fix water shader switching bug

apps/openmw/mwrender/sky.cpp

@@ -1548,14 +1548,19 @@ void SkyManager::update(float duration)
 {
     if (!mEnabled)
     {
-        mRainIntensityUniform->set((float) 0.0);
+        if (mRainIntensityUniform)
+            mRainIntensityUniform->set((float) 0.0);
+
         return;
     }
 
-    if (mIsStorm || (!hasRain() && !mParticleNode))
-        mRainIntensityUniform->set((float) 0.0);
-    else
-        mRainIntensityUniform->set((float) mWeatherAlpha);
+    if (mRainIntensityUniform)
+    {
+        if (mIsStorm || (!hasRain() && !mParticleNode))
+            mRainIntensityUniform->set((float) 0.0);
+        else
+            mRainIntensityUniform->set((float) mWeatherAlpha);
+    }
 
     if (mIsStorm)
     {

apps/openmw/mwrender/water.cpp

@@ -416,13 +416,14 @@ Water::Water(osg::Group *parent, osg::Group* sceneRoot, Resource::ResourceSystem
 
     setHeight(mTop);
 
-    mRainIntensityUniform = NULL;
     updateWaterMaterial();
+
+    mRainIntensityUniform = new osg::Uniform("rainIntensity",(float) 0.0);
 }
 
 osg::Uniform *Water::getRainIntensityUniform()
 {
-    return mRainIntensityUniform;
+    return mRainIntensityUniform.get();
 }
 
 void Water::updateWaterMaterial()
@@ -556,7 +557,6 @@ void Water::createShaderWaterStateSet(osg::Node* node, Reflection* reflection, R
     program->addShader(fragmentShader);
     shaderStateset->setAttributeAndModes(program, osg::StateAttribute::ON);
 
-    mRainIntensityUniform = new osg::Uniform("rainIntensity",(float) 0.0);
     shaderStateset->addUniform(mRainIntensityUniform);
 
     node->setStateSet(shaderStateset);

apps/openmw/mwrender/water.hpp

@@ -51,7 +51,7 @@ namespace MWRender
     {
         static const int CELL_SIZE = 8192;
 
-        osg::Uniform* mRainIntensityUniform;
+        osg::ref_ptr<osg::Uniform> mRainIntensityUniform;
 
         osg::ref_ptr<osg::Group> mParent;
         osg::ref_ptr<osg::Group> mSceneRoot;