Update triangulation example: use input GeoJSON and support multipolygon

examples/triangulation.cpp

@@ -17,8 +17,15 @@
 #include <psemek/math/swizzle.hpp>
 #include <psemek/random/generator.hpp>
 #include <psemek/random/uniform.hpp>
+#include <psemek/io/file_stream.hpp>
 
-#include <fstream>
+// #include <boost/preprocessor/stringize.hpp>
+
+// #define RAPIDJSON_ASSERT(x) if (!(x)) throw ::psemek::util::exception("Error parsing glTF: " BOOST_PP_STRINGIZE(x));
+// #define RAPIDJSON_NOEXCEPT_ASSERT(x)
+
+#include <rapidjson/document.h>
+#include <rapidjson/istreamwrapper.h>
 
 using namespace psemek;
 
@@ -27,54 +34,79 @@ struct triangulation_app
 {
 	triangulation_app(options const &, context const &)
 	{
-		std::ifstream in(PSEMEK_EXAMPLES_DIR "/turkey");
+		std::vector<std::vector<math::point<float, 2>>> rings;
 
-		while (true)
 		{
-			math::point<float, 2> p;
-			in >> p[0] >> p[1];
-			if (!in)
-				break;
-			points_.push_back(p);
-		}
+			auto input_json = io::read_full(io::file_istream(PSEMEK_EXAMPLES_DIR "/turkey.geo.json")).string();
 
-		std::reverse(points_.begin(), points_.end());
+			rapidjson::Document document;
+			document.ParseInsitu(input_json.data());
 
-		for (std::size_t i = 0; i < points_.size();)
+			for (auto const & polygon : document["features"].GetArray()[0]["geometry"]["coordinates"].GetArray())
 			{
-			std::size_t j = (i + 1) % points_.size();
-			if (points_[i] == points_[j])
-			{
-				points_.erase(points_.begin() + i);
-			}
-			else
-			{
-				++i;
+				// Ignore inner rings (holes)
+				auto const & outer_ring = polygon.GetArray()[0].GetArray();
+
+				std::vector<math::point<float, 2>> ring;
+
+				for (auto const & p : outer_ring)
+					ring.push_back({p.GetArray()[0].GetFloat(), p.GetArray()[1].GetFloat()});
+
+				log::info() << "Ring with " << ring.size() << " vertices";
+
+				std::reverse(ring.begin(), ring.end());
+				ring.erase(std::unique(ring.begin(), ring.end()), ring.end());
+
+				rings.push_back(std::move(ring));
 			}
 		}
 
-		log::info() << points_.size() << " input points";
+		{
+			prof::profiler prof("triangulate");
+
+			for (auto const & ring : rings)
+			{
+				auto dcel = cg::monotone_triangulation<std::uint16_t>(math::fast, ring.begin(), ring.end());
+
+				auto const index_offset = points_.size();
+				points_.insert(points_.end(), ring.begin(), ring.end());
+
+				auto edges = cg::edge_mesh(dcel);
+				auto triangles = cg::triangle_mesh(dcel);
+
+				for (auto & e : edges)
+					for (auto & i : e.points)
+						i += index_offset;
+
+				for (auto & t : triangles)
+					for (auto & i : t.points)
+						i += index_offset;
+
+				edges_.insert(edges_.end(), edges.begin(), edges.end());
+				triangles_.insert(triangles_.end(), triangles.begin(), triangles.end());
+
+				for (std::size_t i = 0; i < ring.size(); ++i)
+				{
+					std::size_t j = (i + 1) % ring.size();
+					contour_edges_.push_back({index_offset + i, index_offset + j});
+				}
+			}
+		}
+
+		log::info() << rings.size() << " rings";
+		log::info() << points_.size() << " total input vertices";
 
 		bbox_ = cg::bbox(points_.begin(), points_.end());
 		camera_center_ = bbox_.center();
 		camera_size_ = std::max(bbox_[0].length(), bbox_[1].length()) * 1.125f;
 		camera_size_tgt_ = camera_size_;
 
-		{
-			prof::profiler prof("triangulate");
-
-//			auto dcel = cg::ear_clipping<std::uint16_t>(math::fast, points_.begin(), points_.end());
-			auto dcel = cg::monotone_triangulation<std::uint16_t>(math::fast, points_.begin(), points_.end());
-			edges_ = cg::edge_mesh(dcel);
-			triangles_ = cg::triangle_mesh(dcel);
-		}
-
-		prof::dump();
-
 		log::info() << edges_.size() << " edges";
 		log::info() << triangles_.size() << " triangles";
 		log::info() << "Euler chi: " << (points_.size() - edges_.size() + triangles_.size());
 
+		prof::dump();
+
 		closest_points_.resize(points_.size());
 		std::iota(closest_points_.begin(), closest_points_.end(), std::uint16_t{0});
 	}
@@ -130,19 +162,16 @@ struct triangulation_app
 		for (auto const & t : triangles_)
 		{
 			gfx::color_rgba c;
-			c[0] = random::uniform<std::uint8_t>(rng, {0, 255});
-			c[1] = random::uniform<std::uint8_t>(rng, {0, 255});
-			c[2] = random::uniform<std::uint8_t>(rng, {0, 255});
+			c[0] = random::uniform<std::uint8_t>(rng, {63, 255});
+			c[1] = random::uniform<std::uint8_t>(rng, {63, 255});
+			c[2] = random::uniform<std::uint8_t>(rng, {63, 255});
 			c[3] = 255;
 
 			painter_.triangle(points_[t[0]], points_[t[1]], points_[t[2]], c);
 		}
 
-//		for (auto const & e : edges_)
-//			edge(e[0], e[1], gfx::black);
-
-		for (std::size_t i = 0; i < points_.size(); ++i)
-			edge(i, (i + 1) % points_.size(), gfx::black);
+		for (auto const & e : contour_edges_)
+			edge(e[0], e[1], gfx::black);
 
 		auto camera_transform = math::orthographic_camera{view_bbox}.transform();
 
@@ -188,6 +217,7 @@ struct triangulation_app
 private:
 	std::vector<math::point<float, 2>> points_;
 	std::vector<math::segment<std::uint16_t>> edges_;
+	std::vector<math::segment<std::uint16_t>> contour_edges_;
 	std::vector<math::triangle<std::uint16_t>> triangles_;
 	math::box<float, 2> bbox_;
 	math::point<float, 2> camera_center_;
@@ -207,20 +237,7 @@ namespace psemek::app
 
 	std::unique_ptr<application::factory> make_application_factory()
 	{
-		return default_application_factory<triangulation_app>({.name = "Triangulation example"
-															   ""
-															   ""
-															   ""
-															   ""
-															   ""
-															   ""
-															   ""
-															   ""
-															   ""
-															   ""
-															   ""
-															   ""
-															   ""});
+		return default_application_factory<triangulation_app>({.name = "Triangulation example"});
 	}
 
 }