Hi.

Recently I bought a 3Dconnexion SpaceNavigator to use with OpenSCAD. I
know that this gadget is currently not supported by OpenSCAD. But being
a hacker fluent in C and C++, I thought it would be a nice project to
add support for it myself.

3Dconnexion offers a SDK for there devices, but the SDK is poisoned by a
ridiculous restrictive license. The SDK is impossible to use with Open
Source Software.

Fortunately the SpaceNavigator enumerates as an ordinary USB HID. I had
a look into libusb and the documentation here:
http://libusb.org/wiki/APIs#libusb-1.0currentAPIandimplementation
redirected me to HIDAPI:
http://www.signal11.us/oss/hidapi/
This is a small library with support for Mac OS X, Linux, Windows and
FreeBSD. It is a single .h file and a single .c file per platform.

With the help of HIDAPI I got reasonable output from the SpaceNavigator
using a small self written test program. See attachment. So now I can
get proper values for X/Y/Z translation and rotation as well as button
events. All on MacOS X. Fine. Now get this into OpenSCAD!

I tried to hack class QGLView as it handles mouse events. But getting
data from the SpaceNavigator requires a separate thread and Qt complained:
Cannot make QOpenGLContext current in a different thread

I have no clue about the OpenSCAD source code layout, its dependency
management, (3D) computer graphics nor Qt. So I need a bit of help to
get started with hacking OpenSCAD. As said, I am fluent in C++. So the
basics are covered. Mostly I need to know where to start digging, what
source code files to read, what classes to investigate, where are
similar things done as an example and the like.

Things that need to be done / I need help with:

• Integrate HIDAPI into OpenSCAD.
• At process startup of OpenSCAD I need to hook into a periodic timer
  for polling the USB HID or (preferably) I need to spawn a separate
  std::thread to read USB HID reports.
• If there is a USB HID report determine if OpenSCAD is in focus and
  which window is topmost. Send translate / rotate message to window.
• Handle translate / rotate message from USB HID thread in the window.

Any help appreciated and thanks for your patience.

tschüß,
Jochen

Hi,

I've used libusb myself and also wrote a (user-space) mouse driver (for
a touchscreen) for Linux.

I think you don't need to write a SpaceNavigator libusb-hid-driver.
At least for Linux, several usb-hid-drivers for the SpaceNavigator
exist (e.g.: http://janoc.rd-h.com/archives/74). I think there
should also be some for Mac OS X.

And I don't think that OpenSCAD should include hardware-specific
code. Instead, the SpaceNavigator should behave like a normal (extended)
mouse or joystick. The operating-system and window-manager should
handle the USB-polling, determine the current window and send
mouse-events to this window. At least that's how I think it should
be done.

You can also google for SpaceNavigator and FreeCAD -- it looks like
someone has already done something similar to implement SpaceNavigator-
support in FreeCAD (which also uses Qt AFAIK).

just my 2 ct,
Roland