From 4bea43dc4fa93730eef609f7e0a981a7f91dfc35 Mon Sep 17 00:00:00 2001
From: Yann Thierry-Mieg <yann.thierry-mieg@lip6.fr>
Date: Wed, 17 Oct 2018 20:14:45 +0200
Subject: [PATCH] a couple new useful primitives for working with distances

---
 DistUtil.cpp | 23 ++++++++++++++++++++++-
 DistUtil.h   |  6 +++++-
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/DistUtil.cpp b/DistUtil.cpp
index ba4e120..95c9fb7 100644
--- a/DistUtil.cpp
+++ b/DistUtil.cpp
@@ -8,7 +8,12 @@ namespace sc2util {
 		std::sort(units.begin(), units.end(), [start](const Unit * a, const Unit * b) { return DistanceSquared2D(start, a->pos) < DistanceSquared2D(start, b->pos); });
 	}
 
-	std::vector<int> sortByDistanceTo(std::valarray<float> matrix, int ti, size_t sz) {
+	void sortByDistanceTo(std::vector<sc2::Point2D>& units, const sc2::Point2D & start)
+	{
+		std::sort(units.begin(), units.end(), [start](const auto & a, const auto & b) { return DistanceSquared2D(start, a) < DistanceSquared2D(start, b); });
+	}
+
+	std::vector<int> sortByDistanceTo(const std::valarray<float> & matrix, int ti, size_t sz) {
 		std::vector<int> byDist;
 		for (int i = 0; i < sz; i++) {
 			byDist.push_back(i);
@@ -17,6 +22,22 @@ namespace sc2util {
 		return byDist;
 	}
 
+	std::valarray<float> computeDistanceMatrix(const Units & units) {
+		auto sz = units.size();
+		std::valarray<float> matrix(sz *sz); // no more, no less, than a matrix		
+
+		for (int i = 0; i < sz; i++) {
+			// set diagonal to 0
+			matrix[i*sz + i] = 0;
+			for (int j = i + 1; j < sz; j++) {
+				auto d = DistanceSquared2D(units[i]->pos, units[j]->pos);
+				matrix[i*sz + j] = d;
+				matrix[j*sz + i] = d;
+			}
+		}
+		return matrix;
+	}
+
 	std::valarray<float> computeDistanceMatrix(const std::vector<Point3D> & expansions, QueryInterface * query) {
 		std::vector <sc2::QueryInterface::PathingQuery> queries;
 		auto sz = expansions.size();
diff --git a/DistUtil.h b/DistUtil.h
index a3b0f16..c65ac19 100644
--- a/DistUtil.h
+++ b/DistUtil.h
@@ -6,10 +6,14 @@
 namespace sc2util {
 	// basic sorting, updates units
 	void sortByDistanceTo(sc2::Units & units, const sc2::Point2D & start);
+	// basic sorting, updates units
+	void sortByDistanceTo(std::vector<sc2::Point2D> & units, const sc2::Point2D & start);
 	// sorting using a distance matrix, with respect to one element ti
-	std::vector<int> sortByDistanceTo(std::valarray<float> matrix, int ti, size_t sz);
+	std::vector<int> sortByDistanceTo(const std::valarray<float> & matrix, int ti, size_t sz);
 	// computing a distance matrix, with actual pathing queries
 	std::valarray<float> computeDistanceMatrix(const std::vector<sc2::Point3D> & expansions, sc2::QueryInterface * query);
+	// compute a distance matrix, bird view
+	std::valarray<float> computeDistanceMatrix(const sc2::Units & expansions);
 	// utility for center of gravity
 	const sc2::Point2D cog(const std::vector<sc2::Point2D>& points);
 	// default max is quite large, it amounts to roughly 15 game unit i.e. a  circle roughly the surface of a base