中文版 | English

---

SectionDraft.lsp — AutoCAD Smart Section Automation

Draw one cut line. Let the algorithm build the rest.

---

The Problem

Drawing architectural vertical sections in AutoCAD is a tedious, repetitive, and error-prone process:

• Project lines from the floor plan down
• Offset slab thickness and floor heights
• Manually trim wall intersections
• Figure out where the roof shrinks back (setbacks)
• Draw 2cm plaster lines (粉刷線) everywhere
• Cap machine rooms and handle hanging shafts
• Plan changed? Start all over again.

The old workflow: Drawing endless XLINEs, trimming for hours, and constantly cross-referencing the floor plan to see if a wall is solid, if a door has a sill, if a shaft hangs in mid-air, or if it's an exposed balcony.

---

The Solution

SectionDraft turns this hours-long process into seconds. You simply draw a red cut line on your floor plans, run SECDRAFT, and the script instantly generates a fully drafted, BIM-level vertical section.

• Master Cut Line (Red Line): Placed across your 1F, 2F, 3F... RF floor plans.
• Smart Recognition Engine:
  • Identifies Solid Walls (RC/Brick)
  • Identifies Parapets & Balconies
  • Identifies Openings/Doors (and dynamically catches their sills)
• Automated Output:
  • Generates Slabs & Walls
  • Automatically draws 2cm Plaster Lines (粉刷線) perfectly wrapped
  • Automatically detects Roof Setbacks & Parapets
  • BIM-Level Shaft Auto-Sealing (Machine Rooms & Hanging Voids)

---

How It Works

SectionDraft doesn't just blindly project lines. It uses an advanced Semantic Proximity Radar and BIM Topological Inference:

1. Touch-to-Trigger: The core ray (blade) must physically touch a door/window block to cut an opening. It completely eliminates "ghost openings" from nearby geometry.
2. Adaptive Boundary Radar: When an opening is detected, the script dynamically reads the Bounding Box of the window/door block and shoots targeted rays (±5cm from edges) to capture the exact connecting wall lines.
3. Terrace Smart Setbacks: When generating a floor slab, the script strictly looks at the solid walls below it, explicitly ignoring lower-floor parapets. This ensures slabs do not accidentally project outward and cover open-to-sky balconies.
4. Dual-Wall Shaft Tracking: Voids and shafts (like elevators/stairs) are tracked dynamically across floors. The script requires a dual-wall confirmation (solid walls on both sides of the void) to penetrate the slab.
5. Outer-Wall Exclusion (Machine Rooms): If a shaft reaches the top floor and its boundaries perfectly match the building's outer shell, the algorithm immediately recognizes it as a Machine Room (not a shaft) and automatically caps the roof and floor slabs.

---

Installation

1. Download SectionDraft.lsp
2. In AutoCAD, type APPLOAD
3. Load the file
4. Type SECDRAFT to run

Tip: Add to AutoCAD's Startup Suite (Contents) for automatic loading every session.

---

Setup

1. Prepare Your Cut Lines

Draw a continuous LINE across each of your floor plans indicating where you want to cut the section.

2. Organize Your Layers (Standard Practice)

Ensure your drawing uses consistent layers (e.g., A-WALL for walls, A-OPEN for doors/windows, A-BALC for parapets).

---

Usage

Type SECDRAFT and follow the prompts. The tool features Global Memory, so you can just press Enter to speed through previously used settings!

1. Click the base insertion point for 1F on your screen.
2. Box-select a sample of Solid Walls.
3. Box-select a sample of Parapets/Balconies (Press Enter to skip if none).
4. Box-select a sample of Doors/Windows/Openings (Press Enter to skip if none).
5. Box-select ALL your Cut Lines at once.
6. Choose sorting direction (Left-to-Right, Bottom-to-Top, etc.).
7. Set up BIM void options and plaster thickness.
8. Done!

---

Commands

Command	Description
SECDRAFT	Run the main section generation script

---

Notes

Feature	Details
Global Memory	Remembers selected layers, floor heights, sorting direction, and plaster settings across your AutoCAD session.
Plaster Lines	Automatically offsets 2cm (customizable) around slabs and walls, perfectly joining at corners.
Smart Void/Shaft	Select void boundaries once; the script dynamically auto-seals tops (machine rooms) and bottoms (hanging shafts) based on wall topology.

---

Compatibility

Version	Status
AutoCAD 2014+	✅ Supported

---

Version History

Version	Notes
v121	Outer-Wall Exclusion: Perfected Machine Room detection. Prevents false slab penetrations when shafts align with outer building shells.
v120	Dual-Wall Tracking: Auto-seals hanging shafts and intermediate empty floors by strictly requiring dual-side solid walls to continue a void.
v111	Terrace Smart Setbacks: Slabs perfectly respect open-to-sky balconies by completely ignoring lower-floor parapets during boundary calculation.
v100	1F Solid Base Logic: Introduced robust controls for grounding the first floor and preventing shafts from cutting into the foundation.
v89	Adaptive Boundary Radar: Perfected capture of connecting walls for extra-long windows/openings.
v84	Roof Logic Refinement: Separated roof rendering logic for perfect parapet generation.

---

License

MIT License — Free to use, modify, and distribute.

---

Made with ❤️ for Architectural Drafters & Engineers.