diff --git a/server/gameserver/glmhelper.cc b/server/gameserver/glmhelper.cc
index 93295ed1..00569adf 100644
--- a/server/gameserver/glmhelper.cc
+++ b/server/gameserver/glmhelper.cc
@@ -14,7 +14,17 @@ const glm::vec3 GlmHelper::DONW = glm::vec3(0.0f, 0.0f, 1.0f);
 
 void GlmHelper::RotateY(glm::vec3& v, float angle)
 {
-
+    auto transform =
+        glm::rotate(
+                    glm::mat4(1.0),
+                    angle,
+                    //glm::radians(angle),
+                    glm::vec3(0.0f, 1.0f, 0.0f)
+                    );
+    glm::vec4 v1 = transform * glm::vec4(v.x, v.y, v.z, 0.0f);
+    v.x = v1.x;
+    v.y = v1.y;
+    v.z = v1.z;
 }
 
 void GlmHelper::Normalize(glm::vec3& v)
@@ -33,17 +43,16 @@ void GlmHelper::Normalize(glm::vec3& v)
 
 float GlmHelper::Norm(const glm::vec3& v)
 {
-
+    return glm::length(v);
 }
 
-
 bool GlmHelper::IsZero(const glm::vec3& v)
 {
-
+    return fabs(v.x) < 0.00001f && fabs(v.y) < 0.00001f && fabs(v.z) < 0.00001f;
 }
 
-
 float GlmHelper::CalcAngle(const glm::vec3& v1, const glm::vec3& v2)
 {
-
+    float angle = acos(glm::dot(v1, v2) / Norm(v1) / Norm(v2));
+    return angle / 3.1415926f;
 }