From b46cf55d66f262778bf0353650f00620c7740f2a Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Tue, 31 Oct 2023 19:36:16 +0000
Subject: Make PointFace harder to misuse

---
 game/terrain2.cpp     | 33 +++++++++++++++++++++------------
 game/terrain2.h       | 21 +++++++++++++++++----
 test/test-terrain.cpp | 16 +++++++++++-----
 3 files changed, 49 insertions(+), 21 deletions(-)

diff --git a/game/terrain2.cpp b/game/terrain2.cpp
index 5d1c595..8d29143 100644
--- a/game/terrain2.cpp
+++ b/game/terrain2.cpp
@@ -54,22 +54,32 @@ TerrainMesh::findPoint(glm::vec2 p) const
 	return findPoint(p, *faces_begin());
 }
 
-bool
-TerrainMesh::locate(const TerrainMesh::PointFace & pointFace, FaceHandle start) const
+TerrainMesh::PointFace::PointFace(const glm::vec2 p, const TerrainMesh * mesh) :
+	PointFace {p, mesh, *mesh->faces_begin()}
+{
+}
+
+TerrainMesh::PointFace::PointFace(const glm::vec2 p, const TerrainMesh * mesh, FaceHandle start) :
+	PointFace {p, mesh->findPoint(p, start)}
 {
-	if (pointFace.face.is_valid()) {
-		assert(triangleContainsPoint(pointFace.point, pointFace.face));
-		return true;
+}
+
+TerrainMesh::FaceHandle
+TerrainMesh::PointFace::face(const TerrainMesh * mesh, FaceHandle start) const
+{
+	if (_face.is_valid()) {
+		assert(mesh->triangleContainsPoint(point, _face));
+		return _face;
 	}
 	else {
-		return (pointFace.face = findPoint(pointFace.point, start)).is_valid();
+		return (_face = mesh->findPoint(point, start));
 	}
 }
 
-bool
-TerrainMesh::locate(const TerrainMesh::PointFace & pointFace) const
+TerrainMesh::FaceHandle
+TerrainMesh::PointFace::face(const TerrainMesh * mesh) const
 {
-	return locate(pointFace, *faces_begin());
+	return face(mesh, *mesh->faces_begin());
 }
 
 namespace {
@@ -126,9 +136,8 @@ TerrainMesh::walk(const PointFace & from, const glm::vec2 to, const std::functio
 void
 TerrainMesh::walkUntil(const PointFace & from, const glm::vec2 to, const std::function<bool(FaceHandle)> & op) const
 {
-	locate(from);
-	assert(from.face.is_valid()); // TODO replace with a boundary search
-	auto f = from.face;
+	assert(from.face(this).is_valid()); // TODO replace with a boundary search
+	auto f = from.face(this);
 	FaceHandle previousFace;
 	while (f.is_valid() && !op(f)) {
 		for (auto next = cfh_iter(f); next.is_valid(); ++next) {
diff --git a/game/terrain2.h b/game/terrain2.h
index 1a4e263..641d608 100644
--- a/game/terrain2.h
+++ b/game/terrain2.h
@@ -19,10 +19,26 @@ public:
 	explicit TerrainMesh(const std::filesystem::path &);
 
 	struct PointFace {
+		// NOLINTNEXTLINE(hicpp-explicit-conversions)
 		PointFace(const glm::vec2 p) : point {p} { }
 
+		PointFace(const glm::vec2 p, FaceHandle face) : point {p}, _face {face} { }
+
+		PointFace(const glm::vec2 p, const TerrainMesh *);
+		PointFace(const glm::vec2 p, const TerrainMesh *, FaceHandle start);
+
 		const glm::vec2 point;
-		mutable FaceHandle face {};
+		[[nodiscard]] FaceHandle face(const TerrainMesh *) const;
+		[[nodiscard]] FaceHandle face(const TerrainMesh *, FaceHandle start) const;
+
+		[[nodiscard]] bool
+		isLocated() const
+		{
+			return _face.is_valid();
+		}
+
+	private:
+		mutable FaceHandle _face {};
 	};
 
 	[[nodiscard]] FaceHandle findPoint(glm::vec2) const;
@@ -35,7 +51,4 @@ protected:
 	[[nodiscard]] static bool triangleContainsPoint(const glm::vec2, const glm::vec2, const glm::vec2, const glm::vec2);
 	[[nodiscard]] bool triangleContainsPoint(const glm::vec2, FaceHandle) const;
 	[[nodiscard]] bool triangleContainsPoint(const glm::vec2, ConstFaceVertexIter) const;
-
-	bool locate(const PointFace &) const;
-	bool locate(const PointFace &, FaceHandle start) const;
 };
diff --git a/test/test-terrain.cpp b/test/test-terrain.cpp
index bf30179..bf73356 100644
--- a/test/test-terrain.cpp
+++ b/test/test-terrain.cpp
@@ -49,10 +49,16 @@ BOOST_AUTO_TEST_CASE(trianglesContainsPoints)
 BOOST_AUTO_TEST_CASE(locatePointFace)
 {
 	const PointFace pf {{310002, 490003}};
-	BOOST_CHECK(!pf.face.is_valid());
-	BOOST_CHECK(locate(pf));
-	BOOST_CHECK(pf.face.is_valid());
-	BOOST_CHECK_EQUAL(pf.face.idx(), 0);
+	BOOST_CHECK(!pf.isLocated());
+	BOOST_CHECK(pf.face(this).is_valid());
+	BOOST_CHECK_EQUAL(pf.face(this).idx(), 0);
+}
+
+BOOST_AUTO_TEST_CASE(preLocatePointFace)
+{
+	const PointFace pf {{310002, 490003}, this};
+	BOOST_CHECK(pf.isLocated());
+	BOOST_CHECK_EQUAL(pf.face(this).idx(), 0);
 }
 
 BOOST_AUTO_TEST_SUITE_END();
@@ -107,7 +113,7 @@ BOOST_DATA_TEST_CASE(walkTerrainSetsFromFace,
 {
 	TerrainMesh::PointFace pf {from};
 	BOOST_CHECK_NO_THROW(fixedTerrtain.walk(pf, to, [](auto) {}));
-	BOOST_CHECK_EQUAL(pf.face.idx(), visits.front());
+	BOOST_CHECK_EQUAL(pf.face(&fixedTerrtain).idx(), visits.front());
 }
 
 BOOST_DATA_TEST_CASE(walkTerrainUntil,
-- 
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