From 23a4fb142978127d73aa46b5893ebe3aba903587 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fernando=20Garc=C3=ADa=20Li=C3=B1=C3=A1n?=
 <fernandogarcialinan@gmail.com>
Date: Tue, 2 Feb 2021 18:40:54 +0100
Subject: [PATCH] Add missing null check to SGLight's dim-factor expression

---
 simgear/scene/model/SGLight.cxx          | 12 +++++++-----
 simgear/scene/model/SGLightAnimation.cxx | 12 +++++++-----
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/simgear/scene/model/SGLight.cxx b/simgear/scene/model/SGLight.cxx
index 47a48ef1..93967c0f 100644
--- a/simgear/scene/model/SGLight.cxx
+++ b/simgear/scene/model/SGLight.cxx
@@ -123,11 +123,13 @@ SGLight::appendLight(const SGPropertyNode *configNode,
     if (dim_factor) {
         const SGExpressiond *expression =
             read_value(dim_factor, modelRoot, "", 0, 1);
-        light->setUpdateCallback(
-            new SGLight::UpdateCallback(expression,
-                                        light->getAmbient(),
-                                        light->getDiffuse(),
-                                        light->getSpecular()));
+        if (expression) {
+            light->setUpdateCallback(
+                new SGLight::UpdateCallback(expression,
+                                            light->getAmbient(),
+                                            light->getDiffuse(),
+                                            light->getSpecular()));
+        }
     }
 
     osg::Shape *debug_shape = nullptr;
diff --git a/simgear/scene/model/SGLightAnimation.cxx b/simgear/scene/model/SGLightAnimation.cxx
index c9a4ef71..961fa4b1 100644
--- a/simgear/scene/model/SGLightAnimation.cxx
+++ b/simgear/scene/model/SGLightAnimation.cxx
@@ -56,11 +56,13 @@ SGLightAnimation::SGLightAnimation(simgear::SGTransientModelData &modelData) :
     if (dim_factor) {
         const SGExpressiond *expression =
             read_value(dim_factor, modelData.getModelRoot(), "", 0, 1);
-        light->setUpdateCallback(
-            new SGLight::UpdateCallback(expression,
-                                        light->getAmbient(),
-                                        light->getDiffuse(),
-                                        light->getSpecular()));
+        if (expression) {
+            light->setUpdateCallback(
+                new SGLight::UpdateCallback(expression,
+                                            light->getAmbient(),
+                                            light->getDiffuse(),
+                                            light->getSpecular()));
+        }
     }
 
     align->setName(getConfig()->getStringValue("name"));