OhCAD - Odin CAD System

A focused Part-Design style CAD kernel and 2D technical drawing system implemented in Odin.

Project Status

🎉 Week 12.2 Complete - Constraint Editing with Inline Text Widget! 🎉

Full parametric CAD workflow with editable constraints and live solver updates!

Current Features:

• ✅ 2D parametric sketching (lines, circles, arcs)
• ✅ Constraint solver (12 constraint types with visual feedback)
• ✅ Constraint editing - Double-click dimensions to edit values inline
• ✅ 3D extrusion and revolution with parametric updates
• ✅ Boolean operations (cut/pocket with OCCT - OpenCascade Technology)
• ✅ Face selection and sketch-on-face workflow
• ✅ SDL3 GPU rendering (Metal on macOS)
• ✅ Multi-touch gestures (trackpad support)
• ✅ Feature tree with dependency tracking
• ✅ Undo/redo system (50 command history)
• ✅ Professional UI with toolbar, properties panel, feature tree, and status bar
• ✅ Text rendering with fontstash (BigShoulders font)
• ✅ Shaded rendering with Phong lighting
• ✅ STL export for 3D printing
• ✅ Hover highlights and closed shape visualization

See Development Plan for complete roadmap and SDL3 GPU Migration Summary for technical details.

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Features (Target MVP)

• 2D Parametric Sketcher with constraint solving
• 3D Features: Extrude (pad), pocket (cut), revolve, basic fillet/chamfer
• Parametric Feature Tree with replay/regeneration
• B-rep Topology for robust solid modeling
• Technical Drawing: Orthographic views, hidden line removal, dimensions
• File Export: STL, SVG, PDF

Why Odin?

• Explicit memory layout, no GC pauses
• Easy C interop for reusing libraries
• Simple syntax for systems programming
• Excellent built-in packages (math, graphics, testing, etc.)

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Project Structure

mix_OhCAD/
├── src/
│   ├── main.odin              # Main entry point
│   ├── core/
│   │   ├── math/              # CAD-specific math utilities
│   │   ├── geometry/          # 2D/3D geometric primitives
│   │   ├── topology/          # B-rep data structures
│   │   └── kernel/            # CSG/B-rep operations (future)
│   ├── features/
│   │   ├── sketch/            # 2D sketching system
│   │   ├── extrude/           # Extrude feature (future)
│   │   ├── revolve/           # Revolve feature (future)
│   │   └── constraints/       # Constraint solver (future)
│   ├── io/
│   │   ├── stl/               # STL import/export
│   │   ├── svg/               # SVG export (future)
│   │   └── step/              # STEP I/O (future)
│   └── ui/
│       ├── viewer/            # 3D OpenGL viewer (future)
│       └── drawing/           # Technical drawing (future)
├── tests/                     # Unit and integration tests
├── docs/                      # Documentation
├── examples/                  # Example models (future)
└── Makefile                   # Build system

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Building

Prerequisites

• Odin Compiler (latest version)
• SDL3 (for GPU-accelerated rendering)
• Metal-capable macOS system (for Metal backend)
• OpenGL 3.3+ (for legacy GLFW version)

Quick Start

# Build SDL3 GPU version (recommended)
make gpu

# Run SDL3 GPU application
make run-gpu

# Build GLFW version (legacy backup)
make

# Run GLFW application
make run

# Run tests
make test

# Clean build artifacts
make clean

Manual Build

# SDL3 GPU version (recommended)
odin build src/main_gpu.odin -file -out:bin/ohcad_gpu -debug

# GLFW version (legacy)
odin build src/main.odin -file -out:bin/ohcad -debug

# Run tests
odin test tests -all-packages

Shader Compilation (SDL3 GPU)

cd src/ui/viewer/shaders
./build_shaders.sh
# Generates line_shader.metallib (~15KB)

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Development

Week-by-Week Plan

See the Development Plan for the complete 16-week MVP roadmap.

Current Week: Week 1 - Project Setup & Core Math

Architecture

See the High-Level Design for detailed architecture and design decisions.

Built-in Packages Reference

See Odin Built-in Packages for a catalog of Odin packages we're leveraging.

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Contributing

This is an educational project focused on learning CAD system architecture and Odin programming.

Code Style

• Follow Odin naming conventions (snake_case for functions, PascalCase for types)
• Use f64 for all geometric calculations (CAD precision)
• Document complex algorithms and geometric predicates
• Write unit tests for all math and geometry functions

Testing

# Run all tests
make test

# Run specific test package
odin test tests/math -all-packages

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License

MIT License - See LICENSE file for details.

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Roadmap

Phase 1: Foundation (Weeks 1-4) ✅ COMPLETE

• Project setup
• Core math library (57/57 tests passing)
• Geometry primitives (2D/3D)
• B-rep topology (handle-based system)
• Basic 3D viewer (GLFW + OpenGL)

Phase 2: 2D Sketcher (Weeks 5-8) ✅ COMPLETE

• Sketch data model with coordinate transforms
• Interactive sketch tools (line, circle, select)
• Constraint system (16 constraint types)
• Levenberg-Marquardt constraint solver
• Visual constraint feedback (icons + dimensions)
• Profile detection for extrusion

Phase 3: 3D Features (Weeks 9-12) 🔄 IN PROGRESS

• Week 9: Extrude/pad feature with parametric updates ✅
• Week 9.5: SDL3 GPU migration + multi-touch gestures ✅
• Week 9.6: UI framework & toolbar integration ✅
• Week 10.5: Boolean operations (cut/pocket)
• Week 11: Revolve feature
• Week 12: STL export & basic fillet

Phase 4: Technical Drawing (Weeks 13-16) - MVP Target

• Orthographic projection
• Hidden line removal
• Dimensioning
• SVG/PDF export

Phase 5: Polish (Weeks 17+)

• Boolean robustness
• Advanced fillets
• STEP I/O
• NURBS surfaces

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References

• SolveSpace - Constraint solver reference
• BRL-CAD - CSG concepts
• Open CASCADE - B-rep algorithms
• Odin Documentation - https://odin-lang.org/docs/

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Built with ❤️ and Odin