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Difference between revisions of "Getting Started With Common Lisp"
(→Example Usage) |
(→Example Usage) |
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| Line 38: | Line 38: | ||
(freenect-init ctx-ptr (cffi:null-pointer)) | (freenect-init ctx-ptr (cffi:null-pointer)) | ||
(setf *ctx* (cffi:mem-ref ctx-ptr :pointer))) | (setf *ctx* (cffi:mem-ref ctx-ptr :pointer))) | ||
| + | |||
| + | The second arg to freenect_init is a libusb context, which we set to NULL since we are using only one context here (NULL refers to the default context). | ||
If a Kinect is connected, you can confirm it with a call to freenect_num_devices (which should return 1) | If a Kinect is connected, you can confirm it with a call to freenect_num_devices (which should return 1) | ||
| Line 43: | Line 45: | ||
(freenect-num-devices *ctx*) ; this should return 1 | (freenect-num-devices *ctx*) ; this should return 1 | ||
| − | Now "open" the device with a call to freenect_open_device | + | Now "open" the device with a call to freenect_open_device: |
(let ((dev-ptr (cffi:foreign-alloc :pointer))) | (let ((dev-ptr (cffi:foreign-alloc :pointer))) | ||
(freenect-open-device *ctx* dev-ptr 0) | (freenect-open-device *ctx* dev-ptr 0) | ||
(setf *dev* (cffi:mem-ref dev-ptr :pointer))) | (setf *dev* (cffi:mem-ref dev-ptr :pointer))) | ||
| + | |||
| + | The last arg to freenect_open_device refers to the device number index, which is 0 in case a single device is connected. | ||
Now you can confirm that you are able to work with the device with a call to freenect_set_led (see the LED colour change accordingly): | Now you can confirm that you are able to work with the device with a call to freenect_set_led (see the LED colour change accordingly): | ||
Revision as of 08:06, 13 December 2010
Contents
Dependencies
libfreenect
Install libfreenect as described on the Installation page.
cffi, verrazano
The next step is to create CFFI bindings for libfreenect. We can use Verrazano to generate these bindings for us. Installing these is simple via quicklisp:
(ql:quickload :cffi) (ql:quickload :verrazano)
Generate CFFI bindings
Generate the bindings with verrazano and load them
(verrazano:generate-binding (list :cffi :package-name :libfreenect :input-files (list "libfreenect/libfreenect.h"))) (load (compile-file #p"libfreenect.lisp")) (use-package :libfreenect)
Load libfreenect in your Lisp image
On Linux, you would load libfreenect.so. Change the name accordingly for Mac and Windows.
(cffi:load-foreign-library #p"libfreenect.so")
Example Usage
Define a couple of globals which you would need to pass around for most calls to libfreenect:
(defvar *ctx*) ; freenect_context *ctx; (defvar *dev*) ; freenect_device *dev;
Initialize the library with a call to freenect_init:
(let ((ctx-ptr (cffi:foreign-alloc :pointer))) (freenect-init ctx-ptr (cffi:null-pointer)) (setf *ctx* (cffi:mem-ref ctx-ptr :pointer)))
The second arg to freenect_init is a libusb context, which we set to NULL since we are using only one context here (NULL refers to the default context).
If a Kinect is connected, you can confirm it with a call to freenect_num_devices (which should return 1)
(freenect-num-devices *ctx*) ; this should return 1
Now "open" the device with a call to freenect_open_device:
(let ((dev-ptr (cffi:foreign-alloc :pointer))) (freenect-open-device *ctx* dev-ptr 0) (setf *dev* (cffi:mem-ref dev-ptr :pointer)))
The last arg to freenect_open_device refers to the device number index, which is 0 in case a single device is connected.
Now you can confirm that you are able to work with the device with a call to freenect_set_led (see the LED colour change accordingly):
(freenect-set-led *dev* (cffi:foreign-enum-value 'freenect-led-options :led-blink-red-yellow))
When you are done with Kinect hacking, you should wrap things up cleanly:
(freenect-close-device *dev*) (freenect-shutdown *ctx*)
