tokyo-wangan-racing/tools/probe_ground_truth.luau

-- GROUND-TRUTH PROBE for the floating-scenery finding.
--
-- probe_floating reported 664 parts with "nothing below". That number alone
-- is ambiguous: it reads identically whether (a) the buildings genuinely
-- hang in the air, or (b) the map has no ground/terrain plane at all, so
-- NOTHING can ever return a hit. Distinguish before calling it a defect.
--
-- Measure:
--   1. Does the map contain terrain / a baseplate / a water or ground slab?
--   2. Bottom-face Y of each scenery part vs the road deck Y and vs 0.
--      A building whose bottom is at/below ~0 is "planted" even with no
--      ground mesh; one whose bottom is hundreds of studs up is FLOATING.

local ws = game:GetService("Workspace")
local map = ws:FindFirstChild("Map")
if not map then
	return "NO MAP"
end

local out = {}

-- 1. terrain / ground candidates
local terr = ws:FindFirstChildOfClass("Terrain")
local terrHas = false
if terr then
	local ok, reg = pcall(function()
		return terr.MaxExtents
	end)
	-- MaxExtents is a Region3int16; its Min/Max are Vector3int16 which have
	-- no .Magnitude. Compare components instead.
	if ok and reg then
		local mn, mx = reg.Min, reg.Max
		terrHas = (mx.X - mn.X) > 1 or (mx.Y - mn.Y) > 1 or (mx.Z - mn.Z) > 1
	end
end
table.insert(out, ("Terrain present=%s hasVoxels=%s"):format(tostring(terr ~= nil), tostring(terrHas)))

local groundish = {}
for _, d in ipairs(ws:GetDescendants()) do
	if d:IsA("BasePart") then
		local n = d.Name:lower()
		if
			n:find("ground")
			or n:find("base")
			or n:find("water")
			or n:find("sea")
			or n:find("bay")
			or n:find("floor")
		then
			local sz = d.Size
			if sz.X > 200 or sz.Z > 200 then
				table.insert(
					groundish,
					("%s size=%.0fx%.0f topY=%.1f"):format(d.Name, sz.X, sz.Z, d.Position.Y + sz.Y / 2)
				)
			end
		end
	end
end
table.insert(out, ("large ground-like slabs=%d"):format(#groundish))
for i = 1, math.min(#groundish, 6) do
	table.insert(out, "  " .. groundish[i])
end

-- 2. bottom-face Y of scenery vs deck
local roadY, roadN = {}, 0
local scen = {}
for _, d in ipairs(map:GetDescendants()) do
	if d:IsA("BasePart") then
		local nm = d.Name
		if nm:sub(1, 5) == "Road_" then
			roadN += 1
			table.insert(roadY, d.Position.Y)
		elseif
			nm:find("Building")
			or nm:find("Tower")
			or nm:find("Ginza")
			or nm:find("Shiodome")
			or nm:find("Diet")
		then
			table.insert(scen, d)
		end
	end
end
table.sort(roadY)
local medRoad = roadY[math.max(1, math.floor(#roadY / 2))] or 0
table.insert(out, ("median road Y=%.1f (n=%d)"):format(medRoad, roadN))

local planted, floatHigh = 0, 0
local hist = {}
local worst, worstNm, worstP = -1e9, "none", nil
for _, p in ipairs(scen) do
	local btm = p.Position.Y - p.Size.Y / 2
	if btm <= 5 then
		planted += 1
	else
		floatHigh += 1
		local base = p.Name:gsub("_%d+$", "")
		hist[base] = (hist[base] or 0) + 1
		if btm > worst then
			worst, worstNm, worstP = btm, p.Name, p.Position
		end
	end
end
table.insert(out, ("scenery=%d | bottom<=5 (planted)=%d | bottom>5 (airborne)=%d"):format(#scen, planted, floatHigh))
if worstP then
	table.insert(
		out,
		("HIGHEST bottom: %s btmY=%.0f at %.0f,%.0f,%.0f"):format(worstNm, worst, worstP.X, worstP.Y, worstP.Z)
	)
end
local hl = {}
for k, v in pairs(hist) do
	table.insert(hl, ("%s=%d"):format(k, v))
end
table.sort(hl)
table.insert(out, "airborne byName: " .. (#hl > 0 and table.concat(hl, " ") or "(none)"))

return table.concat(out, "\n")