Re: gEDA-user: General Layers questions

[Martin Kupec <martin.kupec@xxxxxxxxx>]

On Fri, Mar 18, 2011 at 07:18:52PM +0100, Stephan Boettcher wrote:
> The file format need not know about these distictions.  Both are
> graphical layers, with different attributes.  The one has attributes to
> tell DRC to flag overlapping components, the other has attributes to
> tell some autorouter not to put copper there, and attributes to tell DRC
> to check for intruding copper.  Future plugins need more layers to tell
> about different constraints.
> 
> Ideally, any layer type is fully defined via attributes.  The most
> common attribute may be "net:conductive" for normal copper layers, so
> that the HIDs know that the layer contributes to the implementation of
> the netlist.  Copper layers need a second attribute "gbr:layer=inner5"
> to tell the (gerber) exporter where to put it.  A third attribute
> defines the DRC rules that apply "drc:rules=default", plus per layer
> override "drc:minwidth=6mil".
> 
> "drc:courtyard=front"
> "drc:keepout=front"
> "route:keepout=front"


That is a bit complicated. I need a clean definition of layer types, so
one can pick the right layer when needed. But some attributes in
addition to layer type are possible.

Each element has a clearance attribute, so definition of extra space
around pads should be easy. But we can add 'keepout' layer in addition.

Even when we would have more layer, it should be simplier to implement
them than some arbitrary flags.

Defining DRC rules per layer is a bit different story and I hope it will
not be too closely related to changing of layer concept, as I don't want
to touch DRC.

	Martin Kupec



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