Re: gEDA-user: pcb crooked traces

[John Doty <jpd@xxxxxxxxx>]

On Oct 9, 2010, at 4:30 AM, Karl Hammar wrote:

>> 
>> but scaled integers are a bit easier to use and understand,
> 
> Yes (but we are talking about internal values, the user don't have to 
> "see" them, only the developers, think of todays "1mm").

In an open source toolkit, the distinction between "developer" and "user" is blurry. This is a good thing, as far as I'm concerned.

In any case, the developers have to understand the geometry calculations. There are subtle problems with carrying real number analytic geometry into a discrete domain. These are easier to deal with if the granularity is fixed, so if scaled integers have adequate dynamic range, they are to be preferred.

I am surprised by the efficiency debate. I would think that for pcb, the vast bulk of calculation involves rendering graphics in device coordinates, not board geometry in board coordinates. Board coordinates are extremely important as *anchors* for rendering, so precise calculations are important here, but rendering itself is a different thing.

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




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