Board manufacturers typically do not print silkscreen on areas without

soldermask. Nevertheless, it would be nice to have proper gerbers to
begin with, i.e., gerbers with no silkscreen in soldermaskless areas.
Of course, most of the problem can be taken care of by drawing the
footprints properly. However, sometimes the silkscreen of one
footprint ends up on the pads of another one (think components under a
so-dimm card, for example). The attached patch adds an option to
subtract the soldermask from the silkscreen when doing gerber output.

marco

common/common_plotGERBER_functions.cpp

@@ -504,3 +504,11 @@ void GERBER_PLOTTER::flash_pad_rect( wxPoint pos, wxSize size,
     set_current_line_width( -1 );
     poly( 5, &polygon[0].x, aTrace_Mode==FILLED ? FILLED_SHAPE : NO_FILL );
 }
+
+void GERBER_PLOTTER::SetLayerPolarity( bool aPositive )
+{
+    if( aPositive )
+        fprintf( output_file, "%%LPD*%%\n" );
+    else
+        fprintf( output_file, "%%LPC*%%\n" );
+}