Calculate and expose the extents of the terrain mesh

3 files changed, 17 insertions, 0 deletions

diff --git a/game/terrain2.cpp b/game/terrain2.cpp
index 105eb33..0e8b78e 100644
--- a/game/terrain2.cpp
+++ b/game/terrain2.cpp
@@ -24,10 +24,15 @@ TerrainMesh::loadFromAsciiGrid(const std::filesystem::path & input)
 	std::vector<VertexHandle> vertices;
 	vertices.reserve(ncols * nrows);
 	TerrainMesh mesh;
+	mesh.lowerExtent = {xllcorner, yllcorner, std::numeric_limits<float>::max()};
+	mesh.upperExtent
+			= {xllcorner + (cellsize * ncols), yllcorner + (cellsize * nrows), std::numeric_limits<float>::min()};
 	for (size_t row = 0; row < nrows; ++row) {
 		for (size_t col = 0; col < ncols; ++col) {
 			float height = 0;
 			f >> height;
+			mesh.upperExtent.z = std::max(mesh.upperExtent.z, height);
+			mesh.lowerExtent.z = std::min(mesh.lowerExtent.z, height);
 			vertices.push_back(mesh.add_vertex({xllcorner + (col * cellsize), yllcorner + (row * cellsize), height}));
 		}
 	}
diff --git a/game/terrain2.h b/game/terrain2.h
index 69cd380..eda56d0 100644
--- a/game/terrain2.h
+++ b/game/terrain2.h
@@ -77,8 +77,17 @@ public:
 	void walk(const PointFace & from, const glm::vec2 to, const std::function<void(FaceHandle)> & op) const;
 	void walkUntil(const PointFace & from, const glm::vec2 to, const std::function<bool(FaceHandle)> & op) const;
 
+	[[nodiscard]] auto
+	getExtents() const
+	{
+		return std::tie(lowerExtent, upperExtent);
+	}
+
 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;
+
+private:
+	glm::vec3 lowerExtent {}, upperExtent {};
 };
diff --git a/test/test-terrain.cpp b/test/test-terrain.cpp
index 512a90e..71fc1ec 100644
--- a/test/test-terrain.cpp
+++ b/test/test-terrain.cpp
@@ -19,6 +19,9 @@ BOOST_AUTO_TEST_CASE(loadSuccess)
 {
 	BOOST_CHECK_EQUAL(ncols * nrows, n_vertices());
 	BOOST_CHECK_EQUAL(2 * (ncols - 1) * (nrows - 1), n_faces());
+	const auto [lower, upper] = getExtents();
+	BOOST_CHECK_EQUAL(lower, glm::vec3(310000, 490000, -2.6));
+	BOOST_CHECK_EQUAL(upper, glm::vec3(320000, 500000, 571.6));
 }
 
 BOOST_AUTO_TEST_CASE(normalsAllPointUp)