In the sentence 'John entered the room angry', can 'angry' be considered a resultative predicate? This sentence has the same construction as 'John painted the door green', but while 'green' describes the internal argument 'the door', 'angry' describes the external argument 'John', so I am a bit confused.
John entered the room angry.
I'd say that "angry" is an optional depictive functioning as a 'predicative adjunct'.
It's an adjunct because it's an optional item functioning here as a modifier in clause structure, and it's predicative because it's related to a predicand, i.e. "John". (Compare the predicative complement in "John was angry".).
Predicative adjuncts are not restricted to AdjPs; they can also be PPs ("In a bad temper, as usual, John walked on ahead of the main party") or NPs ("A proud teetotaller, John stuck to water while the others drank champagne.").