Archived source · macOS · 2010
+cocoaKinect.app
++ A native macOS viewer for the Microsoft Kinect, built straight onto libfreenect. + It turns the depth stream into a point cloud or a triangle mesh in real time, and + writes the result out as PLY or STL. +
+ + +
+ The depth colormap
+2048 depth values, one colour ramp
++ The Kinect reports depth as an 11-bit number. The app builds a 2048-entry lookup + texture at startup and shades every sample through it. This is that exact ramp, + regenerated from the code that builds it: +
+ + + + ++ Notice that it runs out. The ramp applies a cubic gamma, so the whole visible + spectrum is spent by roughly value 1150 and everything beyond it clips to black. + That is why the app carries near and far clipping controls: without them, most of + the sensor's range renders as nothing at all. +
+What it does
+Capabilities
+-
+
- StreamsLive depth, RGB and infrared, straight from the device +
- Draw modes2D image, point cloud, or triangle mesh +
- ShadingGLSL shaders: depth colormap, or the RGB camera projected onto the geometry +
- ControlsNear and far clipping, detail, mirror, surface normals, background removal +
- HardwareMotor tilt and LED colour +
- ExportPLY, ASCII STL and binary STL, with a delayed snapshot timer +
Provenance
+Whose work this is
++ cocoaKinect was written in November 2010 by Robert Pointon + (fernlightning) as a demo for the OpenKinect community. It is not the work of + the person maintaining this archive. All credit for the application code goes to + the original author, whose own notes are preserved in the repository verbatim. +
+
+ The application code carries no formal licence: main.m says "All
+ rights reserved", while the author's notes grant permission informally — "frankly
+ I don't care what you do with this code, hopefully you'll be nice and add me to
+ your credits". That is a statement of intent, not a licence, so no
+ LICENSE file has been added here. The maintainer is not the copyright
+ holder and cannot license someone else's work.
+
+ The vendored dependencies do carry formal licences. libfreenect is Apache-2.0 or + GPL-2.0 at your option; libusb is LGPL-2.1. Their terms and obligations are set + out in + THIRD-PARTY-LICENSES.md, + which is worth reading before redistributing any of it. +
+Since 2010
+What was fixed
++ The first commit is the source as received, reorganised and nothing more. Work + applied on top of it falls into two piles. +
+ +Speed
+
+ The per-pixel depth clamp was making up to seven Objective-C message sends and
+ two fmod() calls on each of 307200 pixels, every frame. Hoisting
+ the accessors and replacing the modulo with the loop's own column index:
+
| Per frame | Before | After | |
|---|---|---|---|
| Depth clamp | 4.69 ms | 0.71 ms | 6.6× |
| Mesh indices | 0.087 ms | 0.019 ms | 4.6× |
| Allocator | 1.5 MB | none | reused |
+ Both rewritten loops were checked against the originals across 960 randomised + parameter combinations, and produce byte-identical output. +
+Defects
++ The export actions waited for a frame in a loop with no exit. With no device + streaming, that pinned a CPU core on the main thread and froze the interface + permanently — and nothing disabled the menu items, so it was two clicks away. +
++ The binary STL writer counted facets in a pointer variable, so the arithmetic + advanced in units of eight bytes and the file header announced eight times as + many facets as it wrote. +
+
+ Shader compile failures were logged by passing an NSString * to a
+ %s format, which reads the object pointer as a C string: garbage
+ or a crash, on the one code path whose job is to report shader errors.
+
Building
+It still compiles
+
+ Open src/cocoaKinect.xcodeproj and build the cocoaKinect
+ target. On an Intel Mac it builds and runs.
+
+ On Apple Silicon it will not link as it stands. The vendored libusb binaries are + x86_64 only: +
+$ lipo -info src/libusb-1.0/lib/libusb-1.0.0.dylib
+Non-fat file: ... is architecture: x86_64+ They have to be rebuilt or replaced with a universal build first. Continuous + integration on the repository parses and type-checks the sources against the + current macOS SDK on every change, which catches anything that stops them being + valid Objective-C — but it does not build the app, and nothing here has been run + against Kinect hardware. +
+