Ball Tracer Trajectory

-- Blox League ball tracer: thin line showing where the ball will go, including bounces.
-- Press + (numpad + or = key) to toggle.
if getgenv().BallTracerCleanup then pcall(getgenv().BallTracerCleanup) end -- remove a previous run
local RunService = game:GetService("RunService")
local UIS = game:GetService("UserInputService")
local cam = workspace.CurrentCamera

local CFG = {
	Enabled = true,
	Color = Color3.fromRGB(130, 205, 255),
	Thickness = 2,
	SimStep = 1 / 40,      -- seconds per drawn segment
	MaxTime = 3,           -- how far ahead to predict
	MaxBounces = 3,
	Gravity = 34,          -- measured from the real ball's flights (world gravity is 196, ball is floaty)
	FloorBounce = 0.65,
	WallBounce = 0.6,
	CornerRadius = 10,     -- radius of the curved floor/wall/ceiling corners
	GoalHalfWidth = 40,    -- rough goal opening, estimated from the goal model
	GoalHeight = 30,
	GoalDepth = 300,
	MinSpeed = 6,          -- hide the line when the ball is basically still
	Window = 0.15,         -- seconds of ball history used to estimate velocity (bigger = steadier, slower to react)
	GroundY = 5.6,         -- ball centre below this = rolling on the floor (no gravity in the speed fit)
	HitThreshold = 8,      -- studs of surprise movement that count as a hit/bounce and reset the estimate
}

local MAX_PTS = math.ceil(CFG.MaxTime / CFG.SimStep) + 2

-- Drawn with GUI frames (the Drawing library does not render on every setup)
local gui = Instance.new("ScreenGui")
gui.Name = "BallTracer"
gui.IgnoreGuiInset = true
gui.ResetOnSpawn = false
gui.DisplayOrder = 999
gui.Parent = (gethui and gethui()) or game:GetService("CoreGui")

local lines = {}
for i = 1, MAX_PTS do
	local f = Instance.new("Frame")