Working on a new HSI...

I've been working on creating my first gauge for a few days now, and as I've started to get into the swing of it so to speak I've decided to blog about my experiences here and attempt to get together a repository of information for those of you who'd also like to create your own custom gauges for your Saitek FIPs.

I'm currently working on a replacement for the default HSI (Horizontal Situation Indicator), as the default one's dial and CDI is way too small and too much space is wasted on "eye candy" to make it look like the face of a Bendix-King HSI (albeit at half the size).

Concept Image

The end result, I hope, will be pleasing to the eye and at the same time functional and easily read at a glance (as is necessary when you're scanning your instruments during a flight). In addition to improving the "look and feel" of the gauges, I'm also trying to improve upon the defaults in terms of functionality, and fixing things which don't quite work right. An example of this is the NAV and HDG flags which (on the default HSI) move on the screen rather than disappearing.

Another feature that I'm particularly happy with is that my new HSI can select between NAV1, NAV2 and GPS sources (Such as found in the Baron 58 aircraft supplied with X-Plane) whereas the default HSI is locked to NAV1 only.

I'm also adding DME Distance/Speed/Time information for the currently selected navigation source, as well as DME distances for NAV1, NAV2 and GPS sources regardless of which source is selected on the HSI.

So far I have spent most of the time fiddling with the images I'm using for the gauge; it's very easy to get carried away and I did so on many occasions, having to remove a lot of things I crow-barred into the design and later decided were causing the gauge to look cluttered.

I find it easiest to basically create the gauge as a layered image in GIMP so that I can move around all the different bits and get them looking nice before I try to code any XML. Invariably I find something that doesn't work out as well as I'd hoped and I then have to go back and modify the master image, and I find that using layers and groups of layers really helps with this, as well as being able to save several designs and see which one looks best, and so forth.

As noted on the Gauge Development page, I've had massive problems debugging the XML definition files because I get zero information back; it either works or it doesn't, and for the first couple of days it didn't work far more than it did.

I was originally going to use as many stock (ie. provided with the plugin) images as I could, but then decided to do it from the ground up instead. In doing so I discovered that the FIPs are pretty picky about what kind of images you use - Windows Bitmap files at 24-bit colour with a background colour of rgb(1,1,1) or #010101.

That's enough of what I've already done; about time I got on with doing more - I'll be back soon with a breakdown of the full HSI :)

~ Ste

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