In between trying to get work done, I’ve been mulling over interesting aircraft configurations (canard vs tandem vs conventional) that I would use to design and build a light aircraft with a very specific mission that I’ll write about some other time.

Many are familiar with the Hughes Spruce Goose, but another interesting beast from an even earlier time (circa 1920) was the Caproni Ca.60 Noviplano flying boat (youtube video here).

As you can see, this thing featured a whopping three sets of triple wings and an unwieldy number of struts, braces and wires to hold it all together - not to mention 8×400HP V12 Liberty engines! With eight crew and 100 passengers, it was meant to a bit over 100kph from Italy to the USA.

Makes a canard pusher design like the Rutan VariEze (right) look as boring as a Cessna Skychicken.

Working with Ruby occasionally requires the use of irb, the interactive Ruby shell. It’s a terrific tool for quickly exploring new things (in my case, using Ruby to experiment with using sendkeys via the Windows Script Host to automate an awkard windows app).

I’m using Cygwin to do the windows portion of my project at work, and I’ve become quite accustomed to using irb in conjunction with the very nifty utility_belt gem. I find it makes experimenting and making sub 20-liner hacks/tests even quicker, with method tab-completion and neat colorisation.

However, on Cygwin, it doesn’t “just work”. After I installed rubygems and utiltiy_belt on Cygwin, I copied the ~/.irbc file from my Linux PC, which looked something like this:

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require 'rubygems'
require 'utility_belt'
UtilityBelt::Themes.background(:dark)

However, on Cygwin, I got this error every time I started irb (and utility_belt failed to work):

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User@Bulkhead ~
$ irb
load error: /home/User/.irbrc
NameError: uninitialized constant UtilityBelt::Themes
        /home/User/.irbrc:4
        /usr/lib/ruby/1.8/irb/init.rb:207:in `load'
        /usr/lib/ruby/1.8/irb/init.rb:207:in `run_config'
        /usr/lib/ruby/1.8/irb/init.rb:20:in `setup'
irb(main):001:0>

Nobody else seems to be having this problem, so perhaps there’s something wrong with my installation (It’s a relatively fresh install of Cygwin though), but here’s the work-around I came up with:

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require 'rubygems'
require 'utility_belt'
load 'utility_belt/utility_belt.rb'
UtilityBelt::Themes.background(:dark)

Well, somewhere along the line after coming back from a two-month stint with work, Debian testing has had an upgrade that caused all four of my Intel i945 family chipset PCs to burn 100% CPU whenever something changed on the screen. It’s no fun waiting several seconds to alt-tab between windows, so here’s the culprit…

Brice Gordlin wrote on 2007-09-11 some fairly optimistic statements about the state of Xorg’s intel drivers and rendering with EXA acceleration:

Several drivers including Intel and ATI r300 already work great with EXA (no need to use XAA + XAANoOffscreenPixmaps anymore) which means Compiz works very smoothly, even when resizing windows. XAA won’t be removed soon though since lots of things needs to be fixed before that

However it appears that this problem is still ongoing.

More recently, it seems that EXA is now the default rendering mode for my Intel chipsets but I had to use the above mentioned fix (revert back to XAA) that apparently wasn’t meant to be necessary any more.

Then I discovered this Ubuntu bug thread where I found there are some options you can set with EXA acceleration which brings performance back up to where XAA was:

xorg.conf:

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Section "Device"
    Identifier      "Intel"
    Driver          "intel"
    BusID           "PCI:0:2:0"
    Option          "AccelMethod" "EXA"
    Option          "ExaNoComposite" "false"
    Option          "MigrationHeuristic" "greedy"
EndSection

Also, a 3D performance tweak can apparently be had by adding this to /etc/environment:

INTEL_BATCH="1"

However, all this breaks accelerated screen rotation, so my potrait display is slow as molasses.

Isn’t Linux fun?