From b4576e3a40d0416dea4e82042905598680fba3ee Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 15 Dec 2024 15:00:08 +0000
Subject: Reuse close edges when adding new vertices for surface

---
 game/geoData.cpp | 50 +++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 37 insertions(+), 13 deletions(-)

(limited to 'game/geoData.cpp')

diff --git a/game/geoData.cpp b/game/geoData.cpp
index a5fc4ef..d3b5485 100644
--- a/game/geoData.cpp
+++ b/game/geoData.cpp
@@ -430,6 +430,19 @@ GeoData::setHeights(const std::span<const GlobalPosition3D> triangleStrip, const
 			return std::make_pair(v, glm::length(::difference(p, this->point(v).xy())));
 		};
 	};
+	const auto vertexDistFromE = [this](GlobalPosition2D p) {
+		return [p, this](const HalfedgeHandle e) {
+			const auto fromPoint = point(from_vertex_handle(e)).xy();
+			const auto toPoint = point(to_vertex_handle(e)).xy();
+			return std::make_pair(e, Triangle<2> {fromPoint, toPoint, p}.height());
+		};
+	};
+	const auto notBoundary = std::views::filter([this](auto handleItr) {
+		return !is_boundary(*handleItr);
+	});
+	const auto notEdgeBoundary = std::views::filter([this](auto handleItr) {
+		return !is_boundary(edge_handle(*handleItr));
+	});
 
 	std::set<VertexHandle> newOrChangedVerts;
 	auto addVertexForNormalUpdate = [this, &newOrChangedVerts](const VertexHandle vertex) {
@@ -437,21 +450,32 @@ GeoData::setHeights(const std::span<const GlobalPosition3D> triangleStrip, const
 		std::ranges::copy(vv_range(vertex), std::inserter(newOrChangedVerts, newOrChangedVerts.end()));
 	};
 
-	// New vertices for each vertex in triangleStrip
 	std::vector<VertexHandle> newVerts;
+	auto newVertexOnFace = [this, &vertexDistFrom, &opts, &vertexDistFromE, &newVerts, &notBoundary, &notEdgeBoundary](
+								   GlobalPosition3D tsPoint) {
+		const auto face = findPoint(tsPoint);
+		// Check vertices
+		if (const auto nearest = std::ranges::min(std::views::iota(fv_begin(face), fv_end(face)) | notBoundary
+							| std::views::transform(vertexDistFrom(tsPoint)),
+					{}, &std::pair<VertexHandle, float>::second);
+				nearest.second < opts.nearNodeTolerance && !std::ranges::contains(newVerts, nearest.first)) {
+			point(nearest.first) = tsPoint;
+			return nearest.first;
+		}
+		// Check edges
+		if (const auto nearest = std::ranges::min(std::views::iota(fh_begin(face), fh_end(face)) | notEdgeBoundary
+							| std::views::transform(vertexDistFromE(tsPoint)),
+					{}, &std::pair<HalfedgeHandle, float>::second);
+				nearest.second < opts.nearNodeTolerance) {
+			return split(edge_handle(nearest.first), tsPoint);
+		}
+		// Nothing close, split face
+		return split(face, tsPoint);
+	};
+
+	// New vertices for each vertex in triangleStrip
 	newVerts.reserve(newVerts.size());
-	std::transform(triangleStrip.begin(), triangleStrip.end(), std::back_inserter(newVerts),
-			[this, &newVerts, &vertexDistFrom, &opts](const auto tsPoint) {
-				const auto face = findPoint(tsPoint);
-				if (const auto nearest = std::ranges::min(std::views::iota(fv_begin(face), fv_end(face))
-									| std::views::transform(vertexDistFrom(tsPoint)),
-							{}, &std::pair<VertexHandle, float>::second);
-						nearest.second < opts.nearNodeTolerance && !std::ranges::contains(newVerts, nearest.first)) {
-					point(nearest.first) = tsPoint;
-					return nearest.first;
-				}
-				return split(face, tsPoint);
-			});
+	std::transform(triangleStrip.begin(), triangleStrip.end(), std::back_inserter(newVerts), newVertexOnFace);
 	std::ranges::for_each(newVerts, addVertexForNormalUpdate);
 
 	// Create temporary triangles from triangleStrip
-- 
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