1 files changed, 26 insertions, 0 deletions

@@ -1,6 +1,7 @@
 #ifndef DIRECTION_H_AB66A90E
 #define DIRECTION_H_AB66A90E
 
+#include <cmath>
 #include <string>
 #include <stdexcept>
 #include "vector.h"
@@ -64,4 +65,29 @@ inline Direction oppositeDirection(Direction value) {
   }
 }
 
+inline Direction directionFacingPoint(vec2i point) {
+  double theta = atan2(point.y(), point.x());
+  theta /= M_PI;
+
+  if (theta < -7.0/8.0) {
+    return Direction::left;
+  } else if (theta < -5.0/8.0) {
+    return Direction::down_left;
+  } else if (theta < -3.0/8.0) {
+    return Direction::down;
+  } else if (theta < -1.0/8.0) {
+    return Direction::down_right;
+  } else if (theta < 1.0/8.0) {
+    return Direction::right;
+  } else if (theta < 3.0/8.0) {
+    return Direction::up_right;
+  } else if (theta < 5.0/8.0) {
+    return Direction::up;
+  } else if (theta < 7.0/8.0) {
+    return Direction::up_left;
+  } else {
+    return Direction::left;
+  }
+}
+
 #endif /* end of include guard: DIRECTION_H_AB66A90E */