1 files changed, 99 insertions, 0 deletions
diff --git a/src/position_power.cc b/src/position_power.cc
new file mode 100644
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--- /dev/null
+++ b/src/position_power.cc
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+/* -*- Mode: c++ -*- */
+/***************************************************************************
+ *            position_power.cc
+ *
+ *  Wed Jul 24 15:05:27 CEST 2024
+ *  Copyright 2024 Bent Bisballe Nyeng
+ *  deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ *  This file is part of DrumGizmo.
+ *
+ *  DrumGizmo is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License as published by
+ *  the Free Software Foundation; either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  DrumGizmo is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with DrumGizmo; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#include "position_power.h"
+
+#include "sample.h"
+#include "instrument.h"
+
+#include <set>
+#include <algorithm>
+
+Instrument::PowerRange positionPower(const std::vector<Sample*>& samplelist, double position)
+{
+	if(samplelist.empty())
+	{
+		return {0.0, 1.0};
+	}
+
+	struct PosPower
+	{
+		double position;
+		double power;
+		Sample* sample;
+	};
+	auto dist_cmp =
+		[position](const PosPower& a, const PosPower& b)
+		{
+			auto position_delta =
+				std::abs(a.position - position) - std::abs(b.position - position);
+			if(position_delta != 0)
+			{
+				return position_delta < 0.0;
+			}
+			return a.sample < b.sample;
+		};
+	std::set<PosPower, decltype(dist_cmp)> sorted_samples(dist_cmp);
+
+	std::for_each(samplelist.begin(), samplelist.end(),
+	              [&](Sample* s)
+	              {
+		              sorted_samples.insert({s->getPosition(), s->getPower(), s});
+	              });
+
+	// Find the smallest, closest set in terms of delta-position against the note position
+	// and find the contained power range.
+	double power_min{std::numeric_limits<double>::max()};
+	double power_max{std::numeric_limits<double>::min()};
+	auto sample_iter = sorted_samples.begin();
+	auto final_position_boundary = sample_iter->position;
+	for(std::size_t i = 0; i < std::max(sorted_samples.size() / 4, std::size_t(1)); ++i)
+	{
+		auto power = sample_iter->power;
+		final_position_boundary = sample_iter->position;
+		power_min = std::min(power_min, power);
+		power_max = std::max(power_max, power);
+		++sample_iter;
+	}
+
+	// Include upcoming samples from the list as long as their distances are contained in
+	// the final position range.
+	while(sample_iter != sorted_samples.end())
+	{
+		if(sample_iter->position != final_position_boundary)
+		{
+			// Position has left the range - and since the list is sorted; stop.
+			break;
+		}
+
+		auto power = sample_iter->power;
+		power_min = std::min(power_min, power);
+		power_max = std::max(power_max, power);
+		++sample_iter;
+	}
+
+	return {power_min, power_max};
+}