From 7aaaf8671ff6290410b9a0f2a42ef77f256d86aa Mon Sep 17 00:00:00 2001
From: Werner Almesberger <werner@almesberger.net>
Date: Fri, 20 Sep 2013 18:28:19 -0300
Subject: [PATCH] cameo/gerber.c: crudely support some cases of G03

---
 cameo/gerber.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 51 insertions(+), 2 deletions(-)

diff --git a/cameo/gerber.c b/cameo/gerber.c
index 62eaaa4..bd7a634 100644
--- a/cameo/gerber.c
+++ b/cameo/gerber.c
@@ -1,8 +1,8 @@
 /*
  * gerber.c - Gerber file input
  *
- * Written 2010 by Werner Almesberger
- * Copyright 2010 Werner Almesberger
+ * Written 2010, 2013 by Werner Almesberger
+ * Copyright 2010, 2013 Werner Almesberger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -21,6 +21,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <math.h>
 
 #include "path.h"
 #include "gerber.h"
@@ -31,6 +32,45 @@
 #define	KU2MM(in)	((in)/10000.0*25.4)
 
 
+/*
+ * @@@ Very crude implementation of G03. Tested with only one example in
+ * KiCad.
+ *
+ * Command definition from:
+ * http://www.rulabinsky.com/cavd/text/chapa.html
+ */
+
+static void arc(struct path *path, const char *buf, double ax, double ay)
+{
+	int xi, yi, cxi, cyi;
+	double bx, by, cx, cy;
+	double r, a, b, t;
+	double x, y;
+
+	if (sscanf(buf, "G03X%dY%dI%dJ%dD01*\n", &xi, &yi, &cxi, &cyi) != 4)
+		return;
+	bx = KU2MM(xi);
+	by = KU2MM(yi);
+	cx = KU2MM(cxi);
+	cy = KU2MM(cyi);
+	r = hypot(cx, cy);
+	cx += ax;
+	cy += ay;
+	a = atan2(ay-cy, ax-cx);
+	b = atan2(by-cy, bx-cx);
+	if (a > b)
+		b += 2*M_PI;
+//fprintf(stderr, "@(%g,%g) (%g,%g)-(%g-%g) %g %g\n",
+//  cx, cy, ax, ay, bx, by, a/M_PI*180, b/M_PI*180);
+	for (t = a; t <= b; t += M_PI/180) {	/* @@@ 1 deg increment */
+		x = cx+r*cos(t);
+		y = cy+r*sin(t);
+		path_add(path, x, y, 0);
+	}
+	path_add(path, bx, by, 0);
+}
+
+
 struct path *gerber_read(const char *name, double r_tool_default)
 {
 	FILE *file;
@@ -65,6 +105,15 @@ struct path *gerber_read(const char *name, double r_tool_default)
 			}
 			continue;
 		}
+		if (!strncmp(buf, "G03", 3)) {
+			if (path)
+				abort();
+			path = path_new(r_tool_default, name);
+			*anchor = path;
+			anchor = &path->next;
+			arc(path, buf, start_x, start_y);
+			continue;
+		}
 		if (sscanf(buf, "X%dY%dD%d*\n", &xi, &yi, &d) != 3)
 			continue;
 		x = KU2MM(xi);