* resets state updater to apply light settings (#3141)
resets state updater to apply light settings
With this PR we achieve the same effect with fewer lines of code.
* fixes LightSource logic errors
We currently update `LightSource::setActorFade` in `TransparencyUpdater`. There are several logic errors inherent in this approach:
1. We fail to update `LightSource::setActorFade` for off screen actors because their `TransparencyUpdater` cull callback is not invoked.
2. We fail to update `LightSource::setActorFade` in the instant that a `TransparencyUpdater` is removed.
3. We fail to update `setActorFade` when an `mExtraLightSource` is created after calling `Animation::setAlpha`.
With this PR we avoid such issues by updating `LightSource::setActorFade` in `Animation::setAlpha` and `Animation::addExtraLightSource` instead.
With this PR we refactor `SceneUtil::KeyframeController` not to require `virtual osg::Callback` inheritance. I suppose such `virtual` overhead is not justified here because it negatively impacts many other classes we derive from `osg::Callback`.
This PR aims to spark the retirement of a questionable pattern I have found all over our code base. I will illustrate how this pattern encourages code duplication, lacks type safety, requires documentation and can be prone to bugs.
```
std::map<std::string, Object> mMap; // Stored in all lowercase for a case-insensitive lookup
std::string lowerKey = Misc::StringUtils::lowerCase(key);
mMap.emplace(lowerKey, object);
std::string lowerKey = Misc::StringUtils::lowerCase(key);
mMap.find(lowerKey);
mMap.find(key); // Not found. Oops!
```
An alternative approach produces no such issues.
```
std::unordered_map<std::string, Object, Misc::StringUtils::CiHash, Misc::StringUtils::CiEqual> mMap;
mMap.emplace(key, object);
mMap.find(key);
```
Of course, such an alternative will work for a `map` as well, but an `unordered_map` is generally preferable over a `map` with these changes because we have moved `lowerCase` into the comparison operator.
In this PR I have refactored `Animation::mNodeMap` accordingly. I have reviewed and adapted all direct and indirect usage of `Animation::mNodeMap` to ensure we do not change behaviour with this PR.
