psemek/examples/triangulation.cpp

#include <psemek/app/app.hpp>
#include <psemek/app/main.hpp>
#include <psemek/gfx/painter.hpp>
#include <psemek/gfx/gl.hpp>
#include <psemek/geom/scale.hpp>
#include <psemek/geom/camera.hpp>
#include <psemek/geom/constants.hpp>
#include <psemek/cg/bbox.hpp>
#include <psemek/cg/triangulation/ear_clipping.hpp>
#include <psemek/cg/triangulation/monotone.hpp>
#include <psemek/cg/triangulation/delaunay.hpp>
#include <psemek/log/log.hpp>
#include <psemek/prof/profiler.hpp>
#include <psemek/util/clock.hpp>
#include <psemek/util/to_string.hpp>
#include <psemek/geom/homogeneous.hpp>
#include <psemek/geom/swizzle.hpp>
#include <psemek/random/generator.hpp>
#include <psemek/random/uniform.hpp>

#include <fstream>

using namespace psemek;

struct triangulation_app
	: app::app
{
	triangulation_app()
		: app("Triangulation example", 16)
	{
		std::ifstream in(PSEMEK_EXAMPLES_DIR "/turkey");

		while (true)
		{
			geom::point<float, 2> p;
			in >> p[0] >> p[1];
			if (!in)
				break;
			points_.push_back(p);
		}

		std::reverse(points_.begin(), points_.end());

		for (std::size_t i = 0; i < points_.size();)
		{
			std::size_t j = (i + 1) % points_.size();
			if (points_[i] == points_[j])
			{
				points_.erase(points_.begin() + i);
			}
			else
			{
				++i;
			}
		}

		log::info() << points_.size() << " input points";

		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>(geom::fast, points_.begin(), points_.end());
			edges_ = cg::edge_mesh(dcel);
			triangles_ = cg::triangle_mesh(dcel);
		}

		prof::dump();

		log::info() << (triangles_.size() / 3) << " triangles";
	}

	void on_left_button_down() override
	{
		app::on_left_button_down();

		if (mouse())
			drag_start_ = mouse();
	}

	void on_left_button_up() override
	{
		app::on_left_button_up();

		drag_start_ = std::nullopt;
	}

	void on_mouse_wheel(int delta) override
	{
		camera_size_tgt_ *= std::pow(0.8f, delta);
	}

	void update() override
	{
		float const dt = clock_.restart().count();

		if (drag_start_ && mouse())
		{
			auto delta = *mouse() - *drag_start_;
			delta[1] *= -1;
			camera_center_ -= geom::cast<float>(delta) * camera_size_ / (1.f * height());
			drag_start_ = mouse();
		}

		camera_size_ += (camera_size_tgt_ - camera_size_) * (1.f - std::exp(- 20.f * dt));
	}

	void present() override
	{
		gl::ClearColor(1.f, 1.f, 1.f, 1.f);
		gl::Clear(gl::COLOR_BUFFER_BIT);

		float aspect_ratio = (width() * 1.f) / height();
		geom::box<float, 2> view_bbox = geom::expand(geom::box<float, 2>::singleton(camera_center_), geom::vector{camera_size_ * 0.5f * aspect_ratio, camera_size_ * 0.5f});

		float line_width = 4.f * camera_size_ / height();

		auto edge = [this, line_width](auto i0, auto i1, gfx::color_rgba const & color)
		{
			painter_.line(points_[i0], points_[i1], line_width, color, true);
		};

		random::generator rng;
		for (auto const & e : edges_)
			edge(e[0], e[1], gfx::black);
		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[3] = 255;

			painter_.triangle(points_[t[0]], points_[t[1]], points_[t[2]], c);
		}

		for (std::size_t i = 0; i < points_.size(); ++i)
		{
			edge(i, (i + 1) % points_.size(), gfx::black);
		}

		auto camera_transform = geom::orthographic_camera{view_bbox}.transform();

		painter_.render(camera_transform);
	}

private:
	std::vector<geom::point<float, 2>> points_;
	std::vector<geom::segment<std::uint16_t>> edges_;
	std::vector<geom::triangle<std::uint16_t>> triangles_;
	geom::box<float, 2> bbox_;
	geom::point<float, 2> camera_center_;
	float camera_size_;
	float camera_size_tgt_;

	std::optional<geom::point<int, 2>> drag_start_;

	gfx::painter painter_;

	util::clock<std::chrono::duration<float>, std::chrono::high_resolution_clock> clock_;
};

int main()
{
	return app::main<triangulation_app>();
}