gcode support for offset arcs

geometry.c

@@ -0,0 +1,42 @@
+/*
+  geometry.h - a place for geometry helpers
+  Part of Grbl
+
+  Copyright (c) 2009 Simen Svale Skogsrud
+
+  Grbl is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Grbl is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <math.h>
+
+// Find the angle from the positive y axis to the given point with respect to origo.
+double theta(double x, double y)
+{
+  double theta = atan(x/fabs(y));
+  if (y>0) {
+    return(theta);
+  } else {
+    if (theta>0) 
+    {
+      return(theta-M_PI);
+    } else {
+      return(-M_PI-theta);
+    }
+  }
+}
+
+double hypot(double x, double y)
+{
+  sqrt(x*x + y*y);
+}