Split link generation definitions according to terrain

Copies the same imperfect logic from old link addition functions.

5 files changed, 116 insertions, 33 deletions

diff --git a/application/main.cpp b/application/main.cpp
index d96b188..3536cf7 100644
--- a/application/main.cpp
+++ b/application/main.cpp
@@ -64,10 +64,11 @@ public:
 
 			Link::Ptr l3;
 			for (std::optional<Angle> previousDir; const auto [fromPos, toPos] : std::views::pairwise(nodes)) {
-				const auto links = railLinks->create({
-						.fromEnd = {.position = fromPos, .direction = previousDir},
-						.toEnd = {.position = toPos, .direction = std::nullopt},
-				});
+				const auto links = railLinks->create(gameState->terrain.get(),
+						{
+								.fromEnd = {.position = fromPos, .direction = previousDir},
+								.toEnd = {.position = toPos, .direction = std::nullopt},
+						});
 				for (const auto & link : links) {
 					railLinks->add(terrain.get(), link);
 				}
diff --git a/game/network/network.cpp b/game/network/network.cpp
index 561cafb..1c3a122 100644
--- a/game/network/network.cpp
+++ b/game/network/network.cpp
@@ -1,6 +1,8 @@
 #include "network.h"
+#include "game/geoData.h"
 #include "routeWalker.h"
 #include <array>
+#include <collections.h>
 #include <game/network/link.h>
 #include <gfx/models/texture.h>
 #include <glm/gtx/intersect.hpp>
@@ -96,6 +98,66 @@ Network::routeFromTo(const Link::End & end, const Node::Ptr & dest)
 	return RouteWalker().findRouteTo(end, dest);
 }
 
+void
+Network::terrainSplitAt(GenLinkDef & previous, GenLinkDef & next, GlobalPosition3D pos)
+{
+	std::visit(
+			[pos](auto & typedDefPrevious, auto & typedDefNext) {
+				std::get<1>(typedDefPrevious) = std::get<0>(typedDefNext) = pos;
+			},
+			previous, next);
+}
+
+GenLinksDef
+Network::terrainSplit(const GeoData * geoData, const GenStraightDef & def) const
+{
+	GenLinksDef out {def};
+	const auto [fromPos, toPos] = def;
+	geoData->walk(fromPos.xy(), toPos, [geoData, &out](const GeoData::WalkStep & step) {
+		if (step.previous.is_valid() && geoData->getSurface(step.current) != geoData->getSurface(step.previous)) {
+			const auto surfaceEdgePosition = geoData->positionAt(GeoData::PointFace(step.exitPosition, step.current));
+			out.emplace_back(out.back());
+			terrainSplitAt(*out.rbegin(), *++out.rbegin(), surfaceEdgePosition);
+		}
+	});
+	return out;
+}
+
+GenLinksDef
+Network::terrainSplit(const GeoData * geoData, const GenCurveDef & def) const
+{
+	static constexpr auto MIN_DISTANCE = 2000.F;
+	auto [cstart, cend, centre] = def;
+	std::set<GeoData::WalkStepCurve, SortedBy<&GeoData::WalkStepCurve::angle>> breaks;
+	const auto radiusMid = ::distance(cstart.xy(), centre);
+	for (const auto radiusOffset : {-getBaseWidth() / 2.F, 0.F, getBaseWidth() / 2.F}) {
+		const auto radius = radiusOffset + radiusMid;
+		const auto start = centre + (difference(cstart.xy(), centre) * radius) / radiusMid;
+		const auto end = centre + (difference(cend.xy(), centre) * radius) / radiusMid;
+		geoData->walk(start, end, centre, [geoData, &breaks](const GeoData::WalkStepCurve & step) {
+			if (step.previous.is_valid() && geoData->getSurface(step.current) != geoData->getSurface(step.previous)) {
+				breaks.insert(step);
+			}
+		});
+	}
+	std::vector<GlobalPosition3D> points;
+	points.reserve(breaks.size() + 2);
+	points.push_back(cstart);
+	std::ranges::transform(
+			breaks, std::back_inserter(points), [geoData, centre, radiusMid](const GeoData::WalkStepCurve & step) {
+				return (centre + (sincos(step.angle) * radiusMid))
+						|| geoData->positionAt(GeoData::PointFace(step.exitPosition, step.current)).z;
+			});
+	points.push_back(cend);
+	mergeClose(points, ::distance<3, GlobalDistance>, ::midpoint<3, GlobalDistance>, MIN_DISTANCE);
+	GenLinksDef out {def};
+	std::ranges::for_each(++points.begin(), --points.end(), [&out](const auto pos) {
+		out.emplace_back(out.back());
+		terrainSplitAt(*out.rbegin(), *++out.rbegin(), pos);
+	});
+	return out;
+}
+
 GenCurveDef
 Network::genCurveDef(const GlobalPosition3D & start, const GlobalPosition3D & end, float startDir)
 {
@@ -144,7 +206,7 @@ Network::genCurveDef(const GlobalPosition3D & start, const GlobalPosition3D & en
 }
 
 Link::Collection
-Network::create(const CreationDefinition & def)
+Network::create(const GeoData * geoData, const CreationDefinition & def)
 {
 	// TODO
 	// Where to make a straight to join because angles align?
@@ -168,8 +230,17 @@ Network::create(const CreationDefinition & def)
 		// One specific direction, single curve from the other
 		return {genCurveDef(def.toEnd.position, def.fromEnd.position, *def.toEnd.direction)};
 	};
+	const auto splitDefs = [&linkDefs, this, geoData]() {
+		return std::ranges::fold_left(linkDefs(), GenLinksDef {}, [this, geoData](auto && existing, const auto & def) {
+			return existing += std::visit(
+						   [this, geoData](const auto & typedDef) {
+							   return this->terrainSplit(geoData, typedDef);
+						   },
+						   def);
+		});
+	};
 	Link::Collection links;
-	std::ranges::transform(linkDefs(), std::back_inserter(links), [this](const auto & def) {
+	std::ranges::transform(geoData ? splitDefs() : linkDefs(), std::back_inserter(links), [this](const auto & def) {
 		return std::visit(
 				[this](const auto & typedDef) {
 					return this->create(typedDef);
diff --git a/game/network/network.h b/game/network/network.h
index 153b410..65db016 100644
--- a/game/network/network.h
+++ b/game/network/network.h
@@ -64,7 +64,7 @@ public:
 
 	[[nodiscard]] virtual float findNodeDirection(Node::AnyCPtr) const = 0;
 
-	[[nodiscard]] Link::Collection create(const CreationDefinition &);
+	[[nodiscard]] Link::Collection create(const GeoData *, const CreationDefinition &);
 	virtual void add(GeoData *, const Link::Ptr &) = 0;
 
 	[[nodiscard]] virtual const Surface * getBaseSurface() const = 0;
@@ -76,6 +76,9 @@ protected:
 	static std::pair<GenCurveDef, GenCurveDef> genCurveDef(
 			const GlobalPosition3D & start, const GlobalPosition3D & end, float startDir, float endDir);
 
+	[[nodiscard]] GenLinksDef terrainSplit(const GeoData *, const GenStraightDef &) const;
+	[[nodiscard]] GenLinksDef terrainSplit(const GeoData *, const GenCurveDef &) const;
+	static void terrainSplitAt(GenLinkDef & previous, GenLinkDef & next, GlobalPosition3D pos);
 	[[nodiscard]] virtual Link::Ptr create(const GenStraightDef &) = 0;
 	[[nodiscard]] virtual Link::Ptr create(const GenCurveDef &) = 0;
 
diff --git a/test/test-network.cpp b/test/test-network.cpp
index e6b92f3..05e995e 100644
--- a/test/test-network.cpp
+++ b/test/test-network.cpp
@@ -269,10 +269,11 @@ BOOST_DATA_TEST_CASE(GenCurveDefs,
 
 BOOST_AUTO_TEST_CASE(NetworkCreateStraight)
 {
-	const auto link = create(CreationDefinition {
-			.fromEnd = {.position = {0, 0, 0}, .direction = {}},
-			.toEnd = {.position = {0, 1000, 0}, .direction = {}},
-	});
+	const auto link = create(nullptr,
+			CreationDefinition {
+					.fromEnd = {.position = {0, 0, 0}, .direction = {}},
+					.toEnd = {.position = {0, 1000, 0}, .direction = {}},
+			});
 	BOOST_REQUIRE_EQUAL(link.size(), 1);
 	BOOST_CHECK(links.empty());
 	BOOST_CHECK(nodes.empty());
@@ -290,10 +291,11 @@ BOOST_AUTO_TEST_CASE(NetworkCreateStraight)
 
 BOOST_AUTO_TEST_CASE(NetworkCreateExtendingCurve)
 {
-	const auto link = create(CreationDefinition {
-			.fromEnd = {.position = {0, 0, 0}, .direction = half_pi},
-			.toEnd = {.position = {0, 1000, 0}, .direction = {}},
-	});
+	const auto link = create(nullptr,
+			CreationDefinition {
+					.fromEnd = {.position = {0, 0, 0}, .direction = half_pi},
+					.toEnd = {.position = {0, 1000, 0}, .direction = {}},
+			});
 	BOOST_REQUIRE_EQUAL(link.size(), 1);
 	BOOST_CHECK(links.empty());
 	BOOST_CHECK(nodes.empty());
@@ -315,10 +317,11 @@ BOOST_AUTO_TEST_CASE(NetworkCreateExtendingCurve)
 
 BOOST_AUTO_TEST_CASE(NetworkCreateExtendeeCurve)
 {
-	const auto link = create(CreationDefinition {
-			.fromEnd = {.position = {0, 0, 0}, .direction = {}},
-			.toEnd = {.position = {0, 1000, 0}, .direction = half_pi},
-	});
+	const auto link = create(nullptr,
+			CreationDefinition {
+					.fromEnd = {.position = {0, 0, 0}, .direction = {}},
+					.toEnd = {.position = {0, 1000, 0}, .direction = half_pi},
+			});
 	BOOST_REQUIRE_EQUAL(link.size(), 1);
 	BOOST_CHECK(links.empty());
 	BOOST_CHECK(nodes.empty());
@@ -343,10 +346,11 @@ BOOST_AUTO_TEST_CASE(NetworkCreateExtendeeCurve)
 
 BOOST_AUTO_TEST_CASE(NetworkCreateBiarcPair)
 {
-	const auto link = create(CreationDefinition {
-			.fromEnd = {.position = {0, 0, 0}, .direction = pi},
-			.toEnd = {.position = {1000, 1000, 0}, .direction = 0},
-	});
+	const auto link = create(nullptr,
+			CreationDefinition {
+					.fromEnd = {.position = {0, 0, 0}, .direction = pi},
+					.toEnd = {.position = {1000, 1000, 0}, .direction = 0},
+			});
 	BOOST_REQUIRE_EQUAL(link.size(), 2);
 	BOOST_CHECK(links.empty());
 	BOOST_CHECK(nodes.empty());
@@ -382,10 +386,11 @@ BOOST_AUTO_TEST_CASE(NetworkCreateBiarcPair)
 BOOST_AUTO_TEST_CASE(NetworkCreateBiarcPairEqTan)
 {
 	// This could be achieved with a single curve, but not there yet
-	const auto link = create(CreationDefinition {
-			.fromEnd = {.position = {0, 0, 0}, .direction = 0},
-			.toEnd = {.position = {1000, 0, 0}, .direction = 0},
-	});
+	const auto link = create(nullptr,
+			CreationDefinition {
+					.fromEnd = {.position = {0, 0, 0}, .direction = 0},
+					.toEnd = {.position = {1000, 0, 0}, .direction = 0},
+			});
 	BOOST_REQUIRE_EQUAL(link.size(), 2);
 	BOOST_CHECK(links.empty());
 	BOOST_CHECK(nodes.empty());
@@ -402,10 +407,11 @@ BOOST_AUTO_TEST_CASE(NetworkCreateBiarcPairEqTan)
 BOOST_AUTO_TEST_CASE(NetworkCreateBiarcPairEqTanPerp)
 {
 	// This creates an equal pair of semi-circle arcs
-	const auto link = create(CreationDefinition {
-			.fromEnd = {.position = {0, 0, 0}, .direction = 0},
-			.toEnd = {.position = {1000, 0, 0}, .direction = pi},
-	});
+	const auto link = create(nullptr,
+			CreationDefinition {
+					.fromEnd = {.position = {0, 0, 0}, .direction = 0},
+					.toEnd = {.position = {1000, 0, 0}, .direction = pi},
+			});
 	BOOST_REQUIRE_EQUAL(link.size(), 2);
 	BOOST_CHECK(links.empty());
 	BOOST_CHECK(nodes.empty());
diff --git a/ui/editNetwork.cpp b/ui/editNetwork.cpp
index cab13f2..98a60d3 100644
--- a/ui/editNetwork.cpp
+++ b/ui/editNetwork.cpp
@@ -21,7 +21,8 @@ EditNetwork::click(const SDL_MouseButtonEvent & event, const Ray<GlobalPosition3
 			}
 			else {
 				if (const auto def = resolveRay(ray)) {
-					candidates = network->create(CreationDefinition {.fromEnd = *currentStart, .toEnd = *def});
+					candidates = network->create(
+							gameState->terrain.get(), CreationDefinition {.fromEnd = *currentStart, .toEnd = *def});
 					for (const auto & link : candidates) {
 						network->add(gameState->terrain.get(), link);
 					}
@@ -46,7 +47,8 @@ EditNetwork::move(const SDL_MouseMotionEvent &, const Ray<GlobalPosition3D> & ra
 {
 	if (currentStart) {
 		if (const auto def = resolveRay(ray)) {
-			candidates = network->create(CreationDefinition {.fromEnd = *currentStart, .toEnd = *def});
+			candidates = network->create(
+					gameState->terrain.get(), CreationDefinition {.fromEnd = *currentStart, .toEnd = *def});
 		}
 	}
 	return false;