#include <iostream>
#include <SFML/Graphics.hpp>

using namespace sf;

const int SCREEN_WIDTH = 900;
const int SCREEN_HEIGHT = 700;

void update(sf::VertexArray v);

sf::VertexArray interpolation(sf::Quads, 4);

	float bottomright = SCREEN_WIDTH / 2;
	float bottomleft = bottomright;
	bool positivedirection = true;

int main()
{
	const float FPS = 60.0f; //The desired FPS. (The number of updates each second).
	bool redraw = true;      //Do I redraw everything on the screen?

	sf::RenderWindow window(sf::VideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, 32), "My window");
	window.setFramerateLimit(FPS);
	sf::Clock clock;

	// define the position of the triangle's points
	interpolation[0].position = sf::Vector2f((SCREEN_WIDTH * 0.1), (SCREEN_HEIGHT * 0.1));  //Top Left 10 10
	interpolation[1].position = sf::Vector2f((SCREEN_WIDTH * 0.9), (SCREEN_HEIGHT * 0.1));  //Top Right 100 10
	interpolation[2].position = sf::Vector2f(bottomright, (SCREEN_HEIGHT * 0.9)); //bottom right 100 100
	interpolation[3].position = sf::Vector2f(bottomleft, (SCREEN_HEIGHT * 0.9));

	// define the color of the triangle's points
	interpolation[0].color = sf::Color::Red;
	interpolation[1].color = sf::Color::Blue;
	interpolation[2].color = sf::Color::Green;
	interpolation[3].color = sf::Color::Yellow;




	while (window.isOpen())
	{
		sf::Event event;

		//Wait until 1/60th of a second has passed, then update everything.
		if (clock.getElapsedTime().asSeconds() >= 1.0f / FPS)
		{
			redraw = true; //We're ready to redraw everything
			clock.restart();
		}

		while (window.pollEvent(event))
		{

			if (event.type == sf::Event::Closed)
				window.close();
		}


		// redraws according to the 60 fps check
		if (redraw)
		{
			redraw = false;

			window.clear(sf::Color::Black);

			update(interpolation);
			window.draw(interpolation);
			window.display();
		}


		redraw = true;
	}

	return 0;
}


void update(sf::VertexArray v) {
	if (bottomright > (SCREEN_WIDTH * 0.9) && bottomleft < (SCREEN_WIDTH * 0.1))
	{
		positivedirection = false;
	}

	if (bottomright <(SCREEN_WIDTH/2) && bottomleft > (SCREEN_WIDTH/2))
	{
		positivedirection = true;
	}

	if (positivedirection)
	{
	// interpolate on a vertex to make it looks like a quad becoming a triangle
	interpolation[2].position = sf::Vector2f(bottomright += 1, (SCREEN_HEIGHT * 0.9)); //bottom right 100 100
	interpolation[3].position = sf::Vector2f(bottomleft -=1 , (SCREEN_HEIGHT * 0.9));
	}
	else if (!positivedirection)
	{
		// interpolate on a vertex to make it looks like a quad becoming a triangle
		interpolation[2].position = sf::Vector2f(bottomright -= 1, (SCREEN_HEIGHT * 0.9)); //bottom right 100 100
		interpolation[3].position = sf::Vector2f(bottomleft += 1, (SCREEN_HEIGHT * 0.9));
	}

}