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  1. #include <iostream>
  2.  
  3. using namespace std;
  4.  
  5. enum WindingOrder {
  6. 	BOTTOM = 0,
  7. 	RIGHT,
  8. 	TOP,
  9. 	LEFT
  10. };
  11.  
  12. void tester(const int* square, WindingOrder edge, int* output) {
  13. 	switch (edge) {
  14. 	case BOTTOM:
  15. 		output[0] = square[0]; output[1] = square[1]; output[2] = square[2]; output[3] = square[1];
  16. 		break;
  17. 	case RIGHT:
  18. 		output[0] = square[2]; output[1] = square[1]; output[2] = square[2]; output[3] = square[3];
  19. 		break;
  20. 	case TOP:
  21. 		output[0] = square[2]; output[1] = square[3]; output[2] = square[0]; output[3] = square[3];
  22. 		break;
  23. 	case LEFT:
  24. 		output[0] = square[0]; output[1] = square[3]; output[2] = square[0]; output[3] = square[1];
  25. 		break;
  26. 	}
  27. }
  28.  
  29. int getIndex(int i, int edge) {
  30. 	const int ib0 = i & 1;
  31. 	const int ib1 = (i & 2) >> 1;
  32. 	const int eb0 = edge & 1;
  33. 	const int eb1 = (edge & 2) >> 1;
  34.  
  35. 	const int iXor = ib0 ^ ib1;
  36.  
  37. 	const int iNXorCondition = eb0 ^ eb1;
  38. 	const int iXorCondition = ib1 ^ eb1;
  39.  
  40. 	return ((iNXorCondition & ~iXor | iXorCondition & iXor) << 1) | ib0;
  41. }
  42.  
  43. int main() {
  44. 	const int size = 4;
  45. 	const int square[size] = { 0, 1, 2, 3 };
  46. 	int test[size];
  47. 	int output[size];
  48.  
  49. 	for (WindingOrder edge = BOTTOM; edge <= LEFT; edge = static_cast<WindingOrder>(static_cast<int>(edge) + 1)) {
  50. 		tester(square, edge, test);
  51.  
  52. 		for (int i = 0; i < size ; ++i) {
  53. 			output[i] = square[getIndex(i, static_cast<int>(edge))];
  54. 		}
  55.  
  56. 		const bool firstX = output[0] == test[0];
  57. 		const bool firstY = output[1] == test[1];
  58. 		const bool secondX = output[2] == test[2];
  59. 		const bool secondY = output[3] == test[3];
  60.  
  61. 		if (!firstX) {
  62. 			cout << "Mismatch at i = 0: test = " << test[0] << " output = " << output[0] << endl;
  63. 		} else if (!firstY) {
  64. 			cout << "Mismatch at i = 1: test = " << test[1] << " output = " << output[1] << endl;
  65. 		} else if (!secondX) {
  66. 			cout << "Mismatch at i = 2: test = " << test[2] << " output = " << output[2] << endl;
  67. 		} else if (!secondY) {
  68. 			cout << "Mismatch at i = 3: test = " << test[3] << " output = " << output[3] << endl;
  69. 		} else {
  70. 			cout << "Match: " << output[0] << ' ' << output[1] << ' ' << output[2] << ' ' << output[3] << endl;
  71. 		}
  72. 	}
  73.  
  74. 	return 0;
  75. }
Success #stdin #stdout 0s 3460KB
comments ()
stdin
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Standard input is empty
stdout
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Match: 0 1 2 1
Match: 2 1 2 3
Match: 2 3 0 3
Match: 0 3 0 1
https://ideone.com/EeWvoO
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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