instrument: the filter's velocity depth knob returns and multiplies the bipolar curve; the pre-v12 lift is a pure domain re-tag

src/core/instrument/engine/voice.cpp

@@ -131,7 +131,8 @@ void Voice::start(int note, int velocity, const SampleData& sample, bool declick
         filterCutoffNorm_ = static_cast<double>(p.filter.settings.cutoffNorm);
         filterModAmount_ = p.filter.modAmount;
         filterKeyTrack_ = p.filter.keyTrack;
-        filterVelOffset_ = p.filter.velocityCurve.eval(static_cast<double>(velocity));
+        filterVelCurve_ = p.filter.velocityCurve.eval(static_cast<double>(velocity));
+        filterVelOffset_ = p.filter.velAmount * filterVelCurve_;
         filterRate_ = static_cast<double>(sample.sampleRate);
         rModAmount_.set(p.filter.modAmount);
         rResonance_.set(static_cast<double>(p.filter.settings.resonanceNorm));
@@ -248,6 +249,9 @@ void Voice::applyLive(const instrument::engine::LiveValues& live, bool snap) {
     }
     filterCutoffNorm_ = static_cast<double>(live.filterSettings.cutoffNorm);
     filterKeyTrack_ = live.filterKeyTrack;
+    // The note's curve value stays latched; only the depth over it is live. Both this and the
+    // key-track depth land in the base cutoff, so they glide through rBaseCutoff_ below.
+    filterVelOffset_ = live.filterVelAmount * filterVelCurve_;
     filterSettings_.morphLaw = live.filterSettings.morphLaw;
     const double baseTarget = filterCutoffBaseTarget(note_);
     if (snap) {