[gta02-core] Solder mask and other special pads

[Rene Harder]

Werner Almesberger wrote:
> Rene Harder wrote:
>   
>
>> I updated the LIS302DL and WM8753FL footprints to use the new solder
>> mask layer, I also defined a constant in the footprint by which the
>> solder mask is reduced on each side because kicad will still expand the
>> solder mask when generating the Gerber files.
>>     
>
> Hmm, there's one problem with this: fped's visualization output gets
> quite confusing, because it suggests that some of the pad is covered
> by the solder mask.
>
> One way would be to generate the "real" solder mask by running a solder
> mask generating algorithm that's similar to KiCad's, but that's not
> trivial.
>
>   

How about defining a constant in the footprint and when you export the
footprint to kicad, fped will reduce the solder mask by the size defined
in the footprint file. So fped would always show the right solder mask size.

> If we do this or something equivalent, the next problem would be with
> the visual representation: if the solder mask hole is exactly like the
> pad, then all the layers can only be seen in the Postscript, while the
> solder mask would cover the pad in the GUI. One way to solve this would
> be to draw the solder mask outline as a line instead of a just making
> it a pad.
>
> Tricky. This needs some thought.
>   

Indeed that's a little bit annoying because you can't really see the
solder pads and if the solder mask opening is bigger than the actual pad
you can only guess what the pad looks like or where it is located.

If you select a frame or a pad in the GUI you'll highlight this pad and
the pad is drawn above all the other layers. However if you select a
frame, only the first pad which is drawn in this frame gets highlighted.
Maybe it's possible once you select a frame that all pad drawn within
this frame gets selected and highlighted. I this case you can bring all
pad to the front and so  that they are not covered by any other layer.

Or another idea would be to add some sort of layer selection to the GUI
(e.g. a button for each pad type). Once you select a type all pads with
this pad type are highlighted and drawn above other layers.

> By the way, did you notice that having multiple concentric pads with
> the name GND creates an interesting visual effect in the Postscript ? :-)
>   
looks like a nice 3D effect!
I'll remove the name "GND" of the solder mask layer, there is not need
for this.