1 files changed, 8 insertions, 1 deletions
diff --git a/indra/llmath/v2math.cpp b/indra/llmath/v2math.cpp
index 198fedcb03..9d16f1e654 100644
--- a/indra/llmath/v2math.cpp
+++ b/indra/llmath/v2math.cpp
@@ -66,7 +66,14 @@ F32 angle_between(const LLVector2& a, const LLVector2& b)
     return angle;
 }
 
-bool are_parallel(const LLVector2& a, const LLVector2& b, F32 epsilon)
+F32 signed_angle_between(const LLVector2& a, const LLVector2& b)
+{
+    F32 angle = angle_between(a, b);
+    F32 rhombus_square = a[VX] * b[VY] - b[VX] * a[VY];
+    return rhombus_square < 0 ? -angle : angle;
+}
+
+bool are_parallel(const LLVector2 &a, const LLVector2 &b, F32 epsilon)
 {
     LLVector2 an = a;
     LLVector2 bn = b;