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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. namespace vector
  5. {
  6. 	class float2
  7. 	{
  8. 		public:
  9. 		float2(float x,float y):x(x),y(y)
  10. 		{}
  11. 		float x, y;
  12. 	};
  13. 	class float3
  14. 	{
  15. 		public:
  16. 		union {
  17. 			struct {
  18. 				float x,y,z;
  19. 			};
  20. 			float f[3];
  21. 		};
  22.  
  23. 		public:
  24. 		float3(float x,float y,float z):x(x),y(y),z(z)
  25. 		{}
  26.  
  27.  		float2			swizzle_xx()	const;
  28.  		float3			swizzle_xxx()	const;
  29.  		float3			swizzle_yzx()	const;
  30.  		const float3	&swizzle_xyz()	const;
  31.  		float3 			&swizzle_xyz();
  32.  		float2			&swizzle_yz();
  33. 	};
  34.  
  35. 	namespace detail {
  36. 		template <int X, int Y>
  37. 		float2 swizzle2(const float3 &v)
  38. 		{
  39. 			static_assert(X < 3 && Y < 3, "");
  40. 			return float2(v.f[X], v.f[Y]);
  41. 		}
  42. 		template <int X, int Y, int Z>
  43. 		float3 swizzle3(const float3 &v)
  44. 		{
  45. 			static_assert(X < 3 && Y < 3 && Z < 3, "");
  46. 			return float3(v.f[X], v.f[Y], v.f[Z]);
  47. 		}
  48. 	}
  49.  
  50. 	// 結果がfloat2	
  51.  	float2			float3::swizzle_xx()	const	{return detail::swizzle2<0, 0>(*this);}
  52.  	float2			&float3::swizzle_yz()			{return reinterpret_cast<float2 &>(y);}
  53.  
  54. 	// 結果がfloat3
  55.  	float3			float3::swizzle_xxx()	const	{return detail::swizzle3<0, 0, 0>(*this);}
  56.  	float3			float3::swizzle_yzx()	const	{return detail::swizzle3<1, 2, 0>(*this);}
  57.  	const float3	&float3::swizzle_xyz()	const	{return *this;}
  58.  	float3 			&float3::swizzle_xyz()			{return *this;}
  59. }
  60.  
  61. #define xxx swizzle_xxx()
  62. #define yzx swizzle_yzx()
  63. #define xyz swizzle_xyz()
  64. #define xx  swizzle_xx()
  65. #define yz  swizzle_yz()
  66.  
  67.  
  68. int main() {
  69. 	// your code goes here
  70.     using namespace vector;
  71.     float3 a(1,2,3);
  72.     auto b=a.yzx;
  73.     cout<<b.x<<b.y<<b.z<<endl;
  74.  
  75. 	b.yz = a.xx;
  76.     cout<<b.x<<b.y<<b.z<<endl;
  77. 	return 0;
  78. }
Success #stdin #stdout 0s 3468KB
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https://ideone.com/33POAz
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
secret

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