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.

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.)

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

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)

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.

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

License

MIT License - See LICENSE file for details.

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

References

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

Built with ❤️ and Odin