GL: Occlusion query bugfix

code/nel/src/3d/driver/opengl/driver_opengl.cpp

@@ -2803,11 +2803,15 @@ IOcclusionQuery::TOcclusionType COcclusionQueryGL::getOcclusionType()
 		else
 		{
 			GLuint result;
+			nglGetQueryObjectuivARB(ID, GL_QUERY_RESULT_AVAILABLE, &result);
+			if (result != GL_FALSE)
+			{
 				nglGetQueryObjectuivARB(ID, GL_QUERY_RESULT, &result);
 				OcclusionType = result != 0 ? NotOccluded : Occluded;
 				VisibleCount = (uint) result;
 			}
 		}
+	}
 #endif
 	return OcclusionType;
 }