Be explicit about type of angles: either Radians or Degrees.

Angles are always doubles.
Internally use radians as much as possible.

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@1605 0fc631ac-6414-0410-93d0-97cfa31319b6

src/util/angle.hpp

@@ -0,0 +1,77 @@
+//+----------------------------------------------------------------------------+
+//| Description:  Magic Set Editor - Program to make Magic (tm) cards          |
+//| Copyright:    (C) 2001 - 2010 Twan van Laarhoven and Sean Hunt             |
+//| License:      GNU General Public License 2 or later (see file COPYING)     |
+//+----------------------------------------------------------------------------+
+
+#ifndef HEADER_UTIL_ANGLE
+#define HEADER_UTIL_ANGLE
+
+// ----------------------------------------------------------------------------- : Includes
+
+#include <util/prec.hpp>
+
+// ----------------------------------------------------------------------------- : Degrees & radians
+
+typedef double Degrees;
+typedef double Radians;
+
+/// Convert radians to degrees
+inline Degrees rad_to_deg(Radians rad) { return  rad * (180.0 / M_PI); }
+/// Convert degrees to radians
+inline Radians deg_to_rad(Degrees deg) { return  deg * (M_PI / 180.0); }
+
+// ----------------------------------------------------------------------------- : Angle constants
+
+const Radians rad0   = 0;
+const Radians rad45  = 0.25*M_PI;
+const Radians rad90  = 0.5*M_PI;
+const Radians rad180 = M_PI;
+const Radians rad270 = 1.5*M_PI;
+const Radians rad360 = 2.0*M_PI;
+
+/// Are two floating point numbers equal up to a small epsilon?
+inline bool almost_equal(double x, double y) {
+	return fabs(x-y) < 1e-10;
+}
+inline bool is_rad0(double x) {
+	return almost_equal(x,0) || almost_equal(x,rad360);
+}
+inline bool is_rad90(double x) {
+	return almost_equal(x,rad90);
+}
+inline bool is_rad180(double x) {
+	return almost_equal(x,rad180);
+}
+inline bool is_rad270(double x) {
+	return almost_equal(x,rad270);
+}
+
+// ----------------------------------------------------------------------------- : Angle functions
+
+// mod as it should be: answer in range [0..m)
+inline double sane_fmod(double x, double m) {
+	double ans = fmod(x,m);
+	if (ans < 0) return ans + m;
+	else         return ans;
+}
+
+// constrain an angle to [0..2pi)
+inline Radians constrain_radians(Radians angle) {
+	return sane_fmod(angle, 2*M_PI);
+}
+
+/// Is an angle a multiple of 90 degrees?
+inline bool is_straight(Radians angle) {
+	return almost_equal(sane_fmod(angle+rad45,rad90), rad45);
+}
+
+/// Is an angle sideways (i.e. closer to 90 or 270 degrees than to 0 or 180 degrees)?
+inline bool is_sideways(Radians angle) {
+	double a = sane_fmod(angle,M_PI);
+	return (a > 0.25*M_PI && a < 0.75*M_PI);
+}
+
+
+// ----------------------------------------------------------------------------- : EOF
+#endif