Make the dummy texture for the character preview shadow-friendly

apps/openmw/mwrender/characterpreview.cpp

@@ -184,6 +184,9 @@ namespace MWRender
         osg::ref_ptr<osg::Texture2D> dummyTexture = new osg::Texture2D();
         dummyTexture->setInternalFormat(GL_RED);
         dummyTexture->setTextureSize(1, 1);
+        // This might clash with a shadow map, so make sure it doesn't cast shadows
+        dummyTexture->setShadowComparison(true);
+        dummyTexture->setShadowCompareFunc(osg::Texture::ShadowCompareFunc::ALWAYS);
         stateset->setTextureAttributeAndModes(7, dummyTexture, osg::StateAttribute::ON);
         stateset->setTextureAttribute(7, noBlendAlphaEnv, osg::StateAttribute::ON);
         stateset->addUniform(new osg::Uniform("noAlpha", true));