From 18fc7c28b0f0c1e32c455667ce2bbbed6b0ac60e Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Fri, 24 Jun 2016 11:29:25 +0100
Subject: [PATCH] Added handling of empty slides and layers

---
 src/osgPresentation/SlideEventHandler.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/osgPresentation/SlideEventHandler.cpp b/src/osgPresentation/SlideEventHandler.cpp
index 608cf1839..cb6cb3e53 100644
--- a/src/osgPresentation/SlideEventHandler.cpp
+++ b/src/osgPresentation/SlideEventHandler.cpp
@@ -1301,7 +1301,7 @@ osg::Node* SlideEventHandler::getLayer(int slideNum, int layerNum)
 
 bool SlideEventHandler::selectSlide(int slideNum,int layerNum)
 {
-    if (!_presentationSwitch) return false;
+    if (!_presentationSwitch || _presentationSwitch->getNumChildren()==0) return false;
 
     OSG_INFO<<"selectSlide("<<slideNum<<","<<layerNum<<")"<<std::endl;
 
@@ -1398,7 +1398,7 @@ bool SlideEventHandler::selectSlide(int slideNum,int layerNum)
 
 bool SlideEventHandler::selectLayer(int layerNum)
 {
-    if (!_slideSwitch) return false;
+    if (!_slideSwitch || _slideSwitch->getNumChildren()==0) return false;
 
     bool withinSlide = true;