common/vecmat.h

   1 #ifndef COMMON_VECMAT_H
   2 #define COMMON_VECMAT_H
   3
   4 #include <array>
   5 #include <cmath>
   6 #include <cstddef>
   7 #include <limits>
   8 #include <type_traits>
   9
  10 #include "alspan.h"
  11
  12
  13 namespace alu {
  14
  15 template<typename T>
  16 class VectorR {
  17     static_assert(std::is_floating_point<T>::value, "Must use floating-point types");
  18     alignas(16) std::array<T,4> mVals;
  19
  20 public:
  21     constexpr VectorR() noexcept = default;
  22     constexpr VectorR(const VectorR&) noexcept = default;
  23     constexpr explicit VectorR(T a, T b, T c, T d) noexcept : mVals{a, b, c, d} { }
  24
  25     constexpr VectorR& operator=(const VectorR&) noexcept = default;
  26
  27     constexpr T& operator[](size_t idx) noexcept { return mVals[idx]; }
  28     constexpr const T& operator[](size_t idx) const noexcept { return mVals[idx]; }
  29
  30     constexpr VectorR& operator+=(const VectorR &rhs) noexcept
  31     {
  32         mVals[0] += rhs.mVals[0];
  33         mVals[1] += rhs.mVals[1];
  34         mVals[2] += rhs.mVals[2];
  35         mVals[3] += rhs.mVals[3];
  36         return *this;
  37     }
  38
  39     constexpr VectorR operator-(const VectorR &rhs) const noexcept
  40     {
  41         return VectorR{mVals[0] - rhs.mVals[0], mVals[1] - rhs.mVals[1],
  42             mVals[2] - rhs.mVals[2], mVals[3] - rhs.mVals[3]};
  43     }
  44
  45     constexpr T normalize(T limit = std::numeric_limits<T>::epsilon())
  46     {
  47         limit = std::max(limit, std::numeric_limits<T>::epsilon());
  48         const T length_sqr{mVals[0]*mVals[0] + mVals[1]*mVals[1] + mVals[2]*mVals[2]};
  49         if(length_sqr > limit*limit)
  50         {
  51             const T length{std::sqrt(length_sqr)};
  52             T inv_length{T{1}/length};
  53             mVals[0] *= inv_length;
  54             mVals[1] *= inv_length;
  55             mVals[2] *= inv_length;
  56             return length;
  57         }
  58         mVals[0] = mVals[1] = mVals[2] = T{0};
  59         return T{0};
  60     }
  61
  62     [[nodiscard]] constexpr auto cross_product(const alu::VectorR<T> &rhs) const noexcept -> VectorR
  63     {
  64         return VectorR{
  65             mVals[1]*rhs.mVals[2] - mVals[2]*rhs.mVals[1],
  66             mVals[2]*rhs.mVals[0] - mVals[0]*rhs.mVals[2],
  67             mVals[0]*rhs.mVals[1] - mVals[1]*rhs.mVals[0],
  68             T{0}};
  69     }
  70
  71     [[nodiscard]] constexpr auto dot_product(const alu::VectorR<T> &rhs) const noexcept -> T
  72     { return mVals[0]*rhs.mVals[0] + mVals[1]*rhs.mVals[1] + mVals[2]*rhs.mVals[2]; }
  73 };
  74 using Vector = VectorR<float>;
  75
  76 template<typename T>
  77 class MatrixR {
  78     static_assert(std::is_floating_point<T>::value, "Must use floating-point types");
  79     alignas(16) std::array<T,16> mVals;
  80
  81 public:
  82     constexpr MatrixR() noexcept = default;
  83     constexpr MatrixR(const MatrixR&) noexcept = default;
  84     constexpr explicit MatrixR(
  85         T aa, T ab, T ac, T ad,
  86         T ba, T bb, T bc, T bd,
  87         T ca, T cb, T cc, T cd,
  88         T da, T db, T dc, T dd) noexcept
  89         : mVals{aa,ab,ac,ad, ba,bb,bc,bd, ca,cb,cc,cd, da,db,dc,dd}
  90     { }
  91
  92     constexpr MatrixR& operator=(const MatrixR&) noexcept = default;
  93
  94     constexpr auto operator[](size_t idx) noexcept { return al::span<T,4>{&mVals[idx*4], 4}; }
  95     constexpr auto operator[](size_t idx) const noexcept
  96     { return al::span<const T,4>{&mVals[idx*4], 4}; }
  97
  98     static constexpr MatrixR Identity() noexcept
  99     {
 100         return MatrixR{
 101             T{1}, T{0}, T{0}, T{0},
 102             T{0}, T{1}, T{0}, T{0},
 103             T{0}, T{0}, T{1}, T{0},
 104             T{0}, T{0}, T{0}, T{1}};
 105     }
 106 };
 107 using Matrix = MatrixR<float>;
 108
 109 template<typename T>
 110 constexpr VectorR<T> operator*(const MatrixR<T> &mtx, const VectorR<T> &vec) noexcept
 111 {
 112     return VectorR<T>{
 113         vec[0]*mtx[0][0] + vec[1]*mtx[1][0] + vec[2]*mtx[2][0] + vec[3]*mtx[3][0],
 114         vec[0]*mtx[0][1] + vec[1]*mtx[1][1] + vec[2]*mtx[2][1] + vec[3]*mtx[3][1],
 115         vec[0]*mtx[0][2] + vec[1]*mtx[1][2] + vec[2]*mtx[2][2] + vec[3]*mtx[3][2],
 116         vec[0]*mtx[0][3] + vec[1]*mtx[1][3] + vec[2]*mtx[2][3] + vec[3]*mtx[3][3]};
 117 }
 118
 119 } // namespace alu
 120
 121 #endif /* COMMON_VECMAT_H */