sch2fig/: properly interpret KiCad arcs

They can be clockwise or counter-clockwise, but are always < 180 degrees.

sch2fig/TODO

@@ -1,4 +1,3 @@
-- arcs aren't quite right yet
 - comment text orientation ?
 - better text size guessing
 - hierarchical labels

sch2fig/fig.c

@@ -376,14 +376,13 @@ void fig_arc(int x, int y, int r, int sa, int ea,
 	//	Type  Thick    Depth   StyleV   FwdAr
 	//	  SubTy  Color    Pen       Cap   BwdAr
 	//	    Style   FillCol  AreaFil  Dir   points
-	printf("5 1 0 %d %d %d %d -1 %d 0.0 1 0 0 0 %d %d %d %d %d %d %d %d\n",
+	printf("5 1 0 %d %d %d %d -1 %d 0.0 1 1 0 0 %d %d %d %d %d %d %d %d\n",
 	    color == -1 ? 0 : WIDTH_COMP_DWG, color, fill_color, layer,
 	    fill_color == -1 ? -1 : 20,
 	    cx(x), cy(y),
 	    ax(x, y, r, sa), ay(x, y, r, sa),
 	    ax(x, y, r, ma), ay(x, y, r, ma),
 	    ax(x, y, r, ea), ay(x, y, r, ea));
-	/* @@@ Note: with y flipped, we counter-clockwise becomes clockwise */
 }
 
 

sch2fig/lib.c

@@ -461,8 +461,26 @@ static bool parse_arc(struct obj *obj, const char *line)
 	    &arc->thick, &arc->fill) != 9)
 		return 0;
 
-	arc->start_a = a1 / 10;
+	/*
-	arc->end_a = a2 / 10;
+	 * KiCad arcs can be clockwise or counter-clockwise. They must always
+	 * be smaller than 180 degrees.
+	 */
+
+	while (a1 < 0)
+		a1 += 3600;
+	while (a2 < 0)
+		a2 += 3600;
+	a1 %= 3600;
+	a2 %= 3600;
+	if (a2 < a1)
+		a2 += 3600;
+	assert(a2 - a1 != 1800);
+	if (a2 - a1 > 1800)
+		swap(a1, a2);
+
+	arc->start_a = (a1 % 3600) / 10;
+	arc->end_a = (a2 % 3600) / 10;
+
 	return 1;
 }