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  1. #include <array>
  2. #include <iostream>
  3. #include <vector>
  4.  
  5. #include <cassert>
  6. #include <cmath>
  7. #include <cstdint>
  8.  
  9. struct vertex
  10. {
  11. 	std::array<double, 3> vector_;
  12. 	std::uint32_t color_;
  13.  
  14. 	double & operator () (std::size_t index) { assert(index < 3); return vector_[index]; }
  15. 	double operator () (std::size_t index) const { assert(index < 3); return vector_[index]; }
  16.  
  17. 	double abs() const
  18. 	{
  19. 		return std::sqrt(
  20. 			vector_[0] * vector_[0] +
  21. 			vector_[1] * vector_[1] +
  22. 			vector_[2] * vector_[2]
  23. 		);
  24. 	}
  25.  
  26. 	// turns RGBA value to gray, alpha channel is ignored for this
  27. 	std::uint32_t gray() const
  28. 	{
  29. 		std::uint8_t g =
  30. 			((color_ >> 24) +
  31. 			((color_ >> 16) & 0xFF) +
  32. 			((color_ >> 8) & 0xFF)) / 3;
  33. 		return ((g << 24) | (g << 16) | (g << 8) | (color_ & 0xFF));
  34. 	}
  35. };
  36.  
  37. class field
  38. {
  39. public:
  40. 	// the explicit prevents std::size_t's to be implicitely cast into fields ;-)
  41. 	explicit field(std::size_t size)
  42. 		: vertices_(size)
  43. 	{
  44. 	}
  45.  
  46. 	vertex & operator() (std::size_t index) { assert(index < vertices_.size()); return vertices_[index]; }
  47. 	vertex operator() (std::size_t index) const { assert(index < vertices_.size()); return vertices_[index]; }
  48.  
  49. private:
  50. 	// this is still pretty contigous
  51. 	std::vector<vertex> vertices_;
  52. };
  53.  
  54. int main()
  55. {
  56.     field f(2);
  57.     vertex & v = f(1);
  58.     v(2) = 5;
  59.  
  60. 	// also: this is a copy of v, so changing v2 will not affect f[1][2]
  61.     vertex v2 = v;
  62.     v2(2) = 2;
  63.  
  64.     std::cout << f(1)(2) << std::endl;
  65.  
  66.     return 0;
  67. }
Success #stdin #stdout 0s 3272KB
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https://ideone.com/Rxvd7W
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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