Sets environment properties for the entire scene The [WorldEnvironment] node can be added to a scene in order to set default [Environment] variables for the scene. The [WorldEnvironment] can be overridden by an [Environment] node set on the current [Camera]. Additionally, only one [WorldEnvironment] may be instanced in a given scene at a time. The [WorldEnvironment] allows the user to specify default lighting parameters (e.g. ambient lighting), various post-processing effects (e.g. SSAO, DOF, Tonemapping), and how to draw the background (e.g. solid color, skybox). Return the [Environment] currently bound. Set the currently bound [Environment] to the one specified.