Ensure alpha test is off by default

apps/openmw/mwrender/renderingmanager.cpp

@@ -381,6 +381,8 @@ namespace MWRender
 
         // Hopefully, anything genuinely requiring the default alpha func of GL_ALWAYS explicitly sets it
         mRootNode->getOrCreateStateSet()->setAttribute(Shader::RemovedAlphaFunc::getInstance(GL_ALWAYS));
+        // The transparent renderbin sets alpha testing on because that was faster on old GPUs. It's now slower and breaks things.
+        mRootNode->getOrCreateStateSet()->setMode(GL_ALPHA_TEST, osg::StateAttribute::OFF);
 
         mUniformNear = mRootNode->getOrCreateStateSet()->getUniform("near");
         mUniformFar = mRootNode->getOrCreateStateSet()->getUniform("far");