L

box.L

The length of the bounding box, in world units along the Y axis.

Type	Initialised Value	Description
float	eg. 2.4	The length of the box.

Example:

Increase the physical length of two cats every time they collide.

--init.lua
function init()
    if chunk.Dimension == "" and not chunk.Generated then
        if chunk.X == 0 and chunk.Y == 0 then
            api.entity.Create("cat", 32, -32, 0, {side = "bottom"})
            api.entity.Create("cat", 32, 96, 0, {side = "top"})
        end
    end
end

-- cat.lua
local function init(self)
    self.Physics = true

    local box_shape = api.physics.NewBoxShape(1, 2.4, 1) 
    local box = api.physics.NewBody(box_shape, 1)   
    self.Body = box
    	
    print("The "..self.Data.side.." cat's starting width is "..self.Body.Shape.L..".")
end

local function update(self, dt)
    local x,y,z = self:GetPosition()
    if y < 10 and self.Data.side == "bottom" then
    	self.Body:ApplyForce(api.physics.NewVector(0, 0.1, 0))
    elseif y > 54 and self.Data.side == "top" then
        self.Body:ApplyForce(api.physics.NewVector(0, -0.1, 0))
    end
		
    if self.Data.last_velocity then
        local last_velocity = api.physics.NewVector(
            self.Data.last_velocity.X, 
            self.Data.last_velocity.Y, 
       	    self.Data.last_velocity.Z
        )
        local current_velocity = self.Body.Velocity
        
        local current_direction = current_velocity:Normalize()
        local last_direction = last_velocity:Normalize()
        local is_rebounded = last_direction:Dot(current_direction) < 0
        
        if is_rebounded then
            self.Body.Shape.L = self.Body.Shape.L + 5
            print("The "..self.Data.side.." cat just rebounded. ".. 
            	    "Its physical width is now "..self.Body.Shape.L..".")
        end
    end
    self.Data.last_velocity = self.Body.Velocity
end 

-- Spawn two cat's when the origin chunk is first generated, labelled top and bottom.
-- Turn on physics calculations for this entity.
-- Create a box shape and a body. Assign it to the entity and print its current length.
-- Every update, apply a force to push the cats together, if they have moved apart.
-- Check for a change in velocity to indicate that they have rebounded.
-- Increase the length of the entity body by 5, after every rebound.
-- Record the velocity for the next rebound check.

-- Prints:
-- The bottom cat's starting width is 2.4.
-- The top cat's starting width is 2.4.
-- The top cat just rebounded. Its physical width is now 7.4.
-- The bottom cat just rebounded. Its physical width is now 7.4.
-- The top cat just rebounded. Its physical width is now 12.4.
-- The bottom cat just rebounded. Its physical width is now 12.4.
-- ...