在SFML中绘制凸形图形时的奇怪行为

Question

我正在使用SFML库绘制一个凸形图形：

#include <SFML/Graphics.hpp>

using namespace sf;

int main()
{
  RenderWindow window(VideoMode(400, 400), "SFML window");

  ConvexShape convex;

  convex.setPointCount(8);
  convex.setPoint(0, sf::Vector2f(0, 0));
  convex.setPoint(1, sf::Vector2f(180, 0));
  convex.setPoint(2, sf::Vector2f(180, 90));
  convex.setPoint(3, sf::Vector2f(100, 90));
  convex.setPoint(4, sf::Vector2f(100, 180));
  convex.setPoint(5, sf::Vector2f(30, 180));
  convex.setPoint(6, sf::Vector2f(30, 90));
  convex.setPoint(7, sf::Vector2f(0, 90));
  convex.setPosition(100, 100);

  while (window.isOpen())
  {
    sf::Event event;
    while (window.pollEvent(event))
    {
      if (event.type == sf::Event::Closed)
        window.close();
    }
    window.clear();
    window.draw(convex);
    window.display();
  }
  return EXIT_SUCCESS;
}

这些点是按顺时针顺序定义的，一切都很好！convex1

但是，当我稍微改变两个坐标时，我得到了一些我真的没有预料到的东西：

#include <SFML/Graphics.hpp>

using namespace sf;

int main()
{
  RenderWindow window(VideoMode(400, 400), "SFML window");

  ConvexShape convex;

  convex.setPointCount(8);
  convex.setPoint(0, sf::Vector2f(0, 0));
  convex.setPoint(1, sf::Vector2f(180, 0));
  convex.setPoint(2, sf::Vector2f(180, 90));
  convex.setPoint(3, sf::Vector2f(100, 90));
  convex.setPoint(4, sf::Vector2f(100, 200));   // CHANGED 180 to 200
  convex.setPoint(5, sf::Vector2f(30, 200));    // CHANGED 180 to 200
  convex.setPoint(6, sf::Vector2f(30, 90));
  convex.setPoint(7, sf::Vector2f(0, 90));
  convex.setPosition(50, 50);

  while (window.isOpen())
  {
    sf::Event event;
    while (window.pollEvent(event))
    {
      if (event.type == sf::Event::Closed)
        window.close();
    }
    window.clear();
    window.draw(convex);
    window.display();
  }
  return EXIT_SUCCESS;
}

我看到了以下窗口：convex2

为什么会出现这种情况？

Answer 1

这些坐标与凸形中的点相关，您应该只使用这些坐标来更改对象的格式。为了移动整个对象，您应该使用以下命令：

convex.move(x Position, y Position);