libfreenect demos

I got an Xbox 360 Kinect from Salvation Army for $3 a while ago. Cool hardware!!

These demos are deliberately small and slightly mischievous (if that's the right word).

Screen.Recording.2026-03-27.at.5.16.34.PM.mov

They do not install anything, do not rebuild the whole project, and do not try to compete with your Homebrew libfreenect. They reuse the C++ wrapper header in wrappers/cpp/libfreenect.hpp and link against the library you already have on the machine.

What's needed

These demos use libfreenect. On macOS, I downloaded it from Homebrew

brew install libfreenect

Python may seem like the easier way here, but 3.14 breaks a lot of dependencies. I also didn't want to fight with Python in general, and am way more comfortable with C++. This project requires CMake 3.16+ and C++ 17.

Libfreenect gives IR/Camera/Accl/Mics access as a C++ library that you can then use for whatever. There's a Python wrapper, but it needs debugging.

What is here

• kinect_cursor: tracks the closest blob in the depth frame, moves the macOS cursor, and supports a depth-based air-tap click.
• kinect_cursor_debug: opens a glview-style window with depth, RGB, crosshairs, live tracking stats, and the same air-tap click gesture.
• kinect_depth_ascii: turns the nearest depth slice into a live ASCII silhouette in the terminal.
• kinect_pointcloud_snapshot: grabs one registered RGB + depth frame and writes a colored .ply point cloud.

Build

From the repo root:

cmake -S wrappers/cpp/blog_demos -B build-blog-demos
cmake --build build-blog-demos -j

If CMake cannot find Homebrew packages automatically, point it at Homebrew explicitly:

cmake -S wrappers/cpp/blog_demos -B build-blog-demos \
  -DCMAKE_PREFIX_PATH="$(brew --prefix)"

Run

./build-blog-demos/kinect_depth_ascii
./build-blog-demos/kinect_cursor
./build-blog-demos/kinect_cursor_debug
./build-blog-demos/kinect_pointcloud_snapshot hand_scan.ply

Notes

• kinect_cursor is macOS-only because it uses ApplicationServices to move the system pointer.
• kinect_cursor_debug needs OpenGL and GLUT, like the existing viewer demos in this repo.
• Cursor control is intentionally simple: it follows the nearest depth blob with smoothing, which works surprisingly well for blog-demo purposes.
• Clicking uses an air-tap gesture: move your hand forward toward the Kinect briefly, then pull back to re-arm the click detector.
• For the cursor demos on macOS, you may need to grant Accessibility permissions to the terminal app that launches them.
• The point cloud exporter writes plain ASCII PLY so you can open it in MeshLab, CloudCompare, or Blender.
• If the cursor demo feels twitchy, stand farther back and keep only one hand in the active depth band.

I'll be writing a blog post on this soon and attach it here.