I'm using Lucene.NET 2.9.2 as reference point for this answer.
You could build a custom collector which you pass to one of the search overloads.
using System;
using System.Collections.Generic;
using Lucene.Net.Index;
using Lucene.Net.Search;
public class AwesomeCollector : Collector {
private readonly List<Int32> _docIds = new List<Int32>();
private Scorer _scorer;
private Int32 _docBase;
public IEnumerable<Int32> DocumentIds {
get { return _docIds; }
}
public override void SetScorer(Scorer scorer) {
_scorer = scorer;
}
public override void Collect(Int32 doc) {
var score = _scorer.Score();
if (_lowerInclusiveScore <= score)
_docIds.Add(_docBase + doc);
}
public override void SetNextReader(IndexReader reader, Int32 docBase) {
_docBase = docBase;
}
public override bool AcceptsDocsOutOfOrder() {
return true;
}
}