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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. struct POINT	{
  5. 	int x;
  6. 	int y;
  7. };
  8.  
  9. //マウスカーソルが時計回り（正）か反時計回り（負）かの判定
  10. int mouseConvexity(POINT* mousePoints, POINT pt, int threshold, int& s_count, int& s_prev)
  11. {
  12. 	if ( ++s_count % 4 )	//点の採取・判断は毎回やると不安定になる　"4" は要調整
  13. 		return 0;
  14. 	int d = (mousePoints[1].x - mousePoints[0].x) * (pt.y - mousePoints[1].y) -
  15. 			(mousePoints[1].y - mousePoints[0].y) * (pt.x - mousePoints[1].x);
  16. 	mousePoints[0] = mousePoints[1];
  17. 	mousePoints[1] = pt;
  18. 	if ( std::abs(d) < std::abs(threshold) )    //はっきりしないカーブは前回値を返す
  19. 		return s_prev;
  20. 	return s_prev = d;
  21. }
  22.  
  23. int main() {
  24. 	//.............
  25. 	static POINT s_mousePoints[2] = {{0,0},{0,0}};
  26. 	static int s_count = 0;
  27. 	static int s_prev = 0;
  28. 	//case WM_MOUSEMOVE:      // マウスカーソルが移動したとき
  29. 	    POINT mouseEnd;
  30. 	    //.............
  31. 	    int d = mouseConvexity(s_mousePoints, mouseEnd, 10, s_count, s_prev);	//"10" は要調整
  32. 	    //0 < d なら時計回り、d < 0 なら反時計回り
  33. 	    //.............
  34. 	    //break;
  35. 	    //.............
  36. 	return 0;
  37. }
  38.  
Success #stdin #stdout 0s 3336KB
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https://ideone.com/JvT6Ck
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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