Road Architect - Tunnel Mesh

local tMesh = require('editor/tech/roadArchitect/tunnelMesh')

-- Create a tunnel for road 1
local tunnel = road.tunnels[1]
tMesh.createTunnel(1, tunnel.name, road.renderData, tunnel, folder)

-- Remove the tunnel and recover holes
tMesh.tryRemove(1, tunnel.name)

-- Tunnel parameters (from road):
-- tunnel.s, tunnel.e       - start/end div point indices
-- tunnel.radGran           - radial granularity (cross-section segments)
-- tunnel.radOffset         - radius offset beyond road width
-- tunnel.thickness         - wall thickness
-- tunnel.zOffsetFromRoad   - vertical offset of road inside tunnel
-- tunnel.protrudeS/E       - protrusion at start/end along tangent

-- Mesh generation algorithm:
-- 1. Compute pipe center, radius, tangent at each longitudinal point
-- 2. Generate inner and outer ring points using Rodrigues rotation
-- 3. Build inner/outer face arrays with proper winding
-- 4. Add start and end cap geometry
-- 5. Create ProceduralMesh with {outer, inner, startCap, endCap}

-- Hole map management:
-- editHolemap: Sets terrain material index to 255 for grid cells inside pipe
-- recoverHolemap: Restores original material indices when tunnel removed
-- Uses squared-distance-to-line-segment test for pipe intersection
-- Plane clipping at tunnel ends prevents over-extension

-- Material: 'm_asphalt_new_01' for all tunnel surfaces