Re: gEDA-user: PCB format wishlist

[Andrew Poelstra <asp11@xxxxxx>]

On Mon, Sep 06, 2010 at 10:43:50AM -0600, John Doty wrote:
> 
> On Sep 6, 2010, at 10:33 AM, Andrew Poelstra wrote:
> 
> > On Mon, Sep 06, 2010 at 09:53:36AM -0600, John Doty wrote:
> >> 
> >> Need some geometric shapes. Need to be able to attach material properties
> >> to them (including "vacuum" for holes).
> >> 
> > 
> > How about?:
> >  trace      (inc. arcs, pads)
> 
> Trace? Pad? Forget them: they aren't primitive geometric concepts. Remember,
> all shapes should support any use by any material, or vacuum, in any layer
> or collection of layers. A "trace" is a particular (usually itself composite)
> shape of conductive material.
> 

I don't think we want to drop all the way down to geometric shapes - at some point,
why not just call numbers and strings primitives and forget this whole discussion?

A trace has a length, width, and curvature, which are different properties
than that of a polygon (which is a set of points, so I suppose isn't really
a primitive), or a circle, which has a radius and sweep angle.

Perhaps "line" is the word I should be using.

> >  polygon    (inc. rectangle, etc)
> 
> What's the distinction here?
> 

No distinction. I'm just indicating the scope of these primitives.

> >  circle     (inc. quarter-circle, half-circle)
> 
> Versus arc?
> 

A circle could be considered as a "filled arc". I have been considering arcs
as "curved lines", which I think makes more sense.

> >  via
> 
> Definitely not primitive. A hole in one or more layers with conductive material in it.
>

Again, while geometrically a via is not primitive, I think that in PCB
terms, a via is primitive. It can exist on several layers, which the
other shapes do not, so it doesn't make sense to build it out of other
shapes.


Andrew
 


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