Although the SpaceNavigator support six degrees of freedom, I’m only using two (Y axis for forwards/reverse and RZ for turning), that leaves plenty of room for expansion (perhaps hooking up a third motor to another controller axis).

Although the video doesn’t show it too well, the SpaceNavigator does allow for very fine grained control over the robot (as long as the robot has fresh batteries!). The controller is extremely sensitive and with practice the robot can be controlled quite delicately.

Currently only one axis is dominant at a time (that’s actually a preference in the SpaceController System Preferences screen) but it is be possible to control robot steering and speed/direction at the same time. I’ll be trying that out soon.

There doesn’t seem to be much in the way of Mac OS X APIs for controlling NXT via Bluetooth, so I’m putting my code onto my public subversion server and releasing it (like everything else in my public repository) under the BSD License. The code is Leopard only (although all I’m using are some Objective-C 2.0 features, such as properties and the new for loop). The code uses Cocoa bindings/KVC and has a rather simple interface:

robot = [[[CNXTRobot alloc] init] autorelease];
((CNXTMotor *)[robot.ports objectForKey:@"B"]).power = (int)(theMotor1 * 100.0);
((CNXTMotor *)[robot.ports objectForKey:@"C"]).power = (int)(theMotor2 * 100.0);

The sample NXT project relies on my ToxicWarped framework. ToxicWarped was originally created for my Geode project and is designed to help write simple but flexible Object Oriented protocol stacks.

The NXT code is barely a day old, so it is very rough and ready but I’ll be tinkering with the NXT and SpaceNavigator code over the next few weeks (in my spare time) but if anyone has a use for the code and would like to contribute back that would be fantastic.

Update: Couldn’t stand awful Youtube image quality any longer. Videos are now on amazon s3.

Tiilt.mp4

This screencast shows a simple Quartz Composer composition being manipulated by the Wii remote. If there is interest I’ll put the source online.

Source is now online.

(Thanks to Mere Mortal Software for the badge icon)

However today I received an e-mail from Will Thimbleby, who has just released version 1.1 of his drawing program, Lineform. Lineform 1.1 adds, amongst other new features, SVG importing and exporting. This is fantastic news. I had looked at Lineform back when it was still a 1.0 application and found I couldn’t use it mainly because it lacked SVG support.

Version 1.1 also adds support for CoreImage filters. This is full fledged CoreImage support inside a mature and robust drawing tool. Lineform isn’t a toy application that simply lets you apply filters to image files. Lineform is quite possibly a “killer app” for CoreImage and with its addition Lineform could well become an Adobe Illustrator competitor.

What is rewarding to me, is that Will used my PettySVG to help him develop the SVG import/export in Lineform:

It was very helpful in getting an understanding for how NSXML worked and getting started on my own SVG code. [...] In any case you have my thanks for providing the code, it would have taken me much much longer to get to grips with NSXML without it.

I find e-mails (or blog comments) such as this extremely gratifying.

The reason I have so many of these things is that I switch browsers relatively frequently (bouncing between Safari and OmniWeb and occasionally Firefox) and I find weblocs are more permanent and just more convenient than browser bookmarks.

Mostly they’re “organised” into a single folder and I use Spotlight to find the ones I am interested in at that moment. However Spotlight doesn’t have a default webloc metadata importer, and this is where Toxic Software stands up to fill the gap. My Spotlight Importer Collection package includes three importers, one of which as luck would have it is a webloc importer (in fact it also imports a plethora of other internet clipping files: afploc, fileloc, ftploc, inetloc, mailloc, urlloc and webloc).

After installing Toxic URL Importer and waiting for Spotlight to index your volumes each webloc (if you’re in a rush use mdimport to force Spotlight to index files immediately) you’ll be able to view a webloc’s URL directly in the finder:

From Terminal.app you can use mdls to inspect the extra metadata added to the file by Toxic URL Importer:

[schwa@cobweb] Desktop$ mdimport The\ XML\ Bookmark\ Exchange\ Language\ Resource\ Page.webloc 
[schwa@cobweb] Desktop$ mdls The\ XML\ Bookmark\ Exchange\ Language\ Resource\ Page.webloc 
The XML Bookmark Exchange Language Resource Page.webloc -------------
kMDItemContentType                    = "com.toxicsoftware.webloc"
kMDItemContentTypeTree                = (
    "com.toxicsoftware.webloc", 
    "com.toxicsoftware.urlloc", 
    "public.url", 
    "public.data", 
    "public.item"
)
kMDItemDisplayName                    = "The XML Bookmark Exchange Language Resource Page.webloc"
kMDItemID                             = 17168962
kMDItemKind                           = "Web Internet Location"
kMDItemURL                            = "http://pyxml.sourceforge.net/topics/xbel/"
org_spotlightdev_digest_sha1          = "794043e7673e525d654e7b8e4115636408182528"
org_spotlightdev_metadata_mdimporters = ("com.toxicsoftware.url-importer")
org_spotlightdev_metadata_url_host    = "pyxml.sourceforge.net"
org_spotlightdev_metadata_url_scheme  = "http"
org_spotlightdev_metadata_urls        = ("http://pyxml.sourceforge.net/topics/xbel/")

You can then search for weblocs by host or by scheme or a by any text in the url. Very handy:

On the whole using weblocs and Spotlight together is a great solution. But I think I’ve found a better one. Luis de la Rosa’s WebNote Happy is a fantastic application for managing bookmarks. It allows me to manage my bookmarks in a single window (like my folder of weblocs) and integrates really well with del.icio.us. As fast as Spotlight searching is, WebNoteHappy beats it hands down with lightning fast searches.

Unfortunately WebNoteHappy doesn’t yet import or export webloc files (Luis is a very responsive developer and am sure will be making up for this minor deficiency in later releases). But fortunately WebNoteHappy does import XBEL files, which as I’ve already written about in my post about OmniWeb and XBEL is a very handy intermediate file format.

As it turns out I have almost all the tools necessary to get my thousands of weblocs files into WebNoteHappy. I have mdfind2, which like its little cousin mdfind can perform Spotlight searches from the terminal. However mdfind2 can also export an XML file describing the metadata of the found items. All I needed to do was use mdfind2 to find all my webloc files and then transform the XML into XBEL via a custom written XSLT.

Here is the XSLT file “mdfind2_to_xbel.xsl”:

<?xml version="1.0" encoding="iso-8859-1"?>  
<xsl:stylesheet version="1.0"  
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">  

    <xsl:output method="xml" indent="yes" doctype-public="+//IDN python.org//DTD XML Bookmark Exchange Language 1.0//EN//XML" doctype-system="http://www.python.org/topics/xml/dtds/xbel-1.0.dtd"/>  

    <xsl:strip-space elements="*"/>  

    <xsl:template match="/">  
        <xbel version="1.0">  
            <xsl:apply-templates/>  
        </xbel>  
    </xsl:template>  
    <xsl:template match="item">  
        <bookmark>  
            <xsl:attribute name="href"><xsl:value-of select="attributes/attribute[@key='kMDItemURL']"/></xsl:attribute>  
            <xsl:attribute name="id">_<xsl:value-of select="attributes/attribute[@key='kMDItemID']"/></xsl:attribute>           <xsl:attribute name="added"><xsl:value-of select="attributes/attribute[@key='kMDItemContentCreationDate']"/></xsl:attribute>  
            <xsl:attribute name="modified"><xsl:value-of select="attributes/attribute[@key='kMDItemContentModificationDate']"/></xsl:attribute>  
            <xsl:attribute name="visited"><xsl:value-of select="attributes/attribute[@key='kMDItemLastUsedDate']"/></xsl:attribute>  
            <title><xsl:value-of select="name"/></title>  
        </bookmark>  
    </xsl:template>  
    <xsl:template match="text()"></xsl:template>  

</xsl:stylesheet>

And here is the tiny snippet of shell script needed to tie it all together:

mdfind2 --xml "kMDItemContentTypeTree == 'com.toxicsoftware.urlloc'" | \  
xsltproc mdfind2_to_xbel.xsl -  

And here is the final resulting XBEL file (limited to just a single entry) ready to be imported in WebNoteHappy:

<?xml version="1.0"?>  
<!DOCTYPE xbel PUBLIC "+//IDN python.org//DTD XML Bookmark Exchange Language 1.0//EN//XML" "http://www.python.org/topics/xml/dtds/xbel-1.0.dtd">  
<xbel version="1.0">  
  <bookmark href="http://www.txrollergirls.com/teams.htm" id="_9799996" added="2005-02-17 13:54:05 -0500" modified="2005-02-17 13:54:05 -0500" visited="2005-02-17 13:54:05 -0500">  
    <title>texas rollergirls TEAMS</title>  
  </bookmark>  
</xbel>  

After running the script I now have all my weblocs safely imported into WebNoteHappy, with duplicates removed (in fact they were never imported in the first place). I can tag them and add them to del.ici.ous with just a click, and I can now import my current Safari bookmarks into the list and manage all my bookmarks in one place.

Using a little bit of custom coding (my URL Importer, mdfind2 and the XSLT) I was able to use the extensibility of Spotlight and WebNoteHappy to my advantage. A sure sign of how useful a piece of software is how easy it is to be extended by its end users.

Subversion Repository: http://toxic-public.googlecode.com/svn/tags/BlogTag_20070927_729/Projects/Misc/mdfind2_to_xbel

If you’re running bash on an Intel Mac you might see some interesting behavior if you inspect the shell’s variables:

[jwight@ratatosk] jwight$ set | grep TYPE
HOSTTYPE=powerpc
MACHTYPE=powerpc-apple-darwin8.0
OSTYPE=darwin8.0

PowerPC? Darwin 8.0? On my Quad G5 I get identical results. Checking the bash binary with the ‘strings’ command seems to show these values are hardcoded:

[jwight@ratatosk] jwight$ strings which bash | grep powerpc
powerpc-apple-darwin8.0
powerpc

Looks like the OS version and the processor type is hardcoded into bash.

Oh and for the record this is what ‘uname’ reports:

[jwight@ratatosk] jwight$ uname -a
Darwin ratatosk 8.6.1 Darwin Kernel Version 8.6.1: Tue Mar  7 16:55:45 PST 2006; root:xnu-792.9.22.obj~1/RELEASE_I386 i386 i386