Re: gEDA-user: next PCB release - 1.99za vs 4.0

[Andrew Poelstra <asp11@xxxxxx>]

On Sun, Sep 12, 2010 at 12:55:54AM -0400, DJ Delorie wrote:
> 
> I suspect that in the main GUI you'd get a simplified set of options,
> like "add layers" or "remove layers" to switch from, say, 2-layer PCBs
> to 4-layer PCBs, etc.  Outer special layers like silk and mask just
> exist, but you can enable/disable them.
>

When you say "just exist", you mean they are there by default on new
boards, not that they're magic layers, right?
 
> So most users just see one "copper" drawing layer per physical copper
> layer, plus the usual top/bottom silk/mask/paste, plus an outline.
> 
> But if you're in "footprint mode" you get top/inner/outer instead,
> plus the usual t/b s/m/p.  Footprints are a special case of
> sub-assembly that never use specific layers, always layer classes, so
> they can map to your boards.
> 

There are some cases where you might want to have inner layers for
footprint. In that case, the user would get the 'mapping' dialog when
importing the component. (This mapping will need to be editable after
the fact, of course).

However, by /default/, we will only have top and bottom layers when
creating a new footprint.

Actually, we might need the mapping dialog in all cases, just for the
case when the user wants to flip the component so the top is on bottom,
bottom on top.

> Power users can change the association for a layer, so for example,
> one could create a footprint with copper on ALL layers, for a heatsink
> or physical strength.  Or a both-sides silkscreen layer.  Or two
> copper drawing layers per physical copper layer. I've used this
> before, to keep ground/power/signal colored differently.  Gold finger
> plating might take advantage of this too, or multiple conductor types
> (metal plate over copper, conductive ink).  Or two silkscreen layers
> for different ink colors.
> 

Well, a both-sides silkscreen layer makes little sense. If a user wanted
that, he could duplicate the top silkscreen to get the bottom one. I
don't think that would be common enough to require special code.

I think that if we want components on multiple layers (or all layers),
that should be a property of the component, not a layer group/physical
layer thing.

> I don't know what people are going to be using it for, so it made
> sense to just let them do whatever they please, if they know what
> they're doing.  Like I've said before, I want to make things easy for
> most users, and possible for the rest.
> 
> As for the color scheme, I suspect it will be plaid.
>

:)


From a development stance, how do we want to structure layers and
layer groups? It looks to me that we should have layer groups map
to physical layers. Within each layer group, we can have as many
drawing layers (of whatever types) as we want.

The default setup would then look like (for a 4-layer board):

GROUP: Top (TOP)
  LAYER: top-silk	(SILK)
  LAYER: top-trace	(COPPER)
  LAYER: top-paste	(COPPER)

GROUP: Inner 1 (INNER, z-index: 0)
  LAYER: inner1-trace	(COPPER)

GROUP: Inner 2 (INNER, z-index: 1)
  LAYER: inner2-trace	(COPPER)

GROUP: Bottom (BOTTOM)
  LAYER: bottom-silk	(SILK)
  LAYER: bottom-trace	(COPPER)
  LAYER: bottom-paste	(COPPER)


I think that all the UI suggestions voiced here will work well with
this structure.


Andrew
 


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