -- Perform the raycast. This returns a RaycastHit if the ray hits an
        -- object on the ProjectileHit layer within 500 meters. Otherwise it
        -- returns nil.
        local hit = Physics.Raycast(ray, distance, target)

        -- Did the ray hit an object within 500 meters?
        if hit ~= nil then
                -- Yes! The ray hit an object. Store its range for printing to the
                -- console.
                distance = hit.distance
        end

        -- Prints the distance to the Ravenscript console. Note that `print()`
        -- accepts a string. Since `distance` is a number it must be converted
        -- into a string using the `tostring()` function. This function can
        -- convert most values into strings: numbers, booleans, nil, tables,
        -- etc. Use `..` to concatenate two strings.
        print("Distance: " .. tostring(distance))
end

The same script as above but without comments:

behaviour("Rangefinder")

function Rangefinder:Update()
        local distance = 500
        local target = RaycastTarget.ProjectileHit
        local ray = Ray(self.transform.position, self.transform.forward)
        local hit = Physics.Raycast(ray, distance, target)

        if hit ~= nil then
                distance = hit.distance
        end

        print("Distance: " .. tostring(distance))
end

Create a new text file called Rangefinder.txt in your Unity project. Copy and paste the above code.

Create a cylinder or an empty GameObject in Unity. Attach the GameObject to a weapon. Make sure to orient the GameObject so that its Z-axis aligns with the weapon’s shooting direction. The Z-axis is indicated by the blue arrow. Attach a ScriptedBehaviour and add the Rangefinder script as source.