Function Syntax: ParallelPolylinesOption / CLOSEPARALLELPOLYLINES / UNCLOSEPARALLELPOLYLINES Version: 1.0 Date: 22.06.2026 10:38:26AM N/A Description 🧩 ParallelPolylinesOption is a DCL utility for closing two parallel open curves into one joined polyline or reopening a closed lightweight polyline into two parallel open sides. ➗ Both close and unclose workflows can automatically generate a midpoint centerline polyline on layer _HILFSLINIEN. 🎛️ The dialog provides Close Unclose Centerline Apply Undo OK and Cancel controls. Function Syntax Main dialog: ParallelPolylinesOption Direct close: CLOSEPARALLELPOLYLINES Direct unclose: UNCLOSEPARALLELPOLYLINES SEO Optimized Overview 🔗 Close mode accepts LWPOLYLINE LINE ARC and SPLINE entities and converts supported selections to lightweight polylines for processing. 2️⃣ Exactly two resulting polylines are required for the close workflow. ➗ When enabled the centerline is created while the two side polylines are still separate. 📏 The routine evaluates the two possible endpoint pairings and chooses the pairing with the shorter total connector distance. ➕ Two connector LINE entities are created and PEDIT Multiple Join combines the pair into one polyline. ✂️ Unclose mode accepts closed LWPOLYLINE objects and identifies the two shortest closed segments as end connectors. ↔️ The remaining vertex paths are rebuilt as two separate open lightweight polylines. 🧬 Layer color linetype and lineweight are preserved for the rebuilt unclosed sides. 🎛️ Apply and Undo use AutoCAD UNDO marks and Cancel rolls back Apply operations from the dialog session. Primary Workflow • Run ParallelPolylinesOption or one of the direct commands. • Choose Close or Unclose and optionally enable Create centerline polyline. • In Close mode select exactly two open source sides. • In Unclose mode select one or more closed lightweight polylines. • The selected geometry is joined or split and an optional centerline is created. • Use Apply Undo OK and Cancel when working through the DCL. Functionalities ✅ Close parallel sides - joins two open sides into one polyline. ✅ Unclose closed parallel shape - splits a closed lightweight polyline into two open side polylines. ✅ LINE conversion - accepts line source geometry in close mode. ✅ ARC conversion - accepts arc source geometry in close mode. ✅ SPLINE conversion - accepts spline source geometry in close mode. ✅ Automatic endpoint pairing - chooses the shortest total end connection arrangement. ✅ Centerline generation - creates midpoint geometry on _HILFSLINIEN. ✅ Shortest connector detection - unclose mode removes the two shortest boundary segments. ✅ Property preservation - rebuilds unclosed sides with source layer color linetype and lineweight. ✅ Apply and Undo - supports iterative dialog operations. ✅ Cancel rollback - reverses Apply operations from the current run. Important Commands and Aspects 🧩 PPO-SS->LWPolylines converts supported close mode source entities. 🧩 PPO-CreateCenterline uses parametric point averaging between the two sides. 🧩 PPO-DoCloseParallelPolylines performs endpoint linking and PEDIT Join. 🧩 PPO-DoUncloseParallelPolylines rebuilds the two open side paths. Result 🎯 Close mode produces one joined polyline from two parallel sides and two end connectors. ↔️ Unclose mode produces two open lightweight polyline sides from a suitable closed polyline. ➗ An optional centerline can be generated in either workflow. Important Notes ⚠️ Close mode requires exactly two resulting lightweight polylines after source conversion. ⚠️ Unclose mode identifies the two shortest closed polyline segments as the end connectors to remove. ⚠️ The default centerline option is enabled. SEO Keywords 🏷️ AutoCAD, 🏷️ Civil 3D, 🏷️ AutoLISP, 🏷️ ParallelPolylinesOption, 🏷️ Close parallel polylines, 🏷️ Unclose polyline, 🏷️ Centerline, 🏷️ PEDIT Join, 🏷️ LWPOLYLINE, 🏷️ _HILFSLINIEN, 🏷️ DCL